MC9S08GT8A

MC9S08GT16A MC9S08GT8A Data Sheet HCS08 Microcontrollers MC9S08GT16A Rev. 1 7/2006 freescale.com MC9S08GT16A/GT8A Features 8-Bit HCS08 Central Processor Unit (CPU) • • • 40-MHz HCS08 CPU HC08 instruction set with added BGND instruction Support for up to 32 interrupt/reset sources • • • Software selectable pullups on ports when used as input Internal pullup on RESET and IRQ pin to reduce customer system cost Up to 38 general-purpose input/output (I/O) pins, plus one output-only pin, depending on package selection Memory Options • • FLASH read/program/erase down to 1.8 V Up to 16K FLASH; up to 2K RAM Development Support • • Background debugging system Breakpoint capability to allow single breakpoint setting during in-circuit debugging (plus two more breakpoints in on-chip debug module) On-chip, in-circuit emulation (ICE) debug module with real-time bus capture. On-chip ICE debug module containing two comparators and nine trigger modes. Eight deep FIFO for storing change-of-flow addresses and event-only data. Single-wire background debug interface Power-Saving Modes • • • Three very low power stop modes Reduced power wait mode Very low power real time interrupt for use in run, wait, and stop • Clock Source Options • Clock sources to internal hardware frequency locked-loop (FLL): internal, external, crystal, or resonator Internal clock with ±0.2% trimming resolution and ±0.5% deviation across voltage or across temperature • Package Options • • • • 48-pin QFN 44-pin QFP 42-pin PSDIP 32-pin QFN • System Protection • • • • • Optional watchdog computer operating properly (COP) reset Low-voltage detection with reset or interrupt Illegal opcode detection with reset Illegal address detection with reset FLASH block protect and security Peripherals • • • • • • ATD — 8-channel, 10-bit analog-to-digital converter SCI — Two serial communications interface modules SPI — Serial peripheral interface module IIC — Inter-integrated circuit bus module Timer —One 3-channel timer PWM module (TPM) plus one 2-channel TPM KBI — 8-pin keyboard interrupt module Input/Output • 8 high-current pins (20 mA each) MC9S08GT16A/GT8A Data Sheet Covers: MC9S08GT16A MC9S08GT8A MC9S08GT16A Rev. 1 7/2006 Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. © Freescale Semiconductor, Inc., 2006. All rights reserved. Revision History To provide the most up-to-date information, the revision of our documents on the World Wide Web will be the most current. Your printed copy may be an earlier revision. To verify you have the latest information available, refer to: http://freescale.com The following revision history table summarizes changes contained in this document. Revision Number 1 Revision Date 07/17/2006 Initial public release Description of Changes © Freescale Semiconductor, Inc., 2006. All rights reserved. This product incorporates SuperFlash® Technology licensed from SST. List of Chapters Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Appendix A Appendix B Device Overview ...................................................................... 19 Pins and Connections ............................................................. 23 Modes of Operation ................................................................. 33 Memory ..................................................................................... 41 Resets, Interrupts, and System Configuration ..................... 63 Parallel Input/Output ............................................................... 79 Keyboard Interrupt (S08KBIV1) .............................................. 99 Central Processor Unit (S08CPUV2) .................................... 105 Internal Clock Generator (S08ICGV4) .................................. 125 Timer/PWM (S08TPMV2) ...................................................... 153 Serial Communications Interface (S08SCIV1)..................... 169 Serial Peripheral Interface (S08SPIV3) ................................ 187 Inter-Integrated Circuit (S08IICV1) ....................................... 205 Analog-to-Digital Converter (S08ATDV3) ............................ 221 Development Support ........................................................... 237 Electrical Characteristics...................................................... 259 Ordering Information and Mechanical Drawings................ 285 MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 7 Contents Section Number Title Chapter 1 Device Overview 1.1 Introduction .....................................................................................................................................19 1.1.1 Devices in the MC9S08GT16A/GT8A Series ..................................................................19 1.1.2 MCU Block Diagram ........................................................................................................19 System Clock Distribution ..............................................................................................................21 Page 1.2 Chapter 2 Pins and Connections 2.1 2.2 2.3 Introduction .....................................................................................................................................23 Device Pin Assignment ...................................................................................................................23 Recommended System Connections ...............................................................................................27 2.3.1 VDD, VSS, VDDAD, VSSAD, VREFH, VREFL — Power and Voltage References ...............28 2.3.2 PTG1/XTAL, PTG2/EXTAL — Oscillator ......................................................................28 2.3.3 RESET — External Reset Pin ...........................................................................................29 2.3.4 PTG0/BKGD/MS — Background / Mode Select .............................................................29 2.3.5 IRQ — External Interrupt Request Pin .............................................................................30 2.3.6 General-Purpose I/O and Peripheral Ports ........................................................................30 2.3.7 Signal Properties Summary ...............................................................................................31 Chapter 3 Modes of Operation 3.1 3.2 3.3 3.4 3.5 Introduction .....................................................................................................................................33 3.1.1 Features .............................................................................................................................33 Run Mode ........................................................................................................................................33 Active Background Mode ................................................................................................................33 Wait Mode .......................................................................................................................................34 Stop Modes ......................................................................................................................................35 3.5.1 Stop1 Mode .......................................................................................................................35 3.5.2 Stop2 Mode .......................................................................................................................35 3.5.3 Stop3 Mode .......................................................................................................................36 3.5.4 Active BDM Enabled in Stop Mode .................................................................................37 3.5.5 LVD Enabled in Stop Mode ..............................................................................................37 3.5.6 On-Chip Peripheral Modules in Stop Modes ....................................................................38 MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor NON-DISCLOSURE AGREEMENT REQUIRED 9 Section Number Title Chapter 4 Memory Page 4.1 4.2 4.3 4.4 4.5 4.6 MC9S08GT16A/GT8A Memory Map ............................................................................................41 4.1.1 Reset and Interrupt Vector Assignments ...........................................................................42 Register Addresses and Bit Assignments ........................................................................................43 RAM ................................................................................................................................................48 FLASH ............................................................................................................................................48 4.4.1 Features .............................................................................................................................48 4.4.2 Program and Erase Times .................................................................................................49 4.4.3 Program and Erase Command Execution .........................................................................49 4.4.4 Burst Program Execution ..................................................................................................51 4.4.5 Access Errors ....................................................................................................................53 4.4.6 FLASH Block Protection ..................................................................................................53 4.4.7 Vector Redirection ............................................................................................................54 Security ............................................................................................................................................54 Register Definition ..........................................................................................................................56 4.6.1 FLASH Clock Divider Register (FCDIV) ........................................................................56 4.6.2 FLASH Options Register (FOPT and NVOPT) ................................................................57 4.6.3 FLASH Configuration Register (FCNFG) ........................................................................58 4.6.4 FLASH Protection Register (FPROT and NVPROT) .......................................................58 4.6.5 FLASH Status Register (FSTAT) ......................................................................................59 4.6.6 FLASH Command Register (FCMD) ...............................................................................60 Chapter 5 Resets, Interrupts, and System Configuration 5.1 5.2 5.3 5.4 Introduction .....................................................................................................................................63 5.1.1 Features .............................................................................................................................63 MCU Reset ......................................................................................................................................63 Computer Operating Properly (COP) Watchdog .............................................................................64 Interrupts .........................................................................................................................................64 5.4.1 Interrupt Stack Frame .......................................................................................................65 5.4.2 IRQ — External Interrupt Request Pin .............................................................................66 5.4.2.1 Pin Configuration Options ..............................................................................66 5.4.2.2 Edge and Level Sensitivity ..............................................................................67 5.4.3 Interrupt Vectors, Sources, and Local Masks ....................................................................67 Low-Voltage Detect (LVD) System ................................................................................................69 5.5.1 Power-On Reset Operation ...............................................................................................69 5.5.2 LVD Reset Operation ........................................................................................................69 5.5.3 LVD Interrupt Operation ...................................................................................................69 5.5.4 Low-Voltage Warning (LVW) ...........................................................................................69 Real-Time Interrupt (RTI) ...............................................................................................................69 Register Definition ..........................................................................................................................70 MC9S08GT16A/GT8A Data Sheet, Rev. 1 10 Freescale Semiconductor 5.5 5.6 5.7 Section Number 5.7.1 5.7.2 5.7.3 5.7.4 5.7.5 5.7.6 5.7.7 5.7.8 Title Page Interrupt Pin Request Status and Control Register (IRQSC) ............................................71 System Reset Status Register (SRS) .................................................................................72 System Background Debug Force Reset Register (SBDFR) ............................................73 System Options Register (SOPT) .....................................................................................74 System Device Identification Register (SDIDH, SDIDL) ................................................75 System Real-Time Interrupt Status and Control Register (SRTISC) ................................76 System Power Management Status and Control 1 Register (SPMSC1) ...........................77 System Power Management Status and Control 2 Register (SPMSC2) ...........................78 Chapter 6 Parallel Input/Output 6.1 Introduction .....................................................................................................................................79 6.1.1 Features .............................................................................................................................79 6.1.2 Block Diagram ..................................................................................................................81 External Signal Description ............................................................................................................82 6.2.1 Port A and Keyboard Interrupts ........................................................................................82 6.2.2 Port B and Analog to Digital Converter Inputs .................................................................82 6.2.3 Port C and SCI2, IIC, and High-Current Drivers ..............................................................83 6.2.4 Port D, TPM1 and TPM2 ..................................................................................................83 6.2.5 Port E, SCI1, and SPI ........................................................................................................84 6.2.6 Port G, BKGD/MS, and Oscillator ...................................................................................84 Parallel I/O Controls ........................................................................................................................85 6.3.1 Data Direction Control ......................................................................................................85 6.3.2 Internal Pullup Control .....................................................................................................85 6.3.3 Slew Rate Control .............................................................................................................85 Stop Modes ......................................................................................................................................86 Register Definition ..........................................................................................................................86 6.5.1 Port A Registers (PTAD, PTAPE, PTASE, and PTADD) .................................................86 6.5.2 Port B Registers (PTBD, PTBPE, PTBSE, and PTBDD) .................................................89 6.5.3 Port C Registers (PTCD, PTCPE, PTCSE, and PTCDD) .................................................91 6.5.4 Port D Registers (PTDD, PTDPE, PTDSE, and PTDDD) ...............................................93 6.5.5 Port E Registers (PTED, PTEPE, PTESE, and PTEDD) ..................................................95 6.5.6 Port G Registers (PTGD, PTGPE, PTGSE, and PTGDD) ...............................................97 6.2 6.3 6.4 6.5 Chapter 7 Keyboard Interrupt (S08KBIV1) 7.1 Introduction .....................................................................................................................................99 7.1.1 Port A and Keyboard Interrupt Pins ..................................................................................99 7.1.2 Features .............................................................................................................................99 7.1.3 KBI Block Diagram ........................................................................................................101 Register Definition ........................................................................................................................101 7.2.1 KBI Status and Control Register (KBISC) .....................................................................102 MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 11 7.2 Section Number 7.3 Title Page 7.2.2 KBI Pin Enable Register (KBIPE) ..................................................................................103 Functional Description ..................................................................................................................103 7.3.1 Pin Enables ......................................................................................................................103 7.3.2 Edge and Level Sensitivity ..............................................................................................103 7.3.3 KBI Interrupt Controls ....................................................................................................104 Chapter 8 Central Processor Unit (S08CPUV2) 8.1 8.2 Introduction ...................................................................................................................................105 8.1.1 Features ...........................................................................................................................105 Programmer’s Model and CPU Registers .....................................................................................106 8.2.1 Accumulator (A) .............................................................................................................106 8.2.2 Index Register (H:X) .......................................................................................................106 8.2.3 Stack Pointer (SP) ...........................................................................................................107 8.2.4 Program Counter (PC) ....................................................................................................107 8.2.5 Condition Code Register (CCR) .....................................................................................107 Addressing Modes .........................................................................................................................109 8.3.1 Inherent Addressing Mode (INH) ...................................................................................109 8.3.2 Relative Addressing Mode (REL) ...................................................................................109 8.3.3 Immediate Addressing Mode (IMM) ..............................................................................109 8.3.4 Direct Addressing Mode (DIR) ......................................................................................109 8.3.5 Extended Addressing Mode (EXT) ................................................................................110 8.3.6 Indexed Addressing Mode ..............................................................................................110 8.3.6.1 Indexed, No Offset (IX) ................................................................................110 8.3.6.2 Indexed, No Offset with Post Increment (IX+) .............................................110 8.3.6.3 Indexed, 8-Bit Offset (IX1) ...........................................................................110 8.3.6.4 Indexed, 8-Bit Offset with Post Increment (IX1+) .......................................110 8.3.6.5 Indexed, 16-Bit Offset (IX2) .........................................................................110 8.3.6.6 SP-Relative, 8-Bit Offset (SP1) ....................................................................110 8.3.6.7 SP-Relative, 16-Bit Offset (SP2) ..................................................................111 Special Operations .........................................................................................................................111 8.4.1 Reset Sequence ...............................................................................................................111 8.4.2 Interrupt Sequence ..........................................................................................................111 8.4.3 Wait Mode Operation ......................................................................................................112 8.4.4 Stop Mode Operation ......................................................................................................112 8.4.5 BGND Instruction ...........................................................................................................113 HCS08 Instruction Set Summary ..................................................................................................114 8.3 8.4 8.5 MC9S08GT16A/GT8A Data Sheet, Rev. 1 12 Freescale Semiconductor Section Number Title Chapter 9 Internal Clock Generator (S08ICGV4) Page 9.1 9.2 9.3 9.4 9.5 Introduction ...................................................................................................................................125 9.1.1 Features ...........................................................................................................................127 9.1.2 Modes of Operation ........................................................................................................128 9.1.3 Block Diagram ................................................................................................................129 External Signal Description ..........................................................................................................129 9.2.1 EXTAL — External Reference Clock / Oscillator Input ................................................129 9.2.2 XTAL — Oscillator Output ............................................................................................129 9.2.3 External Clock Connections ...........................................................................................130 9.2.4 External Crystal/Resonator Connections ........................................................................130 Register Definition ........................................................................................................................131 9.3.1 ICG Control Register 1 (ICGC1) ....................................................................................131 9.3.2 ICG Control Register 2 (ICGC2) ....................................................................................133 9.3.3 ICG Status Register 1 (ICGS1) .......................................................................................134 9.3.4 ICG Status Register 2 (ICGS2) .......................................................................................135 9.3.5 ICG Filter Registers (ICGFLTU, ICGFLTL) ..................................................................135 9.3.6 ICG Trim Register (ICGTRM) .......................................................................................136 Functional Description ..................................................................................................................136 9.4.1 Off Mode (Off) ................................................................................................................137 9.4.1.1 BDM Active ..................................................................................................137 9.4.1.2 OSCSTEN Bit Set .........................................................................................137 9.4.1.3 Stop/Off Mode Recovery ..............................................................................137 9.4.2 Self-Clocked Mode (SCM) .............................................................................................137 9.4.3 FLL Engaged, Internal Clock (FEI) Mode .....................................................................138 9.4.4 FLL Engaged Internal Unlocked ....................................................................................139 9.4.5 FLL Engaged Internal Locked ........................................................................................139 9.4.6 FLL Bypassed, External Clock (FBE) Mode ..................................................................139 9.4.7 FLL Engaged, External Clock (FEE) Mode ...................................................................139 9.4.7.1 FLL Engaged External Unlocked .................................................................140 9.4.7.2 FLL Engaged External Locked .....................................................................140 9.4.8 FLL Lock and Loss-of-Lock Detection ..........................................................................140 9.4.9 FLL Loss-of-Clock Detection .........................................................................................141 9.4.10 Clock Mode Requirements .............................................................................................142 9.4.11 Fixed Frequency Clock ...................................................................................................143 9.4.12 High Gain Oscillator .......................................................................................................143 Initialization/Application Information ..........................................................................................143 9.5.1 Introduction .....................................................................................................................143 9.5.2 Example #1: External Crystal = 32 kHz, Bus Frequency = 4.19 MHz ...........................145 9.5.3 Example #2: External Crystal = 4 MHz, Bus Frequency = 20 MHz ..............................147 9.5.4 Example #3: No External Crystal Connection, 5.4 MHz Bus Frequency ......................149 9.5.5 Example #4: Internal Clock Generator Trim ..................................................................151 MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 13 Section Number Title Chapter 10 Timer/PWM (S08TPMV2) Page 10.1 Introduction ...................................................................................................................................153 10.1.1 Features ...........................................................................................................................153 10.1.2 Features ...........................................................................................................................155 10.1.3 Block Diagram ................................................................................................................155 10.2 External Signal Description ..........................................................................................................157 10.2.1 External TPM Clock Sources ..........................................................................................157 10.2.2 TPMxCHn — TPMx Channel n I/O Pins .......................................................................157 10.3 Register Definition ........................................................................................................................157 10.3.1 Timer x Status and Control Register (TPMxSC) ............................................................158 10.3.2 Timer x Counter Registers (TPMxCNTH:TPMxCNTL) ................................................159 10.3.3 Timer x Counter Modulo Registers (TPMxMODH:TPMxMODL) ...............................160 10.3.4 Timer x Channel n Status and Control Register (TPMxCnSC) ......................................161 10.3.5 Timer x Channel Value Registers (TPMxCnVH:TPMxCnVL) ......................................162 10.4 Functional Description ..................................................................................................................163 10.4.1 Counter ............................................................................................................................163 10.4.2 Channel Mode Selection .................................................................................................164 10.4.2.1 Input Capture Mode ......................................................................................164 10.4.2.2 Output Compare Mode .................................................................................165 10.4.2.3 Edge-Aligned PWM Mode ...........................................................................165 10.4.3 Center-Aligned PWM Mode ...........................................................................................166 10.5 TPM Interrupts ..............................................................................................................................167 10.5.1 Clearing Timer Interrupt Flags .......................................................................................167 10.5.2 Timer Overflow Interrupt Description ............................................................................167 10.5.3 Channel Event Interrupt Description ..............................................................................168 10.5.4 PWM End-of-Duty-Cycle Events ...................................................................................168 Chapter 11 Serial Communications Interface (S08SCIV1) 11.1 Introduction ...................................................................................................................................169 11.1.1 Features ...........................................................................................................................171 11.1.2 Modes of Operation ........................................................................................................171 11.1.3 Block Diagram ................................................................................................................172 11.2 Register Definition ........................................................................................................................174 11.2.1 SCI Baud Rate Registers (SCIxBDH, SCIxBHL) ..........................................................174 11.2.2 SCI Control Register 1 (SCIxC1) ...................................................................................175 11.2.3 SCI Control Register 2 (SCIxC2) ...................................................................................176 11.2.4 SCI Status Register 1 (SCIxS1) ......................................................................................177 11.2.5 SCI Status Register 2 (SCIxS2) ......................................................................................179 11.2.6 SCI Control Register 3 (SCIxC3) ...................................................................................179 11.2.7 SCI Data Register (SCIxD) .............................................................................................180 MC9S08GT16A/GT8A Data Sheet, Rev. 1 14 Freescale Semiconductor Section Number Title Page 11.3 Functional Description ..................................................................................................................181 11.3.1 Baud Rate Generation .....................................................................................................181 11.3.2 Transmitter Functional Description ................................................................................181 11.3.2.1 Send Break and Queued Idle .........................................................................182 11.3.3 Receiver Functional Description .....................................................................................182 11.3.3.1 Data Sampling Technique .............................................................................183 11.3.3.2 Receiver Wakeup Operation .........................................................................183 11.3.3.2.1Idle-Line Wakeup .....................................................................184 11.3.3.2.2Address-Mark Wakeup .............................................................184 11.3.4 Interrupts and Status Flags ..............................................................................................184 11.3.5 Additional SCI Functions ...............................................................................................185 11.3.5.1 8- and 9-Bit Data Modes ...............................................................................185 11.3.5.2 Stop Mode Operation ....................................................................................185 11.3.5.3 Loop Mode ....................................................................................................186 11.3.5.4 Single-Wire Operation ..................................................................................186 Chapter 12 Serial Peripheral Interface (S08SPIV3) 12.1 Introduction ...................................................................................................................................187 12.1.1 Features ...........................................................................................................................189 12.1.2 Block Diagrams ..............................................................................................................190 12.1.2.1 SPI System Block Diagram ..........................................................................190 12.1.2.2 SPI Module Block Diagram ..........................................................................190 12.1.3 SPI Baud Rate Generation ..............................................................................................191 12.2 External Signal Description ..........................................................................................................192 12.2.1 SPSCK — SPI Serial Clock ............................................................................................192 12.2.2 MOSI — Master Data Out, Slave Data In ......................................................................192 12.2.3 MISO — Master Data In, Slave Data Out ......................................................................192 12.2.4 SS — Slave Select ...........................................................................................................192 12.3 Modes of Operation .......................................................................................................................193 12.3.1 SPI in Stop Modes ..........................................................................................................193 12.4 Register Definition ........................................................................................................................193 12.4.1 SPI Control Register 1 (SPIC1) ......................................................................................193 12.4.2 SPI Control Register 2 (SPIC2) ......................................................................................194 12.4.3 SPI Baud Rate Register (SPIBR) ....................................................................................195 12.4.4 SPI Status Register (SPIS) ..............................................................................................196 12.4.5 SPI Data Register (SPID) ................................................................................................197 12.5 Functional Description ..................................................................................................................198 12.5.1 SPI Clock Formats ..........................................................................................................198 12.5.2 SPI Interrupts ..................................................................................................................201 12.5.3 Mode Fault Detection .....................................................................................................201 12.6 Initialization/Application Information ..........................................................................................201 MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 15 Section Number Title Page 12.6.1 SPI Module Initialization Example .................................................................................201 12.6.1.1 Initialization Sequence ..................................................................................201 12.6.1.2 Pseudo—Code Example ...............................................................................202 Chapter 13 Inter-Integrated Circuit (S08IICV1) 13.1 Introduction ...................................................................................................................................205 13.1.1 Features ...........................................................................................................................207 13.1.2 Modes of Operation ........................................................................................................207 13.1.3 Block Diagram ................................................................................................................208 13.2 External Signal Description ..........................................................................................................208 13.2.1 SCL — Serial Clock Line ...............................................................................................208 13.2.2 SDA — Serial Data Line ................................................................................................208 13.3 Register Definition ........................................................................................................................208 13.3.1 IIC Address Register (IICA) ...........................................................................................209 13.3.2 IIC Frequency Divider Register (IICF) ...........................................................................209 13.3.3 IIC Control Register (IICC) ............................................................................................212 13.3.4 IIC Status Register (IICS) ...............................................................................................213 13.3.5 IIC Data I/O Register (IICD) ..........................................................................................214 13.4 Functional Description ..................................................................................................................215 13.4.1 IIC Protocol .....................................................................................................................215 13.4.1.1 START Signal ...............................................................................................216 13.4.1.2 Slave Address Transmission .........................................................................216 13.4.1.3 Data Transfer .................................................................................................216 13.4.1.4 STOP Signal ..................................................................................................217 13.4.1.5 Repeated START Signal ...............................................................................217 13.4.1.6 Arbitration Procedure ....................................................................................217 13.4.1.7 Clock Synchronization ..................................................................................217 13.4.1.8 Handshaking .................................................................................................218 13.4.1.9 Clock Stretching ............................................................................................218 13.5 Resets ............................................................................................................................................218 13.6 Interrupts .......................................................................................................................................218 13.6.1 Byte Transfer Interrupt ....................................................................................................219 13.6.2 Address Detect Interrupt .................................................................................................219 13.6.3 Arbitration Lost Interrupt ................................................................................................219 Chapter 14 Analog-to-Digital Converter (S08ATDV3) 14.1 Introduction ...................................................................................................................................223 14.1.1 Features ...........................................................................................................................223 14.1.2 Modes of Operation ........................................................................................................223 14.1.2.1 Stop Mode .....................................................................................................223 MC9S08GT16A/GT8A Data Sheet, Rev. 1 16 Freescale Semiconductor Section Number Title Page 14.2 14.3 14.4 14.5 14.6 14.1.2.2 Power Down Mode .......................................................................................223 14.1.3 Block Diagram ................................................................................................................223 External Signal Description ..........................................................................................................224 14.2.1 ADP7–ADP0 — Channel Input Pins ..............................................................................225 14.2.2 VREFH, VREFL — ATD Reference Pins .........................................................................225 14.2.3 VDDAD, VSSAD — ATD Supply Pins ............................................................................225 Register Definition ........................................................................................................................225 14.3.1 ATD Control (ATDC) .....................................................................................................225 14.3.2 ATD Status and Control (ATDSC) ..................................................................................228 14.3.3 ATD Result Data (ATDRH, ATDRL) .............................................................................229 14.3.4 ATD Pin Enable (ATDPE) ..............................................................................................229 Functional Description ..................................................................................................................230 14.4.1 Mode Control ..................................................................................................................230 14.4.2 Sample and Hold .............................................................................................................230 14.4.3 Analog Input Multiplexer ................................................................................................232 14.4.4 ATD Module Accuracy Definitions ................................................................................232 Resets ............................................................................................................................................235 Interrupts .......................................................................................................................................235 Chapter 15 Development Support 15.1 Introduction ...................................................................................................................................237 15.1.1 Features ...........................................................................................................................238 15.2 Background Debug Controller (BDC) ..........................................................................................238 15.2.1 BKGD Pin Description ...................................................................................................239 15.2.2 Communication Details ..................................................................................................240 15.2.3 BDC Commands .............................................................................................................244 15.2.4 BDC Hardware Breakpoint .............................................................................................246 15.3 On-Chip Debug System (DBG) ....................................................................................................247 15.3.1 Comparators A and B ......................................................................................................247 15.3.2 Bus Capture Information and FIFO Operation ...............................................................247 15.3.3 Change-of-Flow Information ..........................................................................................248 15.3.4 Tag vs. Force Breakpoints and Triggers .........................................................................248 15.3.5 Trigger Modes .................................................................................................................249 15.3.6 Hardware Breakpoints ....................................................................................................251 15.4 Register Definition ........................................................................................................................251 15.4.1 BDC Registers and Control Bits .....................................................................................251 15.4.1.1 BDC Status and Control Register (BDCSCR) ..............................................252 15.4.1.2 BDC Breakpoint Match Register (BDCBKPT) ............................................253 15.4.2 System Background Debug Force Reset Register (SBDFR) ..........................................253 15.4.3 DBG Registers and Control Bits .....................................................................................254 15.4.3.1 Debug Comparator A High Register (DBGCAH) ........................................254 MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 17 Section Number 15.4.3.2 15.4.3.3 15.4.3.4 15.4.3.5 15.4.3.6 15.4.3.7 15.4.3.8 15.4.3.9 Title Page Debug Comparator A Low Register (DBGCAL) .........................................254 Debug Comparator B High Register (DBGCBH) .........................................254 Debug Comparator B Low Register (DBGCBL) ..........................................254 Debug FIFO High Register (DBGFH) ..........................................................255 Debug FIFO Low Register (DBGFL) ...........................................................255 Debug Control Register (DBGC) ..................................................................256 Debug Trigger Register (DBGT) ..................................................................257 Debug Status Register (DBGS) .....................................................................258 Appendix A Electrical Characteristics A.1 A.2 A.3 A.4 A.5 A.6 A.7 A.8 A.9 Introduction ...................................................................................................................................259 Parameter Classification ................................................................................................................259 Absolute Maximum Ratings ..........................................................................................................259 Thermal Characteristics .................................................................................................................260 Electrostatic Discharge (ESD) Protection Characteristics ............................................................262 DC Characteristics .........................................................................................................................262 Supply Current Characteristics ......................................................................................................266 ATD Characteristics ......................................................................................................................272 Internal Clock Generation Module Characteristics .......................................................................274 A.9.1 ICG Frequency Specifications ........................................................................................275 A.10 AC Characteristics .........................................................................................................................276 A.10.1 Control Timing ...............................................................................................................277 A.10.2 Timer/PWM (TPM) Module Timing ..............................................................................278 A.10.3 SPI Timing ......................................................................................................................280 A.11 FLASH Specifications ...................................................................................................................283 Appendix B Ordering Information and Mechanical Drawings B.1 Ordering Information ....................................................................................................................285 B.1.1 Device Numbering Scheme ............................................................................................285 B.2 Mechanical Drawings ....................................................................................................................285 MC9S08GT16A/GT8A Data Sheet, Rev. 1 18 Freescale Semiconductor Chapter 1 Device Overview 1.1 Introduction The MC9S08GT16A/GT8A are members of the low-cost, high-performance HCS08 Family of 8-bit microcontroller units (MCUs). All MCUs in the family use the enhanced HCS08 core and are available with a variety of modules, memory sizes, memory types, and package types (see Table 1-1). 1.1.1 Devices in the MC9S08GT16A/GT8A Series Table 1-1 lists the devices available in the MC9S08GT16A/GT8A series and summarizes the differences among them. Table 1-1. Devices in the MC9S08GT16A/GT8A Series Device FLASH RAM TPM (1) 3-ch, (1) 2-ch, 16-bit MC9S08GT16A 16K 2K (2) 2-ch, 16-bit (2) 2-ch, 16-bit (1) 2-ch, (1) 1-ch, 16-bit MC9S08GT8A 8K 1K (1) 3-ch, (1) 2-ch, 16-bit (2) 2-ch, 16-bit (2) 2-ch, 16-bit (1) 2-ch, (1) 1-ch, 16-bit ATD 8 8 8 4 8 8 8 4 KBI 8 8 8 4 8 8 8 4 I/O 39 36 34 24 39 36 34 24 Packages 48 QFN 44 QFP 42 SDIP 32 QFN 48 QFN 44 QFP 42 SDIP 32 QFN 1.1.2 MCU Block Diagram This block diagrams show the structure of the MC9S08GT16A/GT8A MCUs. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 19 Device Overview VREFL VREFH VSSAD VDDAD 4 HCS08 CORE BKGD CPU BDC 10-BIT ANALOG-TO-DIGITAL CONVERTER (ATD) 8 PORT B 4 4 8-BIT KEYBOARD INTERRUPT (KBI) PORT A 8 4 PTA7/KBIP7– PTA4/KBIP4 PTA3/KBIP3– PTA0/KBIP0 PTB7/ADP7– PTB4/ADP4 PTB3/ADP3– PTB0/ADP0 PTC7 PTC6 PTC5 PTC4 PTC3/SCL PTC2/SDA PTC1/RxD2 PTC0/TxD2 NOTE 6 HCS08 SYSTEM CONTROL RESET NOTE 4 RESETS AND INTERRUPTS MODES OF OPERATION POWER MANAGEMENT PORT C RTI IRQ NOTES 2, 3 IRQ COP LVD INTER-IC (IIC) SERIAL COMMUNICATIONS INTERFACE (SCI2) SCL SDA RXD2 TXD2 CH1 CH0 CH0 CH1 CH2 SPSCK MOSI MISO SS RXD1 TXD1 NOTE 5 PORT D USER FLASH (GT16A = 16,384 BYTES) (GT8A = 8192 BYTES) 2-CHANNEL TIMER/PWM (TPM2) PTD4/TPM2CH1 PTD3/TPM2CLK/TPM2CH0 PTD2/TPM1CH2 PTD1/TPM1CH1 PTD0/TPM1CLK/TPM1CH0 PTE5/SPSCK PTE4/MOSI PTE3/MISO PTE2/SS PTE1/RxD1 PTE0/TxD1 PTG3 PTG2/EXTAL PTG1/XTAL PTG0/BKGD/MS USER RAM (GT16A = 2048 BYTES) (GT8A = 1024 BYTES) 3-CHANNEL TIMER/PWM (TPM1) ON-CHIP ICE DEBUG MODULE (DBG) INTERNAL CLOCK GENERATOR (ICG) LOW-POWER OSCILLATOR VDD VSS VSS SERIAL COMMUNICATIONS INTERFACE (SCI1) VOLTAGE REGULATOR = Pins not available in 44-, 42-, or 32-pin packages = Pins not available in 42- or 32-pin packages = Pins not available in 32-pin packages NOTES: 1. Port pins are software configurable with pullup device if input port. 2. Pin contains pullup/pulldown device if IRQ enabled (IRQPE = 1). 3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD. 4. Pin contains integrated pullup device. 5. High current drive 6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available when KBI enabled (KBIPn = 1). Figure 1-1. MC9S08GT16A/GT8A Block Diagram MC9S08GT16A/GT8A Data Sheet, Rev. 1 20 Freescale Semiconductor PORT G EXTAL XTAL BKGD PORT E SERIAL PERIPHERAL INTERFACE (SPI) Device Overview Table 1-2 lists the functional versions of the on-chip modules. Table 1-2. Block Versions Module Analog-to-Digital Converter (ATD) Internal Clock Generator (ICG) Inter-Integrated Circuit (IIC) Keyboard Interrupt (KBI) Serial Communications Interface (SCI) Serial Peripheral Interface (SPI) Timer Pulse-Width Modulator (TPM) Central Processing Unit (CPU) Version 3 4 1 1 1 3 2 2 1.2 System Clock Distribution ICGERCLK FFE SYSTEM CONTROL LOGIC RTI TPM1 TPM2 IIC SCI1 SCI2 SPI ÷2 ICG FIXED FREQ CLOCK (XCLK) ICGOUT ICGLCLK* ÷2 BUSCLK CPU BDC COP ATD RAM FLASH FLASH has frequency requirements for program and erase operation. See Appendix A, “Electrical Characteristics”. * ICGLCLK is the alternate BDC clock source for the MC9S08GT16A/GT8A. ATD has min and max frequency requirements. See Chapter 14, “Analog-to-Digital Converter (S08ATDV3)” and Appendix A, “Electrical Characteristics.” Figure 1-2. System Clock Distribution Diagram MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 21 Device Overview Some of the modules inside the MCU have clock source choices. Figure 1-2 shows a simplified clock connection diagram. The ICG supplies the clock sources: • ICGOUT is an output of the ICG module. It is one of the following: — The external crystal oscillator — An external clock source — The output of the digitally-controlled oscillator (DCO) in the frequency-locked loop sub-module Control bits inside the ICG determine which source is connected. • FFE is a control signal generated inside the ICG. If the frequency of ICGOUT > 4 × the frequency of ICGERCLK, this signal is a logic 1 and the fixed-frequency clock will be the ICGERCLK. Otherwise the fixed-frequency clock will be BUSCLK. • ICGLCLK — Development tools can select this internal self-clocked source (~ 8 MHz) to speed up BDC communications in systems where the bus clock is slow. • ICGERCLK — External reference clock can be selected as the real-time interrupt clock source. MC9S08GT16A/GT8A Data Sheet, Rev. 1 22 Freescale Semiconductor Chapter 2 Pins and Connections 2.1 Introduction This section describes signals that connect to package pins. It includes a pinout diagram, a table of signal properties, and detailed discussion of signals. 2.2 Device Pin Assignment 45 PTG0/BKGD/MS 47 PTG2/EXTAL PTA5/KBIP5 PTA4/KBIP4 42 PTA7/KBIP7 41 PTA6/KBIP6 38 PTA3/KBIP3 PTA2/KBIP2 37 PTD4/TPM2CH1 24 36 PTA1/KBIP1 35 PTA0/KBIP0 34 VREFL 33 VREFH 32 PTB7/ADP7 31 PTB6/ADP6 30 PTB5/ADP5 29 28 27 26 14 15 16 17 18 19 20 21 22 23 25 PTB4/ADP4 PTB3/ADP3 PTB2/ADP2 PTB1/ADP1 PTB0/ADP0 46 PTG1/XTAL 48 PTG3 44 VSSAD 43 VDDAD 40 PTD1/TPM1CH1 RESET 1 PTC0/TxD2 2 PTC1/RxD2 3 PTC2/SDA 4 PTC3/SCL 5 PTC4 6 PTC5 7 PTC6 8 PTC7 9 PTE0/TxD1 10 PTE1/RxD1 11 IRQ 12 13 PTE4/MOSI PTE2/SS PTE3/MISO VDD PTD0/TPM1CLK/TPM1CH0 PTD2/TPM1CH2 39 Figure 2-1. MC9S08GT16A/GT8A in 48-Pin QFN Package MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 23 PTD3/TPM2CLK/TPM2CH0 VSS1 PTE5/SPSCK VSS2 Pins and Connections PTG0/BKGD/MS PTG2/EXTAL PTA5/KBIP5 PTA4/KBIP4 PTA7/KBIP7 PTA6/KBIP6 43 42 41 44 40 39 38 37 36 35 PTA3/KBIP3 RESET PTC0/TxD2 PTC1/RxD2 PTC2/SDA PTC3/SCL PTC4 PTC5 PTC6 PTE0/TxD1 PTE1/RxD1 IRQ 11 34 PTA2/KBIP2 PTG1/XTAL VDDAD VSSAD 1 2 3 4 5 6 7 8 9 10 13 14 15 16 33 32 31 30 29 PTA1/KBIP1 PTA0/KBIP0 VREFL VREFH PTB7/ADP7 PTB6/ADP6 PTB5/ADP5 PTB4/ADP4 PTB3/ADP3 PTB2/ADP2 PTB1/ADP1 28 27 26 25 24 17 18 19 20 21 PTD4/TPM2CH1 22 PTB0/ADP0 23 PTE2/SS 12 PTE5/SPSCK PTE3/MISO VDD PTD0/TPM1CLK/TPM1CH0 PTD1/TPM1CH1 Figure 2-2. MC9S08GT16A/GT8A in 44-Pin QFP Package MC9S08GT16A/GT8A Data Sheet, Rev. 1 24 Freescale Semiconductor PTD3/TPM2CLK/TPM2CH0 PTE4/MOSI VSS Pins and Connections VDDAD VSSAD PTG0/BKGD/MS PTG1/XTAL PTG2/EXTAL RESET PTC0/TxD2 PTC1/RXD2 PTC2/SDA PTC3/SCL PTC4 PTE0/TxD1 PTE1/RxD1 IRQ PTE2/SS PTE3/MISO PTE4/MOSI PTE5/SPSCK VSS VDD PTD0/TPM1CLK/TPM1CH0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 PTA7/KBIP7 PTA6/KBIP6 PTA5/KBIP5 PTA4/KBIP4 PTA3/KBIP3 PTA2/KBIP2 PTA1/KBIP1 PTA0/KBIP0 VREFL VREFH PTB7/ADP7 PTB6/ADP6 PTB5/ADP5 PTB4/ADP4 PTB3/ADP3 PTB2/ADP2 PTB1/ADP1 PTB0/ADP0 PTD4/TPM2CH1 PTD3/TPM2CLK/TPM2CH0 PTD1/TPM1CH1 Figure 2-3. MC9S08GT16A/GT8A in 42-Pin SDIP Package MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 25 Pins and Connections PTG2/EXTAL PTG0/BKGD PTA7/KBIP7 PTA6/KBIP6 26 PTG1/XTAL 32 RESET 1 PTC0/TxD2 2 PTC1/RxD2 3 PTC2/SDA 4 PTC3/SCL 5 PTE0/TxD1 6 PTE1/RxD1 7 IRQ 8 9 PTE2/SS 31 30 29 VSSAD 28 VDDAD 27 PTA5/KBIP5 25 24 PTA4/KBIP4 23 VREFL 22 VREFH 21 PTB3/ADP3 20 PTB2/ADP2 19 PTB1/ADP1 18 PTB0/ADP0 17 PTD3/TPM2CLK/TPM2CH0 16 PTD1/TPM1CH1 10 PTE3/MISO 11 PTE4/MOSI 12 PTE5/SPSCK 13 VSS 14 VDD 15 PTD0/TPM1CLK/TPM1CH0 Figure 2-4. MC9S08GT16A/GT8A in 32-Pin QFN Package MC9S08GT16A/GT8A Data Sheet, Rev. 1 26 Freescale Semiconductor Pins and Connections 2.3 Recommended System Connections Figure 2-5 shows pin connections that are common to almost all MC9S08GT16A application systems. A more detailed discussion of system connections follows. VREFH CBYAD 0.1 µF SYSTEM POWER + 3V VDD VDDAD MC9S08GT16A PTA0/KBIP0 PTA1/KBIP1 PTA2/KBIP2 VSSAD VREFL VDD CBY 0.1 µF VSS VSS BACKGROUND HEADER VDD BKGD/MS VDD 4.7 kΩ–10 kΩ 0.1 µF RESET NOTE 3 PORT B NOTE4 PORT A PTA3/KBIP3 PTA4/KBIP4 PTA5/KBIP5 PTA6/KBIP6 PTA7/KBIP7 PTB0/ADP0 PTB1/ADP1 PTB2/ADP2 PTB3/ADP3 PTB4/ADP4 PTB5/ADP5 PTB6/ADP6 PTB7/ADP7 PTC0/TxD2 PTC1/RxD2 VDD 4.7 kΩ–10 kΩ 0.1 µF IRQ NOTE 3 PORT C PTC2/SDA PTC3/SCL PTC4 PTC5 PTC6 PTC7 PTD0/TPM1CLK/TPM1CH0 PTG0/BKDG/MS PTG1/XTAL PTG2/EXTAL PTG3 NOTE 1 RF C1 C2 EXTAL PORT G PORT D PTD1/TPM1CH1 PTD2/TPM1CH2 PTD3/TPM2CLK/TPM2CH0 PTD4/TPM2CH1 PTE0/TxD1 PTE1/RxD1 X1 PORT E PTE2/SS PTE3/MISO PTE4/MOSI PTE5/SPSCK I/O AND PERIPHERAL INTERFACE TO APPLICATION SYSTEM CBLK + 10 µF OPTIONAL MANUAL RESET ASYNCHRONOUS INTERRUPT INPUT RS XTAL NOTES: 1. Not required if using the internal oscillator option. 2. The 48-pin QFN has 2 VSS pins (VSS1 and VSS2), both of which must be connected to GND. 3. RC filters on RESET and IRQ are recommended for EMC-sensitive applications and systems. Figure 2-5. Basic System Connections MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 27 Pins and Connections 2.3.1 VDD, VSS, VDDAD, VSSAD, VREFH, VREFL — Power and Voltage References VDD and VSS are the primary power supply pins for the MCU. This voltage source supplies power to all I/O buffer circuitry and to an internal voltage regulator. The internal voltage regulator provides regulated lower-voltage source to the CPU and other internal circuitry of the MCU. Typically, application systems have two separate capacitors across the power pins. In this case, there should be a bulk electrolytic capacitor, such as a 10-µF tantalum capacitor, to provide bulk charge storage for the overall system and a 0.1-µF ceramic bypass capacitor located as close to the MCU power pins as practical to suppress high-frequency noise. NOTE The 48-pin QFN version of the MC9S08GT16A/GT8A has two adjacent VSS pins. Both pins must be connected to ground with zero impedance between them. VDDAD and VSSAD are the analog power supply pins for the MCU. This voltage source supplies power to the ATD. A 0.1-µF ceramic bypass capacitor should be located as close to the MCU power pins as practical to suppress high-frequency noise. VREFH and VREFL are the reference voltages for the analog-to-digital converter and for most accurate performance, they must be connected directly to VDDAD and VSSAD with the shortest traces possible. 2.3.2 PTG1/XTAL, PTG2/EXTAL — Oscillator Immediately after reset, the MCU uses an internally generated clock (self-clocked mode — fSelf_reset), that is approximately equivalent to an 8-MHz crystal rate. This frequency source is used during reset startup and can be enabled as the clock source for stop recovery to avoid the need for a long crystal startup delay. This MCU also contains a trimmable internal clock generator (ICG) module that can be used to run the MCU. For more information on the ICG, see Chapter 9, “Internal Clock Generator (S08ICGV4).” The oscillator amplitude on XTAL and EXTAL is gain limited for low-power oscillation. Typically, these pins have a 1-V peak-to-peak signal. For noisy environments, the high gain output (HGO) bit can be set to enable rail-to-rail oscillation. The oscillator in this MCU is a Pierce oscillator that can accommodate a crystal or ceramic resonator in either of two frequency ranges selected by the RANGE bit in the ICGC1 register. Rather than a crystal or ceramic resonator, an external oscillator can be connected to the EXTAL input pin, and the XTAL output pin can be used as general I/O. The external oscillator amplitude must not exceed VDD. Refer to Figure 2-5 for the following discussion. RS (when used) and RF should be low-inductance resistors such as carbon composition resistors. Wire-wound resistors, and some metal film resistors, have too much inductance. C1 and C2 normally should be high-quality ceramic capacitors that are specifically designed for high-frequency applications. RF is used to provide a bias path to keep the EXTAL input in its linear range during crystal startup and its value is not generally critical. Typical systems use 1 MΩ to 10 MΩ. Higher values are sensitive to humidity and lower values reduce gain and (in extreme cases) could prevent startup. MC9S08GT16A/GT8A Data Sheet, Rev. 1 28 Freescale Semiconductor Pins and Connections C1 and C2 are typically in the 5-pF to 25-pF range and are chosen to match the requirements of a specific crystal or resonator. Be sure to take into account printed circuit board (PCB) capacitance and MCU pin capacitance when sizing C1 and C2. The crystal manufacturer typically specifies a load capacitance which is the series combination of C1 and C2 which are usually the same size. As a first-order approximation, use 10 pF as an estimate of combined pin and PCB capacitance for each oscillator pin (EXTAL and XTAL). 2.3.3 RESET — External Reset Pin RESET is a dedicated pin with a pullup device built in. It has input hysteresis, a high current output driver, and no output slew rate control. Internal power-on reset and low-voltage reset circuitry typically make external reset circuitry unnecessary. This pin is normally connected to the standard 6-pin background debug connector so a development system can directly reset the MCU system. If desired, a manual external reset can be added by supplying a simple switch to ground (pull reset pin low to force a reset). Whenever any reset is initiated (whether from an external signal or from an internal system), the reset pin is driven low for approximately 34 cycles of fSelf_reset, released, and sampled again approximately 38 cycles of fSelf_reset later. If reset was caused by an internal source such as low-voltage reset or watchdog timeout, the circuitry expects the reset pin sample to return a logic 1. The reset circuitry decodes the cause of reset and records it by setting a corresponding bit in the system control reset status register (SRS). For EMC-sensitive applications, an external RC filter is recommended on the RESET pin. See Figure 2-5 for an example. 2.3.4 PTG0/BKGD/MS — Background / Mode Select The background/mode select (BKGD/MS) shares its function with an I/O port pin. While in reset, the pin functions as a mode select pin. Immediately after reset rises the pin functions as the background pin and can be used for background debug communication. While functioning as a background/mode select pin, the pin includes an internal pullup device, input hysteresis, a standard output driver, and no output slew rate control. When used as an I/O port (PTG0) the pin is limited to output only. If nothing is connected to this pin, the MCU will enter normal operating mode at the rising edge of reset. If a debug system is connected to the 6-pin standard background debug header, it can hold BKGD/MS low during the rising edge of reset which forces the MCU to active background mode. The BKGD pin is used primarily for background debug controller (BDC) communications using a custom protocol that uses 16 clock cycles of the target MCU’s BDC clock per bit time. The target MCU’s BDC clock could be as fast as the maximum bus clock rate, so there should never be any significant capacitance connected to the BKGD/MS pin that could interfere with background serial communications. Although the BKGD pin is a pseudo open-drain pin, the background debug communication protocol provides brief, actively driven, high speedup pulses to ensure fast rise times. Small capacitances from cables and the absolute value of the internal pullup device play almost no role in determining rise and fall times on the BKGD pin. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 29 Pins and Connections 2.3.5 IRQ — External Interrupt Request Pin IRQ is a dedicated pin with both pullup and pulldown devices built in. This pin has no output capabilities. After a system reset, the IRQ pin is disabled and must be enabled before use. See Section 5.4.2, “IRQ — External Interrupt Request Pin” for more details. For EMC-sensitive applications, an external RC filter is recommended on the IRQ pin. See Figure 2-5 for an example. 2.3.6 General-Purpose I/O and Peripheral Ports The remaining 36 pins are shared among general-purpose I/O and on-chip peripheral functions such as timers and serial I/O systems. (Three of these pins are not bonded out on the 44-pin package, five are not bonded out on the 42-pin package, and 15 are not bonded out on the 32-pin package.) Immediately after reset, all 36 of these pins are configured as high-impedance general-purpose inputs with internal pullup devices disabled. NOTE To avoid extra current drain from floating input pins, the reset initialization routine in the application program should either enable on-chip pullup devices or change the direction of unused pins to outputs so the pins do not float. For information about controlling these pins as general-purpose I/O pins, see Chapter 6, “Parallel Input/Output.” For information about how and when on-chip peripheral systems use these pins, refer to the appropriate section from Table 2-1. Table 2-1. Pin Sharing References Port Pins PTA7–PTA0 PTB7–PTB0 PTC7–PTC4 PTC3–PTC2 PTC1–PTC0 PTD4–PTD3 PTD2–PTD0 PTE5 PTE4 PTE3 PTE2 PTE1–PTE0 PTG3 PTG2–PTG1 PTG0 1 Alternate Function KBIP7–KBIP0 ADP7–ADP0 Reference1 Chapter 7, “Keyboard Interrupt (S08KBIV1)” Chapter 14, “Analog-to-Digital Converter (S08ATDV3)” SCL–SDA RxD2–TxD2 TPM2CH1–TPM2CH0, TPM2CLK TPM1CH2–TPM1CH0, TPM1CLK SPSCK MISO MOSI SS RxD1–TxD1 Chapter 13, “Inter-Integrated Circuit (S08IICV1)” Chapter 11, “Serial Communications Interface (S08SCIV1)” Chapter 10, “Timer/PWM (S08TPMV2)” Chapter 10, “Timer/PWM (S08TPMV2)” Chapter 12, “Serial Peripheral Interface (S08SPIV3)” Chapter 11, “Serial Communications Interface (S08SCIV1)” EXTAL–XTAL BKGD/MS Chapter 9, “Internal Clock Generator (S08ICGV4)” Chapter 15, “Development Support” See this section for information about modules that share these pins. MC9S08GT16A/GT8A Data Sheet, Rev. 1 30 Freescale Semiconductor Pins and Connections When an on-chip peripheral system is controlling a pin, data direction control bits still determine what is read from port data registers even though the peripheral module controls the pin direction by controlling the enable for the pin’s output buffer. See Chapter 6, “Parallel Input/Output,” for details. Pullup enable bits for each input pin control whether on-chip pullup devices are enabled whenever the pin is acting as an input even if it is being controlled by an on-chip peripheral module. When the PTA7–PTA4 pins are controlled by the KBI module and are configured for rising-edge/high-level sensitivity, the pullup enable control bits enable pulldown devices rather than pullup devices. Similarly, when IRQ is configured as the IRQ input and is set to detect rising edges, the pullup enable control bit enables a pulldown device rather than a pullup device. 2.3.7 Signal Properties Summary Table 2-2 summarizes I/O pin characteristics. These characteristics are determined by the way the common pin interfaces are hardwired to internal circuits. Table 2-2. Signal Properties Pin Name VDD VSS VDDAD VSSAD VREFH VREFL RESET I/O Dir High Current Pin — — — — — — Y Output Slew 1 — — — — — — N Pull-Up2 — — — — — — Y Pin contains integrated pullup. IRQPE must be set to enable IRQ function. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD. Pullup/pulldown active when IRQ pin function enabled. Pullup forced on when IRQ enabled for falling edges; pulldown forced on when IRQ enabled for rising edges. The 48-pin QFN package has two VSS pins — VSS1 and VSS2. Comments IRQ I — — Y PTA0/KBIP0 PTA1/KBIP1 PTA2/KBIP2 PTA3/KBIP3 PTA4/KBIP4 PTA5/KBIP5 PTA6/KBIP6 PTA7/KBIP7 PTB0/ADP0 PTB1/ADP1 PTB2/ADP2 I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O N N N N N N N N N N N SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC Pullup/pulldown active when KBI pin function enabled. Pullup forced on when KBIPx enabled for falling edges; pulldown forced on when KBIPx enabled for rising edges. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 31 Pins and Connections Table 2-2. Signal Properties (continued) Pin Name PTB3/ADP3 PTB4/ADP4 PTB5/ADP5 PTB6/ADP6 PTB7/ADP7 PTC0/TxD2 PTC1/RxD2 PTC2/SDA PTC3/SCL PTC4 PTC5 PTC6 PTC7 PTD0/TPM1CLK/TPM1CH0 PTD1/TPM1CH1 PTD2/TPM1CH2 PTD3/TPM2CLK/TPM2CH0 PTD4/TPM2CH1 PTE0/TxD1 PTE1/RxD1 PTE2/SS PTE3/MISO PTE4/MOSI PTE5/SPSCK PTG0/BKGD/MS PTG1/XTAL PTG2/EXTAL PTG3 1 2 Dir I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O I/O O I/O I/O I/O High Current Pin N N N N N Y Y Y Y Y Y Y Y N N N N N N N N N N N N N N N Output Slew 1 SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC Pull-Up2 SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC SWC Comments Not available on 32-pin pkg Not available on 32-pin pkg Not available on 32-pin pkg Not available on 32-pin pkg When pin is configured for SCI function, pin is configured for partial output drive. Not available on 32-pin pkg Not available on 32-pin or 42-pin pkg Not available on 32-pin or 42-pin pkg Not available on 32-pin, 42- or 44-pin pkg Not available on 32-pin, 42- or 44-pin pkg Not available on 32-pin pkg Pullup enabled and slew rate disabled when BDM function enabled. Pullup and slew rate disabled when XTAL pin function. Pullup and slew rate disabled when EXTAL pin function. Not available on 32-pin, 42-, or 44-pin pkg SWC is software controlled slew rate, the register is associated with the respective port. SWC is software controlled pullup resistor, the register is associated with the respective port. MC9S08GT16A/GT8A Data Sheet, Rev. 1 32 Freescale Semiconductor Chapter 3 Modes of Operation 3.1 Introduction The operating modes of the MC9S08GT16A/GT8A are described in this section. Entry into each mode, exit from each mode, and functionality while in each of the modes are described. 3.1.1 • • Features Active background mode for code development Wait mode: — CPU shuts down to conserve power — System clocks running — Full voltage regulation maintained Stop modes: — Stop1 — Full power down of internal circuits for maximum power savings — Stop2 — Partial power down of internal circuits, RAM contents retained — Stop3 — All internal circuits powered for fast recovery • 3.2 Run Mode This is the normal operating mode for the MC9S08GT16A/GT8A. This mode is selected when the BKGD/MS pin is high at the rising edge of reset. In this mode, the CPU executes code from internal memory with execution beginning at the address fetched from memory at 0xFFFE:0xFFFF after reset. 3.3 Active Background Mode The active background mode functions are managed through the background debug controller (BDC) in the HCS08 core. The BDC, together with the on-chip ICE debug module (DBG), provide the means for analyzing MCU operation during software development. Active background mode is entered in any of five ways: • When the BKGD/MS pin is low at the rising edge of reset • When a BACKGROUND command is received through the BKGD pin • When a BGND instruction is executed • When encountering a BDC breakpoint • When encountering a DBG breakpoint MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 33 Modes of Operation After entering active background mode, the CPU is held in a suspended state waiting for serial background commands rather than executing instructions from the user’s application program. Background commands are of two types: • Non-intrusive commands, defined as commands that can be issued while the user program is running. Non-intrusive commands can be issued through the BKGD pin while the MCU is in run mode; non-intrusive commands can also be executed while the MCU is in the active background mode. Non-intrusive commands include: — Memory access commands — Memory-access-with-status commands — BDC register access commands — The BACKGROUND command • Active background commands, which can be executed only while the MCU is in active background mode. Active background commands include commands to: — Read or write CPU registers — Trace one user program instruction at a time — Leave active background mode to return to the user’s application program (GO) The active background mode is used to program a bootloader or user application program into the FLASH program memory before the MCU is operated in run mode for the first time. When the MC9S08GT16A/GT8A is shipped from the Freescale Semiconductor factory, the FLASH program memory is erased by default unless specifically noted so there is no program that could be executed in run mode until the FLASH memory is initially programmed. The active background mode can also be used to erase and reprogram the FLASH memory after it has been previously programmed. For additional information about the active background mode, refer to Chapter 15, “Development Support.” 3.4 Wait Mode Wait mode is entered by executing a WAIT instruction. Upon execution of the WAIT instruction, the CPU enters a low-power state in which it is not clocked. The I bit in CCR is cleared when the CPU enters the wait mode, enabling interrupts. When an interrupt request occurs, the CPU exits the wait mode and resumes processing, beginning with the stacking operations leading to the interrupt service routine. While the MCU is in wait mode, there are some restrictions on which background debug commands can be used. Only the BACKGROUND command and memory-access-with-status commands are available when the MCU is in wait mode. The memory-access-with-status commands do not allow memory access, but they report an error indicating that the MCU is in either stop or wait mode. The BACKGROUND command can be used to wake the MCU from wait mode and enter active background mode. MC9S08GT16A/GT8A Data Sheet, Rev. 1 34 Freescale Semiconductor Modes of Operation 3.5 Stop Modes One of three stop modes is entered upon execution of a STOP instruction when the STOPE bit in the system option register is set. In all stop modes, all internal clocks are halted. If the STOPE bit is not set when the CPU executes a STOP instruction, the MCU will not enter any of the stop modes and an illegal opcode reset is forced. The stop modes are selected by setting the appropriate bits in SPMSC2. Table 3-1 summarizes the behavior of the MCU in each of the stop modes. Table 3-1. Stop Mode Behavior CPU, Digital Peripherals, FLASH Off Off Standby Mode PDC PPDC RAM ICG ATD Disabled1 Disabled Disabled Regulator I/O Pins RTI Stop1 Stop2 Stop3 1 2 1 1 0 0 1 Don’t care Off Standby Standby Off Off Off2 Off Standby Standby Reset States held States held Off Optionally on Optionally on Either ATD stop mode or power-down mode depending on the state of ATDPU. Crystal oscillator can be configured to run in stop3. Please see the ICG registers. 3.5.1 Stop1 Mode The stop1 mode provides the lowest possible standby power consumption by causing the internal circuitry of the MCU to be powered down. Stop1 can be entered only if the LVD circuit is not enabled in stop modes (either LVDE or LVDSE not set). When the MCU is in stop1 mode, all internal circuits that are powered from the voltage regulator are turned off. The voltage regulator is in a low-power standby state, as is the ATD. Exit from stop1 is performed by asserting either of the wake-up pins on the MCU: RESET or IRQ. IRQ is always an active low input when the MCU is in stop1, regardless of how it was configured before entering stop1. Entering stop1 mode automatically asserts LVD. Stop1 cannot be exited until VDD > VLVDH/L rising (VDD must rise above the LVI rearm voltage). Upon wake-up from stop1 mode, the MCU will start up as from a power-on reset (POR). The CPU will take the reset vector. 3.5.2 Stop2 Mode The stop2 mode provides very low standby power consumption and maintains the contents of RAM and the current state of all of the I/O pins. Stop2 can be entered only if the LVD circuit is not enabled in stop modes (either LVDE or LVDSE not set). MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 35 Modes of Operation Before entering stop2 mode, the user must save the contents of the I/O port registers, as well as any other memory-mapped registers they want to restore after exit of stop2, to locations in RAM. Upon exit of stop2, these values can be restored by user software before pin latches are opened. When the MCU is in stop2 mode, all internal circuits that are powered from the voltage regulator are turned off, except for the RAM. The voltage regulator is in a low-power standby state, as is the ATD. Upon entry into stop2, the states of the I/O pins are latched. The states are held while in stop2 mode and after exiting stop2 mode until a 1 is written to PPDACK in SPMSC2. Exit from stop2 is performed by asserting either of the wake-up pins: RESET or IRQ, or by an RTI interrupt. IRQ is always an active low input when the MCU is in stop2, regardless of how it was configured before entering stop2. Upon wake-up from stop2 mode, the MCU will start up as from a power-on reset (POR) except pin states remain latched. The CPU will take the reset vector. The system and all peripherals will be in their default reset states and must be initialized. After waking up from stop2, the PPDF bit in SPMSC2 is set. This flag may be used to direct user code to go to a stop2 recovery routine. PPDF remains set and the I/O pin states remain latched until a 1 is written to PPDACK in SPMSC2. To maintain I/O state for pins that were configured as general-purpose I/O, the user must restore the contents of the I/O port registers, which have been saved in RAM, to the port registers before writing to the PPDACK bit. If the port registers are not restored from RAM before writing to PPDACK, then the register bits will assume their reset states when the I/O pin latches are opened and the I/O pins will switch to their reset states. For pins that were configured as peripheral I/O, the user must reconfigure the peripheral module that interfaces to the pin before writing to the PPDACK bit. If the peripheral module is not enabled before writing to PPDACK, the pins will be controlled by their associated port control registers when the I/O latches are opened. 3.5.3 Stop3 Mode Upon entering the stop3 mode, all of the clocks in the MCU, including the oscillator itself, are halted. The ICG is turned off, the ATD is disabled, and the voltage regulator is put in standby. The states of all of the internal registers and logic, as well as the RAM content, are maintained. The I/O pin states are not latched at the pin as in stop2. Instead they are maintained by virtue of the states of the internal logic driving the pins being maintained. Exit from stop3 is performed by asserting RESET, an asynchronous interrupt pin, or through the real-time interrupt. The asynchronous interrupt pins are the IRQ or KBI pins. If stop3 is exited by means of the RESET pin, then the MCU will be reset and operation will resume after taking the reset vector. Exit by means of an asynchronous interrupt or the real-time interrupt will result in the MCU taking the appropriate interrupt vector. A separate self-clocked source (≈1 kHz) for the real-time interrupt allows a wakeup from stop2 or stop3 mode with no external components. When RTIS2:RTIS1:RTIS0 = 0:0:0, the real-time interrupt function MC9S08GT16A/GT8A Data Sheet, Rev. 1 36 Freescale Semiconductor Modes of Operation and this 1-kHz source are disabled. Power consumption is lower when the 1-kHz source is disabled, but in that case the real-time interrupt cannot wake the MCU from stop. 3.5.4 Active BDM Enabled in Stop Mode Entry into the active background mode from run mode is enabled if the ENBDM bit in BDCSCR is set. This register is described in the Chapter 15, “Development Support,” section of this data sheet. If ENBDM is set when the CPU executes a STOP instruction, the system clocks to the background debug logic remain active when the MCU enters stop mode so background debug communication is still possible. In addition, the voltage regulator does not enter its low-power standby state but maintains full internal regulation. If the user attempts to enter either stop1 or stop2 with ENBDM set, the MCU will instead enter stop3. Most background commands are not available in stop mode. The memory-access-with-status commands do not allow memory access, but they report an error indicating that the MCU is in either stop or wait mode. The BACKGROUND command can be used to wake the MCU from stop and enter active background mode if the ENBDM bit is set. After the device enters background debug mode, all background commands are available. The table below summarizes the behavior of the MCU in stop when entry into the background debug mode is enabled. Table 3-2. BDM Enabled Stop Mode Behavior CPU, Digital Peripherals, FLASH Standby Mode PDC PPDC RAM ICG ATD Disabled1 Regulator I/O Pins RTI Stop3 1 Don’t care Don’t care Standby Active Active States held Optionally on Either ATD stop mode or power-down mode depending on the state of ATDPU. 3.5.5 LVD Enabled in Stop Mode The LVD system is capable of generating either an interrupt or a reset when the supply voltage drops below the LVD voltage. If the LVD is enabled in stop by setting the LVDE and the LVDSE bits in SPMSC1 when the CPU executes a STOP instruction, then the voltage regulator remains active during stop mode. If the user attempts to enter either stop1 or stop2 with the LVD enabled for stop (LVDSE = 1), the MCU will instead enter stop3. The table below summarizes the behavior of the MCU in stop when the LVD is enabled. Table 3-3. LVD Enabled Stop Mode Behavior CPU, Digital Peripherals, FLASH Standby Mode PDC PPDC RAM ICG ATD Disabled1 Regulator I/O Pins RTI Stop3 1 Don’t care Don’t care Standby Standby Active States held Optionally on Either ATD stop mode or power-down mode depending on the state of ATDPU. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 37 Modes of Operation 3.5.6 On-Chip Peripheral Modules in Stop Modes When the MCU enters any stop mode, system clocks to the internal peripheral modules are stopped. Even in the exception case (ENBDM = 1), where clocks to the background debug logic continue to operate, clocks to the peripheral systems are halted to reduce power consumption. Refer to Section 3.5.1, “Stop1 Mode,” Section 3.5.2, “Stop2 Mode,” and Section 3.5.3, “Stop3 Mode,” for specific information on system behavior in stop modes. I/O Pins • All I/O pin states remain unchanged when the MCU enters stop3 mode. • If the MCU is configured to go into stop2 mode, all I/O pins states are latched before entering stop. • If the MCU is configured to go into stop1 mode, all I/O pins are forced to their default reset state upon entry into stop. Memory • All RAM and register contents are preserved while the MCU is in stop3 mode. • All registers will be reset upon wake-up from stop2, but the contents of RAM are preserved and pin states remain latched until the PPDACK bit is written. The user may save any memory-mapped register data into RAM before entering stop2 and restore the data upon exit from stop2. • All registers will be reset upon wake-up from stop1 and the contents of RAM are not preserved. The MCU must be initialized as upon reset. The contents of the FLASH memory are nonvolatile and are preserved in any of the stop modes. ICG — In stop3 mode, the ICG enters its low-power standby state. Either the oscillator or the internal reference may be kept running when the ICG is in standby by setting the appropriate control bit. In both stop2 and stop1 modes, the ICG is turned off. Neither the oscillator nor the internal reference can be kept running in stop2 or stop1, even if enabled within the ICG module. TPM — When the MCU enters stop mode, the clock to the TPM1 and TPM2 modules stop. The modules halt operation. If the MCU is configured to go into stop2 or stop1 mode, the TPM modules will be reset upon wake-up from stop and must be reinitialized. ATD — When the MCU enters stop mode, the ATD will enter a low-power standby state. No conversion operation will occur while in stop. If the MCU is configured to go into stop2 or stop1 mode, the ATD will be reset upon wake-up from stop and must be reinitialized. KBI — During stop3, the KBI pins that are enabled continue to function as interrupt sources that are capable of waking the MCU from stop3. The KBI is disabled in stop1 and stop2 and must be reinitialized after waking up from either of these modes. SCI — When the MCU enters stop mode, the clocks to the SCI1 and SCI2 modules stop. The modules halt operation. If the MCU is configured to go into stop2 or stop1 mode, the SCI modules will be reset upon wake-up from stop and must be reinitialized. SPI — When the MCU enters stop mode, the clocks to the SPI module stop. The module halts operation. If the MCU is configured to go into stop2 or stop1 mode, the SPI module will be reset upon wake-up from stop and must be reinitialized. MC9S08GT16A/GT8A Data Sheet, Rev. 1 38 Freescale Semiconductor Modes of Operation IIC — When the MCU enters stop mode, the clocks to the IIC module stops. The module halts operation. If the MCU is configured to go into stop2 or stop1 mode, the IIC module will be reset upon wake-up from stop and must be reinitialized. Voltage Regulator — The voltage regulator enters a low-power standby state when the MCU enters any of the stop modes unless the LVD is enabled in stop mode or BDM is enabled. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 39 Modes of Operation MC9S08GT16A/GT8A Data Sheet, Rev. 1 40 Freescale Semiconductor Chapter 4 Memory 4.1 MC9S08GT16A/GT8A Memory Map As shown in Figure 4-1, on-chip memory in the MC9S08GT16A/GT8A series of MCUs consists of RAM, FLASH program memory for nonvolatile data storage, plus I/O and control/status registers. The registers are divided into three groups: • Direct-page registers (0x0000 through 0x007F) • High-page registers (0x1800 through 0x182B) • Nonvolatile registers (0xFFB0 through 0xFFBF) 0x0000 DIRECT PAGE REGISTERS 0x007F 0x0080 DIRECT PAGE REGISTERS RAM 1024 BYTES Reserved 1024 BYTES 0x0000 0x007F 0x0080 0x047F 0x0480 0x087F 0x0880 RAM 2048 BYTES 0x087F 0x0880 UNIMPLEMENTED 3968 BYTES UNIMPLEMENTED UNIMPLEMENTED 4992 BYTES 3968 BYTES 0x17FF 0x1800 HIGH PAGE REGISTERS 0x182B 0x182C HIGH PAGE REGISTERS 0x17FF 0x1800 0x182B 0x182C UNIMPLEMENTED 42964 BYTES 0xBFFF 0xC000 FLASH 16384 BYTES UNIMPLEMENTED 42964 BYTES 0xBFFF 0xC000 Reserved 8192 BYTES FLASH 8192 BYTES 0xFFFF MC9S08GT16A MC9S08GT8A 0xDFFF 0xE000 0xFFFF Figure 4-1. MC9S08GT16A/GT8A Memory Map MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 41 Memory 4.1.1 Reset and Interrupt Vector Assignments Table 4-1 shows address assignments for reset and interrupt vectors. The vector names shown in this table are the labels used in the Freescale-provided equate file for the MC9S08GT16A/GT8A. For more details about resets, interrupts, interrupt priority, and local interrupt mask controls, refer to Chapter 5, “Resets, Interrupts, and System Configuration.” Table 4-1. Reset and Interrupt Vectors Address (High/Low) 0xFFC0:FFC1 Unused Vector Space (available for user program) 0xFFCA:FFCB 0xFFCC:FFCD 0xFFCE:FFCF 0xFFD0:FFD1 0xFFD2:FFD3 0xFFD4:FFD5 0xFFD6:FFD7 0xFFD8:FFD9 0xFFDA:FFDB 0xFFDC:FFDD 0xFFDE:FFDF 0xFFE0:FFE1 0xFFE2:FFE3 0xFFE4:FFE9 0xFFEA:FFEB 0xFFEC:FFED 0xFFEE:FFEF 0xFFF0:FFF1 0xFFF2:FFF3 0xFFF4:FFF5 0xFFF6:FFF7 0xFFF8:FFF9 0xFFFA:FFFB 0xFFFC:FFFD 0xFFFE:FFFF RTI IIC ATD Conversion Keyboard SCI2 Transmit SCI2 Receive SCI2 Error SCI1 Transmit SCI1 Receive SCI1 Error SPI TPM2 Overflow Unused Vector Space (available for user program) TPM2 Channel 1 TPM2 Channel 0 TPM1 Overflow TPM1 Channel 2 TPM1 Channel 1 TPM1 Channel 0 ICG Low Voltage Detect IRQ SWI Reset Vtpm2ch1 Vtpm2ch0 Vtpm1ovf Vtpm1ch2 Vtpm1ch1 Vtpm1ch0 Vicg Vlvd Virq Vswi Vreset Vrti Viic Vatd Vkeyboard Vsci2tx Vsci2rx Vsci2err Vsci1tx Vsci1rx Vsci1err Vspi Vtpm2ovf Vector Vector Name MC9S08GT16A/GT8A Data Sheet, Rev. 1 42 Freescale Semiconductor Memory 4.2 Register Addresses and Bit Assignments The registers in the MC9S08GT16A/GT8A are divided into these three groups: • Direct-page registers are located in the first 128 locations in the memory map, so they are accessible with efficient direct addressing mode instructions. • High-page registers are used much less often, so they are located above 0x1800 in the memory map. This leaves more room in the direct page for more frequently used registers and variables. • The nonvolatile register area consists of a block of 16 locations in FLASH memory at 0xFFB0–0xFFBF. Nonvolatile register locations include: — Three values which are loaded into working registers at reset — An 8-byte backdoor comparison key which optionally allows a user to gain controlled access to secure memory Because the nonvolatile register locations are FLASH memory, they must be erased and programmed like other FLASH memory locations. Direct-page registers can be accessed with efficient direct addressing mode instructions. Bit manipulation instructions can be used to access any bit in any direct-page register. Table 4-2 is a summary of all user-accessible direct-page registers and control bits. The direct page registers in Table 4-2 can use the more efficient direct addressing mode which only requires the lower byte of the address. Because of this, the lower byte of the address in column one is shown in bold text. In Table 4-3 and Table 4-4 the whole address in column one is shown in bold. In Table 4-2, Table 4-3, and Table 4-4, the register names in column two are shown in bold to set them apart from the bit names to the right. Cells that are not associated with named bits are shaded. A shaded cell with a 0 indicates this unused bit always reads as a 0. Shaded cells with dashes indicate unused or reserved bit locations that could read as 1s or 0s. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 43 Memory Table 4-2. Direct-Page Register Summary (Sheet 1 of 3) Address Register Name Bit 7 PTAD7 PTAPE7 PTASE7 PTADD7 PTBD7 PTBPE7 PTBSE7 PTBDD7 PTCD7 PTCPE7 PTCSE7 PTCDD7 0 0 0 0 0 0 0 0 0 — KBEDG7 KBIPE7 0 SBR7 LOOPS TIE TDRE 0 R8 Bit 7 0 SBR7 LOOPS TIE TDRE 0 R8 Bit 7 6 PTAD6 PTAPE6 PTASE6 PTADD6 PTBD6 PTBPE6 PTBSE6 PTBDD6 PTCD6 PTCPE6 PTCSE6 PTCDD6 0 0 0 0 0 0 0 0 0 — KBEDG6 KBIPE6 0 SBR6 SCISWAI TCIE TC 0 T8 6 0 SBR6 SCISWAI TCIE TC 0 T8 6 5 PTAD5 PTAPE5 PTASE5 PTADD5 PTBD5 PTBPE5 PTBSE5 PTBDD5 PTCD5 PTCPE5 PTCSE5 PTCDD5 0 0 0 0 PTED5 PTEPE5 PTESE5 PTEDD5 IRQEDG — KBEDG5 KBIPE5 0 SBR5 RSRC RIE RDRF 0 TXDIR 5 0 SBR5 RSRC RIE RDRF 0 TXDIR 5 4 PTAD4 PTAPE4 PTASE4 PTADD4 PTBD4 PTBPE4 PTBSE4 PTBDD4 PTCD4 PTCPE4 PTCSE4 PTCDD4 PTDD4 PTDPE4 PTDSE4 PTDDD4 PTED4 PTEPE4 PTESE4 PTEDD4 IRQPE — KBEDG4 KBIPE4 SBR12 SBR4 M ILIE IDLE 0 0 4 SBR12 SBR4 M ILIE IDLE 0 0 4 3 PTAD3 PTAPE3 PTASE3 PTADD3 PTBD3 PTBPE3 PTBSE3 PTBDD3 PTCD3 PTCPE3 PTCSE3 PTCDD3 PTDD3 PTDPE3 PTDSE3 PTDDD3 PTED3 PTEPE3 PTESE3 PTEDD3 IRQF — KBF KBIPE3 SBR11 SBR3 WAKE TE OR 0 ORIE 3 SBR11 SBR3 WAKE TE OR 0 ORIE 3 2 PTAD2 PTAPE2 PTASE2 PTADD2 PTBD2 PTBPE2 PTBSE2 PTBDD2 PTCD2 PTCPE2 PTCSE2 PTCDD2 PTDD2 PTDPE2 PTDSE2 PTDDD2 PTED2 PTEPE2 PTESE2 PTEDD2 IRQACK — KBACK KBIPE2 SBR10 SBR2 ILT RE NF 0 NEIE 2 SBR10 SBR2 ILT RE NF 0 NEIE 2 1 PTAD1 PTAPE1 PTASE1 PTADD1 PTBD1 PTBPE1 PTBSE1 PTBDD1 PTCD1 PTCPE1 PTCSE1 PTCDD1 PTDD1 PTDPE1 PTDSE1 PTDDD1 PTED1 PTEPE1 PTESE1 PTEDD1 IRQIE — KBIE KBIPE1 SBR9 SBR1 PE RWU FE 0 FEIE 1 SBR9 SBR1 PE RWU FE 0 FEIE 1 Bit 0 PTAD0 PTAPE0 PTASE0 PTADD0 PTBD0 PTBPE0 PTBSE0 PTBDD0 PTCD0 PTCPE0 PTCSE0 PTCDD0 PTDD0 PTDPE0 PTDSE0 PTDDD0 PTED0 PTEPE0 PTESE0 PTEDD0 IRQMOD — KBIMOD KBIPE0 SBR8 SBR0 PT SBK PF RAF PEIE Bit 0 SBR8 SBR0 PT SBK PF RAF PEIE Bit 0 0x0000 0x0001 0x0002 0x0003 0x0004 0x0005 0x0006 0x0007 0x0008 0x0009 0x000A 0x000B 0x000C 0x000D 0x000E 0x000F 0x0010 0x0011 0x0012 0x0013 0x0014 0x0015 0x0016 0x0017 0x0018 0x0019 0x001A 0x001B 0x001C 0x001D 0x001E 0x001F 0x0020 0x0021 0x0022 0x0023 0x0024 0x0025 0x0026 0x0027 PTAD PTAPE PTASE PTADD PTBD PTBPE PTBSE PTBDD PTCD PTCPE PTCSE PTCDD PTDD PTDPE PTDSE PTDDD PTED PTEPE PTESE PTEDD IRQSC Reserved KBISC KBIPE SCI1BDH SCI1BDL SCI1C1 SCI1C2 SCI1S1 SCI1S2 SCI1C3 SCI1D SCI2BDH SCI2BDL SCI2C1 SCI2C2 SCI2S1 SCI2S2 SCI2C3 SCI2D MC9S08GT16A/GT8A Data Sheet, Rev. 1 44 Freescale Semiconductor Memory Table 4-2. Direct-Page Register Summary (Sheet 2 of 3) Address Register Name Bit 7 SPIE 0 0 SPRF 0 Bit 7 0 0 TOF Bit 15 Bit 7 Bit 15 Bit 7 CH0F Bit 15 Bit 7 CH1F Bit 15 Bit 7 CH2F Bit 15 Bit 7 — — 0 0 0 0 HGO LOLRE CLKST 0 0 0 0 6 SPE 0 SPPR2 0 0 6 0 0 TOIE 14 6 14 6 CH0IE 14 6 CH1IE 14 6 CH2IE 14 6 — — 0 0 0 0 RANGE 5 SPTIE 0 SPPR1 SPTEF 0 5 0 0 CPWMS 13 5 13 5 MS0B 13 5 MS1B 13 5 MS2B 13 5 — — 0 0 0 0 REFS MFD REFST 0 0 LOLS 0 0 FLT TRIM 0 ATDPU CCF Bit 7 Bit 7 0 DJM ATDIE 6 6 0 RES8 ATDCO 5 5 4 4 3 3 0 SGN 2 2 0 0 PRS ATDCH 1 1 Bit 0 Bit 0 0 0 4 MSTR MODFEN SPPR0 MODF 0 4 0 0 CLKSB 12 4 12 4 MS0A 12 4 MS1A 12 4 MS2A 12 4 — — 0 0 0 0 3 CPOL BIDIROE 0 0 0 3 0 0 CLKSA 11 3 11 3 ELS0B 11 3 ELS1B 11 3 ELS2B 11 3 — — PTGD3 PTGPE3 PTGSE3 PTGDD3 CLKS LOCRE LOCK 0 LOCS 0 FLT 2 CPHA 0 SPR2 0 0 2 0 0 PS2 10 2 10 2 ELS0A 10 2 ELS1A 10 2 ELS2A 10 2 — — PTGD2 PTGPE2 PTGSE2 PTGDD2 OSCSTEN 1 SSOE SPISWAI SPR1 0 0 1 0 0 PS1 9 1 9 1 0 9 1 0 9 1 0 9 1 — — PTGD1 PTGPE1 PTGSE1 PTGDD1 LOCD RFD ERCS 0 ICGIF DCOS Bit 0 LSBFE SPC0 SPR0 0 0 Bit 0 0 0 PS0 Bit 8 Bit 0 Bit 8 Bit 0 0 Bit 8 Bit 0 0 Bit 8 Bit 0 0 Bit 8 Bit 0 — — PTGD0 PTGPE0 PTGSE0 PTGDD0 0 0x0028 0x0029 0x002A 0x002B 0x002C 0x002D 0x002E 0x002F 0x0030 0x0031 0x0032 0x0033 0x0034 0x0035 0x0036 0x0037 0x0038 0x0039 0x003A 0x003B 0x003C 0x003D 0x003E– 0x0043 0x0044 0x0045 0x0046 0x0047 0x0048 0x0049 0x004A 0x004B 0x004C 0x004D 0x004E 0x004F 0x0050 0x0051 0x0052 0x0053 SPIC1 SPIC2 SPIBR SPIS Reserved SPID Reserved Reserved TPM1SC TPM1CNTH TPM1CNTL TPM1MODH TPM1MODL TPM1C0SC TPM1C0VH TPM1C0VL TPM1C1SC TPM1C1VH TPM1C1VL TPM1C2SC TPM1C2VH TPM1C2VL Reserved PTGD PTGPE PTGSE PTGDD ICGC1 ICGC2 ICGS1 ICGS2 ICGFLTU ICGFLTL ICGTRM Reserved ATDC ATDSC ATDRH ATDRL MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 45 Memory Table 4-2. Direct-Page Register Summary (Sheet 3 of 3) Address Register Name Bit 7 ATDPE7 — — MULT IICEN TCF — — TOF Bit 15 Bit 7 Bit 15 Bit 7 CH0F Bit 15 Bit 7 CH1F Bit 15 Bit 7 — — IICIE IAAS — — TOIE 14 6 14 6 CH0IE 14 6 CH1IE 14 6 — — MST BUSY — — CPWMS 13 5 13 5 MS0B 13 5 MS1B 13 5 — — TX ARBL DATA — — CLKSB 12 4 12 4 MS0A 12 4 MS1A 12 4 — — — — CLKSA 11 3 11 3 ELS0B 11 3 ELS1B 11 3 — — — — PS2 10 2 10 2 ELS0A 10 2 ELS1A 10 2 — — — — PS1 9 1 9 1 0 9 1 0 9 1 — — — — PS0 Bit 8 Bit 0 Bit 8 Bit 0 0 Bit 8 Bit 0 0 Bit 8 Bit 0 — — TXAK 0 6 ATDPE6 — — 5 ATDPE5 — — 4 ATDPE4 — — ADDR ICR RSTA SRW 0 IICIF 0 RXAK 3 ATDPE3 — — 2 ATDPE2 — — 1 ATDPE1 — — Bit 0 ATDPE0 — — 0 0x0054 0x0055– 0x0057 0x0058 0x0059 0x005A 0x005B 0x005C 0x005D– 0x005F 0x0060 0x0061 0x0062 0x0063 0x0064 0x0065 0x0066 0x0067 0x0068 0x0069 0x006A 0x006B– 0x007F ATDPE Reserved IICA IICF IICC IICS IICD Reserved TPM2SC TPM2CNTH TPM2CNTL TPM2MODH TPM2MODL TPM2C0SC TPM2C0VH TPM2C0VL TPM2C1SC TPM2C1VH TPM2C1VL Reserved High-page registers, shown in Table 4-3, are accessed much less often than other I/O and control registers so they have been located outside the direct addressable memory space, starting at 0x1800. Table 4-3. High-Page Register Summary Address Register Name Bit 7 POR 0 COPE — — ID7 RTIF LVDF LVWF — — Bit 15 6 PIN 0 COPT — — ID6 RTIACK LVDACK LVWACK — — 14 5 COP 0 STOPE — — ID5 RTICLKS LVDIE LVDV — — 13 4 ILOP 0 — — — ID4 RTIE LVDRE LVWV — — 12 3 ILAD 0 0 — — ID11 ID3 0 LVDSE PPDF — — 11 2 ICG 0 0 — — ID10 ID2 RTIS2 LVDE PPDACK — — 10 1 LVD 0 BKGDPE — — ID9 ID1 RTIS1 0 PDC — — 9 Bit 0 0 BDFR — — — ID8 ID0 RTIS0 0 PPDC — — Bit 8 0x1800 0x1801 0x1802 0x1803 – 0x1805 0x1806 0x1807 0x1808 0x1809 0x180A 0x180B– 0x180F 0x1810 SRS SBDFR SOPT Reserved SDIDH SDIDL SRTISC SPMSC1 SPMSC2 Reserved DBGCAH MC9S08GT16A/GT8A Data Sheet, Rev. 1 46 Freescale Semiconductor Memory Table 4-3. High-Page Register Summary (continued) Address Register Name Bit 7 Bit 7 Bit 15 Bit 7 Bit 15 Bit 7 DBGEN TRGSEL AF — — DIVLD KEYEN — 0 FPS7 FCBEF FCMD7 — — 6 6 14 6 14 6 ARM BEGIN BF — — PRDIV8 FNORED — 0 FPS6 FCCF FCMD6 — — 5 5 13 5 13 5 TAG 0 ARMF — — DIV5 0 — KEYACC FPS5 FPVIOL FCMD5 — — 4 4 12 4 12 4 BRKEN 0 0 — — DIV4 0 — 0 FPS4 FACCERR FCMD4 — — 3 3 11 3 11 3 RWA TRG3 CNT3 — — DIV3 0 — 0 FPS3 0 FCMD3 — — 2 2 10 2 10 2 RWAEN TRG2 CNT2 — — DIV2 0 — 0 FPS2 FBLANK FCMD2 — — 1 1 9 1 9 1 RWB TRG1 CNT1 — — DIV1 SEC01 — 0 FPS1 0 FCMD1 — — Bit 0 Bit 0 Bit 8 Bit 0 Bit 8 Bit 0 RWBEN TRG0 CNT0 — — DIV0 SEC00 — 0 FPDIS 0 FCMD0 — — 0x1811 0x1812 0x1813 0x1814 0x1815 0x1816 0x1817 0x1818 0x1819– 0x181F 0x1820 0x1821 0x1822 0x1823 0x1824 0x1825 0x1826 0x1827– 0x182B DBGCAL DBGCBH DBGCBL DBGFH DBGFL DBGC DBGT DBGS Reserved FCDIV FOPT Reserved FCNFG FPROT FSTAT FCMD Reserved Nonvolatile FLASH registers, shown in Table 4-4, are located in the FLASH memory. These registers include an 8-byte backdoor key which optionally can be used to gain access to secure memory resources. During reset events, the contents of NVPROT and NVOPT in the nonvolatile register area of the FLASH memory are transferred into corresponding FPROT and FOPT working registers in the high-page registers to control security and block protection options. Table 4-4. Nonvolatile Register Summary Address Register Name Bit 7 6 5 4 3 2 1 Bit 0 0xFFB0 – 0xFFB7 0xFFB8 – 0xFFBC 0xFFBD 0xFFBE 0xFFBF 1 NVBACKKEY Reserved NVPROT NVICGTRM1 NVOPT — — FPS7 KEYEN — — FPS6 FNORED — — FPS5 0 8-Byte Comparison Key — — FPS4 0 NVTRIM 0 0 SEC01 SEC00 — — FPS3 — — FPS2 — — FPS1 — — FPDIS NVICGTRM is the factory trim value. This value must be copied to ICGTRM in user code. Provided the key enable (KEYEN) bit is 1, the 8-byte comparison key can be used to temporarily disengage memory security. This key mechanism can be accessed only through user code running in secure memory. (A security key cannot be entered directly through background debug commands.) This security key can be disabled completely by programming the KEYEN bit to 0. If the security key is disabled, the MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 47 Memory only way to disengage security is by mass erasing the FLASH if needed (normally through the background debug interface) and verifying that FLASH is blank. To avoid returning to secure mode after the next reset, program the security bits (SEC01:SEC00) to the unsecured state (1:0). 4.3 RAM The MC9S08GT16A/GT8A includes static RAM. The locations in RAM below 0x0100 can be accessed using the more efficient direct addressing mode, and any single bit in this area can be accessed with the bit manipulation instructions (BCLR, BSET, BRCLR, and BRSET). Locating the most frequently accessed program variables in this area of RAM is preferred. The RAM retains data when the MCU is in low-power wait, stop2, or stop3 mode. At power-on or after wakeup from stop1, the contents of RAM are uninitialized. RAM data is unaffected by any reset provided that the supply voltage does not drop below the minimum value for RAM retention. For compatibility with older M68HC05 MCUs, the HCS08 resets the stack pointer to 0x00FF. In the MC9S08GT16A/GT8A, it is usually best to re-initialize the stack pointer to the top of the RAM so the direct page RAM can be used for frequently accessed RAM variables and bit-addressable program variables. Include the following 2-instruction sequence in your reset initialization routine (where RamLast is equated to the highest address of the RAM in the Freescale-provided equate file). LDHX TXS #RamLast+1 ;point one past RAM ;SP EXPECTED = 500 (RUNNING TOO FAST) ICGTRM = ICGTRM - 128 / (2**n) (DECREASING ICGTRM INCREASES THE FREQUENCY) ICGTRM = ICGTRM + 128 / (2**n) (INCREASING ICGTRM DECREASES THE FREQUENCY) STORE ICGTRM VALUE IN NON-VOLATILE MEMORY CONTINUE n = n+1 YES IS n > 8? NO Figure 9-17. Trim Procedure In this particular case, the MCU has been attached to a PCB and the entire assembly is undergoing final test with automated test equipment. A separate signal or message is provided to the MCU operating under user provided software control. The MCU initiates a trim procedure as outlined in Figure 9-17 while the tester supplies a precision reference signal. If the intended bus frequency is near the maximum allowed for the device, it is recommended to trim using a reduction divisor (R) twice the final value. After the trim procedure is complete, the reduction divisor can be restored. This will prevent accidental overshoot of the maximum clock frequency. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 151 Internal Clock Generator (S08ICGV4) MC9S08GT16A/GT8A Data Sheet, Rev. 1 152 Freescale Semiconductor Chapter 10 Timer/PWM (S08TPMV2) 10.1 Introduction The MC9S08GT16A/GT8A includes two independent timer/PWM (TPM) modules which support traditional input capture, output compare, or buffered edge-aligned pulse-width modulation (PWM) on each channel. A control bit in each TPM configures all channels in that timer to operate as center-aligned PWM functions. In each of these two TPMs, timing functions are based on a separate 16-bit counter with prescaler and modulo features to control frequency and range (period between overflows) of the time reference. This timing system is ideally suited for a wide range of control applications, and the center-aligned PWM capability on the 3-channel TPM extends the field of applications to motor control in small appliances. The use of the fixed system clock, XCLK, as the clock source for either of the TPM modules allows the TPM prescaler to run using the oscillator rate divided by two (ICGERCLK/2). This clock source must be selected only if the ICG is configured in either FBE or FEE mode. In FBE mode, this selection is redundant because the BUSCLK frequency is the same as XCLK. In FEE mode, the proper conditions must be met for XCLK to equal ICGERCLK/2. Selecting XCLK as the clock source with the ICG in either FEI or SCM mode will result in the TPM being non-functional. 10.1.1 Features The timer system in the MC9S08GT16A includes a 3-channel TPM1 and a separate 5-channel TPM2; the timer system in the MC9S08GT8A includes two 2-channel modules, TPM1 and TPM2. Timer system features include: • A total of eight channels: — Each channel may be input capture, output compare, or buffered edge-aligned PWM — Rising-edge, falling-edge, or any-edge input capture trigger — Set, clear, or toggle output compare action — Selectable polarity on PWM outputs • Each TPM may be configured for buffered, center-aligned pulse-width modulation (CPWM) on all channels • Clock source to prescaler for each TPM is independently selectable as bus clock, fixed system clock, or an external pin • Prescale taps for divide by 1, 2, 4, 8, 16, 32, 64, or 128 • 16-bit free-running or up/down (CPWM) count operation • 16-bit modulus register to control counter range • Timer system enable • One interrupt per channel plus terminal count interrupt MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 153 Timer/PWM (S08TPMV2) VREFL VREFH VSSAD VDDAD 4 HCS08 CORE BKGD CPU BDC 10-BIT ANALOG-TO-DIGITAL CONVERTER (ATD) 8 PORT B 4 4 8-BIT KEYBOARD INTERRUPT (KBI) PORT A 8 4 PTA7/KBIP7– PTA4/KBIP4 PTA3/KBIP3– PTA0/KBIP0 PTB7/ADP7– PTB4/ADP4 PTB3/ADP3– PTB0/ADP0 PTC7 PTC6 PTC5 PTC4 PTC3/SCL PTC2/SDA PTC1/RxD2 PTC0/TxD2 NOTE 6 HCS08 SYSTEM CONTROL RESET NOTE 4 RESETS AND INTERRUPTS MODES OF OPERATION POWER MANAGEMENT PORT C RTI IRQ NOTES 2, 3 IRQ COP LVD INTER-IC (IIC) SERIAL COMMUNICATIONS INTERFACE (SCI2) SCL SDA RXD2 TXD2 CH1 CH0 CH0 CH1 CH2 SPSCK MOSI MISO SS RXD1 TXD1 NOTE 5 PORT D USER FLASH (GT16A = 16,384 BYTES) (GT8A = 8192 BYTES) 2-CHANNEL TIMER/PWM (TPM2) PTD4/TPM2CH1 PTD3/TPM2CLK/TPM2CH0 PTD2/TPM1CH2 PTD1/TPM1CH1 PTD0/TPM1CLK/TPM1CH0 PTE5/SPSCK PTE4/MOSI PTE3/MISO PTE2/SS PTE1/RxD1 PTE0/TxD1 PTG3 PTG2/EXTAL PTG1/XTAL PTG0/BKGD/MS USER RAM (GT16A = 2048 BYTES) (GT8A = 1024 BYTES) 3-CHANNEL TIMER/PWM (TPM1) ON-CHIP ICE DEBUG MODULE (DBG) INTERNAL CLOCK GENERATOR (ICG) LOW-POWER OSCILLATOR VDD VSS VSS SERIAL COMMUNICATIONS INTERFACE (SCI1) VOLTAGE REGULATOR = Pins not available in 44-, 42-, or 32-pin packages = Pins not available in 42- or 32-pin packages = Pins not available in 32-pin packages NOTES: 1. Port pins are software configurable with pullup device if input port. 2. Pin contains pullup/pulldown device if IRQ enabled (IRQPE = 1). 3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD. 4. Pin contains integrated pullup device. 5. High current drive 6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available when KBI enabled (KBIPn = 1). Figure 10-1. Block Diagram Highlighting the TPM Modules MC9S08GT16A/GT8A Data Sheet, Rev. 1 154 Freescale Semiconductor PORT G EXTAL XTAL BKGD PORT E SERIAL PERIPHERAL INTERFACE (SPI) Timer/Pulse-Width Modulator (S08TPMV2) 10.1.2 Features The TPM has the following features: • Each TPM may be configured for buffered, center-aligned pulse-width modulation (CPWM) on all channels • Clock sources independently selectable per TPM (multiple TPMs device) • Selectable clock sources (device dependent): bus clock, fixed system clock, external pin • Clock prescaler taps for divide by 1, 2, 4, 8, 16, 32, 64, or 128 • 16-bit free-running or up/down (CPWM) count operation • 16-bit modulus register to control counter range • Timer system enable • One interrupt per channel plus a terminal count interrupt for each TPM module (multiple TPMs device) • Channel features: — Each channel may be input capture, output compare, or buffered edge-aligned PWM — Rising-edge, falling-edge, or any-edge input capture trigger — Set, clear, or toggle output compare action — Selectable polarity on PWM outputs 10.1.3 Block Diagram Figure 10-2 shows the structure of a TPM. Some MCUs include more than one TPM, with various numbers of channels. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 155 Timer/Pulse-Width Modulator (S08TPMV2) BUSCLK XCLK TPMxCLK SYNC CLOCK SOURCE SELECT OFF, BUS, XCLK, EXT PRESCALE AND SELECT DIVIDE BY 1, 2, 4, 8, 16, 32, 64, or 128 CLKSB CPWMS MAIN 16-BIT COUNTER CLKSA PS2 PS1 PS0 COUNTER RESET 16-BIT COMPARATOR TPMxMODH:TPMxMODL CHANNEL 0 16-BIT COMPARATOR TPMxC0VH:TPMxC0VL 16-BIT LATCH MS0B MS0A CH0IE CH0F ELS0B ELS0A TOF TOIE INTERRUPT LOGIC PORT LOGIC TPMxCH0 INTERRUPT LOGIC INTERNAL BUS CHANNEL 1 16-BIT COMPARATOR TPMxC1VH:TPMxC1VL 16-BIT LATCH ELS1B ELS1A PORT LOGIC CH1F INTERRUPT LOGIC TPMxCH1 MS1B MS1A CH1IE ... ... CHANNEL n 16-BIT COMPARATOR TPMxCnVH:TPMxCnVL 16-BIT LATCH MSnB MSnA CHnIE CHnF ELSnB ELSnA ... PORT LOGIC TPMxCHn INTERRUPT LOGIC Figure 10-2. TPM Block Diagram The central component of the TPM is the 16-bit counter that can operate as a free-running counter, a modulo counter, or an up-/down-counter when the TPM is configured for center-aligned PWM. The TPM counter (when operating in normal up-counting mode) provides the timing reference for the input capture, output compare, and edge-aligned PWM functions. The timer counter modulo registers, TPMxMODH:TPMxMODL, control the modulo value of the counter. (The values 0x0000 or 0xFFFF effectively make the counter free running.) Software can read the counter value at any time without affecting the counting sequence. Any write to either byte of the TPMxCNT counter resets the counter regardless of the data value written. MC9S08GT16A/GT8A Data Sheet, Rev. 1 156 Freescale Semiconductor Timer/Pulse-Width Modulator (S08TPMV2) All TPM channels are programmable independently as input capture, output compare, or buffered edge-aligned PWM channels. 10.2 External Signal Description When any pin associated with the timer is configured as a timer input, a passive pullup can be enabled. After reset, the TPM modules are disabled and all pins default to general-purpose inputs with the passive pullups disabled. 10.2.1 External TPM Clock Sources When control bits CLKSB:CLKSA in the timer status and control register are set to 1:1, the prescaler and consequently the 16-bit counter for TPMx are driven by an external clock source, TPMxCLK, connected to an I/O pin. A synchronizer is needed between the external clock and the rest of the TPM. This synchronizer is clocked by the bus clock so the frequency of the external source must be less than one-half the frequency of the bus rate clock. The upper frequency limit for this external clock source is specified to be one-fourth the bus frequency to conservatively accommodate duty cycle and phase-locked loop (PLL) or frequency-locked loop (FLL) frequency jitter effects. On some devices the external clock input is shared with one of the TPM channels. When a TPM channel is shared as the external clock input, the associated TPM channel cannot use the pin. (The channel can still be used in output compare mode as a software timer.) Also, if one of the TPM channels is used as the external clock input, the corresponding ELSnB:ELSnA control bits must be set to 0:0 so the channel is not trying to use the same pin. 10.2.2 TPMxCHn — TPMx Channel n I/O Pins Each TPM channel is associated with an I/O pin on the MCU. The function of this pin depends on the configuration of the channel. In some cases, no pin function is needed so the pin reverts to being controlled by general-purpose I/O controls. When a timer has control of a port pin, the port data and data direction registers do not affect the related pin(s). See the Pins and Connections chapter for additional information about shared pin functions. 10.3 Register Definition The TPM includes: • An 8-bit status and control register (TPMxSC) • A 16-bit counter (TPMxCNTH:TPMxCNTL) • A 16-bit modulo register (TPMxMODH:TPMxMODL) Each timer channel has: • An 8-bit status and control register (TPMxCnSC) • A 16-bit channel value register (TPMxCnVH:TPMxCnVL) Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address assignments for all TPM registers. This section refers to registers and control bits only by their names. A MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 157 Timer/Pulse-Width Modulator (S08TPMV2) Freescale-provided equate or header file is used to translate these names into the appropriate absolute addresses. Some MCU systems have more than one TPM, so register names include placeholder characters to identify which TPM and which channel is being referenced. For example, TPMxCnSC refers to timer (TPM) x, channel n and TPM1C2SC is the status and control register for timer 1, channel 2. 10.3.1 Timer x Status and Control Register (TPMxSC) TPMxSC contains the overflow status flag and control bits that are used to configure the interrupt enable, TPM configuration, clock source, and prescale divisor. These controls relate to all channels within this timer module. 7 6 5 4 3 2 1 0 R W Reset TOF TOIE 0 0 CPWMS 0 CLKSB 0 CLKSA 0 PS2 0 PS1 0 PS0 0 = Unimplemented or Reserved Figure 10-3. Timer x Status and Control Register (TPMxSC) Table 10-1. TPMxSC Register Field Descriptions Field 7 TOF Description Timer Overflow Flag — This flag is set when the TPM counter changes to 0x0000 after reaching the modulo value programmed in the TPM counter modulo registers. When the TPM is configured for CPWM, TOF is set after the counter has reached the value in the modulo register, at the transition to the next lower count value. Clear TOF by reading the TPM status and control register when TOF is set and then writing a 0 to TOF. If another TPM overflow occurs before the clearing sequence is complete, the sequence is reset so TOF would remain set after the clear sequence was completed for the earlier TOF. Reset clears TOF. Writing a 1 to TOF has no effect. 0 TPM counter has not reached modulo value or overflow 1 TPM counter has overflowed Timer Overflow Interrupt Enable — This read/write bit enables TPM overflow interrupts. If TOIE is set, an interrupt is generated when TOF equals 1. Reset clears TOIE. 0 TOF interrupts inhibited (use software polling) 1 TOF interrupts enabled Center-Aligned PWM Select — This read/write bit selects CPWM operating mode. Reset clears this bit so the TPM operates in up-counting mode for input capture, output compare, and edge-aligned PWM functions. Setting CPWMS reconfigures the TPM to operate in up-/down-counting mode for CPWM functions. Reset clears CPWMS. 0 All TPMx channels operate as input capture, output compare, or edge-aligned PWM mode as selected by the MSnB:MSnA control bits in each channel’s status and control register 1 All TPMx channels operate in center-aligned PWM mode Clock Source Select — As shown in Table 10-2, this 2-bit field is used to disable the TPM system or select one of three clock sources to drive the counter prescaler. The external source and the XCLK are synchronized to the bus clock by an on-chip synchronization circuit. Prescale Divisor Select — This 3-bit field selects one of eight divisors for the TPM clock input as shown in Table 10-3. This prescaler is located after any clock source synchronization or clock source selection, so it affects whatever clock source is selected to drive the TPM system. 6 TOIE 5 CPWMS 4:3 CLKS[B:A] 2:0 PS[2:0] MC9S08GT16A/GT8A Data Sheet, Rev. 1 158 Freescale Semiconductor Timer/Pulse-Width Modulator (S08TPMV2) Table 10-2. TPM Clock Source Selection CLKSB:CLKSA 0:0 0:1 1:0 1:1 1 TPM Clock Source to Prescaler Input No clock selected (TPMx disabled) Bus rate clock (BUSCLK) Fixed system clock (XCLK) External source (TPMxCLK)1,2 The maximum frequency that is allowed as an external clock is one-fourth of the bus frequency. 2 If the external clock input is shared with channel n and is selected as the TPM clock source, the corresponding ELSnB:ELSnA control bits should be set to 0:0 so channel n does not try to use the same pin for a conflicting function. Table 10-3. Prescale Divisor Selection PS2:PS1:PS0 0:0:0 0:0:1 0:1:0 0:1:1 1:0:0 1:0:1 1:1:0 1:1:1 TPM Clock Source Divided-By 1 2 4 8 16 32 64 128 10.3.2 Timer x Counter Registers (TPMxCNTH:TPMxCNTL) The two read-only TPM counter registers contain the high and low bytes of the value in the TPM counter. Reading either byte (TPMxCNTH or TPMxCNTL) latches the contents of both bytes into a buffer where they remain latched until the other byte is read. This allows coherent 16-bit reads in either order. The coherency mechanism is automatically restarted by an MCU reset, a write of any value to TPMxCNTH or TPMxCNTL, or any write to the timer status/control register (TPMxSC). Reset clears the TPM counter registers. 7 6 5 4 3 2 1 0 R W Reset Bit 15 14 13 12 11 10 9 Bit 8 Any write to TPMxCNTH clears the 16-bit counter. 0 0 0 0 0 0 0 0 Figure 10-4. Timer x Counter Register High (TPMxCNTH) MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 159 Timer/Pulse-Width Modulator (S08TPMV2) 7 6 5 4 3 2 1 0 R W Reset Bit 7 6 5 4 3 2 1 Bit 0 Any write to TPMxCNTL clears the 16-bit counter. 0 0 0 0 0 0 0 0 Figure 10-5. Timer x Counter Register Low (TPMxCNTL) When background mode is active, the timer counter and the coherency mechanism are frozen such that the buffer latches remain in the state they were in when the background mode became active even if one or both bytes of the counter are read while background mode is active. 10.3.3 Timer x Counter Modulo Registers (TPMxMODH:TPMxMODL) The read/write TPM modulo registers contain the modulo value for the TPM counter. After the TPM counter reaches the modulo value, the TPM counter resumes counting from 0x0000 at the next clock (CPWMS = 0) or starts counting down (CPWMS = 1), and the overflow flag (TOF) becomes set. Writing to TPMxMODH or TPMxMODL inhibits TOF and overflow interrupts until the other byte is written. Reset sets the TPM counter modulo registers to 0x0000, which results in a free-running timer counter (modulo disabled). 7 6 5 4 3 2 1 0 R Bit 15 W Reset 0 0 0 0 0 0 0 0 14 13 12 11 10 9 Bit 8 Figure 10-6. Timer x Counter Modulo Register High (TPMxMODH) 7 6 5 4 3 2 1 0 R Bit 7 W Reset 0 0 0 0 0 0 0 0 6 5 4 3 2 1 Bit 0 Figure 10-7. Timer x Counter Modulo Register Low (TPMxMODL) It is good practice to wait for an overflow interrupt so both bytes of the modulo register can be written well before a new overflow. An alternative approach is to reset the TPM counter before writing to the TPM modulo registers to avoid confusion about when the first counter overflow will occur. MC9S08GT16A/GT8A Data Sheet, Rev. 1 160 Freescale Semiconductor Timer/Pulse-Width Modulator (S08TPMV2) 10.3.4 Timer x Channel n Status and Control Register (TPMxCnSC) TPMxCnSC contains the channel interrupt status flag and control bits that are used to configure the interrupt enable, channel configuration, and pin function. 7 6 5 4 3 2 1 0 R CHnF W Reset 0 0 0 0 0 0 CHnIE MSnB MSnA ELSnB ELSnA 0 0 0 0 = Unimplemented or Reserved Figure 10-8. Timer x Channel n Status and Control Register (TPMxCnSC) Table 10-4. TPMxCnSC Register Field Descriptions Field 7 CHnF Description Channel n Flag — When channel n is configured for input capture, this flag bit is set when an active edge occurs on the channel n pin. When channel n is an output compare or edge-aligned PWM channel, CHnF is set when the value in the TPM counter registers matches the value in the TPM channel n value registers. This flag is seldom used with center-aligned PWMs because it is set every time the counter matches the channel value register, which correspond to both edges of the active duty cycle period. A corresponding interrupt is requested when CHnF is set and interrupts are enabled (CHnIE = 1). Clear CHnF by reading TPMxCnSC while CHnF is set and then writing a 0 to CHnF. If another interrupt request occurs before the clearing sequence is complete, the sequence is reset so CHnF would remain set after the clear sequence was completed for the earlier CHnF. This is done so a CHnF interrupt request cannot be lost by clearing a previous CHnF. Reset clears CHnF. Writing a 1 to CHnF has no effect. 0 No input capture or output compare event occurred on channel n 1 Input capture or output compare event occurred on channel n Channel n Interrupt Enable — This read/write bit enables interrupts from channel n. Reset clears CHnIE. 0 Channel n interrupt requests disabled (use software polling) 1 Channel n interrupt requests enabled Mode Select B for TPM Channel n — When CPWMS = 0, MSnB = 1 configures TPM channel n for edge-aligned PWM mode. For a summary of channel mode and setup controls, refer to Table 10-5. Mode Select A for TPM Channel n — When CPWMS = 0 and MSnB = 0, MSnA configures TPM channel n for input capture mode or output compare mode. Refer to Table 10-5 for a summary of channel mode and setup controls. Edge/Level Select Bits — Depending on the operating mode for the timer channel as set by CPWMS:MSnB:MSnA and shown in Table 10-5, these bits select the polarity of the input edge that triggers an input capture event, select the level that will be driven in response to an output compare match, or select the polarity of the PWM output. Setting ELSnB:ELSnA to 0:0 configures the related timer pin as a general-purpose I/O pin unrelated to any timer channel functions. This function is typically used to temporarily disable an input capture channel or to make the timer pin available as a general-purpose I/O pin when the associated timer channel is set up as a software timer that does not require the use of a pin. 6 CHnIE 5 MSnB 4 MSnA 3:2 ELSn[B:A] MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 161 Timer/Pulse-Width Modulator (S08TPMV2) Table 10-5. Mode, Edge, and Level Selection CPWMS X 0 MSnB:MSnA XX 00 ELSnB:ELSnA 00 01 10 11 01 00 01 10 11 1X 1 XX 10 X1 10 X1 Edge-aligned PWM Center-aligned PWM Output compare Mode Configuration Pin not used for TPM channel; use as an external clock for the TPM or revert to general-purpose I/O Input capture Capture on rising edge only Capture on falling edge only Capture on rising or falling edge Software compare only Toggle output on compare Clear output on compare Set output on compare High-true pulses (clear output on compare) Low-true pulses (set output on compare) High-true pulses (clear output on compare-up) Low-true pulses (set output on compare-up) If the associated port pin is not stable for at least two bus clock cycles before changing to input capture mode, it is possible to get an unexpected indication of an edge trigger. Typically, a program would clear status flags after changing channel configuration bits and before enabling channel interrupts or using the status flags to avoid any unexpected behavior. 10.3.5 Timer x Channel Value Registers (TPMxCnVH:TPMxCnVL) These read/write registers contain the captured TPM counter value of the input capture function or the output compare value for the output compare or PWM functions. The channel value registers are cleared by reset. 7 6 5 4 3 2 1 0 R Bit 15 W Reset 0 0 0 0 0 0 0 0 14 13 12 11 10 9 Bit 8 Figure 10-9. Timer x Channel Value Register High (TPMxCnVH) 7 6 5 4 3 2 1 0 R Bit 7 W Reset 0 0 0 0 0 0 0 0 6 5 4 3 2 1 Bit 0 Figure 10-10. Timer Channel Value Register Low (TPMxCnVL) In input capture mode, reading either byte (TPMxCnVH or TPMxCnVL) latches the contents of both bytes into a buffer where they remain latched until the other byte is read. This latching mechanism also resets (becomes unlatched) when the TPMxCnSC register is written. MC9S08GT16A/GT8A Data Sheet, Rev. 1 162 Freescale Semiconductor Timer/Pulse-Width Modulator (S08TPMV2) In output compare or PWM modes, writing to either byte (TPMxCnVH or TPMxCnVL) latches the value into a buffer. When both bytes have been written, they are transferred as a coherent 16-bit value into the timer channel value registers. This latching mechanism may be manually reset by writing to the TPMxCnSC register. This latching mechanism allows coherent 16-bit writes in either order, which is friendly to various compiler implementations. 10.4 Functional Description All TPM functions are associated with a main 16-bit counter that allows flexible selection of the clock source and prescale divisor. A 16-bit modulo register also is associated with the main 16-bit counter in the TPM. Each TPM channel is optionally associated with an MCU pin and a maskable interrupt function. The TPM has center-aligned PWM capabilities controlled by the CPWMS control bit in TPMxSC. When CPWMS is set to 1, timer counter TPMxCNT changes to an up-/down-counter and all channels in the associated TPM act as center-aligned PWM channels. When CPWMS = 0, each channel can independently be configured to operate in input capture, output compare, or buffered edge-aligned PWM mode. The following sections describe the main 16-bit counter and each of the timer operating modes (input capture, output compare, edge-aligned PWM, and center-aligned PWM). Because details of pin operation and interrupt activity depend on the operating mode, these topics are covered in the associated mode sections. 10.4.1 Counter All timer functions are based on the main 16-bit counter (TPMxCNTH:TPMxCNTL). This section discusses selection of the clock source, up-counting vs. up-/down-counting, end-of-count overflow, and manual counter reset. After any MCU reset, CLKSB:CLKSA = 0:0 so no clock source is selected and the TPM is inactive. Normally, CLKSB:CLKSA would be set to 0:1 so the bus clock drives the timer counter. The clock source for each of the TPM can be independently selected to be off, the bus clock (BUSCLK), the fixed system clock (XCLK), or an external input. The maximum frequency allowed for the external clock option is one-fourth the bus rate. Refer to Section 10.3.1, “Timer x Status and Control Register (TPMxSC)” and Table 10-2 for more information about clock source selection. When the microcontroller is in active background mode, the TPM temporarily suspends all counting until the microcontroller returns to normal user operating mode. During stop mode, all TPM clocks are stopped; therefore, the TPM is effectively disabled until clocks resume. During wait mode, the TPM continues to operate normally. The main 16-bit counter has two counting modes. When center-aligned PWM is selected (CPWMS = 1), the counter operates in up-/down-counting mode. Otherwise, the counter operates as a simple up-counter. As an up-counter, the main 16-bit counter counts from 0x0000 through its terminal count and then continues with 0x0000. The terminal count is 0xFFFF or a modulus value in TPMxMODH:TPMxMODL. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 163 Timer/Pulse-Width Modulator (S08TPMV2) When center-aligned PWM operation is specified, the counter counts upward from 0x0000 through its terminal count and then counts downward to 0x0000 where it returns to up-counting. Both 0x0000 and the terminal count value (value in TPMxMODH:TPMxMODL) are normal length counts (one timer clock period long). An interrupt flag and enable are associated with the main 16-bit counter. The timer overflow flag (TOF) is a software-accessible indication that the timer counter has overflowed. The enable signal selects between software polling (TOIE = 0) where no hardware interrupt is generated, or interrupt-driven operation (TOIE = 1) where a static hardware interrupt is automatically generated whenever the TOF flag is 1. The conditions that cause TOF to become set depend on the counting mode (up or up/down). In up-counting mode, the main 16-bit counter counts from 0x0000 through 0xFFFF and overflows to 0x0000 on the next counting clock. TOF becomes set at the transition from 0xFFFF to 0x0000. When a modulus limit is set, TOF becomes set at the transition from the value set in the modulus register to 0x0000. When the main 16-bit counter is operating in up-/down-counting mode, the TOF flag gets set as the counter changes direction at the transition from the value set in the modulus register and the next lower count value. This corresponds to the end of a PWM period. (The 0x0000 count value corresponds to the center of a period.) Because the HCS08 MCU is an 8-bit architecture, a coherency mechanism is built into the timer counter for read operations. Whenever either byte of the counter is read (TPMxCNTH or TPMxCNTL), both bytes are captured into a buffer so when the other byte is read, the value will represent the other byte of the count at the time the first byte was read. The counter continues to count normally, but no new value can be read from either byte until both bytes of the old count have been read. The main timer counter can be reset manually at any time by writing any value to either byte of the timer count TPMxCNTH or TPMxCNTL. Resetting the counter in this manner also resets the coherency mechanism in case only one byte of the counter was read before resetting the count. 10.4.2 Channel Mode Selection Provided CPWMS = 0 (center-aligned PWM operation is not specified), the MSnB and MSnA control bits in the channel n status and control registers determine the basic mode of operation for the corresponding channel. Choices include input capture, output compare, and buffered edge-aligned PWM. 10.4.2.1 Input Capture Mode With the input capture function, the TPM can capture the time at which an external event occurs. When an active edge occurs on the pin of an input capture channel, the TPM latches the contents of the TPM counter into the channel value registers (TPMxCnVH:TPMxCnVL). Rising edges, falling edges, or any edge may be chosen as the active edge that triggers an input capture. When either byte of the 16-bit capture register is read, both bytes are latched into a buffer to support coherent 16-bit accesses regardless of order. The coherency sequence can be manually reset by writing to the channel status/control register (TPMxCnSC). An input capture event sets a flag bit (CHnF) that can optionally generate a CPU interrupt request. MC9S08GT16A/GT8A Data Sheet, Rev. 1 164 Freescale Semiconductor Timer/Pulse-Width Modulator (S08TPMV2) 10.4.2.2 Output Compare Mode With the output compare function, the TPM can generate timed pulses with programmable position, polarity, duration, and frequency. When the counter reaches the value in the channel value registers of an output compare channel, the TPM can set, clear, or toggle the channel pin. In output compare mode, values are transferred to the corresponding timer channel value registers only after both 8-bit bytes of a 16-bit register have been written. This coherency sequence can be manually reset by writing to the channel status/control register (TPMxCnSC). An output compare event sets a flag bit (CHnF) that can optionally generate a CPU interrupt request. 10.4.2.3 Edge-Aligned PWM Mode This type of PWM output uses the normal up-counting mode of the timer counter (CPWMS = 0) and can be used when other channels in the same TPM are configured for input capture or output compare functions. The period of this PWM signal is determined by the setting in the modulus register (TPMxMODH:TPMxMODL). The duty cycle is determined by the setting in the timer channel value register (TPMxCnVH:TPMxCnVL). The polarity of this PWM signal is determined by the setting in the ELSnA control bit. Duty cycle cases of 0 percent and 100 percent are possible. As Figure 10-11 shows, the output compare value in the TPM channel registers determines the pulse width (duty cycle) of the PWM signal. The time between the modulus overflow and the output compare is the pulse width. If ELSnA = 0, the counter overflow forces the PWM signal high and the output compare forces the PWM signal low. If ELSnA = 1, the counter overflow forces the PWM signal low and the output compare forces the PWM signal high. OVERFLOW PERIOD PULSE WIDTH OVERFLOW OVERFLOW TPMxC OUTPUT COMPARE OUTPUT COMPARE OUTPUT COMPARE Figure 10-11. PWM Period and Pulse Width (ELSnA = 0) When the channel value register is set to 0x0000, the duty cycle is 0 percent. By setting the timer channel value register (TPMxCnVH:TPMxCnVL) to a value greater than the modulus setting, 100% duty cycle can be achieved. This implies that the modulus setting must be less than 0xFFFF to get 100% duty cycle. Because the HCS08 is a family of 8-bit MCUs, the settings in the timer channel registers are buffered to ensure coherent 16-bit updates and to avoid unexpected PWM pulse widths. Writes to either register, TPMxCnVH or TPMxCnVL, write to buffer registers. In edge-PWM mode, values are transferred to the corresponding timer channel registers only after both 8-bit bytes of a 16-bit register have been written and the value in the TPMxCNTH:TPMxCNTL counter is 0x0000. (The new duty cycle does not take effect until the next full period.) MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 165 Timer/Pulse-Width Modulator (S08TPMV2) 10.4.3 Center-Aligned PWM Mode This type of PWM output uses the up-/down-counting mode of the timer counter (CPWMS = 1). The output compare value in TPMxCnVH:TPMxCnVL determines the pulse width (duty cycle) of the PWM signal and the period is determined by the value in TPMxMODH:TPMxMODL. TPMxMODH:TPMxMODL should be kept in the range of 0x0001 to 0x7FFF because values outside this range can produce ambiguous results. ELSnA will determine the polarity of the CPWM output. pulse width = 2 x (TPMxCnVH:TPMxCnVL) period = 2 x (TPMxMODH:TPMxMODL); for TPMxMODH:TPMxMODL = 0x0001–0x7FFF Eqn. 10-1 Eqn. 10-2 If the channel value register TPMxCnVH:TPMxCnVL is zero or negative (bit 15 set), the duty cycle will be 0%. If TPMxCnVH:TPMxCnVL is a positive value (bit 15 clear) and is greater than the (nonzero) modulus setting, the duty cycle will be 100% because the duty cycle compare will never occur. This implies the usable range of periods set by the modulus register is 0x0001 through 0x7FFE (0x7FFF if generation of 100% duty cycle is not necessary). This is not a significant limitation because the resulting period is much longer than required for normal applications. TPMxMODH:TPMxMODL = 0x0000 is a special case that should not be used with center-aligned PWM mode. When CPWMS = 0, this case corresponds to the counter running free from 0x0000 through 0xFFFF, but when CPWMS = 1 the counter needs a valid match to the modulus register somewhere other than at 0x0000 in order to change directions from up-counting to down-counting. Figure 10-12 shows the output compare value in the TPM channel registers (multiplied by 2), which determines the pulse width (duty cycle) of the CPWM signal. If ELSnA = 0, the compare match while counting up forces the CPWM output signal low and a compare match while counting down forces the output high. The counter counts up until it reaches the modulo setting in TPMxMODH:TPMxMODL, then counts down until it reaches zero. This sets the period equal to two times TPMxMODH:TPMxMODL. COUNT = 0 COUNT = OUTPUT COMPARE (COUNT DOWN) OUTPUT COMPARE (COUNT UP) COUNT = TPMxMODH:TPMx TPMxMODH:TPMx TPM1C PULSE WIDTH 2x 2x PERIOD Figure 10-12. CPWM Period and Pulse Width (ELSnA = 0) Center-aligned PWM outputs typically produce less noise than edge-aligned PWMs because fewer I/O pin transitions are lined up at the same system clock edge. This type of PWM is also required for some types of motor drives. Because the HCS08 is a family of 8-bit MCUs, the settings in the timer channel registers are buffered to ensure coherent 16-bit updates and to avoid unexpected PWM pulse widths. Writes to any of the registers, TPMxMODH, TPMxMODL, TPMxCnVH, and TPMxCnVL, actually write to buffer registers. Values are MC9S08GT16A/GT8A Data Sheet, Rev. 1 166 Freescale Semiconductor Timer/Pulse-Width Modulator (S08TPMV2) transferred to the corresponding timer channel registers only after both 8-bit bytes of a 16-bit register have been written and the timer counter overflows (reverses direction from up-counting to down-counting at the end of the terminal count in the modulus register). This TPMxCNT overflow requirement only applies to PWM channels, not output compares. Optionally, when TPMxCNTH:TPMxCNTL = TPMxMODH:TPMxMODL, the TPM can generate a TOF interrupt at the end of this count. The user can choose to reload any number of the PWM buffers, and they will all update simultaneously at the start of a new period. Writing to TPMxSC cancels any values written to TPMxMODH and/or TPMxMODL and resets the coherency mechanism for the modulo registers. Writing to TPMxCnSC cancels any values written to the channel value registers and resets the coherency mechanism for TPMxCnVH:TPMxCnVL. 10.5 TPM Interrupts The TPM generates an optional interrupt for the main counter overflow and an interrupt for each channel. The meaning of channel interrupts depends on the mode of operation for each channel. If the channel is configured for input capture, the interrupt flag is set each time the selected input capture edge is recognized. If the channel is configured for output compare or PWM modes, the interrupt flag is set each time the main timer counter matches the value in the 16-bit channel value register. See the Resets, Interrupts, and System Configuration chapter for absolute interrupt vector addresses, priority, and local interrupt mask control bits. For each interrupt source in the TPM, a flag bit is set on recognition of the interrupt condition such as timer overflow, channel input capture, or output compare events. This flag may be read (polled) by software to verify that the action has occurred, or an associated enable bit (TOIE or CHnIE) can be set to enable hardware interrupt generation. While the interrupt enable bit is set, a static interrupt will be generated whenever the associated interrupt flag equals 1. It is the responsibility of user software to perform a sequence of steps to clear the interrupt flag before returning from the interrupt service routine. 10.5.1 Clearing Timer Interrupt Flags TPM interrupt flags are cleared by a 2-step process that includes a read of the flag bit while it is set (1) followed by a write of 0 to the bit. If a new event is detected between these two steps, the sequence is reset and the interrupt flag remains set after the second step to avoid the possibility of missing the new event. 10.5.2 Timer Overflow Interrupt Description The conditions that cause TOF to become set depend on the counting mode (up or up/down). In up-counting mode, the 16-bit timer counter counts from 0x0000 through 0xFFFF and overflows to 0x0000 on the next counting clock. TOF becomes set at the transition from 0xFFFF to 0x0000. When a modulus limit is set, TOF becomes set at the transition from the value set in the modulus register to 0x0000. When the counter is operating in up-/down-counting mode, the TOF flag gets set as the counter changes direction at the transition from the value set in the modulus register and the next lower count value. This corresponds to the end of a PWM period. (The 0x0000 count value corresponds to the center of a period.) MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 167 Timer/Pulse-Width Modulator (S08TPMV2) 10.5.3 Channel Event Interrupt Description The meaning of channel interrupts depends on the current mode of the channel (input capture, output compare, edge-aligned PWM, or center-aligned PWM). When a channel is configured as an input capture channel, the ELSnB:ELSnA control bits select rising edges, falling edges, any edge, or no edge (off) as the edge that triggers an input capture event. When the selected edge is detected, the interrupt flag is set. The flag is cleared by the 2-step sequence described in Section 10.5.1, “Clearing Timer Interrupt Flags.” When a channel is configured as an output compare channel, the interrupt flag is set each time the main timer counter matches the 16-bit value in the channel value register. The flag is cleared by the 2-step sequence described in Section 10.5.1, “Clearing Timer Interrupt Flags.” 10.5.4 PWM End-of-Duty-Cycle Events For channels that are configured for PWM operation, there are two possibilities: • When the channel is configured for edge-aligned PWM, the channel flag is set when the timer counter matches the channel value register that marks the end of the active duty cycle period. • When the channel is configured for center-aligned PWM, the timer count matches the channel value register twice during each PWM cycle. In this CPWM case, the channel flag is set at the start and at the end of the active duty cycle, which are the times when the timer counter matches the channel value register. The flag is cleared by the 2-step sequence described in Section 10.5.1, “Clearing Timer Interrupt Flags.” MC9S08GT16A/GT8A Data Sheet, Rev. 1 168 Freescale Semiconductor Chapter 11 Serial Communications Interface (S08SCIV1) 11.1 Introduction The MC9S08GT16A/GT8A includes two independent serial communications interface (SCI) modules — sometimes called universal asynchronous receiver/transmitters (UARTs). Typically, these systems are used to connect to the RS232 serial input/output (I/O) port of a personal computer or workstation, and they can also be used to communicate with other embedded controllers. A flexible, 13-bit, modulo-based baud rate generator supports a broad range of standard baud rates beyond 115.2 kbaud. Transmit and receive within the same SCI use a common baud rate, and each SCI module has a separate baud rate generator. This SCI system offers many advanced features not commonly found on other asynchronous serial I/O peripherals on other embedded controllers. The receiver employs an advanced data sampling technique that ensures reliable communication and noise detection. Hardware parity, receiver wakeup, and double buffering on transmit and receive are also included. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 169 Serial Communications Interface (S08SCIV1) VREFL VREFH VSSAD VDDAD 4 HCS08 CORE BKGD CPU BDC 10-BIT ANALOG-TO-DIGITAL CONVERTER (ATD) 8 PORT B 4 4 8-BIT KEYBOARD INTERRUPT (KBI) PORT A 8 4 PTA7/KBIP7– PTA4/KBIP4 PTA3/KBIP3– PTA0/KBIP0 PTB7/ADP7– PTB4/ADP4 PTB3/ADP3– PTB0/ADP0 PTC7 PTC6 PTC5 PTC4 PTC3/SCL PTC2/SDA PTC1/RxD2 PTC0/TxD2 NOTE 6 HCS08 SYSTEM CONTROL RESET NOTE 4 RESETS AND INTERRUPTS MODES OF OPERATION POWER MANAGEMENT PORT C RTI IRQ NOTES 2, 3 IRQ COP LVD INTER-IC (IIC) SERIAL COMMUNICATIONS INTERFACE (SCI2) SCL SDA RXD2 TXD2 CH1 CH0 CH0 CH1 CH2 SPSCK MOSI MISO SS RXD1 TXD1 NOTE 5 PORT D USER FLASH (GT16A = 16,384 BYTES) (GT8A = 8192 BYTES) 2-CHANNEL TIMER/PWM (TPM2) PTD4/TPM2CH1 PTD3/TPM2CLK/TPM2CH0 PTD2/TPM1CH2 PTD1/TPM1CH1 PTD0/TPM1CLK/TPM1CH0 PTE5/SPSCK PTE4/MOSI PTE3/MISO PTE2/SS PTE1/RxD1 PTE0/TxD1 PTG3 PTG2/EXTAL PTG1/XTAL PTG0/BKGD/MS USER RAM (GT16A = 2048 BYTES) (GT8A = 1024 BYTES) 3-CHANNEL TIMER/PWM (TPM1) ON-CHIP ICE DEBUG MODULE (DBG) INTERNAL CLOCK GENERATOR (ICG) LOW-POWER OSCILLATOR VDD VSS VSS SERIAL COMMUNICATIONS INTERFACE (SCI1) VOLTAGE REGULATOR = Pins not available in 44-, 42-, or 32-pin packages = Pins not available in 42- or 32-pin packages = Pins not available in 32-pin packages NOTES: 1. Port pins are software configurable with pullup device if input port. 2. Pin contains pullup/pulldown device if IRQ enabled (IRQPE = 1). 3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD. 4. Pin contains integrated pullup device. 5. High current drive 6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available when KBI enabled (KBIPn = 1). Figure 11-1. Block Diagram Highlighting the SCI Modules MC9S08GT16A/GT8A Data Sheet, Rev. 1 170 Freescale Semiconductor PORT G EXTAL XTAL BKGD PORT E SERIAL PERIPHERAL INTERFACE (SPI) Serial Communications Interface (S08SCIV1) 11.1.1 Features Features of SCI module include: • Full-duplex, standard non-return-to-zero (NRZ) format • Double-buffered transmitter and receiver with separate enables • Programmable baud rates (13-bit modulo divider) • Interrupt-driven or polled operation: — Transmit data register empty and transmission complete — Receive data register full — Receive overrun, parity error, framing error, and noise error — Idle receiver detect • Hardware parity generation and checking • Programmable 8-bit or 9-bit character length • Receiver wakeup by idle-line or address-mark 11.1.2 Modes of Operation See Section 11.3, “Functional Description,” for a detailed description of SCI operation in the different modes. • 8- and 9- bit data modes • Stop modes — SCI is halted during all stop modes • Loop modes MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 171 Serial Communications Interface (S08SCIV1) 11.1.3 Block Diagram Figure 11-2 shows the transmitter portion of the SCI. (Figure 11-3 shows the receiver portion of the SCI.) INTERNAL BUS (WRITE-ONLY) LOOPS SCID – Tx BUFFER RSRC LOOP CONTROL STOP M 11-BIT TRANSMIT SHIFT REGISTER 8 7 6 5 4 3 2 1 0 LSB START TO RECEIVE DATA IN 1 × BAUD RATE CLOCK H L TO TxD PIN SHIFT DIRECTION PE PT PARITY GENERATION BREAK (ALL 0s) SCI CONTROLS TxD TE ENABLE SBK TXDIR TRANSMIT CONTROL SHIFT ENABLE T8 PREAMBLE (ALL 1s) LOAD FROM SCIxD TxD DIRECTION TO TxD PIN LOGIC TDRE TIE TC TCIE Tx INTERRUPT REQUEST Figure 11-2. SCI Transmitter Block Diagram MC9S08GT16A/GT8A Data Sheet, Rev. 1 172 Freescale Semiconductor Serial Communications Interface (S08SCIV1) Figure 11-3 shows the receiver portion of the SCI. INTERNAL BUS (READ-ONLY) SCID – Rx BUFFER DIVIDE BY 16 STOP START L 16 × BAUD RATE CLOCK M 11-BIT RECEIVE SHIFT REGISTER 8 7 6 5 4 3 2 1 H ALL 1s MSB FROM RxD PIN DATA RECOVERY SHIFT DIRECTION LOOPS RSRC SINGLE-WIRE LOOP CONTROL WAKE ILT WAKEUP LOGIC RWU FROM TRANSMITTER RDRF RIE IDLE ILIE OR ORIE FE FEIE NF NEIE PE PT PARITY CHECKING PF PEIE ERROR INTERRUPT REQUEST Rx INTERRUPT REQUEST Figure 11-3. SCI Receiver Block Diagram MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 173 LSB 0 Serial Communications Interface (S08SCIV1) 11.2 Register Definition The SCI has eight 8-bit registers to control baud rate, select SCI options, report SCI status, and for transmit/receive data. Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address assignments for all SCI registers. This section refers to registers and control bits only by their names. A Freescale-provided equate or header file is used to translate these names into the appropriate absolute addresses. 11.2.1 SCI Baud Rate Registers (SCIxBDH, SCIxBHL) This pair of registers controls the prescale divisor for SCI baud rate generation. To update the 13-bit baud rate setting [SBR12:SBR0], first write to SCIxBDH to buffer the high half of the new value and then write to SCIxBDL. The working value in SCIxBDH does not change until SCIxBDL is written. SCIxBDL is reset to a non-zero value, so after reset the baud rate generator remains disabled until the first time the receiver or transmitter is enabled (RE or TE bits in SCIxC2 are written to 1). 7 6 5 4 3 2 1 0 R W Reset 0 0 0 SBR12 SBR11 0 SBR10 0 SBR9 0 SBR8 0 0 0 0 0 = Unimplemented or Reserved Figure 11-4. SCI Baud Rate Register (SCIxBDH) Table 11-1. SCIxBDH Register Field Descriptions Field 4:0 SBR[12:8] Description Baud Rate Modulo Divisor — These 13 bits are referred to collectively as BR, and they set the modulo divide rate for the SCI baud rate generator. When BR = 0, the SCI baud rate generator is disabled to reduce supply current. When BR = 1 to 8191, the SCI baud rate = BUSCLK/(16×BR). See also BR bits in Table 11-2. 7 6 5 4 3 2 1 0 R SBR7 W Reset 0 0 0 0 0 1 0 0 SBR6 SBR5 SBR4 SBR3 SBR2 SBR1 SBR0 Figure 11-5. SCI Baud Rate Register (SCIxBDL) Table 11-2. SCIxBDL Register Field Descriptions Field 7:0 SBR[7:0] Description Baud Rate Modulo Divisor — These 13 bits are referred to collectively as BR, and they set the modulo divide rate for the SCI baud rate generator. When BR = 0, the SCI baud rate generator is disabled to reduce supply current. When BR = 1 to 8191, the SCI baud rate = BUSCLK/(16×BR). See also BR bits in Table 11-1. MC9S08GT16A/GT8A Data Sheet, Rev. 1 174 Freescale Semiconductor Serial Communications Interface (S08SCIV1) 11.2.2 SCI Control Register 1 (SCIxC1) This read/write register is used to control various optional features of the SCI system. 7 6 5 4 3 2 1 0 R LOOPS W Reset 0 0 0 0 0 0 0 0 SCISWAI RSRC M WAKE ILT PE PT Figure 11-6. SCI Control Register 1 (SCIxC1) Table 11-3. SCIxC1 Register Field Descriptions Field 7 LOOPS Description Loop Mode Select — Selects between loop back modes and normal 2-pin full-duplex modes. When LOOPS = 1, the transmitter output is internally connected to the receiver input. 0 Normal operation — RxD and TxD use separate pins. 1 Loop mode or single-wire mode where transmitter outputs are internally connected to receiver input. (See RSRC bit.) RxD pin is not used by SCI. SCI Stops in Wait Mode 0 SCI clocks continue to run in wait mode so the SCI can be the source of an interrupt that wakes up the CPU. 1 SCI clocks freeze while CPU is in wait mode. Receiver Source Select — This bit has no meaning or effect unless the LOOPS bit is set to 1. When LOOPS = 1, the receiver input is internally connected to the TxD pin and RSRC determines whether this connection is also connected to the transmitter output. 0 Provided LOOPS = 1, RSRC = 0 selects internal loop back mode and the SCI does not use the RxD pins. 1 Single-wire SCI mode where the TxD pin is connected to the transmitter output and receiver input. 9-Bit or 8-Bit Mode Select 0 Normal — start + 8 data bits (LSB first) + stop. 1 Receiver and transmitter use 9-bit data characters start + 8 data bits (LSB first) + 9th data bit + stop. Receiver Wakeup Method Select — Refer to Section 11.3.3.2, “Receiver Wakeup Operation” for more information. 0 Idle-line wakeup. 1 Address-mark wakeup. Idle Line Type Select — Setting this bit to 1 ensures that the stop bit and logic 1 bits at the end of a character do not count toward the 10 or 11 bit times of the logic high level by the idle line detection logic. Refer to Section 11.3.3.2.1, “Idle-Line Wakeup” for more information. 0 Idle character bit count starts after start bit. 1 Idle character bit count starts after stop bit. Parity Enable — Enables hardware parity generation and checking. When parity is enabled, the most significant bit (MSB) of the data character (eighth or ninth data bit) is treated as the parity bit. 0 No hardware parity generation or checking. 1 Parity enabled. Parity Type — Provided parity is enabled (PE = 1), this bit selects even or odd parity. Odd parity means the total number of 1s in the data character, including the parity bit, is odd. Even parity means the total number of 1s in the data character, including the parity bit, is even. 0 Even parity. 1 Odd parity. 6 SCISWAI 5 RSRC 4 M 3 WAKE 2 ILT 1 PE 0 PT MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 175 Serial Communications Interface (S08SCIV1) 11.2.3 SCI Control Register 2 (SCIxC2) This register can be read or written at any time. 7 6 5 4 3 2 1 0 R TIE W Reset 0 0 0 0 0 0 0 0 TCIE RIE ILIE TE RE RWU SBK Figure 11-7. SCI Control Register 2 (SCIxC2) Table 11-4. SCIxC2 Register Field Descriptions Field 7 TIE 6 TCIE 5 RIE 4 ILIE 3 TE Description Transmit Interrupt Enable (for TDRE) 0 Hardware interrupts from TDRE disabled (use polling). 1 Hardware interrupt requested when TDRE flag is 1. Transmission Complete Interrupt Enable (for TC) 0 Hardware interrupt requested when TC flag is 1. 1 Hardware interrupts from TC disabled (use polling). Receiver Interrupt Enable (for RDRF) 0 Hardware interrupts from RDRF disabled (use polling). 1 Hardware interrupt requested when RDRF flag is 1. Idle Line Interrupt Enable (for IDLE) 0 Hardware interrupts from IDLE disabled (use polling). 1 Hardware interrupt requested when IDLE flag is 1. Transmitter Enable 0 Transmitter off. 1 Transmitter on. TE must be 1 in order to use the SCI transmitter. Normally, when TE = 1, the SCI forces the TxD pin to act as an output for the SCI system. If LOOPS = 1 and RSRC = 0, the TxD pin reverts to being a port B general-purpose I/O pin even if TE = 1. When the SCI is configured for single-wire operation (LOOPS = RSRC = 1), TXDIR controls the direction of traffic on the single SCI communication line (TxD pin). TE also can be used to queue an idle character by writing TE = 0 then TE = 1 while a transmission is in progress. Refer to Section 11.3.2.1, “Send Break and Queued Idle,” for more details. When TE is written to 0, the transmitter keeps control of the port TxD pin until any data, queued idle, or queued break character finishes transmitting before allowing the pin to revert to a general-purpose I/O pin. Receiver Enable — When the SCI receiver is off, the RxD pin reverts to being a general-purpose port I/O pin. 0 Receiver off. 1 Receiver on. 2 RE MC9S08GT16A/GT8A Data Sheet, Rev. 1 176 Freescale Semiconductor Serial Communications Interface (S08SCIV1) Table 11-4. SCIxC2 Register Field Descriptions (continued) Field 1 RWU Description Receiver Wakeup Control — This bit can be written to 1 to place the SCI receiver in a standby state where it waits for automatic hardware detection of a selected wakeup condition. The wakeup condition is either an idle line between messages (WAKE = 0, idle-line wakeup), or a logic 1 in the most significant data bit in a character (WAKE = 1, address-mark wakeup). Application software sets RWU and (normally) a selected hardware condition automatically clears RWU. Refer to Section 11.3.3.2, “Receiver Wakeup Operation,” for more details. 0 Normal SCI receiver operation. 1 SCI receiver in standby waiting for wakeup condition. Send Break — Writing a 1 and then a 0 to SBK queues a break character in the transmit data stream. Additional break characters of 10 or 11 bit times of logic 0 are queued as long as SBK = 1. Depending on the timing of the set and clear of SBK relative to the information currently being transmitted, a second break character may be queued before software clears SBK. Refer to Section 11.3.2.1, “Send Break and Queued Idle,” for more details. 0 Normal transmitter operation. 1 Queue break character(s) to be sent. 0 SBK 11.2.4 SCI Status Register 1 (SCIxS1) This register has eight read-only status flags. Writes have no effect. Special software sequences (which do not involve writing to this register) are used to clear these status flags. 7 6 5 4 3 2 1 0 R W Reset TDRE TC RDRF IDLE OR NF FE PF 1 1 0 0 0 0 0 0 = Unimplemented or Reserved Figure 11-8. SCI Status Register 1 (SCIxS1) Table 11-5. SCIxS1 Register Field Descriptions Field 7 TDRE Description Transmit Data Register Empty Flag — TDRE is set immediately after reset and when a transmit data value transfers from the transmit data buffer to the transmit shifter, leaving room for a new character in the buffer. To clear TDRE, read SCIxS1 with TDRE = 1 and then write to the SCI data register (SCIxD). 0 Transmit data register (buffer) full. 1 Transmit data register (buffer) empty. Transmission Complete Flag — TC is set immediately after reset and when TDRE = 1 and no data, preamble, or break character is being transmitted. 0 Transmitter active (sending data, a preamble, or a break). 1 Transmitter idle (transmission activity complete). TC is cleared automatically by reading SCIxS1 with TC = 1 and then doing one of the following three things: • Write to the SCI data register (SCIxD) to transmit new data • Queue a preamble by changing TE from 0 to 1 • Queue a break character by writing 1 to SBK in SCIxC2 6 TC MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 177 Serial Communications Interface (S08SCIV1) Table 11-5. SCIxS1 Register Field Descriptions (continued) Field 5 RDRF Description Receive Data Register Full Flag — RDRF becomes set when a character transfers from the receive shifter into the receive data register (SCIxD). To clear RDRF, read SCIxS1 with RDRF = 1 and then read the SCI data register (SCIxD). 0 Receive data register empty. 1 Receive data register full. Idle Line Flag — IDLE is set when the SCI receive line becomes idle for a full character time after a period of activity. When ILT = 0, the receiver starts counting idle bit times after the start bit. So if the receive character is all 1s, these bit times and the stop bit time count toward the full character time of logic high (10 or 11 bit times depending on the M control bit) needed for the receiver to detect an idle line. When ILT = 1, the receiver doesn’t start counting idle bit times until after the stop bit. So the stop bit and any logic high bit times at the end of the previous character do not count toward the full character time of logic high needed for the receiver to detect an idle line. To clear IDLE, read SCIxS1 with IDLE = 1 and then read the SCI data register (SCIxD). After IDLE has been cleared, it cannot become set again until after a new character has been received and RDRF has been set. IDLE will get set only once even if the receive line remains idle for an extended period. 0 No idle line detected. 1 Idle line was detected. Receiver Overrun Flag — OR is set when a new serial character is ready to be transferred to the receive data register (buffer), but the previously received character has not been read from SCIxD yet. In this case, the new character (and all associated error information) is lost because there is no room to move it into SCIxD. To clear OR, read SCIxS1 with OR = 1 and then read the SCI data register (SCIxD). 0 No overrun. 1 Receive overrun (new SCI data lost). Noise Flag — The advanced sampling technique used in the receiver takes seven samples during the start bit and three samples in each data bit and the stop bit. If any of these samples disagrees with the rest of the samples within any bit time in the frame, the flag NF will be set at the same time as the flag RDRF gets set for the character. To clear NF, read SCIxS1 and then read the SCI data register (SCIxD). 0 No noise detected. 1 Noise detected in the received character in SCIxD. Framing Error Flag — FE is set at the same time as RDRF when the receiver detects a logic 0 where the stop bit was expected. This suggests the receiver was not properly aligned to a character frame. To clear FE, read SCIxS1 with FE = 1 and then read the SCI data register (SCIxD). 0 No framing error detected. This does not guarantee the framing is correct. 1 Framing error. Parity Error Flag — PF is set at the same time as RDRF when parity is enabled (PE = 1) and the parity bit in the received character does not agree with the expected parity value. To clear PF, read SCIxS1 and then read the SCI data register (SCIxD). 0 No parity error. 1 Parity error. 4 IDLE 3 OR 2 NF 1 FE 0 PF MC9S08GT16A/GT8A Data Sheet, Rev. 1 178 Freescale Semiconductor Serial Communications Interface (S08SCIV1) 11.2.5 SCI Status Register 2 (SCIxS2) This register has one read-only status flag. Writes have no effect. 7 6 5 4 3 2 1 0 R W Reset 0 0 0 0 0 0 0 RAF 0 0 0 0 0 0 0 0 = Unimplemented or Reserved Figure 11-9. SCI Status Register 2 (SCIxS2) Table 11-6. SCIxS2 Register Field Descriptions Field 0 RAF Description Receiver Active Flag — RAF is set when the SCI receiver detects the beginning of a valid start bit, and RAF is cleared automatically when the receiver detects an idle line. This status flag can be used to check whether an SCI character is being received before instructing the MCU to go to stop mode. 0 SCI receiver idle waiting for a start bit. 1 SCI receiver active (RxD input not idle). 11.2.6 SCI Control Register 3 (SCIxC3) 7 6 5 4 3 2 1 0 R W Reset R8 T8 0 0 TXDIR 0 0 ORIE 0 0 NEIE 0 FEIE 0 PEIE 0 = Unimplemented or Reserved Figure 11-10. SCI Control Register 3 (SCIxC3) Table 11-7. SCIxC3 Register Field Descriptions Field 7 R8 Description Ninth Data Bit for Receiver — When the SCI is configured for 9-bit data (M = 1), R8 can be thought of as a ninth receive data bit to the left of the MSB of the buffered data in the SCIxD register. When reading 9-bit data, read R8 before reading SCIxD because reading SCIxD completes automatic flag clearing sequences which could allow R8 and SCIxD to be overwritten with new data. Ninth Data Bit for Transmitter — When the SCI is configured for 9-bit data (M = 1), T8 may be thought of as a ninth transmit data bit to the left of the MSB of the data in the SCIxD register. When writing 9-bit data, the entire 9-bit value is transferred to the SCI shift register after SCIxD is written so T8 should be written (if it needs to change from its previous value) before SCIxD is written. If T8 does not need to change in the new value (such as when it is used to generate mark or space parity), it need not be written each time SCIxD is written. TxD Pin Direction in Single-Wire Mode — When the SCI is configured for single-wire half-duplex operation (LOOPS = RSRC = 1), this bit determines the direction of data at the TxD pin. 0 TxD pin is an input in single-wire mode. 1 TxD pin is an output in single-wire mode. 6 T8 5 TXDIR MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 179 Serial Communications Interface (S08SCIV1) Table 11-7. SCIxC3 Register Field Descriptions (continued) Field 3 ORIE 2 NEIE 1 FEIE Description Overrun Interrupt Enable — This bit enables the overrun flag (OR) to generate hardware interrupt requests. 0 OR interrupts disabled (use polling). 1 Hardware interrupt requested when OR = 1. Noise Error Interrupt Enable — This bit enables the noise flag (NF) to generate hardware interrupt requests. 0 NF interrupts disabled (use polling). 1 Hardware interrupt requested when NF = 1. Framing Error Interrupt Enable — This bit enables the framing error flag (FE) to generate hardware interrupt requests. 0 FE interrupts disabled (use polling). 1 Hardware interrupt requested when FE = 1. Parity Error Interrupt Enable — This bit enables the parity error flag (PF) to generate hardware interrupt requests. 0 PF interrupts disabled (use polling). 1 Hardware interrupt requested when PF = 1. 0 PEIE 11.2.7 SCI Data Register (SCIxD) This register is actually two separate registers. Reads return the contents of the read-only receive data buffer and writes go to the write-only transmit data buffer. Reads and writes of this register are also involved in the automatic flag clearing mechanisms for the SCI status flags. 7 6 5 4 3 2 1 0 R W Reset R7 T7 0 R6 T6 0 R5 T5 0 R4 T4 0 R3 T3 0 R2 T2 0 R1 T1 0 R0 T0 0 Figure 11-11. SCI Data Register (SCIxD) MC9S08GT16A/GT8A Data Sheet, Rev. 1 180 Freescale Semiconductor Serial Communications Interface (S08SCIV1) 11.3 Functional Description The SCI allows full-duplex, asynchronous, NRZ serial communication among the MCU and remote devices, including other MCUs. The SCI comprises a baud rate generator, transmitter, and receiver block. The transmitter and receiver operate independently, although they use the same baud rate generator. During normal operation, the MCU monitors the status of the SCI, writes the data to be transmitted, and processes received data. The following describes each of the blocks of the SCI. 11.3.1 Baud Rate Generation As shown in Figure 11-12, the clock source for the SCI baud rate generator is the bus-rate clock. MODULO DIVIDE BY (1 THROUGH 8191) DIVIDE BY 16 Tx BAUD RATE BUSCLK SBR12:SBR0 BAUD RATE GENERATOR OFF IF [SBR12:SBR0] = 0 Rx SAMPLING CLOCK (16 × BAUD RATE) BAUD RATE = BUSCLK [SBR12:SBR0] × 16 Figure 11-12. SCI Baud Rate Generation SCI communications require the transmitter and receiver (which typically derive baud rates from independent clock sources) to use the same baud rate. Allowed tolerance on this baud frequency depends on the details of how the receiver synchronizes to the leading edge of the start bit and how bit sampling is performed. The MCU resynchronizes to bit boundaries on every high-to-low transition, but in the worst case, there are no such transitions in the full 10- or 11-bit time character frame so any mismatch in baud rate is accumulated for the whole character time. For a Freescale Semiconductor SCI system whose bus frequency is driven by a crystal, the allowed baud rate mismatch is about ±4.5 percent for 8-bit data format and about ±4 percent for 9-bit data format. Although baud rate modulo divider settings do not always produce baud rates that exactly match standard rates, it is normally possible to get within a few percent, which is acceptable for reliable communications. 11.3.2 Transmitter Functional Description This section describes the overall block diagram for the SCI transmitter (Figure 11-2), as well as specialized functions for sending break and idle characters. The transmitter is enabled by setting the TE bit in SCIxC2. This queues a preamble character that is one full character frame of the idle state. The transmitter then remains idle until data is available in the transmit data buffer. Programs store data into the transmit data buffer by writing to the SCI data register (SCIxD). The central element of the SCI transmitter is the transmit shift register that is either 10 or 11 bits long depending on the setting in the M control bit. For the remainder of this section, we will assume M = 0, selecting the normal 8-bit data mode. In 8-bit data mode, the shift register holds a start bit, eight data bits, and a stop bit. When the transmit shift register is available for a new SCI character, the value waiting in MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 181 Serial Communications Interface (S08SCIV1) the transmit data register is transferred to the shift register (synchronized with the baud rate clock) and the transmit data register empty (TDRE) status flag is set to indicate another character may be written to the transmit data buffer at SCIxD. If no new character is waiting in the transmit data buffer after a stop bit is shifted out the TxD1 pin, the transmitter sets the transmit complete flag and enters an idle mode, with TxD1 high, waiting for more characters to transmit. Writing 0 to TE does not immediately release the pin to be a general-purpose I/O pin. Any transmit activity that is in progress must first be completed. This includes data characters in progress, queued idle characters, and queued break characters. 11.3.2.1 Send Break and Queued Idle The SBK control bit in SCIxC2 is used to send break characters which were originally used to gain the attention of old teletype receivers. Break characters are a full character time of logic 0 (10 bit times including the start and stop bits). Normally, a program would wait for TDRE to become set to indicate the last character of a message has moved to the transmit shifter, then write 1 and then write 0 to the SBK bit. This action queues a break character to be sent as soon as the shifter is available. If SBK is still 1 when the queued break moves into the shifter (synchronized to the baud rate clock), an additional break character is queued. If the receiving device is another Freescale Semiconductor SCI, the break characters will be received as 0s in all eight data bits and a framing error (FE = 1) occurs. When idle-line wakeup is used, a full character time of idle (logic 1) is needed between messages to wake up any sleeping receivers. Normally, a program would wait for TDRE to become set to indicate the last character of a message has moved to the transmit shifter, then write 0 and then write 1 to the TE bit. This action queues an idle character to be sent as soon as the shifter is available. As long as the character in the shifter does not finish while TE = 0, the SCI transmitter never actually releases control of the TxD1 pin. If there is a possibility of the shifter finishing while TE = 0, set the general-purpose I/O controls so the pin that is shared with TxD1 is an output driving a logic 1. This ensures that the TxD1 line will look like a normal idle line even if the SCI loses control of the port pin between writing 0 and then 1 to TE. 11.3.3 Receiver Functional Description In this section, the data sampling technique used to reconstruct receiver data is described in more detail; two variations of the receiver wakeup function are explained. (The receiver block diagram is shown in Figure 11-3.) The receiver is enabled by setting the RE bit in SCIxC2. Character frames consist of a start bit of logic 0, eight (or nine) data bits (LSB first), and a stop bit of logic 1. For information about 9-bit data mode, refer to Section 11.3.5.1, “8- and 9-Bit Data Modes.” For the remainder of this discussion, we assume the SCI is configured for normal 8-bit data mode. After receiving the stop bit into the receive shifter, and provided the receive data register is not already full, the data character is transferred to the receive data register and the receive data register full (RDRF) status flag is set. If RDRF was already set indicating the receive data register (buffer) was already full, the overrun (OR) status flag is set and the new data is lost. Because the SCI receiver is double-buffered, the program MC9S08GT16A/GT8A Data Sheet, Rev. 1 182 Freescale Semiconductor Serial Communications Interface (S08SCIV1) has one full character time after RDRF is set before the data in the receive data buffer must be read to avoid a receiver overrun. When a program detects that the receive data register is full (RDRF = 1), it gets the data from the receive data register by reading SCIxD. The RDRF flag is cleared automatically by a 2-step sequence which is normally satisfied in the course of the user’s program that handles receive data. Refer to Section 11.3.4, “Interrupts and Status Flags,” for more details about flag clearing. 11.3.3.1 Data Sampling Technique The SCI receiver uses a 16× baud rate clock for sampling. The receiver starts by taking logic level samples at 16 times the baud rate to search for a falling edge on the RxD1 serial data input pin. A falling edge is defined as a logic 0 sample after three consecutive logic 1 samples. The 16× baud rate clock is used to divide the bit time into 16 segments labeled RT1 through RT16. When a falling edge is located, three more samples are taken at RT3, RT5, and RT7 to make sure this was a real start bit and not merely noise. If at least two of these three samples are 0, the receiver assumes it is synchronized to a receive character. The receiver then samples each bit time, including the start and stop bits, at RT8, RT9, and RT10 to determine the logic level for that bit. The logic level is interpreted to be that of the majority of the samples taken during the bit time. In the case of the start bit, the bit is assumed to be 0 if at least two of the samples at RT3, RT5, and RT7 are 0 even if one or all of the samples taken at RT8, RT9, and RT10 are 1s. If any sample in any bit time (including the start and stop bits) in a character frame fails to agree with the logic level for that bit, the noise flag (NF) will be set when the received character is transferred to the receive data buffer. The falling edge detection logic continuously looks for falling edges, and if an edge is detected, the sample clock is resynchronized to bit times. This improves the reliability of the receiver in the presence of noise or mismatched baud rates. It does not improve worst case analysis because some characters do not have any extra falling edges anywhere in the character frame. In the case of a framing error, provided the received character was not a break character, the sampling logic that searches for a falling edge is filled with three logic 1 samples so that a new start bit can be detected almost immediately. In the case of a framing error, the receiver is inhibited from receiving any new characters until the framing error flag is cleared. The receive shift register continues to function, but a complete character cannot transfer to the receive data buffer if FE is still set. 11.3.3.2 Receiver Wakeup Operation Receiver wakeup is a hardware mechanism that allows an SCI receiver to ignore the characters in a message that is intended for a different SCI receiver. In such a system, all receivers evaluate the first character(s) of each message, and as soon as they determine the message is intended for a different receiver, they write logic 1 to the receiver wake up (RWU) control bit in SCIxC2. When RWU = 1, it inhibits setting of the status flags associated with the receiver, thus eliminating the software overhead for handling the unimportant message characters. At the end of a message, or at the beginning of the next message, all receivers automatically force RWU to 0 so all receivers wake up in time to look at the first character(s) of the next message. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 183 Serial Communications Interface (S08SCIV1) 11.3.3.2.1 Idle-Line Wakeup When WAKE = 0, the receiver is configured for idle-line wakeup. In this mode, RWU is cleared automatically when the receiver detects a full character time of the idle-line level. The M control bit selects 8-bit or 9-bit data mode that determines how many bit times of idle are needed to constitute a full character time (10 or 11 bit times because of the start and stop bits). When the RWU bit is set, the idle character that wakes a receiver does not set the receiver idle bit, IDLE, or the receive data register full flag, RDRF. It therefore will not generate an interrupt when this idle character occurs. The receiver will wake up and wait for the next data transmission which will set RDRF and generate an interrupt if enabled. The idle-line type (ILT) control bit selects one of two ways to detect an idle line. When ILT = 0, the idle bit counter starts after the start bit so the stop bit and any logic 1s at the end of a character count toward the full character time of idle. When ILT = 1, the idle bit counter does not start until after a stop bit time, so the idle detection is not affected by the data in the last character of the previous message. 11.3.3.2.2 Address-Mark Wakeup When WAKE = 1, the receiver is configured for address-mark wakeup. In this mode, RWU is cleared automatically when the receiver detects a logic 1 in the most significant bit of a received character (eighth bit in M = 0 mode and ninth bit in M = 1 mode). Address-mark wakeup allows messages to contain idle characters but requires that the MSB be reserved for use in address frames. The logic 1 MSB of an address frame clears the receivers RWU bit before the stop bit is received and sets the RDRF flag. 11.3.4 Interrupts and Status Flags The SCI system has three separate interrupt vectors to reduce the amount of software needed to isolate the cause of the interrupt. One interrupt vector is associated with the transmitter for TDRE and TC events. Another interrupt vector is associated with the receiver for RDRF and IDLE events, and a third vector is used for OR, NF, FE, and PF error conditions. Each of these eight interrupt sources can be separately masked by local interrupt enable masks. The flags can still be polled by software when the local masks are cleared to disable generation of hardware interrupt requests. The SCI transmitter has two status flags that optionally can generate hardware interrupt requests. Transmit data register empty (TDRE) indicates when there is room in the transmit data buffer to write another transmit character to SCIxD. If the transmit interrupt enable (TIE) bit is set, a hardware interrupt will be requested whenever TDRE = 1. Transmit complete (TC) indicates that the transmitter is finished transmitting all data, preamble, and break characters and is idle with TxD1 high. This flag is often used in systems with modems to determine when it is safe to turn off the modem. If the transmit complete interrupt enable (TCIE) bit is set, a hardware interrupt will be requested whenever TC = 1. Instead of hardware interrupts, software polling may be used to monitor the TDRE and TC status flags if the corresponding TIE or TCIE local interrupt masks are 0s. When a program detects that the receive data register is full (RDRF = 1), it gets the data from the receive data register by reading SCIxD. The RDRF flag is cleared by reading SCIxS1 while RDRF = 1 and then reading SCIxD. MC9S08GT16A/GT8A Data Sheet, Rev. 1 184 Freescale Semiconductor Serial Communications Interface (S08SCIV1) When polling is used, this sequence is naturally satisfied in the normal course of the user program. If hardware interrupts are used, SCIxS1 must be read in the interrupt service routine (ISR). Normally, this is done in the ISR anyway to check for receive errors, so the sequence is automatically satisfied. The IDLE status flag includes logic that prevents it from getting set repeatedly when the RxD1 line remains idle for an extended period of time. IDLE is cleared by reading SCIxS1 while IDLE = 1 and then reading SCIxD. After IDLE has been cleared, it cannot become set again until the receiver has received at least one new character and has set RDRF. If the associated error was detected in the received character that caused RDRF to be set, the error flags — noise flag (NF), framing error (FE), and parity error flag (PF) — get set at the same time as RDRF. These flags are not set in overrun cases. If RDRF was already set when a new character is ready to be transferred from the receive shifter to the receive data buffer, the overrun (OR) flag gets set instead and the data and any associated NF, FE, or PF condition is lost. 11.3.5 Additional SCI Functions The following sections describe additional SCI functions. 11.3.5.1 8- and 9-Bit Data Modes The SCI system (transmitter and receiver) can be configured to operate in 9-bit data mode by setting the M control bit in SCIxC1. In 9-bit mode, there is a ninth data bit to the left of the MSB of the SCI data register. For the transmit data buffer, this bit is stored in T8 in SCIxC3. For the receiver, the ninth bit is held in R8 in SCIxC3. For coherent writes to the transmit data buffer, write to the T8 bit before writing to SCIxD. If the bit value to be transmitted as the ninth bit of a new character is the same as for the previous character, it is not necessary to write to T8 again. When data is transferred from the transmit data buffer to the transmit shifter, the value in T8 is copied at the same time data is transferred from SCIxD to the shifter. 9-bit data mode typically is used in conjunction with parity to allow eight bits of data plus the parity in the ninth bit. Or it is used with address-mark wakeup so the ninth data bit can serve as the wakeup bit. In custom protocols, the ninth bit can also serve as a software-controlled marker. 11.3.5.2 Stop Mode Operation During all stop modes, clocks to the SCI module are halted. In stop1 and stop2 modes, all SCI register data is lost and must be re-initialized upon recovery from these two stop modes. No SCI module registers are affected in stop3 mode. Because the clocks are halted, the SCI module will resume operation upon exit from stop (only in stop3 mode). Software should ensure stop mode is not entered while there is a character being transmitted out of or received into the SCI module. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 185 Serial Communications Interface (S08SCIV1) 11.3.5.3 Loop Mode When LOOPS = 1, the RSRC bit in the same register chooses between loop mode (RSRC = 0) or single-wire mode (RSRC = 1). Loop mode is sometimes used to check software, independent of connections in the external system, to help isolate system problems. In this mode, the transmitter output is internally connected to the receiver input and the RxD1 pin is not used by the SCI, so it reverts to a general-purpose port I/O pin. 11.3.5.4 Single-Wire Operation When LOOPS = 1, the RSRC bit in the same register chooses between loop mode (RSRC = 0) or single-wire mode (RSRC = 1). Single-wire mode is used to implement a half-duplex serial connection. The receiver is internally connected to the transmitter output and to the TxD1 pin. The RxD1 pin is not used and reverts to a general-purpose port I/O pin. In single-wire mode, the TXDIR bit in SCIxC3 controls the direction of serial data on the TxD1 pin. When TXDIR = 0, the TxD1 pin is an input to the SCI receiver and the transmitter is temporarily disconnected from the TxD1 pin so an external device can send serial data to the receiver. When TXDIR = 1, the TxD1 pin is an output driven by the transmitter. In single-wire mode, the internal loop back connection from the transmitter to the receiver causes the receiver to receive characters that are sent out by the transmitter. MC9S08GT16A/GT8A Data Sheet, Rev. 1 186 Freescale Semiconductor Chapter 12 Serial Peripheral Interface (S08SPIV3) 12.1 Introduction The MC9S08GT16A/GT8A provides one serial peripheral interface (SPI) module. The four pins associated with SPI functionality are shared with port E pins 2–5. See the Appendix A, “Electrical Characteristics,” appendix for SPI electrical parametric information. When the SPI is enabled, the direction of pins is controlled by module configuration. If the SPI is disabled, all four pins can be used as general-purpose I/O. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 187 Serial Peripheral Interface (S08SPIV3) VREFL VREFH VSSAD VDDAD 4 HCS08 CORE BKGD CPU BDC 10-BIT ANALOG-TO-DIGITAL CONVERTER (ATD) 8 PORT B 4 4 8-BIT KEYBOARD INTERRUPT (KBI) PORT A 8 4 PTA7/KBIP7– PTA4/KBIP4 PTA3/KBIP3– PTA0/KBIP0 PTB7/ADP7– PTB4/ADP4 PTB3/ADP3– PTB0/ADP0 PTC7 PTC6 PTC5 PTC4 PTC3/SCL PTC2/SDA PTC1/RxD2 PTC0/TxD2 NOTE 6 HCS08 SYSTEM CONTROL RESET NOTE 4 RESETS AND INTERRUPTS MODES OF OPERATION POWER MANAGEMENT PORT C RTI IRQ NOTES 2, 3 IRQ COP LVD INTER-IC (IIC) SERIAL COMMUNICATIONS INTERFACE (SCI2) SCL SDA RXD2 TXD2 CH1 CH0 CH0 CH1 CH2 SPSCK MOSI MISO SS RXD1 TXD1 NOTE 5 PORT D USER FLASH (GT16A = 16,384 BYTES) (GT8A = 8192 BYTES) 2-CHANNEL TIMER/PWM (TPM2) PTD4/TPM2CH1 PTD3/TPM2CLK/TPM2CH0 PTD2/TPM1CH2 PTD1/TPM1CH1 PTD0/TPM1CLK/TPM1CH0 PTE5/SPSCK PTE4/MOSI PTE3/MISO PTE2/SS PTE1/RxD1 PTE0/TxD1 PTG3 PTG2/EXTAL PTG1/XTAL PTG0/BKGD/MS USER RAM (GT16A = 2048 BYTES) (GT8A = 1024 BYTES) 3-CHANNEL TIMER/PWM (TPM1) ON-CHIP ICE DEBUG MODULE (DBG) INTERNAL CLOCK GENERATOR (ICG) LOW-POWER OSCILLATOR VDD VSS VSS SERIAL COMMUNICATIONS INTERFACE (SCI1) VOLTAGE REGULATOR = Pins not available in 44-, 42-, or 32-pin packages = Pins not available in 42- or 32-pin packages = Pins not available in 32-pin packages NOTES: 1. Port pins are software configurable with pullup device if input port. 2. Pin contains pullup/pulldown device if IRQ enabled (IRQPE = 1). 3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD. 4. Pin contains integrated pullup device. 5. High current drive 6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available when KBI enabled (KBIPn = 1). Figure 12-1. Block Diagram Highlighting the SPI Module MC9S08GT16A/GT8A Data Sheet, Rev. 1 188 Freescale Semiconductor PORT G EXTAL XTAL BKGD PORT E SERIAL PERIPHERAL INTERFACE (SPI) Serial Peripheral Interface (S08SPIV3) Module Initialization (Slave): Write: Write: SPIC1 SPIC2 to configure to configure interrupts, set primary SPI options, slave mode select, and system enable. optional SPI features Module Initialization (Master): Write: SPIC1 to configure interrupts, set primary SPI options, master mode select, and system enable. optional SPI features baud rate Module Use: After SPI master initiates transfer by checking that SPTEF = 1 and then writing data to SPID: Wait for SPTEF, then write to SPID Wait for SPRF, then read from SPID Mode fault detection can be enabled for master mode in cases where more than one SPI device might become a master at the same time. SPIC1 SPIE SPE SPTIE MSTR CPOL CPHA SSOE LSBFE Write: Write: SPIC2 SPIBR to configure to set Module/interrupt enables and configuration SPIC2 Additional configuration options. MODFEN BIDIROE SPISWAI SPC0 SPIBR SPPR2 SPPR1 SPPR0 SPR2 SPR1 SPR0 Baud rate = (BUSCLK/SPPR[2:0])/SPR2[2:0] SPID SPIS Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 SPRF SPTEF MODF Figure 12-2. SPI Module Quick Start 12.1.1 Features Features of the SPI module include: • Master or slave mode operation • Full-duplex or single-wire bidirectional option • Programmable transmit bit rate • Double-buffered transmit and receive • Serial clock phase and polarity options • Slave select output • Selectable MSB-first or LSB-first shifting MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 189 Serial Peripheral Interface (S08SPIV3) 12.1.2 Block Diagrams This section includes block diagrams showing SPI system connections, the internal organization of the SPI module, and the SPI clock dividers that control the master mode bit rate. 12.1.2.1 SPI System Block Diagram Figure 12-3 shows the SPI modules of two MCUs connected in a master-slave arrangement. The master device initiates all SPI data transfers. During a transfer, the master shifts data out (on the MOSI pin) to the slave while simultaneously shifting data in (on the MISO pin) from the slave. The transfer effectively exchanges the data that was in the SPI shift registers of the two SPI systems. The SPSCK signal is a clock output from the master and an input to the slave. The slave device must be selected by a low level on the slave select input (SS pin). In this system, the master device has configured its SS pin as an optional slave select output. MASTER MOSI SPI SHIFTER 7 6 5 4 3 2 1 0 MISO MISO 7 MOSI SLAVE SPI SHIFTER 6 5 4 3 2 1 0 SPSCK SPSCK CLOCK GENERATOR SS SS Figure 12-3. SPI System Connections The most common uses of the SPI system include connecting simple shift registers for adding input or output ports or connecting small peripheral devices such as serial A/D or D/A converters. Although Figure 12-3 shows a system where data is exchanged between two MCUs, many practical systems involve simpler connections where data is unidirectionally transferred from the master MCU to a slave or from a slave to the master MCU. 12.1.2.2 SPI Module Block Diagram Figure 12-4 is a block diagram of the SPI module. The central element of the SPI is the SPI shift register. Data is written to the double-buffered transmitter (write to SPID) and gets transferred to the SPI shift register at the start of a data transfer. After shifting in a byte of data, the data is transferred into the double-buffered receiver where it can be read (read from SPID). Pin multiplexing logic controls connections between MCU pins and the SPI module. MC9S08GT16A/GT8A Data Sheet, Rev. 1 190 Freescale Semiconductor Serial Peripheral Interface (S08SPIV3) When the SPI is configured as a master, the clock output is routed to the SPSCK pin, the shifter output is routed to MOSI, and the shifter input is routed from the MISO pin. When the SPI is configured as a slave, the SPSCK pin is routed to the clock input of the SPI, the shifter output is routed to MISO, and the shifter input is routed from the MOSI pin. In the external SPI system, simply connect all SPSCK pins to each other, all MISO pins together, and all MOSI pins together. Peripheral devices often use slightly different names for these pins. PIN CONTROL M SPE Tx BUFFER (WRITE SPID) ENABLE SPI SYSTEM SHIFT OUT SPI SHIFT REGISTER SHIFT IN SPC0 BIDIROE LSBFE SHIFT DIRECTION SHIFT CLOCK Rx BUFFER FULL Tx BUFFER EMPTY M S MISO (SISO) S MOSI (MOMI) Rx BUFFER (READ SPID) MASTER CLOCK BUS RATE CLOCK MSTR SPIBR CLOCK GENERATOR MASTER/SLAVE MODE SELECT MODFEN MODE FAULT DETECTION SSOE CLOCK LOGIC SLAVE CLOCK M SPSCK S MASTER/ SLAVE SS SPRF SPTEF SPTIE SPI INTERRUPT REQUEST MODF SPIE Figure 12-4. SPI Module Block Diagram 12.1.3 SPI Baud Rate Generation As shown in Figure 12-5, the clock source for the SPI baud rate generator is the bus clock. The three prescale bits (SPPR2:SPPR1:SPPR0) choose a prescale divisor of 1, 2, 3, 4, 5, 6, 7, or 8. The three rate select bits (SPR2:SPR1:SPR0) divide the output of the prescaler stage by 2, 4, 8, 16, 32, 64, 128, or 256 to get the internal SPI master mode bit-rate clock. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 191 Serial Peripheral Interface (S08SPIV3) PRESCALER BUS CLOCK DIVIDE BY 1, 2, 3, 4, 5, 6, 7, or 8 CLOCK RATE DIVIDER DIVIDE BY 2, 4, 8, 16, 32, 64, 128, or 256 MASTER SPI BIT RATE SPPR2:SPPR1:SPPR0 SPR2:SPR1:SPR0 Figure 12-5. SPI Baud Rate Generation 12.2 External Signal Description The SPI optionally shares four port pins. The function of these pins depends on the settings of SPI control bits. When the SPI is disabled (SPE = 0), these four pins revert to being general-purpose port I/O pins that are not controlled by the SPI. 12.2.1 SPSCK — SPI Serial Clock When the SPI is enabled as a slave, this pin is the serial clock input. When the SPI is enabled as a master, this pin is the serial clock output. 12.2.2 MOSI — Master Data Out, Slave Data In When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not bidirectional mode), this pin is the serial data output. When the SPI is enabled as a slave and SPC0 = 0, this pin is the serial data input. If SPC0 = 1 to select single-wire bidirectional mode, and master mode is selected, this pin becomes the bidirectional data I/O pin (MOMI). Also, the bidirectional mode output enable bit determines whether the pin acts as an input (BIDIROE = 0) or an output (BIDIROE = 1). If SPC0 = 1 and slave mode is selected, this pin is not used by the SPI and reverts to being a general-purpose port I/O pin. 12.2.3 MISO — Master Data In, Slave Data Out When the SPI is enabled as a master and SPI pin control zero (SPC0) is 0 (not bidirectional mode), this pin is the serial data input. When the SPI is enabled as a slave and SPC0 = 0, this pin is the serial data output. If SPC0 = 1 to select single-wire bidirectional mode, and slave mode is selected, this pin becomes the bidirectional data I/O pin (SISO) and the bidirectional mode output enable bit determines whether the pin acts as an input (BIDIROE = 0) or an output (BIDIROE = 1). If SPC0 = 1 and master mode is selected, this pin is not used by the SPI and reverts to being a general-purpose port I/O pin. 12.2.4 SS — Slave Select When the SPI is enabled as a slave, this pin is the low-true slave select input. When the SPI is enabled as a master and mode fault enable is off (MODFEN = 0), this pin is not used by the SPI and reverts to being a general-purpose port I/O pin. When the SPI is enabled as a master and MODFEN = 1, the slave select output enable bit determines whether this pin acts as the mode fault input (SSOE = 0) or as the slave select output (SSOE = 1). MC9S08GT16A/GT8A Data Sheet, Rev. 1 192 Freescale Semiconductor Serial Peripheral Interface (S08SPIV3) 12.3 12.3.1 Modes of Operation SPI in Stop Modes The SPI is disabled in all stop modes, regardless of the settings before executing the STOP instruction. During either stop1 or stop2 mode, the SPI module will be fully powered down. Upon wake-up from stop1 or stop2 mode, the SPI module will be in the reset state. During stop3 mode, clocks to the SPI module are halted. No registers are affected. If stop3 is exited with a reset, the SPI will be put into its reset state. If stop3 is exited with an interrupt, the SPI continues from the state it was in when stop3 was entered. 12.4 Register Definition The SPI has five 8-bit registers to select SPI options, control baud rate, report SPI status, and for transmit/receive data. Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address assignments for all SPI registers. This section refers to registers and control bits only by their names, and a Freescale-provided equate or header file is used to translate these names into the appropriate absolute addresses. 12.4.1 SPI Control Register 1 (SPIC1) This read/write register includes the SPI enable control, interrupt enables, and configuration options. 7 6 5 4 3 2 1 0 R SPIE W Reset 0 0 0 0 0 1 0 0 SPE SPTIE MSTR CPOL CPHA SSOE LSBFE Figure 12-6. SPI Control Register 1 (SPIC1) Table 12-1. SPIC1 Field Descriptions Field 7 SPIE Description SPI Interrupt Enable (for SPRF and MODF) — This is the interrupt enable for SPI receive buffer full (SPRF) and mode fault (MODF) events. 0 Interrupts from SPRF and MODF inhibited (use polling) 1 When SPRF or MODF is 1, request a hardware interrupt SPI System Enable — Disabling the SPI halts any transfer that is in progress and initializes internal state machines. SPRF is cleared and SPTEF is set to indicate the SPI transmit data buffer is empty. 0 SPI system inactive 1 SPI system enabled SPI Transmit Interrupt Enable — This is the interrupt enable bit for SPI transmit buffer empty (SPTEF). 0 Interrupts from SPTEF inhibited (use polling) 1 When SPTEF is 1, hardware interrupt requested 6 SPE 5 SPTIE MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 193 Serial Peripheral Interface (S08SPIV3) Table 12-1. SPIC1 Field Descriptions (continued) Field 4 MSTR 3 CPOL Description Master/Slave Mode Select 0 SPI module configured as a slave SPI device 1 SPI module configured as a master SPI device Clock Polarity — This bit effectively places an inverter in series with the clock signal from a master SPI or to a slave SPI device. Refer to Section 12.5.1, “SPI Clock Formats” for more details. 0 Active-high SPI clock (idles low) 1 Active-low SPI clock (idles high) Clock Phase — This bit selects one of two clock formats for different kinds of synchronous serial peripheral devices. Refer to Section 12.5.1, “SPI Clock Formats” for more details. 0 First edge on SPSCK occurs at the middle of the first cycle of an 8-cycle data transfer 1 First edge on SPSCK occurs at the start of the first cycle of an 8-cycle data transfer Slave Select Output Enable — This bit is used in combination with the mode fault enable (MODFEN) bit in SPIC2 and the master/slave (MSTR) control bit to determine the function of the SS pin as shown in Table 12-2. LSB First (Shifter Direction) 0 SPI serial data transfers start with most significant bit 1 SPI serial data transfers start with least significant bit 2 CPHA 1 SSOE 0 LSBFE Table 12-2. SS Pin Function MODFEN 0 0 1 1 SSOE 0 1 0 1 Master Mode General-purpose I/O (not SPI) General-purpose I/O (not SPI) SS input for mode fault Automatic SS output Slave Mode Slave select input Slave select input Slave select input Slave select input 12.4.2 SPI Control Register 2 (SPIC2) This read/write register is used to control optional features of the SPI system. Bits 7, 6, 5, and 2 are not implemented and always read 0. 7 6 5 4 3 2 1 0 R W Reset 0 0 0 MODFEN BIDIROE 0 0 SPISWAI 0 0 SPC0 0 0 0 0 0 = Unimplemented or Reserved Figure 12-7. SPI Control Register 2 (SPIC2) MC9S08GT16A/GT8A Data Sheet, Rev. 1 194 Freescale Semiconductor Serial Peripheral Interface (S08SPIV3) Table 12-3. SPIC2 Register Field Descriptions Field 4 MODFEN Description Master Mode-Fault Function Enable — When the SPI is configured for slave mode, this bit has no meaning or effect. (The SS pin is the slave select input.) In master mode, this bit determines how the SS pin is used (refer to Table 12-2 for more details). 0 Mode fault function disabled, master SS pin reverts to general-purpose I/O not controlled by SPI 1 Mode fault function enabled, master SS pin acts as the mode fault input or the slave select output Bidirectional Mode Output Enable — When bidirectional mode is enabled by SPI pin control 0 (SPC0) = 1, BIDIROE determines whether the SPI data output driver is enabled to the single bidirectional SPI I/O pin. Depending on whether the SPI is configured as a master or a slave, it uses either the MOSI (MOMI) or MISO (SISO) pin, respectively, as the single SPI data I/O pin. When SPC0 = 0, BIDIROE has no meaning or effect. 0 Output driver disabled so SPI data I/O pin acts as an input 1 SPI I/O pin enabled as an output SPI Stop in Wait Mode 0 SPI clocks continue to operate in wait mode 1 SPI clocks stop when the MCU enters wait mode SPI Pin Control 0 — The SPC0 bit chooses single-wire bidirectional mode. If MSTR = 0 (slave mode), the SPI uses the MISO (SISO) pin for bidirectional SPI data transfers. If MSTR = 1 (master mode), the SPI uses the MOSI (MOMI) pin for bidirectional SPI data transfers. When SPC0 = 1, BIDIROE is used to enable or disable the output driver for the single bidirectional SPI I/O pin. 0 SPI uses separate pins for data input and data output 1 SPI configured for single-wire bidirectional operation 3 BIDIROE 1 SPISWAI 0 SPC0 12.4.3 SPI Baud Rate Register (SPIBR) This register is used to set the prescaler and bit rate divisor for an SPI master. This register may be read or written at any time. 7 6 5 4 3 2 1 0 R W Reset 0 SPPR2 0 0 SPPR1 0 SPPR0 0 0 SPR2 0 0 SPR1 0 SPR0 0 = Unimplemented or Reserved Figure 12-8. SPI Baud Rate Register (SPIBR) Table 12-4. SPIBR Register Field Descriptions Field 6:4 SPPR[2:0] 2:0 SPR[2:0] Description SPI Baud Rate Prescale Divisor — This 3-bit field selects one of eight divisors for the SPI baud rate prescaler as shown in Table 12-5. The input to this prescaler is the bus rate clock (BUSCLK). The output of this prescaler drives the input of the SPI baud rate divider (see Figure 12-5). SPI Baud Rate Divisor — This 3-bit field selects one of eight divisors for the SPI baud rate divider as shown in Table 12-6. The input to this divider comes from the SPI baud rate prescaler (see Figure 12-5). The output of this divider is the SPI bit rate clock for master mode. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 195 Serial Peripheral Interface (S08SPIV3) Table 12-5. SPI Baud Rate Prescaler Divisor SPPR2:SPPR1:SPPR0 0:0:0 0:0:1 0:1:0 0:1:1 1:0:0 1:0:1 1:1:0 1:1:1 Prescaler Divisor 1 2 3 4 5 6 7 8 Table 12-6. SPI Baud Rate Divisor SPR2:SPR1:SPR0 0:0:0 0:0:1 0:1:0 0:1:1 1:0:0 1:0:1 1:1:0 1:1:1 Rate Divisor 2 4 8 16 32 64 128 256 12.4.4 SPI Status Register (SPIS) This register has three read-only status bits. Bits 6, 3, 2, 1, and 0 are not implemented and always read 0. Writes have no meaning or effect. 7 6 5 4 3 2 1 0 R W Reset SPRF 0 SPTEF MODF 0 0 0 0 0 0 1 0 0 0 0 0 = Unimplemented or Reserved Figure 12-9. SPI Status Register (SPIS) MC9S08GT16A/GT8A Data Sheet, Rev. 1 196 Freescale Semiconductor Serial Peripheral Interface (S08SPIV3) Table 12-7. SPIS Register Field Descriptions Field 7 SPRF Description SPI Read Buffer Full Flag — SPRF is set at the completion of an SPI transfer to indicate that received data may be read from the SPI data register (SPID). SPRF is cleared by reading SPRF while it is set, then reading the SPI data register. 0 No data available in the receive data buffer 1 Data available in the receive data buffer SPI Transmit Buffer Empty Flag — This bit is set when there is room in the transmit data buffer. It is cleared by reading SPIS with SPTEF set, followed by writing a data value to the transmit buffer at SPID. SPIS must be read with SPTEF = 1 before writing data to SPID or the SPID write will be ignored. SPTEF generates an SPTEF CPU interrupt request if the SPTIE bit in the SPIC1 is also set. SPTEF is automatically set when a data byte transfers from the transmit buffer into the transmit shift register. For an idle SPI (no data in the transmit buffer or the shift register and no transfer in progress), data written to SPID is transferred to the shifter almost immediately so SPTEF is set within two bus cycles allowing a second 8-bit data value to be queued into the transmit buffer. After completion of the transfer of the value in the shift register, the queued value from the transmit buffer will automatically move to the shifter and SPTEF will be set to indicate there is room for new data in the transmit buffer. If no new data is waiting in the transmit buffer, SPTEF simply remains set and no data moves from the buffer to the shifter. 0 SPI transmit buffer not empty 1 SPI transmit buffer empty Master Mode Fault Flag — MODF is set if the SPI is configured as a master and the slave select input goes low, indicating some other SPI device is also configured as a master. The SS pin acts as a mode fault error input only when MSTR = 1, MODFEN = 1, and SSOE = 0; otherwise, MODF will never be set. MODF is cleared by reading MODF while it is 1, then writing to SPI control register 1 (SPIC1). 0 No mode fault error 1 Mode fault error detected 5 SPTEF 4 MODF 12.4.5 R SPI Data Register (SPID) 7 6 5 4 3 2 1 0 Bit 7 W Reset 0 6 0 5 0 4 0 3 0 2 0 1 0 Bit 0 0 Figure 12-10. SPI Data Register (SPID) Reads of this register return the data read from the receive data buffer. Writes to this register write data to the transmit data buffer. When the SPI is configured as a master, writing data to the transmit data buffer initiates an SPI transfer. Data should not be written to the transmit data buffer unless the SPI transmit buffer empty flag (SPTEF) is set, indicating there is room in the transmit buffer to queue a new transmit byte. Data may be read from SPID any time after SPRF is set and before another transfer is finished. Failure to read the data out of the receive data buffer before a new transfer ends causes a receive overrun condition and the data from the new transfer is lost. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 197 Serial Peripheral Interface (S08SPIV3) 12.5 Functional Description An SPI transfer is initiated by checking for the SPI transmit buffer empty flag (SPTEF = 1) and then writing a byte of data to the SPI data register (SPID) in the master SPI device. When the SPI shift register is available, this byte of data is moved from the transmit data buffer to the shifter, SPTEF is set to indicate there is room in the buffer to queue another transmit character if desired, and the SPI serial transfer starts. During the SPI transfer, data is sampled (read) on the MISO pin at one SPSCK edge and shifted, changing the bit value on the MOSI pin, one-half SPSCK cycle later. After eight SPSCK cycles, the data that was in the shift register of the master has been shifted out the MOSI pin to the slave while eight bits of data were shifted in the MISO pin into the master’s shift register. At the end of this transfer, the received data byte is moved from the shifter into the receive data buffer and SPRF is set to indicate the data can be read by reading SPID. If another byte of data is waiting in the transmit buffer at the end of a transfer, it is moved into the shifter, SPTEF is set, and a new transfer is started. Normally, SPI data is transferred most significant bit (MSB) first. If the least significant bit first enable (LSBFE) bit is set, SPI data is shifted LSB first. When the SPI is configured as a slave, its SS pin must be driven low before a transfer starts and SS must stay low throughout the transfer. If a clock format where CPHA = 0 is selected, SS must be driven to a logic 1 between successive transfers. If CPHA = 1, SS may remain low between successive transfers. See Section 12.5.1, “SPI Clock Formats” for more details. Because the transmitter and receiver are double buffered, a second byte, in addition to the byte currently being shifted out, can be queued into the transmit data buffer, and a previously received character can be in the receive data buffer while a new character is being shifted in. The SPTEF flag indicates when the transmit buffer has room for a new character. The SPRF flag indicates when a received character is available in the receive data buffer. The received character must be read out of the receive buffer (read SPID) before the next transfer is finished or a receive overrun error results. In the case of a receive overrun, the new data is lost because the receive buffer still held the previous character and was not ready to accept the new data. There is no indication for such an overrun condition so the application system designer must ensure that previous data has been read from the receive buffer before a new transfer is initiated. 12.5.1 SPI Clock Formats To accommodate a wide variety of synchronous serial peripherals from different manufacturers, the SPI system has a clock polarity (CPOL) bit and a clock phase (CPHA) control bit to select one of four clock formats for data transfers. CPOL selectively inserts an inverter in series with the clock. CPHA chooses between two different clock phase relationships between the clock and data. Figure 12-11 shows the clock formats when CPHA = 1. At the top of the figure, the eight bit times are shown for reference with bit 1 starting at the first SPSCK edge and bit 8 ending one-half SPSCK cycle after the sixteenth SPSCK edge. The MSB first and LSB first lines show the order of SPI data bits depending on the setting in LSBFE. Both variations of SPSCK polarity are shown, but only one of these waveforms applies for a specific transfer, depending on the value in CPOL. The SAMPLE IN waveform applies to the MOSI input of a slave or the MISO input of a master. The MOSI waveform applies to the MOSI output MC9S08GT16A/GT8A Data Sheet, Rev. 1 198 Freescale Semiconductor Serial Peripheral Interface (S08SPIV3) pin from a master and the MISO waveform applies to the MISO output from a slave. The SS OUT waveform applies to the slave select output from a master (provided MODFEN and SSOE = 1). The master SS output goes to active low one-half SPSCK cycle before the start of the transfer and goes back high at the end of the eighth bit time of the transfer. The SS IN waveform applies to the slave select input of a slave. BIT TIME # (REFERENCE) 1 2 ... 6 7 8 SPSCK (CPOL = 0) SPSCK (CPOL = 1) SAMPLE IN (MISO OR MOSI) MOSI (MASTER OUT) MSB FIRST LSB FIRST MISO (SLAVE OUT) BIT 7 BIT 0 BIT 6 BIT 1 ... ... BIT 2 BIT 5 BIT 1 BIT 6 BIT 0 BIT 7 SS OUT (MASTER) SS IN (SLAVE) Figure 12-11. SPI Clock Formats (CPHA = 1) When CPHA = 1, the slave begins to drive its MISO output when SS goes to active low, but the data is not defined until the first SPSCK edge. The first SPSCK edge shifts the first bit of data from the shifter onto the MOSI output of the master and the MISO output of the slave. The next SPSCK edge causes both the master and the slave to sample the data bit values on their MISO and MOSI inputs, respectively. At the third SPSCK edge, the SPI shifter shifts one bit position which shifts in the bit value that was just sampled, and shifts the second data bit value out the other end of the shifter to the MOSI and MISO outputs of the master and slave, respectively. When CHPA = 1, the slave’s SS input is not required to go to its inactive high level between transfers. Figure 12-12 shows the clock formats when CPHA = 0. At the top of the figure, the eight bit times are shown for reference with bit 1 starting as the slave is selected (SS IN goes low), and bit 8 ends at the last SPSCK edge. The MSB first and LSB first lines show the order of SPI data bits depending on the setting MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 199 Serial Peripheral Interface (S08SPIV3) in LSBFE. Both variations of SPSCK polarity are shown, but only one of these waveforms applies for a specific transfer, depending on the value in CPOL. The SAMPLE IN waveform applies to the MOSI input of a slave or the MISO input of a master. The MOSI waveform applies to the MOSI output pin from a master and the MISO waveform applies to the MISO output from a slave. The SS OUT waveform applies to the slave select output from a master (provided MODFEN and SSOE = 1). The master SS output goes to active low at the start of the first bit time of the transfer and goes back high one-half SPSCK cycle after the end of the eighth bit time of the transfer. The SS IN waveform applies to the slave select input of a slave. BIT TIME # (REFERENCE) SPSCK (CPOL = 0) 1 2 ... 6 7 8 SPSCK (CPOL = 1) SAMPLE IN (MISO OR MOSI) MOSI (MASTER OUT) MSB FIRST LSB FIRST MISO (SLAVE OUT) BIT 7 BIT 0 BIT 6 BIT 1 ... ... BIT 2 BIT 5 BIT 1 BIT 6 BIT 0 BIT 7 SS OUT (MASTER) SS IN (SLAVE) Figure 12-12. SPI Clock Formats (CPHA = 0) When CPHA = 0, the slave begins to drive its MISO output with the first data bit value (MSB or LSB depending on LSBFE) when SS goes to active low. The first SPSCK edge causes both the master and the slave to sample the data bit values on their MISO and MOSI inputs, respectively. At the second SPSCK edge, the SPI shifter shifts one bit position which shifts in the bit value that was just sampled and shifts the second data bit value out the other end of the shifter to the MOSI and MISO outputs of the master and slave, respectively. When CPHA = 0, the slave’s SS input must go to its inactive high level between transfers. MC9S08GT16A/GT8A Data Sheet, Rev. 1 200 Freescale Semiconductor Serial Peripheral Interface (S08SPIV3) 12.5.2 SPI Interrupts There are three flag bits, two interrupt mask bits, and one interrupt vector associated with the SPI system. The SPI interrupt enable mask (SPIE) enables interrupts from the SPI receiver full flag (SPRF) and mode fault flag (MODF). The SPI transmit interrupt enable mask (SPTIE) enables interrupts from the SPI transmit buffer empty flag (SPTEF). When one of the flag bits is set, and the associated interrupt mask bit is set, a hardware interrupt request is sent to the CPU. If the interrupt mask bits are cleared, software can poll the associated flag bits instead of using interrupts. The SPI interrupt service routine (ISR) should check the flag bits to determine what event caused the interrupt. The service routine should also clear the flag bit(s) before returning from the ISR (usually near the beginning of the ISR). 12.5.3 Mode Fault Detection A mode fault occurs and the mode fault flag (MODF) becomes set when a master SPI device detects an error on the SS pin (provided the SS pin is configured as the mode fault input signal). The SS pin is configured to be the mode fault input signal when MSTR = 1, mode fault enable is set (MODFEN = 1), and slave select output enable is clear (SSOE = 0). The mode fault detection feature can be used in a system where more than one SPI device might become a master at the same time. The error is detected when a master’s SS pin is low, indicating that some other SPI device is trying to address this master as if it were a slave. This could indicate a harmful output driver conflict, so the mode fault logic is designed to disable all SPI output drivers when such an error is detected. When a mode fault is detected, MODF is set and MSTR is cleared to change the SPI configuration back to slave mode. The output drivers on the SPSCK, MOSI, and MISO (if not bidirectional mode) are disabled. MODF is cleared by reading it while it is set, then writing to the SPI control register 1 (SPIC1). User software should verify the error condition has been corrected before changing the SPI back to master mode. 12.6 12.6.1 Initialization/Application Information SPI Module Initialization Example Initialization Sequence 12.6.1.1 Before the SPI module can be used for communication, an initialization procedure must be carried out, as follows: 1. Update control register 1 (SPIC1) to enable the SPI and to control interrupt enables. This register also sets the SPI as master or slave, determines clock phase and polarity, and configures the main SPI options. 2. Update control register 2 (SPIC2) to enable additional SPI functions such as the master mode-fault function and bidirectional mode output. Other optional SPI functions are configured here as well. 3. Update the baud rate register (SPIBR) to set the prescaler and bit rate divisor for an SPI master. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 201 Serial Peripheral Interface (S08SPIV3) 12.6.1.2 Pseudo—Code Example In this example, the SPI module will be set up for master mode with only transmit interrupts enabled to run at a maximum baud rate of bus clock divided by 2. Clock phase and polarity will be set for an active-high SPI clock where the first edge on SPSCK occurs at the start of the first cycle of a data transfer. SPIC1 = 0x74(%01110100) Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 SPIE SPE SPTIE MSTR CPOL CPHA SSOE LSBFE =0 =1 =1 =1 =0 =1 =0 =0 Disables receive and mode fault interrupts Enables the SPI system Enables SPI transmit interrupts Sets the SPI module as a master SPI device Configures SPI clock as active-high First edge on SPSCK at start of first data transfer cycle Determines SS pin function when mode fault enabled SPI serial data transfers start with most significant bit SPIC2 = 0x00(%00000000) Bit 7:5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 SPISWAI SPC0 MODFEN BIDIROE = 000 =0 =0 =0 =0 =0 Unimplemented Disables mode fault function SPI data I/O pin acts as input Unimplemented SPI clocks operate in wait mode SPI uses separate pins for data input and output SPIBR = 0x00(%00000000) Bit 7 Bit 6:4 Bit 3 Bit 2:0 =0 = 000 =0 = 000 Unimplemented Sets prescale divisor to 1 Unimplemented Sets baud rate divisor to 2 SPIS = 0x00(%00000000) Bit 7 Bit 6 Bit 5 Bit 4 Bit 3:0 SPTEF MODF SPRF =0 =0 =0 =0 =0 Flag is set when receive data buffer is full Unimplemented Flag is set when transmit data buffer is empty Mode fault flag for master mode Unimplemented SPID = 0xxx Holds data to be transmitted by transmit buffer and data received by receive buffer. MC9S08GT16A/GT8A Data Sheet, Rev. 1 202 Freescale Semiconductor Serial Peripheral Interface (S08SPIV3) RESET INITIALIZE SPI SPIC1 = 0x74 SPIC2 = 0x00 SPIBR = 0x00 SPTEF = 1 ? YES READ SPIS WITH SPTEF SET TO CLEAR FLAG, THEN WRITE DATA TO SPID NO CONTINUE Figure 12-13. Initialization Flowchart Example for SPI Master Device MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 203 Serial Peripheral Interface (S08SPIV3) MC9S08GT16A/GT8A Data Sheet, Rev. 1 204 Freescale Semiconductor Chapter 13 Inter-Integrated Circuit (S08IICV1) 13.1 Introduction The MC9S08GT16A/GT8A series of microcontrollers provides one inter-integrated circuit (IIC) module for communication with other integrated circuits. The two pins associated with this module, SDA and SCL share port C pins 2 and 3, respectively. All functionality as described in this section is available on MC9S08GT16A/GT8A. When the IIC is enabled, the direction of pins is controlled by module configuration. If the IIC is disabled, both pins can be used as general-purpose I/O. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 205 Inter-Integrated Circuit (S08IICV1) VREFL VREFH VSSAD VDDAD 4 HCS08 CORE BKGD CPU BDC 10-BIT ANALOG-TO-DIGITAL CONVERTER (ATD) 8 PORT B 4 4 8-BIT KEYBOARD INTERRUPT (KBI) PORT A 8 4 PTA7/KBIP7– PTA4/KBIP4 PTA3/KBIP3– PTA0/KBIP0 PTB7/ADP7– PTB4/ADP4 PTB3/ADP3– PTB0/ADP0 PTC7 PTC6 PTC5 PTC4 PTC3/SCL PTC2/SDA PTC1/RxD2 PTC0/TxD2 NOTE 6 HCS08 SYSTEM CONTROL RESET NOTE 4 RESETS AND INTERRUPTS MODES OF OPERATION POWER MANAGEMENT PORT C RTI IRQ NOTES 2, 3 IRQ COP LVD INTER-IC (IIC) SERIAL COMMUNICATIONS INTERFACE (SCI2) SCL SDA RXD2 TXD2 CH1 CH0 CH0 CH1 CH2 SPSCK MOSI MISO SS RXD1 TXD1 NOTE 5 PORT D USER FLASH (GT16A = 16,384 BYTES) (GT8A = 8192 BYTES) 2-CHANNEL TIMER/PWM (TPM2) PTD4/TPM2CH1 PTD3/TPM2CLK/TPM2CH0 PTD2/TPM1CH2 PTD1/TPM1CH1 PTD0/TPM1CLK/TPM1CH0 PTE5/SPSCK PTE4/MOSI PTE3/MISO PTE2/SS PTE1/RxD1 PTE0/TxD1 PTG3 PTG2/EXTAL PTG1/XTAL PTG0/BKGD/MS USER RAM (GT16A = 2048 BYTES) (GT8A = 1024 BYTES) 3-CHANNEL TIMER/PWM (TPM1) ON-CHIP ICE DEBUG MODULE (DBG) INTERNAL CLOCK GENERATOR (ICG) LOW-POWER OSCILLATOR VDD VSS VSS SERIAL COMMUNICATIONS INTERFACE (SCI1) VOLTAGE REGULATOR = Pins not available in 44-, 42-, or 32-pin packages = Pins not available in 42- or 32-pin packages = Pins not available in 32-pin packages NOTES: 1. Port pins are software configurable with pullup device if input port. 2. Pin contains pullup/pulldown device if IRQ enabled (IRQPE = 1). 3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD. 4. Pin contains integrated pullup device. 5. High current drive 6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available when KBI enabled (KBIPn = 1). Figure 13-1. Block Diagram Highlighting the IIC Module MC9S08GT16A/GT8A Data Sheet, Rev. 1 206 Freescale Semiconductor PORT G EXTAL XTAL BKGD PORT E SERIAL PERIPHERAL INTERFACE (SPI) Inter-Integrated Circuit (S08IICV1) 13.1.1 Features The IIC includes these distinctive features: • Compatible with IIC bus standard • Multi-master operation • Software programmable for one of 64 different serial clock frequencies • Software selectable acknowledge bit • Interrupt driven byte-by-byte data transfer • Arbitration lost interrupt with automatic mode switching from master to slave • Calling address identification interrupt • START and STOP signal generation/detection • Repeated START signal generation • Acknowledge bit generation/detection • Bus busy detection 13.1.2 Modes of Operation The IIC functions the same in normal and monitor modes. A brief description of the IIC in the various MCU modes is given here. • Run mode — This is the basic mode of operation. To conserve power in this mode, disable the module. • Wait mode — The module will continue to operate while the MCU is in wait mode and can provide a wake-up interrupt. • Stop mode — The IIC is inactive in stop3 mode for reduced power consumption. The STOP instruction does not affect IIC register states. Stop1 and stop2 will reset the register contents. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 207 Inter-Integrated Circuit (S08IICV1) 13.1.3 Block Diagram ADDRESS INTERRUPT ADDR_DECODE DATA_MUX DATA BUS Figure 13-2 is a block diagram of the IIC. CTRL_REG FREQ_REG ADDR_REG STATUS_REG DATA_REG INPUT SYNC START STOP ARBITRATION CONTROL CLOCK CONTROL IN/OUT DATA SHIFT REGISTER ADDRESS COMPARE SCL SDA Figure 13-2. IIC Functional Block Diagram 13.2 External Signal Description This section describes each user-accessible pin signal. 13.2.1 SCL — Serial Clock Line The bidirectional SCL is the serial clock line of the IIC system. 13.2.2 SDA — Serial Data Line The bidirectional SDA is the serial data line of the IIC system. 13.3 Register Definition This section consists of the IIC register descriptions in address order. MC9S08GT16A/GT8A Data Sheet, Rev. 1 208 Freescale Semiconductor Inter-Integrated Circuit (S08IICV1) Refer to the direct-page register summary in the Memory chapter of this data sheet for the absolute address assignments for all IIC registers. This section refers to registers and control bits only by their names. A Freescale-provided equate or header file is used to translate these names into the appropriate absolute addresses. 13.3.1 IIC Address Register (IICA) 7 6 5 4 3 2 1 0 R ADDR W Reset 0 0 0 0 0 0 0 0 0 = Unimplemented or Reserved Figure 13-3. IIC Address Register (IICA) Table 13-1. IICA Register Field Descriptions Field 7:1 ADDR[7:1] Description IIC Address Register — The ADDR contains the specific slave address to be used by the IIC module. This is the address the module will respond to when addressed as a slave. 13.3.2 IIC Frequency Divider Register (IICF) 7 6 5 4 3 2 1 0 R MULT W Reset 0 0 0 0 0 0 0 0 ICR Figure 13-4. IIC Frequency Divider Register (IICF) MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 209 Inter-Integrated Circuit (S08IICV1) Table 13-2. IICA Register Field Descriptions Field 7:6 MULT Description IIC Multiplier Factor — The MULT bits define the multiplier factor mul. This factor is used along with the SCL divider to generate the IIC baud rate. The multiplier factor mul as defined by the MULT bits is provided below. 00 mul = 01 01 mul = 02 10 mul = 04 11 Reserved IIC Clock Rate — The ICR bits are used to prescale the bus clock for bit rate selection. These bits are used to define the SCL divider and the SDA hold value. The SCL divider multiplied by the value provided by the MULT register (multiplier factor mul) is used to generate IIC baud rate. IIC baud rate = bus speed (Hz)/(mul * SCL divider) SDA hold time is the delay from the falling edge of the SCL (IIC clock) to the changing of SDA (IIC data). The ICR is used to determine the SDA hold value. SDA hold time = bus period (s) * SDA hold value Table 13-3 provides the SCL divider and SDA hold values for corresponding values of the ICR. These values can be used to set IIC baud rate and SDA hold time. For example: Bus speed = 8 MHz MULT is set to 01 (mul = 2) Desired IIC baud rate = 100 kbps IIC baud rate = bus speed (Hz)/(mul * SCL divider) 100000 = 8000000/(2*SCL divider) SCL divider = 40 Table 13-3 shows that ICR must be set to 0B to provide an SCL divider of 40 and that this will result in an SDA hold value of 9. SDA hold time = bus period (s) * SDA hold value * mul SDA hold time = 1/8000000 * 9 * mul = 1.125 µs * mul If the generated SDA hold value is not acceptable, the MULT bits can be used to change the ICR. This will result in a different SDA hold value. 5:0 ICR MC9S08GT16A/GT8A Data Sheet, Rev. 1 210 Freescale Semiconductor Inter-Integrated Circuit (S08IICV1) Table 13-3. IIC Divider and Hold Values ICR (hex) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F SCL Divider 20 22 24 26 28 30 34 40 28 32 36 40 44 48 56 68 48 56 64 72 80 88 104 128 80 96 112 128 144 160 192 240 SDA Hold Value 7 7 8 8 9 9 10 10 7 7 9 9 11 11 13 13 9 9 13 13 17 17 21 21 9 9 17 17 25 25 33 33 ICR (hex) 20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F 30 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F SCL Divider 160 192 224 256 288 320 384 480 320 384 448 512 576 640 768 960 640 768 896 1024 1152 1280 1536 1920 1280 1536 1792 2048 2304 2560 3072 3840 SDA Hold Value 17 17 33 33 49 49 65 65 33 33 65 65 97 97 129 129 65 65 129 129 193 193 257 257 129 129 257 257 385 385 513 513 MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 211 Inter-Integrated Circuit (S08IICV1) 13.3.3 IIC Control Register (IICC) 7 6 5 4 3 2 1 0 R IICEN W Reset 0 0 0 0 0 IICIE MST TX TXAK 0 RSTA 0 0 0 0 0 = Unimplemented or Reserved Figure 13-5. IIC Control Register (IICC) Table 13-4. IICC Register Field Descriptions Field 7 IICEN 6 IICIE 5 MST Description IIC Enable — The IICEN bit determines whether the IIC module is enabled. 0 IIC is not enabled. 1 IIC is enabled. IIC Interrupt Enable — The IICIE bit determines whether an IIC interrupt is requested. 0 IIC interrupt request not enabled. 1 IIC interrupt request enabled. Master Mode Select — The MST bit is changed from a 0 to a 1 when a START signal is generated on the bus and master mode is selected. When this bit changes from a 1 to a 0 a STOP signal is generated and the mode of operation changes from master to slave. 0 Slave Mode. 1 Master Mode. Transmit Mode Select — The TX bit selects the direction of master and slave transfers. In master mode this bit should be set according to the type of transfer required. Therefore, for address cycles, this bit will always be high. When addressed as a slave this bit should be set by software according to the SRW bit in the status register. 0 Receive. 1 Transmit. Transmit Acknowledge Enable — This bit specifies the value driven onto the SDA during data acknowledge cycles for both master and slave receivers. 0 An acknowledge signal will be sent out to the bus after receiving one data byte. 1 No acknowledge signal response is sent. Repeat START — Writing a one to this bit will generate a repeated START condition provided it is the current master. This bit will always be read as a low. Attempting a repeat at the wrong time will result in loss of arbitration. 4 TX 3 TXAK 2 RSTA MC9S08GT16A/GT8A Data Sheet, Rev. 1 212 Freescale Semiconductor Inter-Integrated Circuit (S08IICV1) 13.3.4 IIC Status Register (IICS) 7 6 5 4 3 2 1 0 R W Reset TCF IAAS 1 0 BUSY ARBL 0 0 0 SRW IICIF RXAK 0 0 0 0 = Unimplemented or Reserved Figure 13-6. IIC Status Register (IICS) Table 13-5. IICS Register Field Descriptions Field 7 TCF Description Transfer Complete Flag — This bit is set on the completion of a byte transfer. Note that this bit is only valid during or immediately following a transfer to the IIC module or from the IIC module.The TCF bit is cleared by reading the IICD register in receive mode or writing to the IICD in transmit mode. 0 Transfer in progress. 1 Transfer complete. Addressed as a Slave — The IAAS bit is set when the calling address matches the programmed slave address. Writing the IICC register clears this bit. 0 Not addressed. 1 Addressed as a slave. Bus Busy — The BUSY bit indicates the status of the bus regardless of slave or master mode. The BUSY bit is set when a START signal is detected and cleared when a STOP signal is detected. 0 Bus is idle. 1 Bus is busy. Arbitration Lost — This bit is set by hardware when the arbitration procedure is lost. The ARBL bit must be cleared by software, by writing a one to it. 0 Standard bus operation. 1 Loss of arbitration. Slave Read/Write — When addressed as a slave the SRW bit indicates the value of the R/W command bit of the calling address sent to the master. 0 Slave receive, master writing to slave. 1 Slave transmit, master reading from slave. IIC Interrupt Flag — The IICIF bit is set when an interrupt is pending. This bit must be cleared by software, by writing a one to it in the interrupt routine. One of the following events can set the IICIF bit: • One byte transfer completes • Match of slave address to calling address • Arbitration lost 0 No interrupt pending. 1 Interrupt pending. Receive Acknowledge — When the RXAK bit is low, it indicates an acknowledge signal has been received after the completion of one byte of data transmission on the bus. If the RXAK bit is high it means that no acknowledge signal is detected. 0 Acknowledge received. 1 No acknowledge received. 6 IAAS 5 BUSY 4 ARBL 2 SRW 1 IICIF 0 RXAK MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 213 Inter-Integrated Circuit (S08IICV1) 13.3.5 IIC Data I/O Register (IICD) 7 6 5 4 3 2 1 0 R DATA W Reset 0 0 0 0 0 0 0 0 Figure 13-7. IIC Data I/O Register (IICD) Table 13-6. IICD Register Field Descriptions Field 7:0 DATA Description Data — In master transmit mode, when data is written to the IICD, a data transfer is initiated. The most significant bit is sent first. In master receive mode, reading this register initiates receiving of the next byte of data. NOTE When transmitting out of master receive mode, the IIC mode should be switched before reading the IICD register to prevent an inadvertent initiation of a master receive data transfer. In slave mode, the same functions are available after an address match has occurred. Note that the TX bit in IICC must correctly reflect the desired direction of transfer in master and slave modes for the transmission to begin. For instance, if the IIC is configured for master transmit but a master receive is desired, then reading the IICD will not initiate the receive. Reading the IICD will return the last byte received while the IIC is configured in either master receive or slave receive modes. The IICD does not reflect every byte that is transmitted on the IIC bus, nor can software verify that a byte has been written to the IICD correctly by reading it back. In master transmit mode, the first byte of data written to IICD following assertion of MST is used for the address transfer and should comprise of the calling address (in bit 7–bit 1) concatenated with the required R/W bit (in position bit 0). MC9S08GT16A/GT8A Data Sheet, Rev. 1 214 Freescale Semiconductor Inter-Integrated Circuit (S08IICV1) 13.4 Functional Description This section provides a complete functional description of the IIC module. 13.4.1 IIC Protocol The IIC bus system uses a serial data line (SDA) and a serial clock line (SCL) for data transfer. All devices connected to it must have open drain or open collector outputs. A logic AND function is exercised on both lines with external pull-up resistors. The value of these resistors is system dependent. Normally, a standard communication is composed of four parts: • START signal • Slave address transmission • Data transfer • STOP signal The STOP signal should not be confused with the CPU STOP instruction. The IIC bus system communication is described briefly in the following sections and illustrated in Figure 13-8. MSB SCL 1 2 3 4 5 6 7 LSB 8 9 MSB 1 2 3 4 5 6 7 LSB 8 9 SDA AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W XXX D7 D6 D5 D4 D3 D2 D1 D0 START SIGNAL MSB SCL 1 2 CALLING ADDRESS READ/ ACK WRITE BIT LSB MSB 9 1 2 3 DATA BYTE NO STOP ACK SIGNAL BIT LSB 3 4 5 6 7 8 4 5 6 7 8 9 SDA AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W XX AD7 AD6 AD5 AD4 AD3 AD2 AD1 R/W START SIGNAL CALLING ADDRESS READ/ ACK WRITE BIT REPEATED START SIGNAL NEW CALLING ADDRESS READ/ NO STOP WRITE ACK SIGNAL BIT Figure 13-8. IIC Bus Transmission Signals MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 215 Inter-Integrated Circuit (S08IICV1) 13.4.1.1 START Signal When the bus is free; i.e., no master device is engaging the bus (both SCL and SDA lines are at logical high), a master may initiate communication by sending a START signal. As shown in Figure 13-8, a START signal is defined as a high-to-low transition of SDA while SCL is high. This signal denotes the beginning of a new data transfer (each data transfer may contain several bytes of data) and brings all slaves out of their idle states. 13.4.1.2 Slave Address Transmission The first byte of data transferred immediately after the START signal is the slave address transmitted by the master. This is a seven-bit calling address followed by a R/W bit. The R/W bit tells the slave the desired direction of data transfer. 1 = Read transfer, the slave transmits data to the master. 0 = Write transfer, the master transmits data to the slave. Only the slave with a calling address that matches the one transmitted by the master will respond by sending back an acknowledge bit. This is done by pulling the SDA low at the 9th clock (see Figure 13-8). No two slaves in the system may have the same address. If the IIC module is the master, it must not transmit an address that is equal to its own slave address. The IIC cannot be master and slave at the same time. However, if arbitration is lost during an address cycle, the IIC will revert to slave mode and operate correctly even if it is being addressed by another master. 13.4.1.3 Data Transfer Before successful slave addressing is achieved, the data transfer can proceed byte-by-byte in a direction specified by the R/W bit sent by the calling master. All transfers that come after an address cycle are referred to as data transfers, even if they carry sub-address information for the slave device Each data byte is 8 bits long. Data may be changed only while SCL is low and must be held stable while SCL is high as shown in Figure 13-8. There is one clock pulse on SCL for each data bit, the MSB being transferred first. Each data byte is followed by a 9th (acknowledge) bit, which is signalled from the receiving device. An acknowledge is signalled by pulling the SDA low at the ninth clock. In summary, one complete data transfer needs nine clock pulses. If the slave receiver does not acknowledge the master in the 9th bit time, the SDA line must be left high by the slave. The master interprets the failed acknowledge as an unsuccessful data transfer. If the master receiver does not acknowledge the slave transmitter after a data byte transmission, the slave interprets this as an end of data transfer and releases the SDA line. In either case, the data transfer is aborted and the master does one of two things: • Relinquishes the bus by generating a STOP signal. • Commences a new calling by generating a repeated START signal. MC9S08GT16A/GT8A Data Sheet, Rev. 1 216 Freescale Semiconductor Inter-Integrated Circuit (S08IICV1) 13.4.1.4 STOP Signal The master can terminate the communication by generating a STOP signal to free the bus. However, the master may generate a START signal followed by a calling command without generating a STOP signal first. This is called repeated START. A STOP signal is defined as a low-to-high transition of SDA while SCL at logical 1 (see Figure 13-8). The master can generate a STOP even if the slave has generated an acknowledge at which point the slave must release the bus. 13.4.1.5 Repeated START Signal As shown in Figure 13-8, a repeated START signal is a START signal generated without first generating a STOP signal to terminate the communication. This is used by the master to communicate with another slave or with the same slave in different mode (transmit/receive mode) without releasing the bus. 13.4.1.6 Arbitration Procedure The IIC bus is a true multi-master bus that allows more than one master to be connected on it. If two or more masters try to control the bus at the same time, a clock synchronization procedure determines the bus clock, for which the low period is equal to the longest clock low period and the high is equal to the shortest one among the masters. The relative priority of the contending masters is determined by a data arbitration procedure, a bus master loses arbitration if it transmits logic 1 while another master transmits logic 0. The losing masters immediately switch over to slave receive mode and stop driving SDA output. In this case, the transition from master to slave mode does not generate a STOP condition. Meanwhile, a status bit is set by hardware to indicate loss of arbitration. 13.4.1.7 Clock Synchronization Because wire-AND logic is performed on the SCL line, a high-to-low transition on the SCL line affects all the devices connected on the bus. The devices start counting their low period and after a device’s clock has gone low, it holds the SCL line low until the clock high state is reached. However, the change of low to high in this device clock may not change the state of the SCL line if another device clock is still within its low period. Therefore, synchronized clock SCL is held low by the device with the longest low period. Devices with shorter low periods enter a high wait state during this time (see Figure 13-9). When all devices concerned have counted off their low period, the synchronized clock SCL line is released and pulled high. There is then no difference between the device clocks and the state of the SCL line and all the devices start counting their high periods. The first device to complete its high period pulls the SCL line low again. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 217 Inter-Integrated Circuit (S08IICV1) START COUNTING HIGH PERIOD DELAY SCL1 SCL2 SCL INTERNAL COUNTER RESET Figure 13-9. IIC Clock Synchronization 13.4.1.8 Handshaking The clock synchronization mechanism can be used as a handshake in data transfer. Slave devices may hold the SCL low after completion of one byte transfer (9 bits). In such case, it halts the bus clock and forces the master clock into wait states until the slave releases the SCL line. 13.4.1.9 Clock Stretching The clock synchronization mechanism can be used by slaves to slow down the bit rate of a transfer. After the master has driven SCL low the slave can drive SCL low for the required period and then release it. If the slave SCL low period is greater than the master SCL low period then the resulting SCL bus signal low period is stretched. 13.5 Resets The IIC is disabled after reset. The IIC cannot cause an MCU reset. 13.6 Interrupts The IIC generates a single interrupt. An interrupt from the IIC is generated when any of the events in Table 13-7 occur provided the IICIE bit is set. The interrupt is driven by bit IICIF (of the IIC status register) and masked with bit IICIE (of the IIC control register). The IICIF bit must be cleared by software by writing a one to it in the interrupt routine. The user can determine the interrupt type by reading the status register. Table 13-7. Interrupt Summary Interrupt Source Complete 1-byte transfer Match of received calling address Arbitration Lost Status TCF IAAS ARBL Flag IICIF IICIF IICIF Local Enable IICIE IICIE IICIE MC9S08GT16A/GT8A Data Sheet, Rev. 1 218 Freescale Semiconductor Inter-Integrated Circuit (S08IICV1) 13.6.1 Byte Transfer Interrupt The TCF (transfer complete flag) bit is set at the falling edge of the 9th clock to indicate the completion of byte transfer. 13.6.2 Address Detect Interrupt When the calling address matches the programmed slave address (IIC address register), the IAAS bit in the status register is set. The CPU is interrupted provided the IICIE is set. The CPU must check the SRW bit and set its Tx mode accordingly. 13.6.3 Arbitration Lost Interrupt The IIC is a true multi-master bus that allows more than one master to be connected on it. If two or more masters try to control the bus at the same time, the relative priority of the contending masters is determined by a data arbitration procedure. The IIC module asserts this interrupt when it loses the data arbitration process and the ARBL bit in the status register is set. Arbitration is lost in the following circumstances: • SDA sampled as a low when the master drives a high during an address or data transmit cycle. • SDA sampled as a low when the master drives a high during the acknowledge bit of a data receive cycle. • A START cycle is attempted when the bus is busy. • A repeated START cycle is requested in slave mode. • A STOP condition is detected when the master did not request it. This bit must be cleared by software by writing a one to it. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 219 Inter-Integrated Circuit (S08IICV1) MC9S08GT16A/GT8A Data Sheet, Rev. 1 220 Freescale Semiconductor Chapter 14 Analog-to-Digital Converter (S08ATDV3) The MC9S08GT16A/GT8A provides one 8-channel analog-to-digital (ATD) module. The eight ATD channels share port B. Each channel individually can be configured for general-purpose I/O or for ATD functionality. All features of the ATD module as described in this section are available on the MC9S08GT16A/GT8A. Electrical parametric information for the ATD may be found in Appendix A, “Electrical Characteristics.” MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 221 Analog-to-Digital Converter (S08ATDV3) VREFL VREFH VSSAD VDDAD 4 HCS08 CORE BKGD CPU BDC 10-BIT ANALOG-TO-DIGITAL CONVERTER (ATD) 8 PORT B 4 4 8-BIT KEYBOARD INTERRUPT (KBI) PORT A 8 4 PTA7/KBIP7– PTA4/KBIP4 PTA3/KBIP3– PTA0/KBIP0 PTB7/ADP7– PTB4/ADP4 PTB3/ADP3– PTB0/ADP0 PTC7 PTC6 PTC5 PTC4 PTC3/SCL PTC2/SDA PTC1/RxD2 PTC0/TxD2 NOTE 6 HCS08 SYSTEM CONTROL RESET NOTE 4 RESETS AND INTERRUPTS MODES OF OPERATION POWER MANAGEMENT PORT C RTI IRQ NOTES 2, 3 IRQ COP LVD INTER-IC (IIC) SERIAL COMMUNICATIONS INTERFACE (SCI2) SCL SDA RXD2 TXD2 CH1 CH0 CH0 CH1 CH2 SPSCK MOSI MISO SS RXD1 TXD1 NOTE 5 PORT D USER FLASH (GT16A = 16,384 BYTES) (GT8A = 8192 BYTES) 2-CHANNEL TIMER/PWM (TPM2) PTD4/TPM2CH1 PTD3/TPM2CLK/TPM2CH0 PTD2/TPM1CH2 PTD1/TPM1CH1 PTD0/TPM1CLK/TPM1CH0 PTE5/SPSCK PTE4/MOSI PTE3/MISO PTE2/SS PTE1/RxD1 PTE0/TxD1 PTG3 PTG2/EXTAL PTG1/XTAL PTG0/BKGD/MS USER RAM (GT16A = 2048 BYTES) (GT8A = 1024 BYTES) 3-CHANNEL TIMER/PWM (TPM1) ON-CHIP ICE DEBUG MODULE (DBG) INTERNAL CLOCK GENERATOR (ICG) LOW-POWER OSCILLATOR VDD VSS VSS SERIAL COMMUNICATIONS INTERFACE (SCI1) VOLTAGE REGULATOR = Pins not available in 44-, 42-, or 32-pin packages = Pins not available in 42- or 32-pin packages = Pins not available in 32-pin packages NOTES: 1. Port pins are software configurable with pullup device if input port. 2. Pin contains pullup/pulldown device if IRQ enabled (IRQPE = 1). 3. IRQ does not have a clamp diode to VDD. IRQ should not be driven above VDD. 4. Pin contains integrated pullup device. 5. High current drive. 6. Pins PTA[7:4] contain both pullup and pulldown devices. Pulldown available when KBI enabled (KBIPn = 1). Figure 14-1. MC9S08GT16A Block Diagram Highlighting ATD Block and Pins MC9S08GT16A/GT8A Data Sheet, Rev. 1 222 Freescale Semiconductor PORT G EXTAL XTAL BKGD PORT E SERIAL PERIPHERAL INTERFACE (SPI) Analog-to-Digital Converter (S08ATDV3) 14.1 Introduction The ATD module is an analog-to-digital converter with a successive approximation register (SAR) architecture with sample and hold. 14.1.1 • • • • • • • Features 8-/10-bit resolution 14.0 µsec, 10-bit single conversion time at a conversion frequency of 2 MHz Left-/right-justified result data Left-justified signed data mode Conversion complete flag or conversion complete interrupt generation Analog input multiplexer for up to eight analog input channels Single or continuous conversion mode 14.1.2 Modes of Operation The ATD has two modes for low power • Stop mode • Power-down mode 14.1.2.1 Stop Mode When the MCU goes into stop mode, the MCU stops the clocks and the ATD analog circuitry is turned off, placing the module into a low-power state. Once in stop mode, the ATD module aborts any single or continuous conversion in progress. Upon exiting stop mode, no conversions occur and the registers have their previous values. As long as the ATDPU bit is set prior to entering stop mode, the module is reactivated coming out of stop. 14.1.2.2 Power Down Mode Clearing the ATDPU bit in register ATDC also places the ATD module in a low-power state. The ATD conversion clock is disabled and the analog circuitry is turned off, placing the module in power-down mode. (This mode does not remove power to the ATD module.) Once in power-down mode, the ATD module aborts any conversion in progress. Upon setting the ATDPU bit, the module is reactivated. During power-down mode, the ATD registers are still accessible. Note that the reset state of the ATDPU bit is zero. Therefore, the module is reset into the power-down state. 14.1.3 Block Diagram Figure 14-2 illustrates the functional structure of the ATD module. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 223 Analog-to-Digital Converter (S08ATDV3) CONTROL INTERRUPT ADDRESS R/W DATA CONTROL AND STATUS REGISTERS DATA JUSTIFICATION RESULT REGISTERS SAR_REG VDD VSS BUSCLK PRESCALER STATUS CTL CTL CLOCK PRESCALER CONVERSION MODE CONTROL BLOCK STATE MACHINE CONVERSION CLOCK DIGITAL ANALOG POWERDOWN VREFH VREFL VDDAD VSSAD ADP0 ADP1 ADP2 ADP3 ADP4 ADP5 ADP6 ADP7 = INTERNAL PINS = CHIP PADS INPUT MUX CONVERSION REGISTER CTL SUCCESSIVE APPROXIMATION REGISTER ANALOG-TO-DIGITAL CONVERTER (ATD) BLOCK Figure 14-2. ATD Block Diagram 14.2 External Signal Description The ATD supports eight input channels and requires four supply/reference/ground pins. These pins are listed in Table 14-1. MC9S08GT16A/GT8A Data Sheet, Rev. 1 224 Freescale Semiconductor Analog-to-Digital Converter (S08ATDV3) Table 14-1. Signal Properties Name AD7–AD0 VREFH VREFL VDDAD VSSAD Function Channel input pins High reference voltage for ATD converter Low reference voltage for ATD converter ATD power supply voltage ATD ground supply voltage 14.2.1 ADP7–ADP0 — Channel Input Pins The channel pins are used as the analog input pins of the ATD. Each pin is connected to an analog switch which serves as the signal gate into the sample submodule. 14.2.2 VREFH, VREFL — ATD Reference Pins These pins serve as the source for the high and low reference potentials for the converter. Separation from the power supply pins accommodates the filtering necessary to achieve the accuracy of which the system is capable. 14.2.3 VDDAD, VSSAD — ATD Supply Pins These two pins are used to supply power and ground to the analog section of the ATD. Dedicated power is required to isolate the sensitive analog circuitry from the normal levels of noise present on digital power supplies. NOTE VDDAD1 and VDD must be at the same potential. Likewise, VSSAD1 and VSS must be at the same potential. 14.3 Register Definition The ATD has seven registers that control ATD functions. Refer to the direct-page register summary in the memory chapter of this data sheet for the absolute address assignments for all ATD registers. This section refers to registers and control bits only by their names. A Freescale-provided equate or header file is used to translate these names into the appropriate absolute addresses. 14.3.1 ATD Control (ATDC) Writes to the ATD control register will abort the current conversion, but will not start a new conversion. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 225 Analog-to-Digital Converter (S08ATDV3) 7 6 5 4 3 2 1 0 R W Reset ATDPU 0 DJM 0 RES8 0 SGN 0 0 0 PRS 0 0 Figure 14-3. ATD Control Register (ATDC) Table 14-2. ATDC Field Descriptions Field 7 ATDPU Description ATD Power Up — This bit provides program on/off control over the ATD, reducing power consumption when the ATD is not being used. When cleared, the ATDPU bit aborts any conversion in progress. 0 Disable the ATD and enter a low-power state. 1 ATD functionality. Data Justification Mode — This bit determines how the 10-bit conversion result data maps onto the ATD result register bits. When RES8 is set, bit DJM has no effect and the 8-bit result is always located in ATDRH. For left-justified mode, result data bits 9–2 map onto bits 7–0 of ATDRH, result data bits 1 and 0 map onto ATDRL bits 7 and 6, where bit 7 of ATDRH is the most significant bit (MSB). For right-justified mode, result data bits 9 and 8 map onto bits 1 and 0 of ATDRH, result data bits 7–0 map onto ATDRL bits 7–0, where bit 1 of ATDRH is the most significant bit (MSB). The effect of the DJM bit on the result is shown in Table 14-3. 0 Result register data is left justified. See Figure 14-4. 1 Result register data is right justified. See Figure 14-5. ATD Resolution Select — This bit determines the resolution of the ATD converter, 8-bits or 10-bits. The ATD converter has the accuracy of a 10-bit converter. However, if 8-bit compatibility is required, selecting 8-bit resolution will map result data bits 9-2 onto ATDRH bits 7-0. The effect of the RES8 bit on the result is shown in Table 14-3. 0 10-bit resolution selected. 1 8-bit resolution selected. Signed Result Select — This bit determines whether the result will be signed or unsigned data. Signed data is represented as 2’s complement data and is achieved by complementing the MSB of the result. Signed data mode can be used only when the result is left justified (DJM = 0) and is not available for right-justified mode (DJM = 1). When a signed result is selected, the range for conversions becomes –512 ($200) to 511 ($1FF) for 10-bit resolution and –128 ($80) to 127 ($7F) for 8-bit resolution. The effect of the SGN bit on the result is shown in Table 14-3. 0 Left justified result data is unsigned. 1 Left justified result data is signed. Prescaler Rate Select — This field of bits determines the prescaled factor for the ATD conversion clock. Table 14-4 illustrates the divide-by operation and the appropriate range of bus clock frequencies. 6 DJM 5 RES8 4 SGN 3:0 PRS 7 6 9 ATDRH 7 ATDRH 6 5 4 3 2 RESULT 1 0 7 ATDRL 6 0 5 4 3 2 1 0 Figure 14-4. Left-Justified Mode 5 4 3 2 1 9 0 7 ATDRL Figure 14-5. Right-Justified Mode 6 5 RESULT 4 3 2 1 0 0 MC9S08GT16A/GT8A Data Sheet, Rev. 1 226 Freescale Semiconductor Analog-to-Digital Converter (S08ATDV3) Table 14-3. Available Result Data Formats Analog Input VREFH = VDDA, VREFL = VSSA ATDRH:ATDRL VDDA 1 1 1 0 0 0 1 2 RES8 DJM SGN Data Formats of Result VSSA $00:$00 $80:$00 $00:$00 $00:$00 $80:$00 $00:$00 0 0 1 0 0 1 0 1 X1 0 1 X1 8-bit : left justified : unsigned 8-bit : left justified : signed 8-bit : left justified2 : unsigned 10-bit : left justified : unsigned 10-bit : left justified : signed 10-bit : right justified : unsigned $FF:$00 $7F:$00 $FF:$00 $FF:$C0 $7F:$C0 $03:$FF The SGN bit is only effective when DJM = 0. When DJM = 1, SGN is ignored. 8-bit results are always in ATDRH. Table 14-4. Clock Prescaler Values PRS Factor = (PRS +1) × 2 Min Bus Clock3 Max Bus Clock Max Bus Clock MHz MHz MHz (2 MHz max ATD Clock)1 (1 MHz max ATD Clock)2 (500 kHz min ATD Clock) 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 1 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 4 8 12 16 20 20 20 20 20 20 20 20 20 20 20 20 2 4 6 8 10 12 14 16 18 20 20 20 20 20 20 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Maximum ATD conversion clock frequency is 2 MHz. The max bus clock frequency is computed from the max ATD conversion clock frequency times the indicated prescaler setting; i.e., for a PRS of 0, max bus clock = 2 (max ATD conversion clock frequency) × 2 (Factor) = 4 MHz. 2 Use these settings if the maximum desired ATD conversion clock frequency is 1 MHz. The max bus clock frequency is computed from the max ATD conversion clock frequency times the indicated prescaler setting; i.e., for a PRS of 0, max bus clock = 1 (max ATD conversion clock frequency) × 2 (Factor) = 2 MHz. 3 Minimum ATD conversion clock frequency is 500 kHz. The min bus clock frequency is computed from the min ATD conversion clock frequency times the indicated prescaler setting; i.e., for a PRS of 1, min bus clock = 0.5 (min ATD conversion clock frequency) × 2 (Factor) = 1 MHz. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 227 Analog-to-Digital Converter (S08ATDV3) 14.3.2 ATD Status and Control (ATDSC) Writes to the ATD status and control register clears the CCF flag, cancels any pending interrupts, and initiates a new conversion. 7 6 5 4 3 2 1 0 R W Reset CCF ATDIE 0 ATDCO 0 0 0 ATDCH 0 0 1 0 = Unimplemented or Reserved Figure 14-6. ATD Status and Control Register (ATDSC) Table 14-5. ATDSC Register Field Descriptions Field 7 CCF Description Conversion Complete Flag — The CCF is a read-only bit which is set each time a conversion is complete. The CCF bit is cleared whenever the ATDSC register is written. It is also cleared whenever the result registers, ATDRH or ATDRL, are read. 0 Current conversion is not complete. 1 Current conversion is complete. ATD Interrupt Enabled — When this bit is set, an interrupt is generated upon completion of an ATD conversion. At this time, the result registers contain the result data generated by the conversion. The interrupt will remain pending as long as the conversion complete flag CCF is set. If the ATDIE bit is cleared, then the CCF bit must be polled to determine when the conversion is complete. Note that system reset clears pending interrupts. 0 ATD interrupt disabled. 1 ATD interrupt enabled. ATD Continuous Conversion — When this bit is set, the ATD will convert samples continuously and update the result registers at the end of each conversion. When this bit is cleared, only one conversion is completed between writes to the ATDSC register. 0 Single conversion mode. 1 Continuous conversion mode. Analog Input Channel Select — This field of bits selects the analog input channel whose signal is sampled and converted to digital codes. Table 14-6 lists the coding used to select the various analog input channels. 6 ATDIE 5 ATDCO 4:0 ATDCH Table 14-6. Analog Input Channel Select Coding ATDCH 00 01 02 03 04 05 06 07 08–1D 1E 1F Analog Input Channel AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7 Reserved (default to VREFL) VREFH VREFL MC9S08GT16A/GT8A Data Sheet, Rev. 1 228 Freescale Semiconductor Analog-to-Digital Converter (S08ATDV3) 14.3.3 ATD Result Data (ATDRH, ATDRL) For left-justified mode, result data bits 9–2 map onto bits 7–0 of ATDRH, result data bits 1 and 0 map onto ATDRL bits 7 and 6, where bit 7 of ATDRH is the most significant bit (MSB). 7 9 ATD1RH 6 5 4 3 2 RESULT ATD1RL Figure 14-7. Left-Justified Mode 1 0 7 6 0 5 4 3 2 1 0 For right-justified mode, result data bits 9 and 8 map onto bits 1 and 0 of ATDRH, result data bits 7–0 map onto ATDRL bits 7–0, where bit 1 of ATDRH is the most significant bit (MSB). 7 6 5 4 3 2 1 9 ATD1RH ATD1RL Figure 14-8. Right-Justified Mode 0 7 6 5 RESULT 4 3 2 1 0 0 The ATD 10-bit conversion results are stored in two 8-bit result registers, ATDRH and ATDRL. The result data is formatted either left or right justified where the format is selected using the DJM control bit in the ATDC register. The 10-bit result data is mapped either between ATDRH bits 7–0 and ATDRL bits 7–6 (left justified), or ATDRH bits 1–0 and ATDRL bits 7–0 (right justified). For 8-bit conversions, the 8-bit result is always located in ATDRH bits 7–0, and the ATDRL bits read 0. For 10-bit conversions, the six unused bits always read 0. The ATDRH and ATDRL registers are read-only. 14.3.4 ATD Pin Enable (ATDPE) 7 6 5 4 3 2 1 0 R ATDPE7 W Reset 0 ATDPE6 0 ATDPE5 0 ATDPE4 0 ATDPE3 0 ATDPE2 0 ATDPE1 0 ATDPE0 0 Figure 14-9. ATD Pin Enable Register (ATDPE) Table 14-7. ATDSC Register Field Descriptions Field Description 7:0 ATD Pin 7–0 Enables — The ATD pin enable register allows the pins dedicated to the ATD module to be ATDPE[7:0] configured for ATD usage. A write to this register will abort the current conversion but will not initiate a new conversion. If the ATDPEx bit is 0 (disabled for ATD usage) but the corresponding analog input channel is selected via the ATDCH bits, the ATD will not convert the analog input but will instead convert VREFL placing zeroes in the ATD result registers. 0 Pin disabled for ATD usage. 1 Pin enabled for ATD usage. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 229 Analog-to-Digital Converter (S08ATDV3) 14.4 Functional Description The ATD uses a successive approximation register (SAR) architecture. The ATD contains all the necessary elements to perform a single analog-to-digital conversion. A write to the ATDSC register initiates a new conversion. A write to the ATDC register will interrupt the current conversion but it will not initiate a new conversion. A write to the ATDPE register will also abort the current conversion but will not initiate a new conversion. If a conversion is already running when a write to the ATDSC register is made, it will be aborted and a new one will be started. 14.4.1 Mode Control The ATD has a mode control unit to communicate with the sample and hold (S/H) machine and the SAR machine when necessary to collect samples and perform conversions. The mode control unit signals the S/H machine to begin collecting a sample and for the SAR machine to begin receiving a sample. At the end of the sample period, the S/H machine signals the SAR machine to begin the analog-to-digital conversion process. The conversion process is terminated when the SAR machine signals the end of conversion to the mode control unit. For VREFL and VREFH, the SAR machine uses the reference potentials to set the sampled signal level within itself without relying on the S/H machine to deliver them. The mode control unit organizes the conversion, specifies the input sample channel, and moves the digital output data from the SAR register to the result register. The result register consists of a dual-port register. The SAR register writes data into the register through one port while the module data bus reads data out of the register through the other port. 14.4.2 Sample and Hold The S/H machine accepts analog signals and stores them as capacitor charge on a storage node located in the SAR machine. Only one sample can be held at a time so the S/H machine and the SAR machine can not run concurrently even though they are independent machines. Figure 14-10 shows the placement of the various resistors and capacitors. RAS VAIN INPUT PIN RAIN1 CHANNEL SELECT 0 RAIN2 CHANNEL SELECT 1 INPUT PIN RAIN3 . . . INPUT PIN RAINn CHANNEL SELECT n CHANNEL SELECT 2 ATD SAR ENGINE + – CAS INPUT PIN CAIN Figure 14-10. Resistor and Capacitor Placement MC9S08GT16A/GT8A Data Sheet, Rev. 1 230 Freescale Semiconductor Analog-to-Digital Converter (S08ATDV3) When the S/H machine is not sampling, it disables its own internal clocks.The input analog signals are unipolar. The signals must fall within the potential range of VSSAD to VDDAD. The S/H machine is not required to perform special conversions (i.e., convert VREFL and VREFH). Proper sampling is dependent on the following factors: • Analog source impedance (the real portion, RAS – see the electricals characteristics at the end of this data sheet) — This is the resistive (or real, in the case of high frequencies) portion of the network driving the analog input voltage VAIN. • Analog source capacitance (CAS) — This is the filtering capacitance on the analog input, which (if large enough) may help the analog source network charge the ATD input in the case of high RAS. • ATD input resistance (RAIN – maximum value 7 kΩ) — This is the internal resistance of the ATD circuit in the path between the external ATD input and the ATD sample and hold circuit. This resistance varies with temperature, voltage, and process variation but a worst case number is necessary to compute worst case sample error. • ATD input capacitance (CAIN – maximum value 25 pF) — This is the internal capacitance of the ATD sample and hold circuit. This capacitance varies with temperature, voltage, and process variation but a worst case number is necessary to compute worst case sample error. • ATD conversion clock frequency (fATDCLK – maximum value 2 MHz) — This is the frequency of the clock input to the ATD and is dependent on the bus clock frequency and the ATD prescaler. This frequency determines the width of the sample window, which is 14 ATDCLK cycles. • Input sample frequency (fSAMP – see the electrical characteristics at the end of this data sheet) — This is the frequency that a given input is sampled. • Delta-input sample voltage (∆VSAMP) — This is the difference between the current input voltage (intended for conversion) and the previously sampled voltage (which may be from a different channel). In non-continuous convert mode, this is assumed to be the greater of (VREFH – VAIN) and (VAIN – VREFL). In continuous convert mode, 5 LSB should be added to the known difference to account for leakage and other losses. • Delta-analog input voltage (∆VAIN) — This is the difference between the current input voltage and the input voltage during the last conversion on a given channel. This is based on the slew rate of the input. In cases where there is no external filtering capacitance, the sampling error is determined by the number of time constants of charging and the change in input voltage relative to the resolution of the ATD: # of time constants (τ) = (14 / fATDCLK) / ((RAS + RAIN) * CAIN) Eqn. 14-1 sampling error in LSB (ES) = 2N * (∆VSAMP / (VREFH - VREFL)) * e−τ The maximum sampling error (assuming maximum change on the input voltage) will be: ES = (3.6/3.6) * e–(14/((7 k + 10 k) * 50 p * 2 M)) * 1024 = 0.271 LSB Eqn. 14-2 In the case where an external filtering capacitance is applied, the sampling error can be reduced based on the size of the source capacitor (CAS) relative to the analog input capacitance (CAIN). Ignoring the analog source impedance (RAS), CAS will charge CAIN to a value of: MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 231 Analog-to-Digital Converter (S08ATDV3) ES = 2N * (∆VSAMP / (VREFH – VREFL)) * (CAIN / (CAIN + CAS)) Eqn. 14-3 In the case of a 0.1 µF CAS, a worst case sampling error of 0.5 LSB is achieved regardless of RAS. However, in the case of repeated conversions at a rate of fSAMP, RAS must re-charge CAS. This recharge is continuous and controlled only by RAS (not RAIN), and reduces the overall sampling error to: ES = 2N * {(∆VAIN / (VREFH – VREFL)) * e−(1 / (fSAMP * RAS * CAS ) + (∆VSAMP / (VREFH - VREFL)) * Min[(CAIN / (CAIN + CAS)), e−(1 / (fATDCLK * (RAS + RAIN) * CAIN )]} Eqn. 14-4 This is a worst case sampling error which does not account for RAS recharging the combination of CAS and CAIN during the sample window. It does illustrate that high values of RAS (>10 kΩ) are possible if a large CAS is used and sufficient time to recharge CAS is provided between samples. In order to achieve accuracy specified under the worst case conditions of maximum ∆VSAMP and minimum CAS, RAS must be less than the maximum value of 10 kΩ. The maximum value of 10 kΩ for RAS is to ensure low sampling error in the worst case condition of maximum ∆VSAMP and minimum CAS. 14.4.3 Analog Input Multiplexer The analog input multiplexer selects one of the eight external analog input channels to generate an analog sample. The analog input multiplexer includes negative stress protection circuitry which prevents cross-talk between channels when the applied input potentials are within specification. Only analog input signals within the potential range of VREFL to VREFH (ATD reference potentials) will result in valid ATD conversions. 14.4.4 ATD Module Accuracy Definitions Figure 14-11 illustrates an ideal ATD transfer function. The horizontal axis represents the ATD input voltage in millivolts. The vertical axis the conversion result code. The ATD is specified with the following figures of merit: • Number of bits (N) — The number of bits in the digitized output • Resolution (LSB) — The resolution of the ATD is the step size of the ideal transfer function. This is also referred to as the ideal code width, or the difference between the transition voltages to a given code and to the next code. This unit, known as 1LSB, is equal to 1LSB = (VREFH – VREFL) / 2N Eqn. 14-5 • • • Inherent quantization error (EQ) — This is the error caused by the division of the perfect ideal straight-line transfer function into the quantized ideal transfer function with 2N steps. This error is ± 1/2 LSB. Differential non-linearity (DNL) — This is the difference between the current code width and the ideal code width (1LSB). The current code width is the difference in the transition voltages to the current code and to the next code. A negative DNL means the transfer function spends less time at the current code than ideal; a positive DNL, more. The DNL cannot be less than –1.0; a DNL of greater than 1.0 reduces the effective number of bits by 1. Integral non-linearity (INL) — This is the difference between the transition voltage to the current code and the transition to the corresponding code on the adjusted transfer curve. INL is a measure MC9S08GT16A/GT8A Data Sheet, Rev. 1 232 Freescale Semiconductor Analog-to-Digital Converter (S08ATDV3) of how straight the line is (how far it deviates from a straight line). The adjusted ideal transition voltage is: Eqn. 14-6 Adjusted Ideal Trans. V = (Current Code - 1/2) * ((VREFH + EFS) - (VREFL + EZS)) 2N • Zero scale error (EZS) — This is the difference between the transition voltage to the first valid code and the ideal transition to that code. Normally, it is defined as the difference between the actual and ideal transition to code $001, but in some cases the first transition may be to a higher code. The ideal transition to any code is: Eqn. 14-7 Ideal Transition V = • (Current Code - 1/2) 2N *(VREFH – VREFL) Full scale error (EFS) — This is the difference between the transition voltage to the last valid code and the ideal transition to that code. Normally, it is defined as the difference between the actual and ideal transition to code $3FF, but in some cases the last transition may be to a lower code. The ideal transition to any code is: Eqn. 14-8 Ideal Transition V = • (Current Code - 1/2) 2N *(VREFH – VREFL) • Total unadjusted error (ETU) — This is the difference between the transition voltage to a given code and the ideal straight-line transfer function. An alternate definition (with the same result) is the difference between the actual transfer function and the ideal straight-line transfer function. This measure of error includes inherent quantization error and all forms of circuit error (INL, DNL, zero-scale, and full-scale) except input leakage error, which is not due to the ATD. Input leakage error (EIL) — This is the error between the transition voltage to the current code and the ideal transition to that code that is the result of input leakage across the real portion of the impedance of the network that drives the analog input. This error is a system-observable error which is not inherent to the ATD, so it is not added to total error. This error is: EIL (in V) = input leakage * RAS Eqn. 14-9 There are two other forms of error which are not specified which can also affect ATD accuracy. These are: • Sampling error (ES) — The error due to inadequate time to charge the ATD circuitry • Noise error (EN) — The error due to noise on VAIN, VREFH, or VREFL due to either direct coupling (noise source capacitively coupled directly on the signal) or power supply (VDDAD, VSSAD, VDD, and VSS) noise interfering with the ATD’s ability to resolve the input accurately. The error due to internal sources can be reduced (and specified operation achieved) by operating the ATD conversion in wait mode and ceasing all IO activity. Reducing the error due to external sources is dependent on system activity and board layout. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 233 Analog-to-Digital Converter (S08ATDV3) CODE D C TOTAL UNADJUSTED B ERROR BOUNDARY A IDEAL TRANSFER 9 FUNCTION NEGATIVE DNL (CODE WIDTH 1LSB) 0 1 2 3 4 8 12 LSB NOTES: Graph is for example only and may not represent actual performance Figure 14-11. ATD Accuracy Definitions MC9S08GT16A/GT8A Data Sheet, Rev. 1 234 Freescale Semiconductor Analog-to-Digital Converter (S08ATDV3) 14.5 Resets The ATD module is reset on system reset. If the system reset signal is activated, the ATD registers are initialized back to their reset state and the ATD module is powered down. This occurs as a function of the register file initialization; the reset definition of the ATDPU bit (power down bit) is zero or disabled. The MCU places the module back into an initialized state. If the module is performing a conversion, the current conversion is terminated, the conversion complete flag is cleared, and the SAR register bits are cleared. Any pending interrupts are also cancelled. Note that the control, test, and status registers are initialized on reset; the initialized register state is defined in the register description section of this specification. Enabling the module (using the ATDPU bit) does not cause the module to reset since the register file is not initialized. Finally, writing to control register ATDC does not cause the module to reset; the current conversion will be terminated. 14.6 Interrupts The ATD module originates interrupt requests and the MCU handles or services these requests. Details on how the ATD interrupt requests are handled can be found in the resets and interrupts chapter of this data sheet. The ATD interrupt function is enabled by setting the ATDIE bit in the ATDSC register. When the ATDIE bit is set, an interrupt is generated at the end of an ATD conversion and the ATD result registers (ATDRH and ATDRL) contain the result data generated by the conversion. If the interrupt function is disabled (ATDIE = 0), then the CCF flag must be polled to determine when a conversion is complete. The interrupt will remain pending as long as the CCF flag is set. The CCF bit is cleared whenever the ATD status and control (ATDSC) register is written. The CCF bit is also cleared whenever the ATD result registers (ATDRH or ATDRL) are read. Table 14-8. Interrupt Summary Interrupt CCF Local Enable ATDIE Description Conversion complete MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 235 Analog-to-Digital Converter (S08ATDV3) MC9S08GT16A/GT8A Data Sheet, Rev. 1 236 Freescale Semiconductor Chapter 15 Development Support 15.1 Introduction Development support systems in the HCS08 include the background debug controller (BDC) and the on-chip debug module (DBG). The BDC provides a single-wire debug interface to the target MCU that provides a convenient interface for programming the on-chip FLASH and other nonvolatile memories. The BDC is also the primary debug interface for development and allows non-intrusive access to memory data and traditional debug features such as CPU register modify, breakpoints, and single instruction trace commands. In the HCS08 Family, address and data bus signals are not available on external pins (not even in test modes). Debug is done through commands fed into the target MCU via the single-wire background debug interface. The debug module provides a means to selectively trigger and capture bus information so an external development system can reconstruct what happened inside the MCU on a cycle-by-cycle basis without having external access to the address and data signals. The alternate BDC clock source for MC9S08GT16A/GT8A is the ICGLCLK. See the Chapter 9, “Internal Clock Generator (S08ICGV4),” for more information about ICGCLK and how to select clock sources. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 237 Development Support 15.1.1 Features Features of the BDC module include: • Single pin for mode selection and background communications • BDC registers are not located in the memory map • SYNC command to determine target communications rate • Non-intrusive commands for memory access • Active background mode commands for CPU register access • GO and TRACE1 commands • BACKGROUND command can wake CPU from stop or wait modes • One hardware address breakpoint built into BDC • Oscillator runs in stop mode, if BDC enabled • COP watchdog disabled while in active background mode Features of the ICE system include: • Two trigger comparators: Two address + read/write (R/W) or one full address + data + R/W • Flexible 8-word by 16-bit FIFO (first-in, first-out) buffer for capture information: — Change-of-flow addresses or — Event-only data • Two types of breakpoints: — Tag breakpoints for instruction opcodes — Force breakpoints for any address access • Nine trigger modes: — Basic: A-only, A OR B — Sequence: A then B — Full: A AND B data, A AND NOT B data — Event (store data): Event-only B, A then event-only B — Range: Inside range (A ≤ address ≤ B), outside range (address < A or address > B) 15.2 Background Debug Controller (BDC) All MCUs in the HCS08 Family contain a single-wire background debug interface that supports in-circuit programming of on-chip nonvolatile memory and sophisticated non-intrusive debug capabilities. Unlike debug interfaces on earlier 8-bit MCUs, this system does not interfere with normal application resources. It does not use any user memory or locations in the memory map and does not share any on-chip peripherals. BDC commands are divided into two groups: • Active background mode commands require that the target MCU is in active background mode (the user program is not running). Active background mode commands allow the CPU registers to be read or written, and allow the user to trace one user instruction at a time, or GO to the user program from active background mode. MC9S08GT16A/GT8A Data Sheet, Rev. 1 238 Freescale Semiconductor Development Support • Non-intrusive commands can be executed at any time even while the user’s program is running. Non-intrusive commands allow a user to read or write MCU memory locations or access status and control registers within the background debug controller. Typically, a relatively simple interface pod is used to translate commands from a host computer into commands for the custom serial interface to the single-wire background debug system. Depending on the development tool vendor, this interface pod may use a standard RS-232 serial port, a parallel printer port, or some other type of communications such as a universal serial bus (USB) to communicate between the host PC and the pod. The pod typically connects to the target system with ground, the BKGD pin, RESET, and sometimes VDD. An open-drain connection to reset allows the host to force a target system reset, which is useful to regain control of a lost target system or to control startup of a target system before the on-chip nonvolatile memory has been programmed. Sometimes VDD can be used to allow the pod to use power from the target system to avoid the need for a separate power supply. However, if the pod is powered separately, it can be connected to a running target system without forcing a target system reset or otherwise disturbing the running application program. BKGD 1 NO CONNECT 3 NO CONNECT 5 2 GND 4 RESET 6 VDD Figure 15-1. BDM Tool Connector 15.2.1 BKGD Pin Description BKGD is the single-wire background debug interface pin. The primary function of this pin is for bidirectional serial communication of active background mode commands and data. During reset, this pin is used to select between starting in active background mode or starting the user’s application program. This pin is also used to request a timed sync response pulse to allow a host development tool to determine the correct clock frequency for background debug serial communications. BDC serial communications use a custom serial protocol first introduced on the M68HC12 Family of microcontrollers. This protocol assumes the host knows the communication clock rate that is determined by the target BDC clock rate. All communication is initiated and controlled by the host that drives a high-to-low edge to signal the beginning of each bit time. Commands and data are sent most significant bit first (MSB first). For a detailed description of the communications protocol, refer to Section 15.2.2, “Communication Details.” If a host is attempting to communicate with a target MCU that has an unknown BDC clock rate, a SYNC command may be sent to the target MCU to request a timed sync response signal from which the host can determine the correct communication speed. BKGD is a pseudo-open-drain pin and there is an on-chip pullup so no external pullup resistor is required. Unlike typical open-drain pins, the external RC time constant on this pin, which is influenced by external capacitance, plays almost no role in signal rise time. The custom protocol provides for brief, actively driven speedup pulses to force rapid rise times on this pin without risking harmful drive level conflicts. Refer to Section 15.2.2, “Communication Details,” for more detail. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 239 Development Support When no debugger pod is connected to the 6-pin BDM interface connector, the internal pullup on BKGD chooses normal operating mode. When a development system is connected, it can pull both BKGD and RESET low, release RESET to select active background mode rather than normal operating mode, then release BKGD. It is not necessary to reset the target MCU to communicate with it through the background debug interface. 15.2.2 Communication Details The BDC serial interface requires the external controller to generate a falling edge on the BKGD pin to indicate the start of each bit time. The external controller provides this falling edge whether data is transmitted or received. BKGD is a pseudo-open-drain pin that can be driven either by an external controller or by the MCU. Data is transferred MSB first at 16 BDC clock cycles per bit (nominal speed). The interface times out if 512 BDC clock cycles occur between falling edges from the host. Any BDC command that was in progress when this timeout occurs is aborted without affecting the memory or operating mode of the target MCU system. The custom serial protocol requires the debug pod to know the target BDC communication clock speed. The clock switch (CLKSW) control bit in the BDC status and control register allows the user to select the BDC clock source. The BDC clock source can either be the bus or the alternate BDC clock source. The BKGD pin can receive a high or low level or transmit a high or low level. The following diagrams show timing for each of these cases. Interface timing is synchronous to clocks in the target BDC, but asynchronous to the external host. The internal BDC clock signal is shown for reference in counting cycles. MC9S08GT16A/GT8A Data Sheet, Rev. 1 240 Freescale Semiconductor Development Support Figure 15-2 shows an external host transmitting a logic 1 or 0 to the BKGD pin of a target HCS08 MCU. The host is asynchronous to the target so there is a 0-to-1 cycle delay from the host-generated falling edge to where the target perceives the beginning of the bit time. Ten target BDC clock cycles later, the target senses the bit level on the BKGD pin. Typically, the host actively drives the pseudo-open-drain BKGD pin during host-to-target transmissions to speed up rising edges. Because the target does not drive the BKGD pin during the host-to-target transmission period, there is no need to treat the line as an open-drain signal during this period. BDC CLOCK (TARGET MCU) HOST TRANSMIT 1 HOST TRANSMIT 0 10 CYCLES EARLIEST START OF NEXT BIT SYNCHRONIZATION UNCERTAINTY PERCEIVED START OF BIT TIME TARGET SENSES BIT LEVEL Figure 15-2. BDC Host-to-Target Serial Bit Timing MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 241 Development Support Figure 15-3 shows the host receiving a logic 1 from the target HCS08 MCU. Because the host is asynchronous to the target MCU, there is a 0-to-1 cycle delay from the host-generated falling edge on BKGD to the perceived start of the bit time in the target MCU. The host holds the BKGD pin low long enough for the target to recognize it (at least two target BDC cycles). The host must release the low drive before the target MCU drives a brief active-high speedup pulse seven cycles after the perceived start of the bit time. The host should sample the bit level about 10 cycles after it started the bit time. BDC CLOCK (TARGET MCU) HOST DRIVE TO BKGD PIN HIGH-IMPEDANCE TARGET MCU SPEEDUP PULSE HIGH-IMPEDANCE PERCEIVED START OF BIT TIME R-C RISE BKGD PIN HIGH-IMPEDANCE 10 CYCLES 10 CYCLES HOST SAMPLES BKGD PIN EARLIEST START OF NEXT BIT Figure 15-3. BDC Target-to-Host Serial Bit Timing (Logic 1) MC9S08GT16A/GT8A Data Sheet, Rev. 1 242 Freescale Semiconductor Development Support Figure 15-4 shows the host receiving a logic 0 from the target HCS08 MCU. Because the host is asynchronous to the target MCU, there is a 0-to-1 cycle delay from the host-generated falling edge on BKGD to the start of the bit time as perceived by the target MCU. The host initiates the bit time but the target HCS08 finishes it. Because the target wants the host to receive a logic 0, it drives the BKGD pin low for 13 BDC clock cycles, then briefly drives it high to speed up the rising edge. The host samples the bit level about 10 cycles after starting the bit time. BDC CLOCK (TARGET MCU) HOST DRIVE TO BKGD PIN HIGH-IMPEDANCE TARGET MCU DRIVE AND SPEED-UP PULSE PERCEIVED START OF BIT TIME SPEEDUP PULSE BKGD PIN 10 CYCLES 10 CYCLES EARLIEST START OF NEXT BIT HOST SAMPLES BKGD PIN Figure 15-4. BDM Target-to-Host Serial Bit Timing (Logic 0) MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 243 Development Support 15.2.3 BDC Commands BDC commands are sent serially from a host computer to the BKGD pin of the target HCS08 MCU. All commands and data are sent MSB-first using a custom BDC communications protocol. Active background mode commands require that the target MCU is currently in the active background mode while non-intrusive commands may be issued at any time whether the target MCU is in active background mode or running a user application program. Table 15-1 shows all HCS08 BDC commands, a shorthand description of their coding structure, and the meaning of each command. Coding Structure Nomenclature This nomenclature is used in Table 15-1 to describe the coding structure of the BDC commands. Commands begin with an 8-bit hexadecimal command code in the host-to-target direction (most significant bit first) / = separates parts of the command d = delay 16 target BDC clock cycles AAAA = a 16-bit address in the host-to-target direction RD = 8 bits of read data in the target-to-host direction WD = 8 bits of write data in the host-to-target direction RD16 = 16 bits of read data in the target-to-host direction WD16 = 16 bits of write data in the host-to-target direction SS = the contents of BDCSCR in the target-to-host direction (STATUS) CC = 8 bits of write data for BDCSCR in the host-to-target direction (CONTROL) RBKP = 16 bits of read data in the target-to-host direction (from BDCBKPT breakpoint register) WBKP = 16 bits of write data in the host-to-target direction (for BDCBKPT breakpoint register) MC9S08GT16A/GT8A Data Sheet, Rev. 1 244 Freescale Semiconductor Development Support Table 15-1. BDC Command Summary Command Mnemonic SYNC ACK_ENABLE ACK_DISABLE BACKGROUND READ_STATUS WRITE_CONTROL READ_BYTE READ_BYTE_WS READ_LAST WRITE_BYTE WRITE_BYTE_WS READ_BKPT WRITE_BKPT GO TRACE1 TAGGO READ_A READ_CCR READ_PC READ_HX READ_SP READ_NEXT READ_NEXT_WS WRITE_A WRITE_CCR WRITE_PC WRITE_HX WRITE_SP WRITE_NEXT WRITE_NEXT_WS 1 Active BDM/ Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Non-intrusive Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM Active BDM n/a1 D5/d D6/d 90/d E4/SS C4/CC Coding Structure Description Request a timed reference pulse to determine target BDC communication speed Enable acknowledge protocol. Refer to Freescale document order no. HCS08RMv1/D. Disable acknowledge protocol. Refer to Freescale document order no. HCS08RMv1/D. Enter active background mode if enabled (ignore if ENBDM bit equals 0) Read BDC status from BDCSCR Write BDC controls in BDCSCR Read a byte from target memory Read a byte and report status Re-read byte from address just read and report status Write a byte to target memory Write a byte and report status Read BDCBKPT breakpoint register Write BDCBKPT breakpoint register Go to execute the user application program starting at the address currently in the PC Trace 1 user instruction at the address in the PC, then return to active background mode Same as GO but enable external tagging (HCS08 devices have no external tagging pin) Read accumulator (A) Read condition code register (CCR) Read program counter (PC) Read H and X register pair (H:X) Read stack pointer (SP) Increment H:X by one then read memory byte located at H:X Increment H:X by one then read memory byte located at H:X. Report status and data. Write accumulator (A) Write condition code register (CCR) Write program counter (PC) Write H and X register pair (H:X) Write stack pointer (SP) Increment H:X by one, then write memory byte located at H:X Increment H:X by one, then write memory byte located at H:X. Also report status. E0/AAAA/d/RD E1/AAAA/d/SS/RD E8/SS/RD C0/AAAA/WD/d C1/AAAA/WD/d/SS E2/RBKP C2/WBKP 08/d 10/d 18/d 68/d/RD 69/d/RD 6B/d/RD16 6C/d/RD16 6F/d/RD16 70/d/RD 71/d/SS/RD 48/WD/d 49/WD/d 4B/WD16/d 4C/WD16/d 4F/WD16/d 50/WD/d 51/WD/d/SS The SYNC command is a special operation that does not have a command code. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 245 Development Support The SYNC command is unlike other BDC commands because the host does not necessarily know the correct communications speed to use for BDC communications until after it has analyzed the response to the SYNC command. To issue a SYNC command, the host: • Drives the BKGD pin low for at least 128 cycles of the slowest possible BDC clock (The slowest clock is normally the reference oscillator/64 or the self-clocked rate/64.) • Drives BKGD high for a brief speedup pulse to get a fast rise time (This speedup pulse is typically one cycle of the fastest clock in the system.) • Removes all drive to the BKGD pin so it reverts to high impedance • Monitors the BKGD pin for the sync response pulse The target, upon detecting the SYNC request from the host (which is a much longer low time than would ever occur during normal BDC communications): • Waits for BKGD to return to a logic high • Delays 16 cycles to allow the host to stop driving the high speedup pulse • Drives BKGD low for 128 BDC clock cycles • Drives a 1-cycle high speedup pulse to force a fast rise time on BKGD • Removes all drive to the BKGD pin so it reverts to high impedance The host measures the low time of this 128-cycle sync response pulse and determines the correct speed for subsequent BDC communications. Typically, the host can determine the correct communication speed within a few percent of the actual target speed and the communication protocol can easily tolerate speed errors of several percent. 15.2.4 BDC Hardware Breakpoint The BDC includes one relatively simple hardware breakpoint that compares the CPU address bus to a 16-bit match value in the BDCBKPT register. This breakpoint can generate a forced breakpoint or a tagged breakpoint. A forced breakpoint causes the CPU to enter active background mode at the first instruction boundary following any access to the breakpoint address. The tagged breakpoint causes the instruction opcode at the breakpoint address to be tagged so that the CPU will enter active background mode rather than executing that instruction if and when it reaches the end of the instruction queue. This implies that tagged breakpoints can only be placed at the address of an instruction opcode while forced breakpoints can be set at any address. The breakpoint enable (BKPTEN) control bit in the BDC status and control register (BDCSCR) is used to enable the breakpoint logic (BKPTEN = 1). When BKPTEN = 0, its default value after reset, the breakpoint logic is disabled and no BDC breakpoints are requested regardless of the values in other BDC breakpoint registers and control bits. The force/tag select (FTS) control bit in BDCSCR is used to select forced (FTS = 1) or tagged (FTS = 0) type breakpoints. The on-chip debug module (DBG) includes circuitry for two additional hardware breakpoints that are more flexible than the simple breakpoint in the BDC module. MC9S08GT16A/GT8A Data Sheet, Rev. 1 246 Freescale Semiconductor Development Support 15.3 On-Chip Debug System (DBG) Because HCS08 devices do not have external address and data buses, the most important functions of an in-circuit emulator have been built onto the chip with the MCU. The debug system consists of an 8-stage FIFO that can store address or data bus information, and a flexible trigger system to decide when to capture bus information and what information to capture. The system relies on the single-wire background debug system to access debug control registers and to read results out of the eight stage FIFO. The debug module includes control and status registers that are accessible in the user’s memory map. These registers are located in the high register space to avoid using valuable direct page memory space. Most of the debug module’s functions are used during development, and user programs rarely access any of the control and status registers for the debug module. The one exception is that the debug system can provide the means to implement a form of ROM patching. This topic is discussed in greater detail in Section 15.3.6, “Hardware Breakpoints.” 15.3.1 Comparators A and B Two 16-bit comparators (A and B) can optionally be qualified with the R/W signal and an opcode tracking circuit. Separate control bits allow you to ignore R/W for each comparator. The opcode tracking circuitry optionally allows you to specify that a trigger will occur only if the opcode at the specified address is actually executed as opposed to only being read from memory into the instruction queue. The comparators are also capable of magnitude comparisons to support the inside range and outside range trigger modes. Comparators are disabled temporarily during all BDC accesses. The A comparator is always associated with the 16-bit CPU address. The B comparator compares to the CPU address or the 8-bit CPU data bus, depending on the trigger mode selected. Because the CPU data bus is separated into a read data bus and a write data bus, the RWAEN and RWA control bits have an additional purpose, in full address plus data comparisons they are used to decide which of these buses to use in the comparator B data bus comparisons. If RWAEN = 1 (enabled) and RWA = 0 (write), the CPU’s write data bus is used. Otherwise, the CPU’s read data bus is used. The currently selected trigger mode determines what the debugger logic does when a comparator detects a qualified match condition. A match can cause: • Generation of a breakpoint to the CPU • Storage of data bus values into the FIFO • Starting to store change-of-flow addresses into the FIFO (begin type trace) • Stopping the storage of change-of-flow addresses into the FIFO (end type trace) 15.3.2 Bus Capture Information and FIFO Operation The usual way to use the FIFO is to setup the trigger mode and other control options, then arm the debugger. When the FIFO has filled or the debugger has stopped storing data into the FIFO, you would read the information out of it in the order it was stored into the FIFO. Status bits indicate the number of words of valid information that are in the FIFO as data is stored into it. If a trace run is manually halted by writing 0 to ARM before the FIFO is full (CNT = 1:0:0:0), the information is shifted by one position and MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 247 Development Support the host must perform ((8 – CNT) – 1) dummy reads of the FIFO to advance it to the first significant entry in the FIFO. In most trigger modes, the information stored in the FIFO consists of 16-bit change-of-flow addresses. In these cases, read DBGFH then DBGFL to get one coherent word of information out of the FIFO. Reading DBGFL (the low-order byte of the FIFO data port) causes the FIFO to shift so the next word of information is available at the FIFO data port. In the event-only trigger modes (see Section 15.3.5, “Trigger Modes”), 8-bit data information is stored into the FIFO. In these cases, the high-order half of the FIFO (DBGFH) is not used and data is read out of the FIFO by simply reading DBGFL. Each time DBGFL is read, the FIFO is shifted so the next data value is available through the FIFO data port at DBGFL. In trigger modes where the FIFO is storing change-of-flow addresses, there is a delay between CPU addresses and the input side of the FIFO. Because of this delay, if the trigger event itself is a change-of-flow address or a change-of-flow address appears during the next two bus cycles after a trigger event starts the FIFO, it will not be saved into the FIFO. In the case of an end-trace, if the trigger event is a change-of-flow, it will be saved as the last change-of-flow entry for that debug run. The FIFO can also be used to generate a profile of executed instruction addresses when the debugger is not armed. When ARM = 0, reading DBGFL causes the address of the most-recently fetched opcode to be saved in the FIFO. To use the profiling feature, a host debugger would read addresses out of the FIFO by reading DBGFH then DBGFL at regular periodic intervals. The first eight values would be discarded because they correspond to the eight DBGFL reads needed to initially fill the FIFO. Additional periodic reads of DBGFH and DBGFL return delayed information about executed instructions so the host debugger can develop a profile of executed instruction addresses. 15.3.3 Change-of-Flow Information To minimize the amount of information stored in the FIFO, only information related to instructions that cause a change to the normal sequential execution of instructions is stored. With knowledge of the source and object code program stored in the target system, an external debugger system can reconstruct the path of execution through many instructions from the change-of-flow information stored in the FIFO. For conditional branch instructions where the branch is taken (branch condition was true), the source address is stored (the address of the conditional branch opcode). Because BRA and BRN instructions are not conditional, these events do not cause change-of-flow information to be stored in the FIFO. Indirect JMP and JSR instructions use the current contents of the H:X index register pair to determine the destination address, so the debug system stores the run-time destination address for any indirect JMP or JSR. For interrupts, RTI, or RTS, the destination address is stored in the FIFO as change-of-flow information. 15.3.4 Tag vs. Force Breakpoints and Triggers Tagging is a term that refers to identifying an instruction opcode as it is fetched into the instruction queue, but not taking any other action until and unless that instruction is actually executed by the CPU. This distinction is important because any change-of-flow from a jump, branch, subroutine call, or interrupt causes some instructions that have been fetched into the instruction queue to be thrown away without being executed. MC9S08GT16A/GT8A Data Sheet, Rev. 1 248 Freescale Semiconductor Development Support A force-type breakpoint waits for the current instruction to finish and then acts upon the breakpoint request. The usual action in response to a breakpoint is to go to active background mode rather than continuing to the next instruction in the user application program. The tag vs. force terminology is used in two contexts within the debug module. The first context refers to breakpoint requests from the debug module to the CPU. The second refers to match signals from the comparators to the debugger control logic. When a tag-type break request is sent to the CPU, a signal is entered into the instruction queue along with the opcode so that if/when this opcode ever executes, the CPU will effectively replace the tagged opcode with a BGND opcode so the CPU goes to active background mode rather than executing the tagged instruction. When the TRGSEL control bit in the DBGT register is set to select tag-type operation, the output from comparator A or B is qualified by a block of logic in the debug module that tracks opcodes and only produces a trigger to the debugger if the opcode at the compare address is actually executed. There is separate opcode tracking logic for each comparator so more than one compare event can be tracked through the instruction queue at a time. 15.3.5 Trigger Modes The trigger mode controls the overall behavior of a debug run. The 4-bit TRG field in the DBGT register selects one of nine trigger modes. When TRGSEL = 1 in the DBGT register, the output of the comparator must propagate through an opcode tracking circuit before triggering FIFO actions. The BEGIN bit in DBGT chooses whether the FIFO begins storing data when the qualified trigger is detected (begin trace), or the FIFO stores data in a circular fashion from the time it is armed until the qualified trigger is detected (end trigger). A debug run is started by writing a 1 to the ARM bit in the DBGC register, which sets the ARMF flag and clears the AF and BF flags and the CNT bits in DBGS. A begin-trace debug run ends when the FIFO gets full. An end-trace run ends when the selected trigger event occurs. Any debug run can be stopped manually by writing a 0 to ARM or DBGEN in DBGC. In all trigger modes except event-only modes, the FIFO stores change-of-flow addresses. In event-only trigger modes, the FIFO stores data in the low-order eight bits of the FIFO. The BEGIN control bit is ignored in event-only trigger modes and all such debug runs are begin type traces. When TRGSEL = 1 to select opcode fetch triggers, it is not necessary to use R/W in comparisons because opcode tags would only apply to opcode fetches that are always read cycles. It would also be unusual to specify TRGSEL = 1 while using a full mode trigger because the opcode value is normally known at a particular address. The following trigger mode descriptions only state the primary comparator conditions that lead to a trigger. Either comparator can usually be further qualified with R/W by setting RWAEN (RWBEN) and the corresponding RWA (RWB) value to be matched against R/W. The signal from the comparator with optional R/W qualification is used to request a CPU breakpoint if BRKEN = 1 and TAG determines whether the CPU request will be a tag request or a force request. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 249 Development Support A-Only — Trigger when the address matches the value in comparator A A OR B — Trigger when the address matches either the value in comparator A or the value in comparator B A Then B — Trigger when the address matches the value in comparator B but only after the address for another cycle matched the value in comparator A. There can be any number of cycles after the A match and before the B match. A AND B Data (Full Mode) — This is called a full mode because address, data, and R/W (optionally) must match within the same bus cycle to cause a trigger event. Comparator A checks address, the low byte of comparator B checks data, and R/W is checked against RWA if RWAEN = 1. The high-order half of comparator B is not used. In full trigger modes it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if you do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and the CPU breakpoint is issued when the comparator A address matches. A AND NOT B Data (Full Mode) — Address must match comparator A, data must not match the low half of comparator B, and R/W must match RWA if RWAEN = 1. All three conditions must be met within the same bus cycle to cause a trigger. In full trigger modes it is not useful to specify a tag-type CPU breakpoint (BRKEN = TAG = 1), but if you do, the comparator B data match is ignored for the purpose of issuing the tag request to the CPU and the CPU breakpoint is issued when the comparator A address matches. Event-Only B (Store Data) — Trigger events occur each time the address matches the value in comparator B. Trigger events cause the data to be captured into the FIFO. The debug run ends when the FIFO becomes full. A Then Event-Only B (Store Data) — After the address has matched the value in comparator A, a trigger event occurs each time the address matches the value in comparator B. Trigger events cause the data to be captured into the FIFO. The debug run ends when the FIFO becomes full. Inside Range (A ≤ Address ≤ B) — A trigger occurs when the address is greater than or equal to the value in comparator A and less than or equal to the value in comparator B at the same time. Outside Range (Address < A or Address > B) — A trigger occurs when the address is either less than the value in comparator A or greater than the value in comparator B. MC9S08GT16A/GT8A Data Sheet, Rev. 1 250 Freescale Semiconductor Development Support 15.3.6 Hardware Breakpoints The BRKEN control bit in the DBGC register may be set to 1 to allow any of the trigger conditions described in Section 15.3.5, “Trigger Modes,” to be used to generate a hardware breakpoint request to the CPU. TAG in DBGC controls whether the breakpoint request will be treated as a tag-type breakpoint or a force-type breakpoint. A tag breakpoint causes the current opcode to be marked as it enters the instruction queue. If a tagged opcode reaches the end of the pipe, the CPU executes a BGND instruction to go to active background mode rather than executing the tagged opcode. A force-type breakpoint causes the CPU to finish the current instruction and then go to active background mode. If the background mode has not been enabled (ENBDM = 1) by a serial WRITE_CONTROL command through the BKGD pin, the CPU will execute an SWI instruction instead of going to active background mode. 15.4 Register Definition This section contains the descriptions of the BDC and DBG registers and control bits. Refer to the high-page register summary in the device overview chapter of this data sheet for the absolute address assignments for all DBG registers. This section refers to registers and control bits only by their names. A Freescale-provided equate or header file is used to translate these names into the appropriate absolute addresses. 15.4.1 BDC Registers and Control Bits The BDC has two registers: • The BDC status and control register (BDCSCR) is an 8-bit register containing control and status bits for the background debug controller. • The BDC breakpoint match register (BDCBKPT) holds a 16-bit breakpoint match address. These registers are accessed with dedicated serial BDC commands and are not located in the memory space of the target MCU (so they do not have addresses and cannot be accessed by user programs). Some of the bits in the BDCSCR have write limitations; otherwise, these registers may be read or written at any time. For example, the ENBDM control bit may not be written while the MCU is in active background mode. (This prevents the ambiguous condition of the control bit forbidding active background mode while the MCU is already in active background mode.) Also, the four status bits (BDMACT, WS, WSF, and DVF) are read-only status indicators and can never be written by the WRITE_CONTROL serial BDC command. The clock switch (CLKSW) control bit may be read or written at any time. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 251 Development Support 15.4.1.1 BDC Status and Control Register (BDCSCR) This register can be read or written by serial BDC commands (READ_STATUS and WRITE_CONTROL) but is not accessible to user programs because it is not located in the normal memory map of the MCU. 7 6 5 4 3 2 1 0 R ENBDM W Normal Reset Reset in Active BDM: 0 1 BDMACT BKPTEN 0 1 0 0 FTS 0 0 CLKSW 0 1 WS WSF DVF 0 0 0 0 0 0 = Unimplemented or Reserved Figure 15-5. BDC Status and Control Register (BDCSCR) Table 15-2. BDCSCR Register Field Descriptions Field 7 ENBDM Description Enable BDM (Permit Active Background Mode) — Typically, this bit is written to 1 by the debug host shortly after the beginning of a debug session or whenever the debug host resets the target and remains 1 until a normal reset clears it. 0 BDM cannot be made active (non-intrusive commands still allowed) 1 BDM can be made active to allow active background mode commands Background Mode Active Status — This is a read-only status bit. 0 BDM not active (user application program running) 1 BDM active and waiting for serial commands BDC Breakpoint Enable — If this bit is clear, the BDC breakpoint is disabled and the FTS (force tag select) control bit and BDCBKPT match register are ignored. 0 BDC breakpoint disabled 1 BDC breakpoint enabled Force/Tag Select — When FTS = 1, a breakpoint is requested whenever the CPU address bus matches the BDCBKPT match register. When FTS = 0, a match between the CPU address bus and the BDCBKPT register causes the fetched opcode to be tagged. If this tagged opcode ever reaches the end of the instruction queue, the CPU enters active background mode rather than executing the tagged opcode. 0 Tag opcode at breakpoint address and enter active background mode if CPU attempts to execute that instruction 1 Breakpoint match forces active background mode at next instruction boundary (address need not be an opcode) Select Source for BDC Communications Clock — CLKSW defaults to 0, which selects the alternate BDC clock source. 0 Alternate BDC clock source 1 MCU bus clock 6 BDMACT 5 BKPTEN 4 FTS 3 CLKSW MC9S08GT16A/GT8A Data Sheet, Rev. 1 252 Freescale Semiconductor Development Support Table 15-2. BDCSCR Register Field Descriptions (continued) Field 2 WS Description Wait or Stop Status — When the target CPU is in wait or stop mode, most BDC commands cannot function. However, the BACKGROUND command can be used to force the target CPU out of wait or stop and into active background mode where all BDC commands work. Whenever the host forces the target MCU into active background mode, the host should issue a READ_STATUS command to check that BDMACT = 1 before attempting other BDC commands. 0 Target CPU is running user application code or in active background mode (was not in wait or stop mode when background became active) 1 Target CPU is in wait or stop mode, or a BACKGROUND command was used to change from wait or stop to active background mode Wait or Stop Failure Status — This status bit is set if a memory access command failed due to the target CPU executing a wait or stop instruction at or about the same time. The usual recovery strategy is to issue a BACKGROUND command to get out of wait or stop mode into active background mode, repeat the command that failed, then return to the user program. (Typically, the host would restore CPU registers and stack values and re-execute the wait or stop instruction.) 0 Memory access did not conflict with a wait or stop instruction 1 Memory access command failed because the CPU entered wait or stop mode Data Valid Failure Status — This status bit is not used in the MC9S08GT16A/GT8A because it does not have any slow access memory. 0 Memory access did not conflict with a slow memory access 1 Memory access command failed because CPU was not finished with a slow memory access 1 WSF 0 DVF 15.4.1.2 BDC Breakpoint Match Register (BDCBKPT) This 16-bit register holds the address for the hardware breakpoint in the BDC. The BKPTEN and FTS control bits in BDCSCR are used to enable and configure the breakpoint logic. Dedicated serial BDC commands (READ_BKPT and WRITE_BKPT) are used to read and write the BDCBKPT register but is not accessible to user programs because it is not located in the normal memory map of the MCU. Breakpoints are normally set while the target MCU is in active background mode before running the user application program. For additional information about setup and use of the hardware breakpoint logic in the BDC, refer to Section 15.2.4, “BDC Hardware Breakpoint.” 15.4.2 System Background Debug Force Reset Register (SBDFR) This register contains a single write-only control bit. A serial background mode command such as WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are ignored. Reads always return 0x00. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 253 Development Support 7 6 5 4 3 2 1 0 R W Reset 0 0 0 0 0 0 0 0 BDFR1 0 0 0 0 0 0 0 0 = Unimplemented or Reserved 1 BDFR is writable only through serial background mode debug commands, not from user programs. Figure 15-6. System Background Debug Force Reset Register (SBDFR) Table 15-3. SBDFR Register Field Description Field 0 BDFR Description Background Debug Force Reset — A serial active background mode command such as WRITE_BYTE allows an external debug host to force a target system reset. Writing 1 to this bit forces an MCU reset. This bit cannot be written from a user program. 15.4.3 DBG Registers and Control Bits The debug module includes nine bytes of register space for three 16-bit registers and three 8-bit control and status registers. These registers are located in the high register space of the normal memory map so they are accessible to normal application programs. These registers are rarely if ever accessed by normal user application programs with the possible exception of a ROM patching mechanism that uses the breakpoint logic. 15.4.3.1 Debug Comparator A High Register (DBGCAH) This register contains compare value bits for the high-order eight bits of comparator A. This register is forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1. 15.4.3.2 Debug Comparator A Low Register (DBGCAL) This register contains compare value bits for the low-order eight bits of comparator A. This register is forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1. 15.4.3.3 Debug Comparator B High Register (DBGCBH) This register contains compare value bits for the high-order eight bits of comparator B. This register is forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1. 15.4.3.4 Debug Comparator B Low Register (DBGCBL) This register contains compare value bits for the low-order eight bits of comparator B. This register is forced to 0x00 at reset and can be read at any time or written at any time unless ARM = 1. MC9S08GT16A/GT8A Data Sheet, Rev. 1 254 Freescale Semiconductor Development Support 15.4.3.5 Debug FIFO High Register (DBGFH) This register provides read-only access to the high-order eight bits of the FIFO. Writes to this register have no meaning or effect. In the event-only trigger modes, the FIFO only stores data into the low-order byte of each FIFO word, so this register is not used and will read 0x00. Reading DBGFH does not cause the FIFO to shift to the next word. When reading 16-bit words out of the FIFO, read DBGFH before reading DBGFL because reading DBGFL causes the FIFO to advance to the next word of information. 15.4.3.6 Debug FIFO Low Register (DBGFL) This register provides read-only access to the low-order eight bits of the FIFO. Writes to this register have no meaning or effect. Reading DBGFL causes the FIFO to shift to the next available word of information. When the debug module is operating in event-only modes, only 8-bit data is stored into the FIFO (high-order half of each FIFO word is unused). When reading 8-bit words out of the FIFO, simply read DBGFL repeatedly to get successive bytes of data from the FIFO. It isn’t necessary to read DBGFH in this case. Do not attempt to read data from the FIFO while it is still armed (after arming but before the FIFO is filled or ARMF is cleared) because the FIFO is prevented from advancing during reads of DBGFL. This can interfere with normal sequencing of reads from the FIFO. Reading DBGFL while the debugger is not armed causes the address of the most-recently fetched opcode to be stored to the last location in the FIFO. By reading DBGFH then DBGFL periodically, external host software can develop a profile of program execution. After eight reads from the FIFO, the ninth read will return the information that was stored as a result of the first read. To use the profiling feature, read the FIFO eight times without using the data to prime the sequence and then begin using the data to get a delayed picture of what addresses were being executed. The information stored into the FIFO on reads of DBGFL (while the FIFO is not armed) is the address of the most-recently fetched opcode. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 255 Development Support 15.4.3.7 Debug Control Register (DBGC) This register can be read or written at any time. 7 6 5 4 3 2 1 0 R DBGEN W Reset 0 0 0 0 0 0 0 0 ARM TAG BRKEN RWA RWAEN RWB RWBEN Figure 15-7. Debug Control Register (DBGC) Table 15-4. DBGC Register Field Descriptions Field 7 DBGEN 6 ARM Description Debug Module Enable — Used to enable the debug module. DBGEN cannot be set to 1 if the MCU is secure. 0 DBG disabled 1 DBG enabled Arm Control — Controls whether the debugger is comparing and storing information in the FIFO. A write is used to set this bit (and ARMF) and completion of a debug run automatically clears it. Any debug run can be manually stopped by writing 0 to ARM or to DBGEN. 0 Debugger not armed 1 Debugger armed Tag/Force Select — Controls whether break requests to the CPU will be tag or force type requests. If BRKEN = 0, this bit has no meaning or effect. 0 CPU breaks requested as force type requests 1 CPU breaks requested as tag type requests Break Enable — Controls whether a trigger event will generate a break request to the CPU. Trigger events can cause information to be stored in the FIFO without generating a break request to the CPU. For an end trace, CPU break requests are issued to the CPU when the comparator(s) and R/W meet the trigger requirements. For a begin trace, CPU break requests are issued when the FIFO becomes full. TRGSEL does not affect the timing of CPU break requests. 0 CPU break requests not enabled 1 Triggers cause a break request to the CPU R/W Comparison Value for Comparator A — When RWAEN = 1, this bit determines whether a read or a write access qualifies comparator A. When RWAEN = 0, RWA and the R/W signal do not affect comparator A. 0 Comparator A can only match on a write cycle 1 Comparator A can only match on a read cycle Enable R/W for Comparator A — Controls whether the level of R/W is considered for a comparator A match. 0 R/W is not used in comparison A 1 R/W is used in comparison A R/W Comparison Value for Comparator B — When RWBEN = 1, this bit determines whether a read or a write access qualifies comparator B. When RWBEN = 0, RWB and the R/W signal do not affect comparator B. 0 Comparator B can match only on a write cycle 1 Comparator B can match only on a read cycle Enable R/W for Comparator B — Controls whether the level of R/W is considered for a comparator B match. 0 R/W is not used in comparison B 1 R/W is used in comparison B 5 TAG 4 BRKEN 3 RWA 2 RWAEN 1 RWB 0 RWBEN MC9S08GT16A/GT8A Data Sheet, Rev. 1 256 Freescale Semiconductor Development Support 15.4.3.8 Debug Trigger Register (DBGT) This register can be read any time, but may be written only if ARM = 0, except bits 4 and 5 are hard-wired to 0s. 7 6 5 4 3 2 1 0 R TRGSEL W Reset 0 0 BEGIN 0 0 TRG3 TRG2 0 TRG1 0 TRG0 0 0 0 0 = Unimplemented or Reserved Figure 15-8. Debug Trigger Register (DBGT) Table 15-5. DBGT Register Field Descriptions Field 7 TRGSEL Description Trigger Type — Controls whether the match outputs from comparators A and B are qualified with the opcode tracking logic in the debug module. If TRGSEL is set, a match signal from comparator A or B must propagate through the opcode tracking logic and a trigger event is only signalled to the FIFO logic if the opcode at the match address is actually executed. 0 Trigger on access to compare address (force) 1 Trigger if opcode at compare address is executed (tag) Begin/End Trigger Select — Controls whether the FIFO starts filling at a trigger or fills in a circular manner until a trigger ends the capture of information. In event-only trigger modes, this bit is ignored and all debug runs are assumed to be begin traces. 0 Data stored in FIFO until trigger (end trace) 1 Trigger initiates data storage (begin trace) Select Trigger Mode — Selects one of nine triggering modes, as described below. 0000 A-only 0001 A OR B 0010 A Then B 0011 Event-only B (store data) 0100 A then event-only B (store data) 0101 A AND B data (full mode) 0110 A AND NOT B data (full mode) 0111 Inside range: A ≤ address ≤ B 1000 Outside range: address < A or address > B 1001 – 1111 (No trigger) 6 BEGIN 3:0 TRG[3:0] MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 257 Development Support 15.4.3.9 Debug Status Register (DBGS) This is a read-only status register. 7 6 5 4 3 2 1 0 R W Reset AF BF ARMF 0 CNT3 CNT2 CNT1 CNT0 0 0 0 0 0 0 0 0 = Unimplemented or Reserved Figure 15-9. Debug Status Register (DBGS) Table 15-6. DBGS Register Field Descriptions Field 7 AF Description Trigger Match A Flag — AF is cleared at the start of a debug run and indicates whether a trigger match A condition was met since arming. 0 Comparator A has not matched 1 Comparator A match Trigger Match B Flag — BF is cleared at the start of a debug run and indicates whether a trigger match B condition was met since arming. 0 Comparator B has not matched 1 Comparator B match Arm Flag — While DBGEN = 1, this status bit is a read-only image of ARM in DBGC. This bit is set by writing 1 to the ARM control bit in DBGC (while DBGEN = 1) and is automatically cleared at the end of a debug run. A debug run is completed when the FIFO is full (begin trace) or when a trigger event is detected (end trace). A debug run can also be ended manually by writing 0 to ARM or DBGEN in DBGC. 0 Debugger not armed 1 Debugger armed FIFO Valid Count — These bits are cleared at the start of a debug run and indicate the number of words of valid data in the FIFO at the end of a debug run. The value in CNT does not decrement as data is read out of the FIFO. The external debug host is responsible for keeping track of the count as information is read out of the FIFO. 0000 Number of valid words in FIFO = No valid data 0001 Number of valid words in FIFO = 1 0010 Number of valid words in FIFO = 2 0011 Number of valid words in FIFO = 3 0100 Number of valid words in FIFO = 4 0101 Number of valid words in FIFO = 5 0110 Number of valid words in FIFO = 6 0111 Number of valid words in FIFO = 7 1000 Number of valid words in FIFO = 8 6 BF 5 ARMF 3:0 CNT[3:0] MC9S08GT16A/GT8A Data Sheet, Rev. 1 258 Freescale Semiconductor Appendix A Electrical Characteristics A.1 Introduction This section contains electrical and timing specifications. A.2 Parameter Classification The electrical parameters shown in this supplement are guaranteed by various methods. To give the customer a better understanding the following classification is used and the parameters are tagged accordingly in the tables where appropriate: Table A-1. Parameter Classifications P C Those parameters are guaranteed during production testing on each individual device. Those parameters are achieved by the design characterization by measuring a statistically relevant sample size across process variations. Those parameters are achieved by design characterization on a small sample size from typical devices under typical conditions unless otherwise noted. All values shown in the typical column are within this category. Those parameters are derived mainly from simulations. T D NOTE The classification is shown in the column labeled “C” in the parameter tables where appropriate. A.3 Absolute Maximum Ratings Absolute maximum ratings are stress ratings only, and functional operation at the maxima is not guaranteed. Stress beyond the limits specified in Table A-2 may affect device reliability or cause permanent damage to the device. For functional operating conditions, refer to the remaining tables in this section. This device contains circuitry protecting against damage due to high static voltage or electrical fields; however, it is advised that normal precautions be taken to avoid application of any voltages higher than maximum-rated voltages to this high-impedance circuit. Reliability of operation is enhanced if unused inputs are tied to an appropriate logic voltage level (for instance, either VSS or VDD) or the programmable pull-up resistor associated with the pin is enabled. MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 259 Electrical Characteristics Table A-2. Absolute Maximum Ratings Rating Supply voltage Maximum current into VDD Digital input voltage Instantaneous maximum current Single pin limit (applies to all port pins)1, 2, 3 Storage temperature range Maximum junction temperature 1 Symbol VDD IDD VIn ID Tstg TJ Value –0.3 to +3.8 120 –0.3 to VDD + 0.3 ± 25 –55 to 150 150 Unit V mA V mA °C °C Input must be current limited to the value specified. To determine the value of the required current-limiting resistor, calculate resistance values for positive (VDD) and negative (VSS) clamp voltages, then use the larger of the two resistance values. 2 All functional non-supply pins are internally clamped to V SS and VDD. 3 Power supply must maintain regulation within operating V DD range during instantaneous and operating maximum current conditions. If positive injection current (VIn > VDD) is greater than IDD, the injection current may flow out of VDD and could result in external power supply going out of regulation. Ensure external VDD load will shunt current greater than maximum injection current. This will be the greatest risk when the MCU is not consuming power. Examples are: if no system clock is present, or if the clock rate is very low which would reduce overall power consumption. A.4 Thermal Characteristics This section provides information about operating temperature range, power dissipation, and package thermal resistance. Power dissipation on I/O pins is usually small compared to the power dissipation in on-chip logic and voltage regulator circuits and it is user-determined rather than being controlled by the MCU design. In order to take PI/O into account in power calculations, determine the difference between actual pin voltage and VSS or VDD and multiply by the pin current for each I/O pin. Except in cases of unusually high pin current (heavy loads), the difference between pin voltage and VSS or VDD will be very small. MC9S08GT16A/GT8A Data Sheet, Rev. 1 260 Freescale Semiconductor Electrical Characteristics Table A-3. Thermal Characteristics Rating Operating temperature range (packaged) Thermal resistance 1s board type 48-pin QFN 44-pin QFP 42-pin SDIP 32-pin QFN Thermal resistance 2s2p board type 48-pin QFN 44-pin QFP 42-pin SDIP 32-pin QFN 1 Symbol TA Value TL to TH –40 to 125 Unit °C 84 θJA1, 2 72 62 99 °C/W 26 θJA1,2 54 51 33 °C/W Junction temperature is a function of die size, on-chip power dissipation, package thermal resistance, mounting site (board) temperature, ambient temperature, airflow, power dissipation of other components on the board, and board thermal resistance. 2 Per SEMI G38-87 and JEDEC JESD51-2 with the single layer board horizontal. Single layer board is designed per JEDEC JESD51-3. The average chip-junction temperature (TJ) in °C can be obtained from: TJ = TA + (PD × θJA) Eqn. A-1 where: TA = Ambient temperature, °C θJA = Package thermal resistance, junction-to-ambient, °C/W PD = Pint + PI/O Pint = IDD × VDD, Watts — chip internal power PI/O = Power dissipation on input and output pins — user determined For most applications, PI/O 2.3 V) (all digital inputs) Input high voltage (1.8 V ≤ VDD ≤ 2.3 V) (all digital inputs) Input low voltage (VDD > 2.3 V) (all digital inputs) Input low voltage (1.8 V ≤ VDD ≤ 2.3 V) (all digital inputs) Input hysteresis (all digital inputs) Input leakage current (per pin) VIn = VDD or VSS, all input only pins High impedance (off-state) leakage current (per pin) VIn = VDD or VSS, all input/output Internal pullup and pulldown resistors3 (all port pins and IRQ) Internal pulldown resistors (Port A4–A7 and IRQ) Output high voltage (VDD ≥ 1.8 V) IOH = –2 mA (ports A, B, D, E, and G) Output high voltage (port C) IOH = –10 mA (VDD ≥ 2.7 V) IOH = –6 mA (VDD ≥ 2.3 V) IOH = –3 mA (VDD ≥ 1.8 V) Maximum total IOH for all port pins VOH VDD – 0.5 — — — 60 mA Symbol VRAM VLVDH 2.08 2.16 VLVDL 1.80 1.88 VLVWH 2.35 2.35 VLVWL 2.08 2.16 0.20 0.50 0.70 × VDD 0.85 × VDD — — 0.06 × VDD — — 17.5 17.5 VDD – 0.5 0.025 0.025 2.40 2.40 2.1 2.19 0.30 0.80 2.5 2.5 V 2.2 2.27 V VRearm VIH VIH VIL VIL Vhys |IIn| |IOZ| RPU RPD 0.40 1.2 — — 0.35 × VDD 0.30 × VDD — 1.0 1.0 52.5 52.5 V V V V V µA µA kΩ kΩ V 1.82 1.90 1.91 1.99 V 2.1 2.19 2.2 2.27 V Min 1.02 Typical1 Max — Unit V V P P P P P P P P Y P P P p P — P D |IOHT| — MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 263 Electrical Characteristics Table A-6. DC Characteristics (Sheet 2 of 2) (Temperature Range = –40 to 125°C Ambient) C D D Parameter Output low voltage (VDD ≥ 1.8 V) IOL = 2.0 mA (ports A, B, D, E, and G) Output low voltage (port C) IOL = 10.0 mA (VDD ≥ 2.7 V) IOL = 6 mA (VDD ≥ 2.3 V) IOL = 3 mA (VDD ≥ 1.8 V) Maximum total IOL for all port pins dc injection current 4, 5, 6, 7 DC Injection Current A, B, C, D Single pin limit VIN > VDD VIN < VSS Total MCU limit, includes sum of all stressed pins VIN > VDD VIN < VSS C 1 2 3 4 Symbol Min Typical1 Max Unit — VOL — — — IOLT — 0.5 0.5 0.5 0.5 60 V D mA |IIC| 0 0 0 0 - 2 –0.2 25 –5 7 mA mA mA mA pF Input capacitance (all non-supply pins)(2) CIn — 5 6 7 Typicals are measured at 25°C. This parameter is characterized and not tested on each device. Measurement condition for pull resistors: VIn = VSS for pullup and VIn = VDD for pulldown. Power supply must maintain regulation within operating VDD range during instantaneous and operating maximum current conditions. If positive injection current (VIn > VDD) is greater than IDD, the injection current may flow out of VDD and could result in external power supply going out of regulation. Ensure external VDD load will shunt current greater than maximum injection current. This will be the greatest risk when the MCU is not consuming power. Examples are: if no system clock is present, or if clock rate is very low which (would reduce overall power consumption). All functional non-supply pins are internally clamped to VSS and VDD. Input must be current limited to the value specified. To determine the value of the required current-limiting resistor, calculate resistance values for positive and negative clamp voltages, then use the larger of the two values. IRQ does not have a clamp diode to VDD. Do not drive IRQ above VDD. 40 PULL-UP RESISTOR (kΩ) 35 30 25 20 1.8 2 2.2 2.4 2.6 2.8 VDD (V) 3 3.2 3.4 3.6 PULLUP RESISTOR TYPICALS PULLDOWN RESISTANCE (kΩ) 85°C 25°C –40°C 40 35 30 25 20 1.8 PULLDOWN RESISTOR TYPICALS 85°C 25°C –40°C 2.3 2.8 VDD (V) 3.3 3.6 Figure A-1. Pullup and Pulldown Typical Resistor Values (VDD = 3.0 V) MC9S08GT16A/GT8A Data Sheet, Rev. 1 264 Freescale Semiconductor Electrical Characteristics TYPICAL VOL VS IOL AT VDD = 3.0 V 1 0.8 0.6 VOL (V) VOL (V) 0.4 0.2 0 0 10 IOL (mA) 20 30 0.2 0.1 IOL = 3 mA 0 1 2 VDD (V) 3 4 IOL = 6 mA IOL = 10 mA 85°C 25°C –40°C TYPICAL VOL VS VDD 0.4 0.3 85°C 25°C –40°C Figure A-2. Typical Low-Side Driver (Sink) Characteristics (Port C) TYPICAL VOL VS IOL AT VDD = 3.0 V 1.2 1 0.8 VOL (V) VOL (V) 0.6 0.4 0.2 0 0 5 10 IOL (mA) 15 20 0 1 2 VDD (V) 3 4 85°C 25°C –40°C 0.2 0.15 0.1 0.05 TYPICAL VOL VS VDD 85°C, IOL = 2 mA 25°C, IOL = 2 mA –40°C, IOL = 2 mA Figure A-3. Typical Low-Side Driver (Sink) Characteristics (Ports A, B, D, E, and G) TYPICAL VDD – VOH VS VDD AT SPEC IOH 0.8 TYPICAL VDD – VOH VS IOH AT VDD = 3.0 V 0.4 0.3 VDD – VOH (V) 0.2 0.1 0 1 VDD – VOH (V) 0.6 0.4 0.2 0 0 85°C 25°C –40°C 85°C 25°C –40°C IOH = –10 mA IOH = –6 mA IOH = –3 mA 2 VDD (V) 3 4 –5 –10 –15 IOH (mA) –20 –25 –30 Figure A-4. Typical High-Side Driver (Source) Characteristics (Port C) MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 265 Electrical Characteristics TYPICAL VDD – VOH VS IOH AT VDD = 3.0 V 1.2 1 VDD – VOH (V) 0.8 0.6 0.4 0.2 0 0 –5 –10 IOH (mA) –15 –20 85°C 25°C –40°C TYPICAL VDD – VOH VS VDD AT SPEC IOH 0.25 0.2 VDD – VOH (V) 0.15 0.1 0.05 0 1 2 VDD (V) 3 4 85°C, IOH = 2 mA 25°C, IOH = 2 mA –40°C, IOH = 2 mA Figure A-5. Typical High-Side (Source) Characteristics (Ports A, B, D, E, and G) A.7 Supply Current Characteristics Table A-7. Supply Current Characteristics Parameter Symbol RIDD VDD (V) 3 2 3 RIDD 2 Typical1 0.8 mA 0.66 mA 4.3 mA 3.3 mA Max2 1.3 mA4 1.0 mA(4) 7.0 mA5 4.5 mA(4) 0.6 µA(4) 1.8 µA(4) 4.0 µA(5) 13 µA(5) 500 nA(4) 1.5 µA(4) 3.3 µA(4) 10 µA(4) 3.0 µA(4) 5.5 µA(4) 11 µA(5) 20 µA(5) 2.4 µA(4) 5.0 µA(4) 9.5 µA(4) 17 µA(4) Temp. (°C) 125 125 125 125 55 70 85 125 55 70 85 125 55 70 85 125 55 70 85 125 Run supply current measured at (CPU clock = 2 MHz, fBus = 1 MHz) Run supply current (3) measured at (CPU clock = 16 MHz, fBus = 8 MHz) 3 3 Stop1 mode supply current 25 nA S1IDD 2 20 nA 3 Stop2 mode supply current 550 nA S2IDD 2 400 nA MC9S08GT16A/GT8A Data Sheet, Rev. 1 266 Freescale Semiconductor Electrical Characteristics Table A-7. Supply Current Characteristics (continued) Parameter Symbol VDD (V) Typical1 Max2 4.3 µA(4) 7.2 µA(4) 17.0 µA(5) 45 µA(5) 3.5 µA(4) 6.2 µA(4) 15.0 µA(4) 40 µA(4) Temp. (°C) 55 70 85 125 55 70 85 125 3 Stop3 mode supply current 675 nA S3IDD 2 500 nA RTI adder to stop2 or stop36 LVI adder to stop3 (LVDSE = LVDE = 1) Adder to stop3 for oscillator enabled7 (OSCSTEN =1) Adder for loss-of-clock enabled (LOCD=0) Adder for high gain oscillator enabled (HGO=1) 1 2 3 4 5 6 7 3 2 3 2 3 2 3 2 3 2 300 nA 300 nA 70 µA 60 µA 5 µA 5 µA 9 µA 9 µA 28 µA 2 µA Typicals are measured at 25°C. See Table A-6 through Table A-9 for typical curves across voltage/temperature. Values given here are preliminary estimates prior to completing characterization. All modules except ATD active, ICG configured for FBE, and does not include any dc loads on port pins Values are characterized but not tested on every part. Every unit tested to this parameter. All other values in the Max column are guaranteed by characterization. Most customers are expected to find that auto-wakeup from stop2 or stop3 can be used instead of the higher current wait mode. Wait mode typical is 560 µA at 3 V and 422 µA at 2V with fBus = 1 MHz. Values given under the following conditions: low range operation (RANGE = 0), low power mode (HGO = 0), clock monitor disabled (LOCD = 1). MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 267 Electrical Characteristics 14 = FEI mode, ATD off, 20 MHz 12 10 = FBE mode, ATD off, 20 MHz = FEI mode, ATD off, 16 MHz 8 IDD (mA) 6 = FBE mode, all modules enabled, 8 MHz = FEI mode, ATD off, 8 MHz 4 2 = FEI mode, ATD off, 1 MHz = FBE mode, ATD off, 1 MHz 0 0 3.6 0 3.5 0 3.4 0 3.3 0 3.2 0 3.1 0 3.0 0 2.9 0 2.8 0 2.7 0 2.6 0 2.5 0 2.4 0 2.3 0 2.2 0 2.1 0 2.0 0 1.9 0 VDD (Vdc) 1.8 Figure A-6. Typical Run IDD for FBE and FEE Modes, IDD vs VDD MC9S08GT16A/GT8A Data Sheet, Rev. 1 268 Freescale Semiconductor Electrical Characteristics 1.4 1.2 1 0.8 0.6 25°C 75°C 85°C 105°C 125°C IDD (µA) 0.4 0.2 0 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 VDD (Vdc) Figure A-7. Typical Stop1 IDD MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 269 Electrical Characteristics Figure A-8. Typical Stop 2 IDD MC9S08GT16A/GT8A Data Sheet, Rev. 1 270 Freescale Semiconductor Electrical Characteristics Figure A-9. Typical Stop3 IDD MC9S08GT16A/GT8A Data Sheet, Rev. 1 Freescale Semiconductor 271 Electrical Characteristics A.8 No. 1 2 ATD Characteristics Table A-8. ATD Electrical Characteristics (Operating) Characteristic ATD supply1 ATD supply current Enabled Disabled (ATDPU = 0 or STOP) Condition Symbol VDDAD IDDADrun IDDADstop Min 1.80 — — Typ — 0.7 0.02 Max 3.6 1.2 0.6 Unit V mA µA 3 4 5 Differential supply voltage Differential ground voltage Reference potential, low Reference potential, high VDD–VDDAD VSS–VSSAD |VDDLT| |VSDLT| |VREFL| — — — 2.08 VDDAD — — — — — 200