Freescale Semiconductor
HC11
MC68HC11F1
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Technical Data
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TABLE OF CONTENTS
Paragraph
Title
Page
SECTION 1INTRODUCTION
1.1
Features .................................................................................................... 1-1
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SECTION 2 PIN DESCRIPTIONS
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.11.1
2.11.2
2.11.3
2.11.4
2.11.5
2.11.6
2.11.7
VDD and VSS .............................................................................................. 2-2
Reset (RESET) .......................................................................................... 2-3
E-Clock Output (E) .................................................................................... 2-3
Crystal Driver and External Clock Input (XTAL, EXTAL) ........................... 2-3
Four Times E-Clock Frequency Output (4XOUT) ..................................... 2-5
Interrupt Request (IRQ) ............................................................................. 2-5
Non-Maskable Interrupt (XIRQ) ................................................................. 2-5
MODA and MODB (MODA/LIR and MODB/VSTBY) .................................. 2-6
VRH and VRL .............................................................................................. 2-6
R/W ........................................................................................................... 2-6
Port Signals ............................................................................................... 2-6
Port A ................................................................................................ 2-7
Port B ................................................................................................ 2-8
Port C ................................................................................................ 2-8
Port D ................................................................................................ 2-8
Port E ................................................................................................ 2-9
Port F ................................................................................................. 2-9
Port G ................................................................................................ 2-9
SECTION 3 CENTRAL PROCESSING UNIT
3.1
CPU Registers ........................................................................................... 3-1
3.1.1
Accumulators A, B, and D ................................................................. 3-2
3.1.2
Index Register X (IX) ......................................................................... 3-3
3.1.3
Index Register Y (IY) ......................................................................... 3-3
3.1.4
Stack Pointer (SP) ............................................................................. 3-3
3.1.5
Program Counter (PC) ...................................................................... 3-5
3.1.6
Condition Code Register (CCR) ........................................................ 3-5
3.1.6.1
Carry/Borrow (C) ....................................................................... 3-5
3.1.6.2
Overflow (V) .............................................................................. 3-5
3.1.6.3
Zero (Z) ..................................................................................... 3-6
3.1.6.4
Negative (N) .............................................................................. 3-6
3.1.6.5
Interrupt Mask (I) ....................................................................... 3-6
3.1.6.6
Half Carry (H) ............................................................................ 3-6
3.1.6.7
X Interrupt Mask (X) .................................................................. 3-6
3.1.6.8
Stop Disable (S) ........................................................................ 3-7
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TABLE OF CONTENTS
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Paragraph
3.2
3.3
3.4
3.4.1
3.4.2
3.4.3
3.4.4
3.4.5
3.4.6
3.5
(Continued)
Title
Page
Data Types ................................................................................................ 3-7
Opcodes and Operands ............................................................................ 3-7
Addressing Modes ..................................................................................... 3-7
Immediate .......................................................................................... 3-7
Direct ................................................................................................. 3-8
Extended ........................................................................................... 3-8
Indexed .............................................................................................. 3-8
Inherent ............................................................................................. 3-8
Relative ............................................................................................. 3-8
Instruction Set ........................................................................................... 3-8
SECTION 4OPERATING MODES AND ON-CHIP MEMORY
4.1
4.1.1
4.1.2
4.1.3
4.1.4
4.2
4.2.1
4.2.2
4.2.2.1
4.2.2.2
4.2.2.3
4.2.3
4.3
4.3.1
4.3.1.1
4.3.2
4.3.2.1
4.3.2.2
4.3.2.3
4.3.2.4
4.3.2.5
4.4
4.4.1
4.4.1.1
4.4.1.2
4.4.1.3
4.4.1.4
4.4.2
4.4.3
Operating Modes ....................................................................................... 4-1
Single-Chip Operating Mode ............................................................. 4-1
Expanded Operating Mode ............................................................... 4-1
Special Test Mode ............................................................................. 4-1
Special Bootstrap Mode .................................................................... 4-1
On-Chip Memory ....................................................................................... 4-2
Mapping Allocations .......................................................................... 4-2
Memory Map ..................................................................................... 4-3
RAM .......................................................................................... 4-3
Bootloader ROM ....................................................................... 4-4
EEPROM ................................................................................... 4-4
Registers ........................................................................................... 4-4
System Initialization ................................................................................... 4-6
Mode Selection .................................................................................. 4-7
HPRIO Register ........................................................................ 4-8
Initialization ........................................................................................ 4-9
CONFIG Register ...................................................................... 4-9
INIT Register ........................................................................... 4-10
OPTION Register .................................................................... 4-11
OPT2 Register ........................................................................ 4-12
Block Protect Register (BPROT) ............................................. 4-13
EEPROM and CONFIG Register ............................................................ 4-14
EEPROM ......................................................................................... 4-14
EEPROM Programming .......................................................... 4-14
EEPROM Bulk Erase .............................................................. 4-15
EEPROM Row Erase .............................................................. 4-15
EEPROM Byte Erase .............................................................. 4-16
PPROG EEPROM Programming Control Register ......................... 4-16
CONFIG Register Programming ..................................................... 4-17
TECHNICAL DATA
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Paragraph
4.5
4.5.1
4.5.2
4.5.3
(Continued)
Title
Page
Chip Selects ............................................................................................ 4-18
Program Chip Select ....................................................................... 4-18
I/O Chip Selects .............................................................................. 4-18
General-Purpose Chip Select .......................................................... 4-19
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SECTION 5 RESETS AND INTERRUPTS
5.1
5.1.1
5.1.2
5.1.3
5.1.4
5.1.5
5.1.6
5.2
5.2.1
5.2.2
5.2.3
5.2.4
5.2.5
5.2.6
5.2.7
5.2.8
5.2.9
5.2.10
5.2.11
5.3
5.3.1
5.4
5.4.1
5.4.2
5.4.3
5.4.4
5.4.5
5.4.6
5.5
5.5.1
5.5.2
Resets ....................................................................................................... 5-1
Power-On Reset ................................................................................ 5-1
External Reset (RESET) ................................................................... 5-1
Computer Operating Properly (COP) Reset ...................................... 5-2
Clock Monitor Reset .......................................................................... 5-2
OPTION Register .............................................................................. 5-3
CONFIG Register .............................................................................. 5-4
Effects of Reset ......................................................................................... 5-4
Central Processing Unit ..................................................................... 5-5
Memory Map ..................................................................................... 5-5
Parallel I/O ......................................................................................... 5-5
Timer ................................................................................................. 5-5
Real-Time Interrupt (RTI) .................................................................. 5-5
Pulse Accumulator ............................................................................ 5-6
Computer Operating Properly (COP) ................................................ 5-6
Serial Communications Interface (SCI) ............................................. 5-6
Serial Peripheral Interface (SPI) ........................................................ 5-6
Analog-to-Digital Converter ............................................................... 5-6
System .............................................................................................. 5-6
Reset and Interrupt Priority ....................................................................... 5-6
Highest Priority Interrupt and Miscellaneous Register ...................... 5-7
Interrupts ................................................................................................... 5-8
Interrupt Recognition and Register Stacking ..................................... 5-9
Non-Maskable Interrupt Request (XIRQ) ........................................ 5-10
Illegal Opcode Trap ......................................................................... 5-10
Software Interrupt ............................................................................ 5-11
Maskable Interrupts ......................................................................... 5-11
Reset and Interrupt Processing ....................................................... 5-11
Low Power Operation .............................................................................. 5-16
WAIT ............................................................................................... 5-17
STOP ............................................................................................... 5-17
SECTION 6 PARALLEL INPUT/OUTPUT
6.1
Port A ........................................................................................................ 6-1
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Paragraph
6.2
6.3
6.4
6.5
6.6
6.7
6.8
(Continued)
Title
Page
Port B ........................................................................................................ 6-2
Port C ........................................................................................................ 6-2
Port D ........................................................................................................ 6-3
Port E ........................................................................................................ 6-4
Port F ......................................................................................................... 6-4
Port G ........................................................................................................ 6-5
System Configuration Options 2 ................................................................ 6-5
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SECTION 7 SERIAL COMMUNICATIONS INTERFACE
7.1
7.2
7.3
7.4
7.4.1
7.4.2
7.5
7.6
7.6.1
7.6.2
7.6.3
7.6.4
7.6.5
7.7
7.7.1
Data Format .............................................................................................. 7-1
Transmit Operation .................................................................................... 7-1
Receive Operation ..................................................................................... 7-2
Wakeup Feature ........................................................................................ 7-4
Idle-Line Wakeup .............................................................................. 7-4
Address-Mark Wakeup ...................................................................... 7-4
SCI Error Detection ................................................................................... 7-5
SCI Registers ............................................................................................ 7-5
Serial Communications Data Register .............................................. 7-5
Serial Communications Control Register 1 ....................................... 7-5
Serial Communications Control Register 2 ....................................... 7-6
Serial Communication Status Register .............................................. 7-7
Baud Rate Register ........................................................................... 7-8
Status Flags and Interrupts ..................................................................... 7-10
Receiver Flags ................................................................................ 7-11
SECTION 8 SERIAL PERIPHERAL INTERFACE
8.1
8.2
8.2.1
8.3
8.3.1
8.3.2
8.3.3
8.3.4
8.4
8.5
8.5.1
8.5.2
8.5.3
Functional Description ............................................................................... 8-1
SPI Transfer Formats ................................................................................ 8-2
Clock Phase and Polarity Controls .................................................... 8-3
SPI Signals ................................................................................................ 8-3
Master In Slave Out ........................................................................... 8-4
Master Out Slave In ........................................................................... 8-4
Serial Clock ....................................................................................... 8-4
Slave Select ...................................................................................... 8-4
SPI System Errors ..................................................................................... 8-4
SPI Registers ............................................................................................ 8-5
Serial Peripheral Control ................................................................... 8-5
Serial Peripheral Status ..................................................................... 8-7
Serial Peripheral Data Register ......................................................... 8-7
TECHNICAL DATA
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Paragraph
(Continued)
Title
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SECTION 9 TIMING SYSTEM
9.1
9.2
9.2.1
9.2.2
9.2.3
9.3
9.3.1
9.3.2
9.3.3
9.3.4
9.3.5
9.3.6
9.3.7
9.3.8
9.3.9
9.3.10
9.4
9.4.1
9.4.2
9.4.3
9.5
9.6
9.6.1
9.6.2
9.6.3
Timer Structure .......................................................................................... 9-3
Input Capture ............................................................................................. 9-5
Timer Control Register 2 ................................................................... 9-5
Timer Input Capture Registers .......................................................... 9-6
Timer Input Capture 4/Output Compare 5 Register .......................... 9-6
Output Compare ........................................................................................ 9-6
Timer Output Compare Registers ..................................................... 9-7
Timer Compare Force Register ......................................................... 9-8
Output Compare Mask Registers ...................................................... 9-8
Output Compare Data Register ......................................................... 9-9
Timer Counter Register ..................................................................... 9-9
Timer Control Register 1 ................................................................... 9-9
Timer Interrupt Mask Register 1 ...................................................... 9-10
Timer Interrupt Flag Register 1 ....................................................... 9-11
Timer Interrupt Mask Register 2 ...................................................... 9-11
Timer Interrupt Flag Register 2 ....................................................... 9-12
Real-Time Interrupt ................................................................................. 9-12
Timer Interrupt Mask Register 2 ...................................................... 9-13
Timer Interrupt Flag Register 2 ....................................................... 9-14
Pulse Accumulator Control Register ............................................... 9-14
Computer Operating Properly Watchdog Function ................................. 9-15
Pulse Accumulator .................................................................................. 9-15
Pulse Accumulator Control Register ............................................... 9-16
Pulse Accumulator Count Register ................................................. 9-17
Pulse Accumulator Status and Interrupt Bits ................................... 9-18
SECTION 10 ANALOG-TO-DIGITAL CONVERTER
10.1
10.1.1
10.1.2
10.1.3
10.1.4
10.1.5
10.1.6
10.2
10.3
10.4
10.5
10.6
Overview ................................................................................................. 10-1
Multiplexer ....................................................................................... 10-1
Analog Converter ............................................................................ 10-3
Digital Control .................................................................................. 10-3
Result Registers .............................................................................. 10-3
A/D Converter Clocks ...................................................................... 10-4
Conversion Sequence ..................................................................... 10-4
A/D Converter Power-Up and Clock Select ............................................. 10-5
Conversion Process ................................................................................ 10-5
Channel Assignments ............................................................................. 10-6
Single-Channel Operation ....................................................................... 10-6
Multiple-Channel Operation ..................................................................... 10-6
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Paragraph
10.7
10.8
10.9
(Continued)
Title
Page
Operation in STOP and WAIT Modes .................................................... 10-7
A/D Control/Status Registers .................................................................. 10-7
A/D Converter Result Registers .............................................................. 10-8
APPENDIX A ELECTRICAL CHARACTERISTICS
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APPENDIX BMECHANICAL DATA AND ORDERING INFORMATION
B.1
B.2
B.3
Pin Assignments ....................................................................................... B-1
Package Dimensions ................................................................................ B-2
Ordering Information ................................................................................ B-3
APPENDIX CDEVELOPMENT SUPPORT
C.1
C.2
C.3
MC68HC11F1 Development Tools .......................................................... C-1
MC68HC11EVS — Evaluation System .................................................... C-1
M68MMDS11 — Modular Development System for M68HC11 Devices . C-1
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LIST OF ILLUSTRATIONS
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Figure
1-1
2-1
2-2
2-3
2-4
2-5
2-6
2-7
3-1
3-2
4-1
4-2
4-3
4-4
5-1
5-2
5-3
5-4
5-5
7-1
7-2
7-3
7-4
8-1
8-2
9-1
9-2
9-3
10-1
10-2
10-3
A-1
A-2
A-3
A-4
A-5
A-6
A-7
A-8
A-9
A-10
Title
Page
MC68HC11F1 Block Diagram ........................................................................ 1-2
Pin Assignments for MC68HC11F1 68-Pin PLCC ......................................... 2-1
Pin Assignments for MC68HC11F1 80-Pin QFP ............................................ 2-2
External Reset Circuit ..................................................................................... 2-3
Common Crystal Connections ........................................................................ 2-4
External Oscillator Connections ..................................................................... 2-4
One Crystal Driving Two MCUs ..................................................................... 2-4
4XOUT Signal Driving a Second MCU ........................................................... 2-5
Programming Model ....................................................................................... 3-2
Stacking Operations ....................................................................................... 3-4
MC68HC11F1 Memory Map .......................................................................... 4-3
RAM Standby MODB/VSTBY Connections ..................................................... 4-4
Address Map for I/O and Program Chip Selects .......................................... 4-19
Address Map for General-Purpose Chip Select ........................................... 4-20
Processing Flow Out of Reset (1 of 2) ......................................................... 5-12
Processing Flow Out of Reset (2 of 2) ......................................................... 5-13
Interrupt Priority Resolution (1 of 2) ............................................................. 5-14
Interrupt Priority Resolution (2 of 2) ............................................................. 5-15
Interrupt Source Resolution Within SCI ........................................................ 5-16
SCI Transmitter Block Diagram ...................................................................... 7-2
SCI Receiver Block Diagram .......................................................................... 7-3
SCI Baud Rate Generator Block Diagram .................................................... 7-10
Interrupt Source Resolution Within SCI ........................................................ 7-12
SPI Block Diagram ......................................................................................... 8-2
SPI Transfer Format ....................................................................................... 8-3
Timer Clock Divider Chains ............................................................................ 9-2
Capture/Compare Block Diagram .................................................................. 9-4
Pulse Accumulator ....................................................................................... 9-16
A/D Converter Block Diagram ...................................................................... 10-2
Electrical Model of an A/D Input Pin (Sample Mode) ................................... 10-3
A/D Conversion Sequence ........................................................................... 10-4
Test Methods .................................................................................................. A-4
Timer Inputs ................................................................................................... A-5
POR External Reset Timing Diagram ............................................................. A-6
STOP Recovery Timing Diagram ................................................................... A-7
WAIT Recovery from Interrupt Timing Diagram ............................................. A-8
Interrupt Timing Diagram ................................................................................ A-9
Port Read Timing Diagram ........................................................................... A-10
Port Write Timing Diagram ........................................................................... A-10
Expansion Bus Timing .................................................................................. A-13
SPI Master Timing (CPHA = 0) .................................................................... A-15
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LIST OF ILLUSTRATIONS
Figure
Page
SPI Master Timing (CPHA = 1) .................................................................... A-15
SPI Slave Timing (CPHA = 0) ...................................................................... A-16
SPI Slave Timing (CPHA = 1) ...................................................................... A-16
MC68HC11F1 68-Pin PLCC .......................................................................... B-1
MC68HC11F1 80-Pin Quad Flat Pack ........................................................... B-2
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A-11
A-12
A-13
B-1
B-2
(Continued)
Title
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LIST OF TABLES
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Table
2-1
3-1
3-2
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
5-1
5-2
5-3
5-4
5-5
6-1
7-1
7-2
8-1
9-1
9-2
9-3
9-4
9-5
9-6
10-1
10-2
A-1
A-2
A-3
A-4
A-5
A-6
A-7
A-8
A-9
Title
Page
Port Signal Functions ...................................................................................... 2-7
Reset Vector Comparison ............................................................................... 3-5
Instruction Set ................................................................................................. 3-9
Register and Control Bit Assignments............................................................. 4-5
Write Access Limited Registers....................................................................... 4-7
Hardware Mode Select Summary ................................................................... 4-7
EEPROM Mapping ........................................................................................ 4-10
RAM and Register Mapping .......................................................................... 4-11
EEPROM Block Protection............................................................................ 4-14
EEPROM Erase Mode Control...................................................................... 4-17
Chip Select Clock Stretch Control ................................................................. 4-20
Program Chip Select Size Control................................................................. 4-21
General-Purpose Chip Select Starting Address ............................................ 4-22
General-Purpose Chip Select Size Control ................................................... 4-22
Chip Select Control Parameter Summary ..................................................... 4-23
COP Timer Rate Selection .............................................................................. 5-2
Reset Cause, Operating Mode, and Reset Vector .......................................... 5-4
Highest Priority Interrupt Selection.................................................................. 5-8
Interrupt and Reset Vector Assignments......................................................... 5-9
Stacking Order on Entry to Interrupts............................................................ 5-10
I/O Port Configuration...................................................................................... 6-1
Baud Rate Prescaler Selection ....................................................................... 7-8
Baud Rate Selection........................................................................................ 7-9
SPI Clock Rates .............................................................................................. 8-6
Timer Summary............................................................................................... 9-3
Timer Output Compare Configuration ........................................................... 9-10
Timer Prescaler Selection ............................................................................. 9-12
RTI Rate Selection ........................................................................................ 9-13
Pulse Accumulator Timing............................................................................. 9-16
Pulse Accumulator Edge Detection Control .................................................. 9-17
A/D Converter Channel Assignments............................................................ 10-6
A/D Converter Channel Selection ................................................................. 10-8
Maximum Ratings............................................................................................ A-1
Thermal Characteristics .................................................................................. A-2
DC Electrical Characteristics........................................................................... A-3
Control Timing ................................................................................................. A-5
Peripheral Port Timing................................................................................... A-10
Analog-To-Digital Converter Characteristics ................................................. A-11
Expansion Bus Timing................................................................................... A-12
Serial Peripheral Interface Timing ................................................................. A-14
EEPROM Characteristics .............................................................................. A-17
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LIST OF TABLES
Table
Page
Device Ordering Information ........................................................................... B-3
MC68HC11F1 Development Tools .................................................................C-1
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B-1
C-1
(Continued)
Title
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SECTION 1INTRODUCTION
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The MC68HC11F1 high-performance microcontroller unit (MCU) is an enhanced derivative of the M68HC11 family of microcontrollers and includes many advanced features. This MCU, with a nonmultiplexed expanded bus, is characterized by high speed
and low power consumption. The fully static design allows operation at frequencies
from 4 MHz to dc.
1.1 Features
• M68HC11 Central Processing Unit (CPU)
• Power Saving STOP and WAIT Modes
• 512 Bytes Electrically Erasable Programmable Read-Only Memory (EEPROM)
• 1024 Bytes RAM, Data Retained During Standby
• Nonmultiplexed Address and Data Buses
• Enhanced 16-Bit Timer
• Three Input Capture (IC) Channels
• Four Output Compare (OC) Channels
• One Additional Channel, Selectable as Fourth IC or Fifth OC
• 8-Bit Pulse Accumulator
• Real-Time Interrupt Circuit
• Computer Operating Properly (COP) Watchdog
• Enhanced Asynchronous Nonreturn to Zero (NRZ) Serial Communications Interface (SCI)
• Enhanced Synchronous Serial Peripheral Interface (SPI)
• Eight-Channel 8-Bit Analog-to-Digital (A/D) Converter
• Four Chip-Select Signal Outputs with Programmable Clock Stretching
— Two I/O Chip Selects
— One Program Chip Select
— One General-Purpose Chip Select
• Available in 68-Pin Plastic Leaded Chip Carrier (PLCC) and 80-Pin Plastic Quad
Flat Pack (QFP)
INTRODUCTION
TECHNICAL DATA
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1-1
Freescale Semiconductor, Inc.
XTAL
EXTAL
E
4XOUT
R/W
AN7
AN6
AN5
AN4
AN3
AN2
AN1
AN0
PERIODIC
INTERRUPT
VRH
VRL
VDD
VSS
CPU
512
BYTES
EEPROM
CSPROG
CSGEN
CSIO1
CSIO2
SPI
SS
SCK
MOSI
MISO
SCI
TxD
RxD
R/W
PORT G DDR
PORT G
CHIP
SELECTS
1024
BYTES
RAM
PE7
PE6
PE5
PE4
PE3
PE2
PE1
PE0
VRH
VRL
PORT D DDR
PORT D
DATA7
DATA6
DATA5
DATA4
DATA3
DATA2
DATA1
DATA0
MODB/
VSTBY
A/D
CONVERTER
TIMER
SYSTEM
ADDRESS BUS
PORT A
PORT A DDR
PORT B
ADDR7
ADDR6
ADDR5
ADDR4
ADDR3
ADDR2
ADDR1
ADDR0
OSCILLATOR
CLOCK
LOGIC
DATA BUS
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
PORT F
PF7
PF6
PF5
PF4
PF3
PF2
PF1
PF0
ADDR15
ADDR14
ADDR13
ADDR12
ADDR11
ADDR10
ADDR9
ADDR8
PORT C
PORT C DDR
Freescale Semiconductor, Inc...
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
OC2/OC1
OC3/OC1
OC4/OC1
OC5/IC4/OC1
IC1
IC2
IC3
COP
MODA/
LIR
MODE
CONTROL
PORT E
PULSE
PAI/OC1 ACCUMULATOR
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
IRQ
XIRQ
RESET
INTERRUPT
LOGIC
PG7
PG6
PG5
PG4
PG3
PG2
PG1
PG0
PD5
PD4
PD3
PD2
PD1
PD0
Figure 1-1 MC68HC11F1 Block Diagram
INTRODUCTION
1-2
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SECTION 2 PIN DESCRIPTIONS
PE7/AN7
PE3/AN3
PE6/AN6
PE2/AN2
PE5/AN5
PE1/AN1
68
67
66
65
64
63
62
61
PC0/DATA0
4XOUT
XTAL
EXTAL
R/W
E
MODA/LIR
MODB/VSTBY
VSS
VRH
VRL
9
8
7
6
5
4
3
2
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
1
MC68HC11F1
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
PE4/AN4
PE0/AN0
PF0/ADDR0
PF1/ADDR1
PF2/ADDR2
PF3/ADDR3
PF4/ADDR4
PF5/ADDR5
PF6/ADDR6
PF7/ADDR7
PB0/ADDR8
PB1/ADDR9
PB2/ADDR10
PB3/ADDR11
PB4/ADDR12
PB5/ADDR13
PB6/ADDR14
PA7/PAI/OC1
PA6/OC2/OC1
PA5/OC3/OC1
PA4/OC4/OC1
PA3/OC5/IC4/OC1
PA2/IC1
PA1/IC2
PA0/IC3
PB7/ADDR15
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
PC1/DATA1
PC2/DATA2
PC3/DATA3
PC4/DATA4
PC5/DATA5
PC6/DATA6
PC7/DATA7
RESET
XIRQ
IRQ
PG7/CSPROG
PG6/CSGEN
PG5/CSIO1
PG4/CSIO2
PG3
PG2
PG1
PG0
PD0/RxD
PD1/TxD
PD2/MISO
PD3/MOSI
PD4/SCK
PD5/SS
VDD
Freescale Semiconductor, Inc...
The MC68HC11F1 MCU is available in a 68-pin plastic leaded chip carrier (PLCC) and
an 80-pin plastic quad flat pack (QFP). Most pins on this MCU serve two or more functions, as described in the following paragraphs. Figure 2-1 shows the pin assignments
for the PLCC. Figure 2-2 shows the pin assignments for the QFP.
Figure 2-1 Pin Assignments for MC68HC11F1 68-Pin PLCC
PIN DESCRIPTIONS
TECHNICAL DATA
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2-1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
PD5/SS
PD4/SCK
PD3/MOSI
PD2/MISO
PD1/TxD
PD0/RxD
PG0
NC
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
MC68HC11F1
NC
PG1
PG2
PG3
PG4/CSIO2
PG5/CSIO1
PG6/CSGEN
PG7/CSPROG
IRQ
XIRQ
RESET
PC7/DATA7
PC6/DATA6
PC5/DATA5
PC4/DATA4
PC3/DATA3
PC2/DATA2
PC1/DATA1
NC
NC
MODA/LIR
E
R/W
EXTAL
XTAL
NC
4XOUT
PC0/DATA0
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
NC
NC
PB6/ADDR14
PB5/ADDR13
PB4/ADDR12
PB3/ADDR11
PB2/ADDR10
PB1/ADDR9
PB0/ADDR8
PF7/ADDR7
PF6/ADDR6
PF5/ADDR5
PF4/ADDR4
PF3/ADDR3
PF2/ADDR2
PF1/ADDR1
PF0/ADDR0
PE0/AN0
PE4/AN4
NC
NC
NC
PE1/AN1
PE5/AN5
PE2/AN2
PE6/AN6
PE3/AN3
PE7/AN7
VRL
VRH
VSS
MODB/VSTBY
Freescale Semiconductor, Inc...
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
NC
NC
PB7/ADDR15
PA0/IC3
PA1/IC2
PA2/IC1
PA3/OC5/IC4/OC1
PA4/OC4/OC1
PA5/OC3/OC1
PA6/OC2/OC1
PA7/PAI/OC1
VDD
Freescale Semiconductor, Inc.
Figure 2-2 Pin Assignments for MC68HC11F1 80-Pin QFP
2.1 VDD and VSS
Power is supplied to the MCU through VDD and VSS. VDD is the power supply, and
VSS is ground. The MCU operates from a single 5-volt (nominal) power supply. Very
fast signal transitions occur on the MCU pins. The short rise and fall times place high,
short duration current demands on the power supply. To prevent noise problems, provide good power-supply bypassing at the MCU. Also, use bypass capacitors that have
good high-frequency characteristics and situate them as close to the MCU as possible.
Bypass requirements vary, depending on how heavily the MCU pins are loaded.
PIN DESCRIPTIONS
2-2
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2.2 Reset (RESET)
An active low bidirectional control signal, RESET, acts as an input to initialize the MCU
to a known start-up state. It also acts as an open-drain output to indicate that an internal failure has been detected in either the clock monitor or COP watchdog circuit. The
CPU distinguishes between internal and external reset conditions by sensing whether
the reset pin rises to a logic one in less than two E-clock cycles after a reset has occurred. It is not advisable to connect an external resistor-capacitor (RC) power-up delay circuit to the reset pin of M68HC11 devices because the circuit charge time
constant can cause the device to misinterpret the type of reset that occurred. Refer to
SECTION 5 RESETS AND INTERRUPTS for further information.
Figure 2-3 illustrates a reset circuit that uses an external switch. Other circuits can be
used, however, it is important to incorporate a low voltage interrupt (LVI) circuit to prevent operation at insufficient voltage levels which could result in erratic behavior or corruption of RAM.
VDD
VDD
VDD
MC34064
2
4.7 kΩ
IN
MANUAL
RESET SWITCH
RESET
4.7 kΩ
4.7 kΩ
1.0 µF
MC34164
TO RESET
OF M68HC11
GND
3
2
IN
RESET
OPTIONAL POWER-ON DELAY
AND MANUAL RESET SWITCH
1
1
GND
3
Figure 2-3 External Reset Circuit
2.3 E-Clock Output (E)
E is the output connection for the internally generated E clock. The signal from E is
used as a timing reference. The frequency of the E-clock output is one fourth that of
the input frequency at the EXTAL pin. When E-clock output is low, an internal process
is taking place. When it is high, data is being accessed. All clocks, including the E
clock, are halted when the MCU is in STOP mode. The E clock can be turned off in
single-chip modes to reduce the effects of radio frequency interference (RFI). Refer to
SECTION 9 TIMING SYSTEM.
2.4 Crystal Driver and External Clock Input (XTAL, EXTAL)
These two pins provide the interface for either a crystal or a CMOS-compatible clock
to control the internal clock generator circuitry. Either a crystal oscillator or a CMOS
compatible clock can be used. The resulting E-clock rate is the input frequency divided
by four.
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The XTAL pin is normally left unterminated when an external CMOS compatible clock
is connected to the EXTAL pin. However, a 10 kΩ to 100 kΩ load resistor connected
from the XTAL output to ground can be used to reduce RFI noise emission.
The XTAL output is normally used to drive a crystal. The XTAL output can be buffered
with a high-impedance buffer, or it can be used to drive the EXTAL input of another
M68HC11 device. Refer to Figure 2-6.
In all cases, use caution when designing circuitry associated with the oscillator pins.
Load capacitances shown in the oscillator circuits include all stray layout capacitances. Refer to Figure 2-4, Figure 2-5, and Figure 2-6.
Freescale Semiconductor, Inc...
25 pF*
EXTAL
MCU
10M
4xE
CRYSTAL
XTAL
25 pF*
* Values include all stray capacitances.
Figure 2-4 Common Crystal Connections
CMOS-COMPATIBLE
EXTERNAL
OSCILLATOR
EXTAL
MCU
NC OR
10 k – 100 k
LOAD
XTAL
Figure 2-5 External Oscillator Connections
25 pF*
220
EXTAL
FIRST
MCU
EXTAL
10M
4xE
CRYSTAL
XTAL
25 pF*
NC OR
10 k – 100 k
LOAD
SECOND
MCU
XTAL
* Values include all stray capacitances.
Figure 2-6 One Crystal Driving Two MCUs
PIN DESCRIPTIONS
2-4
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2.5 Four Times E-Clock Frequency Output (4XOUT)
Although the circuit shown in Figure 2-6 will work for any M68HC11 MCU, the
MC68HC11F1 has an additional clock output that is four times the E-clock frequency.
This output (4XOUT) can be used to directly drive the EXTAL input of another
M68HC11 MCU. Refer to Figure 2-7. The 4XOUT output is enabled after reset and
can be disabled by clearing the CLK4X bit in the OPT2 register.
4XOUT
EXTAL
MC68HC11F1
EXTAL
Freescale Semiconductor, Inc...
XTAL
OSCILLATOR
CIRCUIT OR
CMOS-COMPATIBLE
CLOCK
NC OR
10 k – 100 k
LOAD
XTAL
SECOND
MCU
Figure 2-7 4XOUT Signal Driving a Second MCU
2.6 Interrupt Request (IRQ)
The IRQ input provides a means of generating asynchronous interrupt requests for the
CPU. Either falling-edge triggering or low-level triggering is selected by the IRQE bit
in the OPTION register. IRQ is always configured for level-sensitive triggering at reset.
Connect an external pull-up resistor, typically 4.7 kΩ, to VDD when IRQ is used in a
level-sensitive wired-OR configuration. Refer to SECTION 5 RESETS AND INTERRUPTS.
2.7 Non-Maskable Interrupt (XIRQ)
The XIRQ input provides a means of requesting a non-maskable interrupt after reset
initialization. During reset, the X bit in the condition code register (CCR) is set and any
interrupt is masked until MCU software enables it. Because the XIRQ input is level
sensitive, it can be connected to a multiple-source wired-OR network with an external
pull-up resistor to VDD. XIRQ is often used as a power loss detect interrupt.
Whenever XIRQ or IRQ are used with multiple interrupt sources (IRQ must be configured for level-sensitive operation if there is more than one source of IRQ interrupt),
each source must drive the interrupt input with an open-drain type of driver to avoid
contention between outputs. There should be a single pull-up resistor near the MCU
interrupt input pin (typically 4.7 kΩ). There must also be an interlock mechanism at
each interrupt source so that the source holds the interrupt line low until the MCU recognizes and acknowledges the interrupt request. If one or more interrupt sources are
still pending after the MCU services a request, the interrupt line will still be held low
and the MCU will be interrupted again as soon as the interrupt mask bit in the condition
code register (CCR) is cleared (normally upon return from an interrupt). Refer to SECTION 5 RESETS AND INTERRUPTS.
PIN DESCRIPTIONS
TECHNICAL DATA
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2.8 MODA and MODB (MODA/LIR and MODB/VSTBY)
During reset, MODA and MODB select one of the four operating modes. Refer to SECTION 4 OPERATING MODES AND ON-CHIP MEMORY.
Freescale Semiconductor, Inc...
After the operating mode has been selected, the LIR pin provides an open-drain output
to indicate that execution of an instruction has begun. The LIR pin is configured for
wired-OR operation (only pulls low). A series of E-clock cycles occurs during execution
of each instruction. The LIR signal is asserted (drives low) during the first E-clock cycle
of each instruction (opcode fetch). This output is provided for assistance in program
debugging.
The VSTBY pin is used to input RAM standby power. The MCU is powered from the
VDD signal unless the difference between the level of VSTBY and Vdd is greater than
one MOS threshold (about 0.7 volts). When these voltages differ by more than 0.7
volts, the internal 768-byte RAM and part of the reset logic are powered from VSTBY
rather than VDD. This allows RAM contents to be retained without VDD power applied
to the MCU. Reset must be driven low before VDD is removed and must remain low
until VDD has been restored to a valid level.
2.9 VRH and VRL
These pins provide the reference voltage for the analog-to-digital converter. Bypass
capacitors should be used to minimize noise on these signals. Any noise on VRH and
VRL will directly affect A/D accuracy.
2.10 R/W
In expanded and test modes, R/W indicates the direction of transfers on the external
data bus. A logic level one on this pin indicates that a read cycle is in progress. A logic
zero on this pin indicates that a write cycle is in progress and that no external device
should drive the data bus.
The E-clock can be used to enable external devices to drive data onto the data bus
during the second half of a read bus cycle (E clock high). R/W can then be used to
control the direction of data transfers. R/W drives low when data is being written to the
external data bus. R/W will remain low during consecutive data bus write cycles, such
as when a double-byte store occurs.
2.11 Port Signals
For the MC68HC11F1, 54 pins are arranged into six 8-bit ports: A, B, C, E, F, and G,
and one 6-bit port (D). Each of these seven ports serves a purpose other than I/O, depending on the operating mode or peripheral functions selected. Note that ports B, C,
and F are available for I/O functions only in single-chip and bootstrap modes. The pins
of ports A, C, D, and G are fully bidirectional. Ports B and F are output-only ports. Port
E is an input-only port. Refer to Table 2-1 for details about the 54 port signals’ functions within different operating modes.
PIN DESCRIPTIONS
2-6
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Table 2-1 Port Signal Functions
Freescale Semiconductor, Inc...
Port/Bit
PA0
PA1
PA2
PA3
PA4
PA5
PA6
PA7
PB[7:0]
PC[7:0]
PD0
PD1
PD2
PD3
PD4
PD5
PE[7:0]
PF[7:0]
PG0
PG1
PG2
PG3
PG4
PG5
PG6
PG7
Single-Chip and
Expanded and
Bootstrap Mode
Special Test Mode
PA0/IC3
PA1/IC2
PA2/IC1
PA3/OC5/IC4/OC1
PA4/OC4/OC1
PA5/OC3/OC1
PA6/OC2/OC1
PA7/PAI/OC1
PB[7:0]
ADDR[15:8]
PC[7:0]
DATA[7:0]
PD0/RxD
PD1/TxD
PD2/MISO
PD3/MOSI
PD4/SCK
PD5/SS
PE[7:0]/AN[7:0]
PF[7:0]
ADDR[7:0]
PG0
PG1
PG2
PG3
PG4
PG4/CSIO2
PG5
PG5/CSIO1
PG6
PG6/CSGEN
PG7
PG7/CSPROG
2.11.1 Port A
Port A is an 8-bit general-purpose I/O port with a data register (PORTA) and a data
direction register (DDRA). Port A pins share functions with the 16-bit timer system.
PORTA can be read at any time. Inputs return the pin level; outputs return the pin driver input level. If written, PORTA stores the data in internal latches. It drives the pins
only if they are configured as outputs. Writes to PORTA do not change the pin state
when the pins are configured for timer output compares.
Out of reset, port A pins [7:0] are general-purpose high-impedance inputs. When the
timer functions associated with these pins are disabled, the bits in DDRA govern the
I/O state of the associated pin. For further information, refer to SECTION 6 PARALLEL INPUT/OUTPUT.
NOTE
When using the information about port functions, do not confuse pin
function with the electrical state of the pin at reset. All general-purpose I/O pins configured as inputs at reset are in a high-impedance
state. Port data registers reflect the logic state of the port at reset.
The pin function is mode dependent.
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2.11.2 Port B
Port B is an 8-bit output-only port. In single-chip modes, port B pins are general-purpose output pins (PB[7:0]). In expanded modes, port B pins act as the high-order address lines (ADDR[15:8]) of the address bus.
PORTB can be read at any time. Reads of PORTB return the pin driver input level. If
PORTB is written, the data is stored in internal latches. It drives the pins only in singlechip or bootstrap mode. In expanded operating modes, port B pins are the high-order
address outputs (ADDR[15:8]).
Freescale Semiconductor, Inc...
Refer to SECTION 6 PARALLEL INPUT/OUTPUT.
2.11.3 Port C
Port C is an 8-bit general-purpose I/O port with a data register (PORTC) and a data
direction register (DDRC). In single-chip modes, port C pins are general-purpose I/O
pins (PC[7:0]). In expanded modes, port C pins are configured as data bus pins (DATA[7:0]).
PORTC can be read at any time. Inputs return the pin level; outputs return the pin driver input level. If PORTC is written, the data is stored in internal latches. It drives the
pins only if they are configured as outputs in single-chip or bootstrap mode. Port C pins
are general-purpose inputs out of reset in single-chip and bootstrap modes. In expanded and test modes, these pins are data bus lines out of reset.
The CWOM control bit in the OPT2 register disables port C’s P-channel output drivers.
Because the N-channel driver is not affected by CWOM, setting CWOM causes port
C to become an open-drain-type output port suitable for wired-OR operation. In wiredOR mode, (PORTC bits are at logic level zero), pins are actively driven low by the Nchannel driver. When a port C bit is at logic level one, the associated pin is in a highimpedance state, as neither the N-channel nor the P-channel devices are active. It is
customary to have an external pull-up resistor on lines that are driven by open-drain
devices. Port C can only be configured for wired-OR operation when the MCU is in single-chip or bootstrap modes.
Refer to SECTION 6 PARALLEL INPUT/OUTPUT.
2.11.4 Port D
Port D, a 6-bit general-purpose I/O port, has a data register (PORTD) and a data direction register (DDRD). The six port D lines (D[5:0]) can be used for general-purpose
I/O, for the serial communications interface (SCI) and serial peripheral interface (SPI)
subsystems.
PORTD can be read at any time. Inputs return the pin level; outputs return the pin driver input level. If PORTD is written, the data is stored in internal latches and can be driven only if port D is configured for general-purpose output.
The DWOM control bit in the SPCR register disables port D’s P-channel output drivers.
Because the N-channel driver is not affected by DWOM, setting DWOM causes port
D to become an open-drain-type output port suitable for wired-OR operation. In wiredPIN DESCRIPTIONS
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OR mode, (PORTD bits are at logic level zero), pins are actively driven low by the Nchannel driver. When a port D bit is at logic level one, the associated pin is in a highimpedance state, as neither the N-channel nor the P-channel devices are active. It is
customary to have an external pull-up resistor on lines that are driven by open-drain
devices. Port D can be configured for wired-OR operation in any operating mode.
Freescale Semiconductor, Inc...
Refer to SECTION 6 PARALLEL INPUT/OUTPUT, SECTION 7 SERIAL COMMUNICATIONS INTERFACE, and SECTION 8 SERIAL PERIPHERAL INTERFACE.
2.11.5 Port E
Port E is an 8-bit input-only port that is also used as the analog input port for the analog-to-digital converter. Port E pins that are not used for the A/D system can be used
as general-purpose inputs. However, PORTE should not be read during the sample
portion of an A/D conversion sequence.
Refer to SECTION 10 ANALOG-TO-DIGITAL CONVERTER.
2.11.6 Port F
Port F is an 8-bit output-only port. In single-chip mode, port F pins are general-purpose
output pins (PF[7:0]). In expanded mode, port F pins act as the low-order address outputs (ADDR[7:0]).
PORTF can be read at any time. Reads of PORTF return the pin driver input level. If
PORTF is written, the data is stored in internal latches. It drives the pins only in singlechip or bootstrap mode. In expanded operating modes, port F pins are the low-order
address outputs (ADDR[7:0]).
Refer to SECTION 6 PARALLEL INPUT/OUTPUT.
2.11.7 Port G
Port G is an 8-bit general-purpose I/O port. When enabled, four chip select signals are
alternate functions of port G bits [7:4].
PORTG can be read at any time. Inputs return the pin level; outputs return the pin driver input level. If PORTG is written, the data is stored in internal latches. It drives the
pins only if they are configured as outputs.
The GWOM control bit in the OPT2 register disables port G's P-channel output drivers.
Because the N-channel driver is not affected by GWOM, setting GWOM causes port
G to become an open-drain-type output port suitable for wired-OR operation. In wiredOR mode, (PORTG bits are at logic level zero), pins are actively driven low by the Nchannel driver. When a port G bit is at logic level one, the associated pin is in a highimpedance state, as neither the N-channel nor the P-channel devices are active. It is
customary to have an external pull-up resistor on lines that are driven by open-drain
devices. Port G can be configured for wired-OR operation in any operating mode.
Refer to SECTION 6 PARALLEL INPUT/OUTPUT and SECTION 4 OPERATING
MODES AND ON-CHIP MEMORY.
PIN DESCRIPTIONS
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PIN DESCRIPTIONS
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SECTION 3 CENTRAL PROCESSING UNIT
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This section presents information on M68HC11 central processing unit (CPU) architecture. Data types, addressing modes, the instruction set, and the extended addressing range required to support this MCU’s memory expansion feature are also included,
as are special operations such as subroutine calls and interrupts.
The CPU is designed to treat all peripheral, I/O, and memory locations identically as
addresses in the 64 Kbyte memory map. This is referred to as memory-mapped I/O.
There are no special instructions for I/O that are separate from those used for memory.
This architecture also allows accessing an operand from an external memory location
with no execution-time penalty.
3.1 CPU Registers
M68HC11 CPU registers are an integral part of the CPU and are not addressed as if
they were memory locations. The seven registers, discussed in the following paragraphs, are shown in Figure 3-1.
CENTRAL PROCESSING UNIT
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7
0
ACCUMULATOR A
A
7
0
ACCUMULATOR B
B
15
0
DOUBLE ACCUMULATOR D
D
15
0
INDEX REGISTER X
IX
15
0
INDEX REGISTER Y
IY
15
0
Freescale Semiconductor, Inc...
STACK POINTER
SP
15
0
PROGRAM COUNTER
CONDITION CODE REGISTER
PC
7
6
5
4
3
2
1
0
S
X
H
I
N
Z
V
C
CCR
CARRY
OVERFLOW
ZERO
NEGATIVE
I INTERRUPT MASK
HALF-CARRY (FROM BIT 3)
X INTERRUPT MASK
STOP DISABLE
Figure 3-1 Programming Model
3.1.1 Accumulators A, B, and D
Accumulators A and B are general-purpose 8-bit registers that hold operands and results of arithmetic calculations or data manipulations. For some instructions, these two
accumulators are treated as a single double-byte (16-bit) accumulator called accumulator D. Although most instructions can use accumulators A or B interchangeably, the
following exceptions apply:
The ABX and ABY instructions add the contents of 8-bit accumulator B to the contents
of 16-bit register X or Y, but there are no equivalent instructions that use A instead of B.
The TAP and TPA instructions transfer data from accumulator A to the condition code
register, or from the condition code register to accumulator A, however, there are no
equivalent instructions that use B rather than A.
The decimal adjust accumulator A (DAA) instruction is used after binary-coded decimal (BCD) arithmetic operations, but there is no equivalent BCD instruction to adjust
accumulator B.
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The add, subtract, and compare instructions associated with both A and B (ABA, SBA,
and CBA) only operate in one direction, making it important to plan ahead to ensure
that the correct operand is in the correct accumulator.
Freescale Semiconductor, Inc...
3.1.2 Index Register X (IX)
The IX register provides a 16-bit indexing value that can be added to the 8-bit offset
provided in an instruction to create an effective address. The IX register can also be
used as a counter or as a temporary storage register.
3.1.3 Index Register Y (IY)
The 16-bit IY register performs an indexed mode function similar to that of the IX register. However, most instructions using the IY register require an extra byte of machine
code and an extra cycle of execution time because of the way the opcode map is implemented. Refer to 3.3 Opcodes and Operands for further information.
3.1.4 Stack Pointer (SP)
The M68HC11 CPU has an automatic program stack. This stack can be located anywhere in the address space and can be any size up to the amount of memory available
in the system. Normally the SP is initialized by one of the first instructions in an application program. The stack is configured as a data structure that grows downward from
high memory to low memory. Each time a new byte is pushed onto the stack, the SP
is decremented. Each time a byte is pulled from the stack, the SP is incremented. At
any given time, the SP holds the 16-bit address of the next free location in the stack.
Figure 3-2 is a summary of SP operations.
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RTI, RETURN FROM INTERRUPT
INTERRUPT PROGRAM
JSR, JUMP TO SUBROUTINE
MAIN PROGRAM
$9D = JSR
dd
SP+1
CONDITION CODE
RTN
NEXT MAIN INSTR
SP+2
ACMLTR B
MAIN PROGRAM
SP+3
ACMLTR A
DIRECT
PC
INDXD,X
SP+5
NEXT MAIN INSTR
MAIN PROGRAM
PC
$18 = PRE
$AD = JSR
INDXD,Y
SP
SP+4 INDEX REGISTER (XH)
$AD = JSR
ff
RTN
Freescale Semiconductor, Inc...
PC
$3B = RTI
STACK
PC
INDEX REGISTER (XL)
SP+6 INDEX REGISTER (YH)
STACK
SP+7
INDEX REGISTER (YL)
SP-1
RTNH
SP+8
RTNH
SP
RTNL
SP+9
RTNL
SP-2
ff
RTN
NEXT MAIN INSTR
SWI, SOFTWARE INTERRUPT
MAIN PROGRAM
MAIN PROGRAM
PC
EXTEND
RTN
$BD = JSR
PC
hh
RTN
$3F = SWI
STACK
SP-9
SP-8
CONDITION CODE
ll
SP-7
ACMLTR B
NEXT MAIN INSTR
SP-6
ACMLTR A
SP-5 INDEX REGISTER (XH)
BSR, BRANCH TO SUBROUTINE
MAIN PROGRAM
PC
RTN
SP-2
rr
SP-1
NEXT MAIN INSTR
RTS, RETURN FROM SUBROUTINE
SUBROUTINE
PC
STACK
$8D = BSR
$39 = RTS
SP
WAI, WAIT FOR INTERRUPT
MAIN PROGRAM
PC
RTNH
$3E = WAI
RTN
RTNL
STACK
SP
SP+1
RTNH
SP+2
RTNL
SP-4
INDEX REGISTER (XL)
SP-3 INDEX REGISTER (YH)
SP-2
INDEX REGISTER (YL)
SP-1
RTNH
SP
RTNL
LEGEND:
RTN Address of next instruction in main program to be
executed upon return from subroutine.
RTNH Most significant byte of return address.
RTNL Least significant byte of return address.
Shaded cells show stack pointer position after
operation is complete.
dd 8-bit direct address ($0000-$00FF) (high byte
assumed to be $00).
ff 8-bit positive offset $00 (0) to $FF (256) is added
to index.
hh High-order byte of 16-bit extended address.
ll Low-order byte of 16-bit extended address.
rr Signed-relative offset $80 (-128) to $7F (+127)
(offset relative to the address following the
machine code offset byte).
Figure 3-2 Stacking Operations
When a subroutine is called by a jump to subroutine (JSR) or branch to subroutine
(BSR) instruction, the address of the instruction after the JSR or BSR is automatically
pushed onto the stack, least significant byte first. When the subroutine is finished, a
return from subroutine (RTS) instruction is executed. The RTS pulls the previously
stacked return address from the stack, and loads it into the program counter. Execution then continues at this recovered return address.
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When an interrupt is recognized, the current instruction finishes normally, the return
address (the current value in the program counter) is pushed onto the stack, all of the
CPU registers are pushed onto the stack, and execution continues at the address
specified by the vector for the interrupt. At the end of the interrupt service routine, an
RTI instruction is executed. The RTI instruction causes the saved registers to be pulled
off the stack in reverse order. Program execution resumes at the return address.
Freescale Semiconductor, Inc...
There are instructions that push and pull the A and B accumulators and the X and Y
index registers. These instructions are often used to preserve program context. For
example, pushing accumulator A onto the stack when entering a subroutine that uses
accumulator A, and then pulling accumulator A off the stack just before leaving the
subroutine, ensures that the contents of a register will be the same after returning from
the subroutine as it was before starting the subroutine.
3.1.5 Program Counter (PC)
The program counter, a 16-bit register, contains the address of the next instruction to
be executed. After reset, the program counter is initialized from one of six possible
vectors, depending on operating mode and the cause of reset.
Table 3-1 Reset Vector Comparison
Normal
Test or Boot
POR or RESET Pin
$FFFE, F
$BFFE, F
Clock Monitor
$FFFC, D
$BFFC, D
COP Watchdog
$FFFA, B
$BFFA, B
3.1.6 Condition Code Register (CCR)
This 8-bit register contains five condition code indicators (C, V, Z, N, and H), two interrupt masking bits, (I and X) and a stop disable bit (S). In the M68HC11 CPU, condition
codes are automatically updated by most instructions. For example, load accumulator
A (LDAA) and store accumulator A (STAA) instructions automatically set or clear the
N, Z, and V condition code flags. Pushes, pulls, add B to X (ABX), add B to Y (ABY),
and transfer/exchange instructions do not affect the condition codes. Refer to Table
3-2, which shows what condition codes are affected by a particular instruction.
3.1.6.1 Carry/Borrow (C)
The C bit is set if the arithmetic logic unit (ALU) performs a carry or borrow during an
arithmetic operation. The C bit also acts as an error flag for multiply and divide operations. Shift and rotate instructions operate with and through the carry bit to facilitate
multiple-word shift operations.
3.1.6.2 Overflow (V)
The overflow bit is set if an operation causes an arithmetic overflow. Otherwise, the V
bit is cleared.
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3.1.6.3 Zero (Z)
The Z bit is set if the result of an arithmetic, logic, or data manipulation operation is
zero. Otherwise, the Z bit is cleared. Compare instructions do an internal implied subtraction and the condition codes, including Z, reflect the results of that subtraction. A
few operations (INX, DEX, INY, and DEY) affect the Z bit and no other condition flags.
For these operations, only = and - conditions can be determined.
3.1.6.4 Negative (N)
The N bit is set if the result of an arithmetic, logic, or data manipulation operation is
negative (MSB = 1). Otherwise, the N bit is cleared. A result is said to be negative if
its most significant bit (MSB) is a one. A quick way to test whether the contents of a
memory location has the MSB set is to load it into an accumulator and then check the
status of the N bit.
3.1.6.5 Interrupt Mask (I)
The interrupt request (IRQ) mask (I bit) is a global mask that disables all maskable interrupt sources. While the I bit is set, interrupts can become pending, but the operation
of the CPU continues uninterrupted until the I bit is cleared. After any reset, the I bit is
set by default and can only be cleared by a software instruction. When an interrupt is
recognized, the I bit is set after the registers are stacked, but before the interrupt vector
is fetched. After the interrupt has been serviced, a return from interrupt instruction is
normally executed, restoring the registers to the values that were present before the
interrupt occurred. Normally, the I bit is zero after a return from interrupt is executed.
Although the I bit can be cleared within an interrupt service routine, “nesting” interrupts
in this way should only be done when there is a clear understanding of latency and of
the arbitration mechanism. Refer to SECTION 5 RESETS AND INTERRUPTS.
3.1.6.6 Half Carry (H)
The H bit is set when a carry occurs between bits 3 and 4 of the arithmetic logic unit
during an ADD, ABA, or ADC instruction. Otherwise, the H bit is cleared. Half carry is
used during BCD operations.
3.1.6.7 X Interrupt Mask (X)
The XIRQ mask (X) bit disables interrupts from the XIRQ pin. After any reset, X is set
by default and must be cleared by a software instruction. When an XIRQ interrupt is
recognized, the X and I bits are set after the registers are stacked, but before the interrupt vector is fetched. After the interrupt has been serviced, an RTI instruction is
normally executed, causing the registers to be restored to the values that were present
before the interrupt occurred. The X interrupt mask bit is set only by hardware (RESET
or XIRQ acknowledge). X is cleared only by program instruction (TAP, where the associated bit of A is zero; or RTI, where bit 6 of the value loaded into the CCR from the
stack has been cleared). There is no hardware action for clearing X.
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3.1.6.8 Stop Disable (S)
Setting the STOP disable (S) bit prevents the STOP instruction from putting the
M68HC11 into a low-power stop condition. If the CPU encounters a STOP instruction
while the S bit is set, it is treated as a no-operation (NOP) instruction, and processing
continues to the next instruction. S is set by reset — STOP disabled by default.
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3.2 Data Types
The M68HC11 CPU supports the following data types:
• Bit data
• 8-bit and 16-bit signed and unsigned integers
• 16-bit unsigned fractions
• 16-bit addresses
A byte is eight bits wide and can be accessed at any byte location. A word is composed
of two consecutive bytes with the most significant byte at the lower value address. Because the M68HC11 is an 8-bit CPU, there are no special requirements for alignment
of instructions or operands.
3.3 Opcodes and Operands
The M68HC11 family of microcontrollers uses 8-bit opcodes. Each opcode identifies
a particular instruction and associated addressing mode to the CPU. Several opcodes
are required to provide each instruction with a range of addressing capabilities. Only
256 opcodes would be available if the range of values were restricted to the number
able to be expressed in 8-bit binary numbers.
A four-page opcode map has been implemented to expand the number of instructions.
An additional byte, called a prebyte, directs the processor from page 0 of the opcode
map to one of the other three pages. As its name implies, the additional byte precedes
the opcode.
A complete instruction consists of a prebyte, if any, an opcode, and zero, one, two, or
three operands. The operands contain information the CPU needs for executing the
instruction. Complete instructions can be from one to five bytes long.
3.4 Addressing Modes
Six addressing modes can be used to access memory: immediate, direct, extended,
indexed, inherent, and relative. These modes are detailed in the following paragraphs.
All modes except inherent mode use an effective address. The effective address is the
memory address from which the argument is fetched or stored, or the address from
which execution is to proceed. The effective address can be specified within an instruction, or it can be calculated.
3.4.1 Immediate
In the immediate addressing mode an argument is contained in the byte(s) immediately following the opcode. The number of bytes following the opcode matches the size
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(if prebyte is required) byte immediate instructions. The effective address is the address of the byte following the instruction.
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3.4.2 Direct
In the direct addressing mode, the low-order byte of the operand address is contained
in a single byte following the opcode, and the high-order byte of the address is assumed to be $00. Addresses $00–$FF are thus accessed directly, using two-byte instructions. Execution time is reduced by eliminating the additional memory access
required for the high-order address byte. In most applications, this 256-byte area is reserved for frequently referenced data. In M68HC11 MCUs, the memory map can be
configured for combinations of internal registers, RAM, or external memory to occupy
these addresses.
3.4.3 Extended
In the extended addressing mode, the effective address of the argument is contained
in two bytes following the opcode byte. These are three-byte instructions (or four-byte
instructions if a prebyte is required). One or two bytes are needed for the opcode and
two for the effective address.
3.4.4 Indexed
In the indexed addressing mode, an 8-bit unsigned offset contained in the instruction
is added to the value contained in an index register (IX or IY). The sum is the effective
address. This addressing mode allows referencing any memory location in the 64
Kbyte address space. These are two- to five-byte instructions, depending on whether
or not a prebyte is required.
3.4.5 Inherent
In the inherent addressing mode, all the information necessary to execute the instruction is contained in the opcode. Operations that use only the index registers or accumulators, as well as control instructions with no arguments, are included in this
addressing mode. These are one- or two-byte instructions.
3.4.6 Relative
The relative addressing mode is used only for branch instructions. If the branch condition is true, an 8-bit signed offset included in the instruction is added to the contents
of the program counter to form the effective branch address. Otherwise, control proceeds to the next instruction. These are usually two-byte instructions.
3.5 Instruction Set
Refer to Table 3-2, which shows all the M68HC11 instructions in all possible addressing modes. For each instruction, the table shows the operand construction, the number of machine code bytes, and execution time in CPU E clock cycles.
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Table 3-2 Instruction Set (Sheet 1 of 6)
Mnemonic
ABA
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ABX
ABY
ADCA (opr)
Operation
Add
Accumulators
Add B to X
Add B to Y
Add with Carry
to A
Description
Addressing
Mode
INH
A+B⇒A
IX + (00 : B) ⇒ IX
IY + (00 : B) ⇒ IY
A+M+C⇒A
ADCB (opr)
Add with Carry
to B
B+M+C⇒B
ADDA (opr)
Add Memory
to A
A+M⇒A
ADDB (opr)
Add Memory
to B
B+M⇒B
ADDD (opr)
Add 16-Bit to D D + (M : M + 1) ⇒ D
ANDA (opr)
AND A with
Memory
A•M⇒A
ANDB (opr)
AND B with
Memory
B•M⇒B
ASL (opr)
Arithmetic
Shift Left
C
ASLA
0
b0
b7
18
18
18
18
18
18
18
18
18
3A
3A
89
99
B9
A9
A9
C9
D9
F9
E9
E9
8B
9B
BB
AB
AB
CB
DB
FB
EB
EB
C3
D3
F3
E3
E3
84
94
B4
A4
A4
C4
D4
F4
E4
E4
78
68
68
—
—
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
jj kk
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
hh ll
ff
ff
3
4
2
3
4
4
5
2
3
4
4
5
2
3
4
4
5
2
3
4
4
5
4
5
6
6
7
2
3
4
4
5
2
3
4
4
5
6
6
7
S
—
X
—
Condition Codes
H
I
N
Z
∆
—
∆
∆
V
∆
C
∆
—
—
—
—
—
—
—
—
∆
—
—
—
—
—
∆
—
—
∆
—
—
∆
—
—
∆
—
—
∆
—
∆
∆
∆
∆
—
—
∆
—
∆
∆
∆
∆
—
—
∆
—
∆
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
∆
∆
A
INH
48
—
2
—
—
—
—
∆
∆
∆
∆
B
INH
58
—
2
—
—
—
—
∆
∆
∆
∆
INH
05
—
3
—
—
—
—
∆
∆
∆
∆
77
67
67
47
hh ll
ff
ff
—
6
6
7
2
—
—
—
—
∆
∆
∆
∆
A
EXT
IND,X
IND,Y
INH
—
—
—
—
∆
∆
∆
∆
B
INH
57
—
2
—
—
—
—
∆
∆
∆
∆
REL
24
rr
3
—
—
—
—
—
—
—
—
15
1D
1D
25
dd mm
ff mm
ff mm
rr
6
7
8
3
—
—
—
—
∆
∆
0
—
?C=1
DIR
IND,X
IND,Y
REL
—
—
—
—
—
—
—
—
?Z=1
REL
27
rr
3
—
—
—
—
—
—
—
—
?N⊕V=0
REL
2C
rr
3
—
—
—
—
—
—
—
—
0
b0
b7
Arithmetic
Shift Left B
C
ASLD
A
A
A
A
A
B
B
B
B
B
Arithmetic
Shift Left A
C
ASLB
A
A
A
A
A
B
B
B
B
B
A
A
A
A
A
B
B
B
B
B
INH
INH
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
EXT
IND,X
IND,Y
Instruction
Opcode
Operand Cycles
1B
—
2
0
b0
b7
Arithmetic
Shift Left D
0
C b7 A b0 b7 B b0
ASR
Arithmetic
Shift Right
ASRA
Arithmetic
Shift Right A
ASRB
Arithmetic
Shift Right B
BCC (rel)
Branch if Carry
Clear
Clear Bit(s)
b7
b7
b7
BCLR (opr)
(msk)
BCS (rel)
BEQ (rel)
BGE (rel)
Branch if Carry
Set
Branch if =
Zero
Branch if ∆
Zero
b0
b0
b0
C
18
C
C
?C=0
M • (mm) ⇒ M
18
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Table 3-2 Instruction Set (Sheet 2 of 6)
Mnemonic
BGT (rel)
BHI (rel)
BHS (rel)
BITA (opr)
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BITB (opr)
Operation
Branch if >
Zero
Branch if
Higher
Branch if
Higher or
Same
Bit(s) Test A
with Memory
? Z + (N ⊕ V) = 0
Bit(s) Test B
with Memory
B•M
Branch if ∆
Zero
BLO (rel)
Branch if
Lower
BLS (rel)
Branch if
Lower or
Same
BLT (rel)
Branch if <
Zero
BMI (rel)
Branch if
Minus
BNE (rel)
Branch if not =
Zero
BPL (rel)
Branch if Plus
BRA (rel)
Branch Always
BRCLR(opr)
Branch if
(msk)
Bit(s) Clear
(rel)
BRN (rel)
Branch Never
BRSET(opr)
Branch if Bit(s)
(msk)
Set
(rel)
BSET (opr)
Set Bit(s)
(msk)
BLE (rel)
BSR (rel)
BVC (rel)
BVS (rel)
CBA
CLC
CLI
CLR (opr)
CLRA
CLRB
CLV
CMPA (opr)
CMPB (opr)
Description
Addressing
Mode
REL
Instruction
Opcode
Operand Cycles
2E rr
3
S
—
X
—
Condition Codes
H
I
N
Z
—
—
—
—
V
—
C
—
?C+Z=0
REL
22
rr
3
—
—
—
—
—
—
—
—
?C=0
REL
24
rr
3
—
—
—
—
—
—
—
—
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
REL
85
95
B5
A5
A5
C5
D5
F5
E5
E5
2F
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
rr
2
3
4
4
5
2
3
4
4
5
3
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
—
—
—
—
—
—
—
—
A•M
A
A
A
A
A
B
B
B
B
B
? Z + (N ⊕ V) = 1
18
18
?C=1
REL
25
rr
3
—
—
—
—
—
—
—
—
?C+Z=1
REL
23
rr
3
—
—
—
—
—
—
—
—
?N⊕V=1
REL
2D
rr
3
—
—
—
—
—
—
—
—
?N=1
REL
2B
rr
3
—
—
—
—
—
—
—
—
?Z=0
REL
26
rr
3
—
—
—
—
—
—
—
—
REL
REL
DIR
IND,X
IND,Y
REL
DIR
IND,X
IND,Y
DIR
IND,X
IND,Y
REL
2A
20
13
1F
1F
21
12
1E
1E
14
1C
1C
8D
rr
rr
dd mm rr
ff mm rr
ff mm rr
rr
dd mm rr
ff mm rr
ff mm rr
dd mm
ff mm
ff mm
rr
3
3
6
7
8
3
6
7
8
6
7
8
6
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
∆
∆
0
—
—
—
—
—
—
—
—
—
?N=0
?1=1
? M • mm = 0
?1=0
? (M) • mm = 0
M + mm ⇒ M
Branch to
Subroutine
Branch if
Overflow Clear
Branch if
Overflow Set
Compare A to
B
Clear Carry Bit
Clear Interrupt
Mask
Clear Memory
Byte
See Figure 3–2
Clear
Accumulator A
Clear
Accumulator B
Clear Overflow
Flag
Compare A to
Memory
0⇒A
0⇒B
Compare B to
Memory
B–M
18
18
18
?V=0
REL
28
rr
3
—
—
—
—
—
—
—
—
?V=1
REL
29
rr
3
—
—
—
—
—
—
—
—
A–B
INH
11
—
2
—
—
—
—
∆
∆
∆
∆
0⇒C
0⇒I
INH
INH
0C
0E
—
—
2
2
—
—
—
—
—
—
—
0
—
—
—
—
—
—
0
—
0⇒M
7F
6F
6F
4F
hh ll
ff
ff
—
6
6
7
2
—
—
—
—
0
1
0
0
A
EXT
IND,X
IND,Y
INH
—
—
—
—
0
1
0
0
B
INH
5F
—
2
—
—
—
—
0
1
0
0
INH
0A
—
2
—
—
—
—
—
—
0
—
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
81
91
B1
A1
A1
C1
D1
F1
E1
E1
2
3
4
4
5
2
3
4
4
5
—
—
—
—
∆
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
0⇒V
A–M
A
A
A
A
A
B
B
B
B
B
18
18
18
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
CENTRAL PROCESSING UNIT
3-10
For More Information On This Product,
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MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
Table 3-2 Instruction Set (Sheet 3 of 6)
Mnemonic
COM (opr)
COMA
COMB
Freescale Semiconductor, Inc...
CPD (opr)
Operation
Ones
Complement
Memory Byte
Ones
Complement
A
Ones
Complement
B
Compare D to
Memory 16-Bit
Description
$FF – A ⇒ A
Addressing
Mode
EXT
IND,X
IND,Y
A
INH
$FF – B ⇒ B
B
$FF – M ⇒ M
D–M:M +1
Instruction
Opcode
Operand Cycles
73 hh ll
6
63 ff
6
18
63 ff
7
43
—
2
INH
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
INH
X
—
Condition Codes
H
I
N
Z
—
—
∆
∆
—
—
—
—
∆
V
0
C
1
∆
0
1
—
2
—
—
—
—
∆
∆
0
1
83
93
B3
A3
A3
8C
9C
BC
AC
AC
8C
9C
BC
AC
AC
19
jj kk
dd
hh ll
ff
ff
jj kk
dd
hh ll
ff
ff
jj kk
dd
hh ll
ff
ff
—
5
6
7
7
7
4
5
6
6
7
5
6
7
7
7
2
—
—
—
—
∆
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
7A
6A
6A
4A
hh ll
ff
ff
—
6
6
7
2
—
—
—
—
∆
∆
∆
—
—
—
—
—
∆
∆
∆
—
53
1A
1A
1A
1A
CD
S
—
CPX (opr)
Compare X to
Memory 16-Bit
IX – M : M + 1
CPY (opr)
Compare Y to
Memory 16-Bit
IY – M : M + 1
DAA
Decimal Adjust
A
Decrement
Memory Byte
Adjust Sum to BCD
Decrement
Accumulator
A
Decrement
Accumulator
B
Decrement
Stack Pointer
Decrement
Index Register
X
Decrement
Index Register
Y
Exclusive OR
A with Memory
A–1⇒A
A
EXT
IND,X
IND,Y
INH
B–1⇒B
B
INH
5A
—
2
—
—
—
—
∆
∆
∆
—
SP – 1 ⇒ SP
INH
34
—
3
—
—
—
—
—
—
—
—
IX – 1 ⇒ IX
INH
09
—
3
—
—
—
—
—
∆
—
—
IY – 1 ⇒ IY
INH
09
—
4
—
—
—
—
—
∆
—
—
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
—
2
3
4
4
5
2
3
4
4
5
41
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
—
—
—
—
—
∆
∆
∆
DEC (opr)
DECA
DECB
DES
DEX
DEY
EORA (opr)
M–1⇒M
A⊕M⇒A
18
18
EORB (opr)
Exclusive OR
B with Memory
B⊕M⇒B
FDIV
Fractional
Divide 16 by
16
Integer Divide
16 by 16
Increment
Memory Byte
D / IX ⇒ IX; r ⇒ D
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
INH
D / IX ⇒ IX; r ⇒ D
INH
02
—
41
—
—
—
—
—
∆
0
∆
7C
6C
6C
4C
hh ll
ff
ff
—
6
6
7
2
—
—
—
—
∆
∆
∆
—
—
—
—
—
∆
∆
∆
—
IDIV
INC (opr)
INCA
INCB
INS
INX
Increment
Accumulator
A
Increment
Accumulator
B
Increment
Stack Pointer
Increment
Index Register
X
A
A
A
A
A
B
B
B
B
B
CD
18
18
18
1A
18
M+1⇒M
18
18
88
98
B8
A8
A8
C8
D8
F8
E8
E8
03
A+1⇒A
A
EXT
IND,X
IND,Y
INH
B+1⇒B
B
INH
5C
—
2
—
—
—
—
∆
∆
∆
—
SP + 1 ⇒ SP
INH
31
—
3
—
—
—
—
—
—
—
—
IX + 1 ⇒ IX
INH
08
—
3
—
—
—
—
—
∆
—
—
18
CENTRAL PROCESSING UNIT
TECHNICAL DATA
For More Information On This Product,
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3-11
Freescale Semiconductor, Inc.
Table 3-2 Instruction Set (Sheet 4 of 6)
Mnemonic
INY
Freescale Semiconductor, Inc...
JMP (opr)
Operation
Description
Addressing
Mode
INH
IY + 1 ⇒ IY
Increment
Index Register
Y
Jump
See Figure 3–2
JSR (opr)
Jump to
Subroutine
See Figure 3–2
LDAA (opr)
Load
Accumulator
A
M⇒A
LDAB (opr)
Load
Accumulator
B
M⇒B
LDD (opr)
Load Double
Accumulator
D
M ⇒ A,M + 1 ⇒ B
LDS (opr)
Load Stack
Pointer
M : M + 1 ⇒ SP
LDX (opr)
Load Index
Register
X
M : M + 1 ⇒ IX
LDY (opr)
Load Index
Register
Y
M : M + 1 ⇒ IY
LSL (opr)
Logical Shift
Left
C
LSLA
C
LSLB
LSRA
LSRB
LSRD
MUL
NEG (opr)
NEGA
NEGB
b7
b0
b7
b0
Logical Shift
Right
Logical Shift
Right A
0
Logical Shift
Right B
Logical Shift
Right Double
Multiply 8 by 8
Two’s
Complement
Memory Byte
Two’s
Complement
A
Two’s
Complement
B
0
0
b7
b7
b7
Condition Codes
H
I
N
Z
—
—
—
∆
V
—
C
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
A
B
INH
58
—
2
—
—
—
—
∆
∆
∆
∆
INH
05
—
3
—
—
—
—
∆
∆
∆
∆
74
64
64
44
hh ll
ff
ff
—
6
6
7
2
—
—
—
—
0
∆
∆
∆
A
EXT
IND,X
IND,Y
INH
—
—
—
—
0
∆
∆
∆
B
INH
54
—
2
—
—
—
—
0
∆
∆
∆
INH
04
—
3
—
—
—
—
0
∆
∆
∆
3D
70
60
60
40
—
hh ll
ff
ff
—
10
6
6
7
2
—
—
—
—
—
—
—
—
—
∆
—
∆
—
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
50
—
2
—
—
—
—
∆
∆
∆
∆
18
18
18
18
18
CD
18
18
18
1A
18
18
hh ll
ff
ff
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
jj kk
dd
hh ll
ff
ff
jj kk
dd
hh ll
ff
ff
jj kk
dd
hh ll
ff
ff
jj kk
dd
hh ll
ff
ff
hh ll
ff
ff
—
3
3
4
5
6
6
7
2
3
4
4
5
2
3
4
4
5
3
4
5
5
6
3
4
5
5
6
3
4
5
5
6
4
5
6
6
6
6
6
7
2
—
—
—
—
∆
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
0
b7 A b0 b7 B b0
0
X
—
0
Logical Shift
Left Double
C
LSR (opr)
b0
Logical Shift
Left B
C
LSLD
b7
0
18
7E
6E
6E
9D
BD
AD
AD
86
96
B6
A6
A6
C6
D6
F6
E6
E6
CC
DC
FC
EC
EC
8E
9E
BE
AE
AE
CE
DE
FE
EE
EE
CE
DE
FE
EE
EE
78
68
68
48
S
—
EXT
IND,X
IND,Y
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
EXT
IND,X
IND,Y
INH
A
A
A
A
A
B
B
B
B
B
Logical Shift
Left A
Instruction
Opcode
Operand Cycles
18
08
—
4
0
b0 C
18
b0 C
b0 C
b7 A b0 b7 B b0 C
A∗B⇒D
0–M⇒M
0–A⇒A
A
INH
EXT
IND,X
IND,Y
INH
0–B⇒B
B
INH
18
CENTRAL PROCESSING UNIT
3-12
For More Information On This Product,
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MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
Table 3-2 Instruction Set (Sheet 5 of 6)
Mnemonic
NOP
ORAA (opr)
ORAB (opr)
PSHA
PSHB
Freescale Semiconductor, Inc...
PSHX
PSHY
PULA
PULB
PULX
PULY
ROL (opr)
Operation
No operation
OR
Accumulator
A (Inclusive)
Description
No Operation
A+M⇒A
A
A
A
A
A
OR
B+M⇒B
B
Accumulator
B
B (Inclusive)
B
B
B
Push A onto A ⇒ Stk,SP = SP – 1 A
Stack
Push B onto B ⇒ Stk,SP = SP – 1 B
Stack
Push X onto IX ⇒ Stk,SP = SP – 2
Stack (Lo
First)
Push Y onto IY ⇒ Stk,SP = SP – 2
Stack (Lo
First)
Pull A from SP = SP + 1, A ⇐ Stk A
Stack
Pull B from SP = SP + 1, B ⇐ Stk B
Stack
Pull X From
SP = SP + 2, IX ⇐
Stack (Hi
Stk
First)
Pull Y from
SP = SP + 2, IY ⇐
Stack (Hi
Stk
First)
Rotate Left
—
—
—
—
∆
—
—
—
—
V
—
0
C
—
—
∆
0
—
—
—
—
—
INH
37
—
3
—
—
—
—
—
—
—
—
INH
3C
—
4
—
—
—
—
—
—
—
—
3C
—
5
—
—
—
—
—
—
—
—
INH
32
—
4
—
—
—
—
—
—
—
—
INH
33
—
4
—
—
—
—
—
—
—
—
INH
38
—
5
—
—
—
—
—
—
—
—
18
38
—
6
—
—
—
—
—
—
—
—
hh ll
ff
ff
—
6
6
7
2
—
—
—
—
∆
∆
∆
∆
18
79
69
69
49
—
—
—
—
∆
∆
∆
∆
INH
INH
18
59
—
2
—
—
—
—
∆
∆
∆
∆
76
66
66
46
hh ll
ff
ff
—
6
6
7
2
—
—
—
—
∆
∆
∆
∆
A
EXT
IND,X
IND,Y
INH
—
—
—
—
∆
∆
∆
∆
B
INH
56
—
2
—
—
—
—
∆
∆
∆
∆
See Figure 3–2
INH
3B
—
12
∆
↓
∆
∆
∆
∆
∆
∆
See Figure 3–2
INH
39
—
5
—
—
—
—
—
—
—
—
A–B⇒A
INH
10
—
2
—
—
—
—
∆
∆
∆
∆
82
92
B2
A2
A2
C2
D2
F2
E2
E2
0D
0F
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
—
—
2
3
4
4
5
2
3
4
4
5
2
2
—
—
—
—
∆
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
1⇒C
1⇒I
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
INH
INH
—
—
—
—
—
—
—
1
—
—
—
—
—
—
1
—
1⇒V
INH
0B
—
2
—
—
—
—
—
—
1
—
DIR
EXT
IND,X
IND,Y
97
B7
A7
A7
3
4
4
5
—
—
—
—
∆
∆
0
—
ROR (opr)
Rotate Right
RORA
Rotate Right A
RORB
Rotate Right B
RTI
Return from
Interrupt
Return from
Subroutine
Subtract B
from A
Subtract with
Carry from A
SBCB (opr)
Subtract with
Carry from B
B–M–C⇒B
SEC
SEI
Set Carry
Set Interrupt
Mask
Set Overflow
Flag
Store
Accumulator
A
C
C
b7
b7
b7
STAA (opr)
Condition Codes
H
I
N
Z
—
—
—
—
—
—
∆
∆
INH
Rotate Left B
SEV
X
—
—
B
b0
b7
ROLB
SBCA (opr)
S
—
—
A
C
Rotate Left A
SBA
Instruction
Opcode
Operand Cycles
01
—
2
8A ii
2
9A dd
3
BA hh ll
4
AA ff
4
18
AA ff
5
CA ii
2
DA dd
3
FA hh ll
4
EA ff
4
18
EA ff
5
36
—
3
EXT
IND,X
IND,Y
INH
ROLA
RTS
Addressing
Mode
INH
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
INH
b0
b7
b0
b7
b0 C
18
b0 C
b0 C
A–M–C⇒A
A⇒M
A
A
A
A
A
B
B
B
B
B
A
A
A
A
18
18
18
dd
hh ll
ff
ff
CENTRAL PROCESSING UNIT
TECHNICAL DATA
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3-13
Freescale Semiconductor, Inc.
Table 3-2 Instruction Set (Sheet 6 of 6)
Mnemonic
Description
STAB (opr)
Store
Accumulator
B
B⇒M
STD (opr)
Store
Accumulator
D
A ⇒ M, B ⇒ M + 1
STOP
Stop Internal
Clocks
Store Stack
Pointer
—
STS (opr)
Freescale Semiconductor, Inc...
Operation
SP ⇒ M : M + 1
STX (opr)
Store Index
Register X
IX ⇒ M : M + 1
STY (opr)
Store Index
Register Y
IY ⇒ M : M + 1
SUBA (opr)
Subtract
Memory from
A
A–M⇒A
SUBB (opr)
Subtract
Memory from
B
B–M⇒B
SUBD (opr)
Subtract
Memory from
D
D–M:M+1⇒D
SWI
TAB
TAP
TBA
TEST
TPA
TST (opr)
TSTA
TSTB
TSX
TSY
TXS
TYS
WAI
XGDX
XGDY
B
B
B
B
A
A
A
A
A
A
A
A
A
A
Software
See Figure 3–2
Interrupt
Transfer A to B
A⇒B
Transfer A to
A ⇒ CCR
CC Register
Transfer B to A
B⇒A
TEST (Only in Address Bus Counts
Test Modes)
Transfer CC
CCR ⇒ A
Register to A
Test for Zero
M–0
or Minus
Test A for Zero
A–0
A
or Minus
Test B for Zero
B–0
B
or Minus
Transfer
SP + 1 ⇒ IX
Stack Pointer
to X
Transfer
SP + 1 ⇒ IY
Stack Pointer
to Y
Transfer X to
IX – 1 ⇒ SP
Stack Pointer
Transfer Y to
IY – 1 ⇒ SP
Stack Pointer
Wait for
Stack Regs & WAIT
Interrupt
Exchange D
IX ⇒ D, D ⇒ IX
with X
Exchange D
IY ⇒ D, D ⇒ IY
with Y
Addressing
Mode
DIR
EXT
IND,X
IND,Y
DIR
EXT
IND,X
IND,Y
INH
DIR
EXT
IND,X
IND,Y
DIR
EXT
IND,X
IND,Y
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
IMM
DIR
EXT
IND,X
IND,Y
INH
Instruction
Opcode
Operand Cycles
D7 dd
3
F7 hh ll
4
E7 ff
4
18
E7 ff
5
DD dd
4
FD hh ll
5
ED ff
5
18
ED ff
6
CF
—
2
18
CD
18
18
1A
18
18
18
18
9F
BF
AF
AF
DF
FF
EF
EF
DF
FF
EF
EF
80
90
B0
A0
A0
C0
D0
F0
E0
E0
83
93
B3
A3
A3
3F
S
—
X
—
Condition Codes
H
I
N
Z
—
—
∆
∆
—
—
—
—
∆
—
—
—
—
C
—
∆
0
—
—
—
—
—
dd
hh ll
ff
ff
dd
hh ll
ff
ff
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
ii
dd
hh ll
ff
ff
jj kk
dd
hh ll
ff
ff
—
4
5
5
6
4
5
5
6
5
6
6
6
2
3
4
4
5
2
3
4
4
5
4
5
6
6
7
14
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
0
—
—
—
—
—
∆
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
—
—
—
—
∆
∆
∆
∆
—
—
—
1
—
—
—
—
INH
INH
16
06
—
—
2
2
—
∆
—
↓
—
∆
—
∆
∆
∆
∆
∆
0
∆
—
∆
INH
INH
17
00
—
—
2
*
—
—
—
—
—
—
—
—
∆
—
∆
—
0
—
—
—
INH
07
—
2
—
—
—
—
—
—
—
—
EXT
IND,X
IND,Y
INH
7D
6D
6D
4D
hh ll
ff
ff
—
6
6
7
2
—
—
—
—
∆
∆
0
0
—
—
—
—
∆
∆
0
0
INH
5D
—
2
—
—
—
—
∆
∆
0
0
INH
30
—
3
—
—
—
—
—
—
—
—
30
—
4
—
—
—
—
—
—
—
—
35
—
3
—
—
—
—
—
—
—
—
35
—
4
—
—
—
—
—
—
—
—
INH
3E
—
**
—
—
—
—
—
—
—
—
INH
8F
—
3
—
—
—
—
—
—
—
—
8F
—
4
—
—
—
—
—
—
—
—
INH
18
18
INH
INH
INH
18
18
CENTRAL PROCESSING UNIT
3-14
V
0
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MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
SECTION 4OPERATING MODES AND ON-CHIP MEMORY
Freescale Semiconductor, Inc...
This section contains information about the modes that define MC68HC11F1 operating conditions, and about the on-chip memory that allows the MCU to be configured
for various applications.
4.1 Operating Modes
The values of the mode select inputs MODB and MODA during reset determine the
operating mode. Single chip and expanded modes are the normal modes. In singlechip mode only on-board resources are available. Expanded mode, however, allows
access to external memory or peripheral devices. Each of these two normal modes is
paired with a special mode. Bootstrap mode, a variation of the single-chip mode, executes a bootloader program from an internal bootstrap ROM. Test mode allows privileged access to internal resources.
4.1.1 Single-Chip Operating Mode
In single-chip operating mode, the MC68HC11F1 has no external address or data bus.
Ports B, C, and F are available for general-purpose I/O.
4.1.2 Expanded Operating Mode
In expanded operating mode, the MCU can access a 64-Kbyte physical address
space. The address space includes the same on-chip memory addresses used for single-chip mode, in addition to external memory and peripheral devices.
The expansion bus is made up of ports B, C, F and the R/W signal. In expanded mode,
high order address bits are output on the port B pins, low order address bits on the port
F pins, and the data bus on port C. The R/W pin indicates the direction of data transfer
on the port C bus.
4.1.3 Special Test Mode
Special test mode, a variation of the expanded mode, is primarily used during Motorola's internal production testing; however, it is accessible for programming the CONFIG register, programming calibration data into EEPROM, and supporting emulation
and debugging during development.
4.1.4 Special Bootstrap Mode
Bootstrap mode is a special variation of the single-chip mode. Bootstrap mode allows
special-purpose programs to be entered into internal RAM. When boot mode is selected at reset, a small bootstrap ROM becomes present in the memory map. Reset and
interrupt vectors are located in bootstrap ROM at $BFC0–$BFFF. The MCU fetches
the reset vector, then executes the bootloader.
OPERATING MODES AND ON-CHIP MEMORY
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The bootstrap ROM contains a small program which initializes the SCI and allows the
user to download a program of up to 1024 bytes into on-chip RAM. After a four-character delay, or after receiving the character for address $03FF, control passes to the
loaded program at $0000. An external pull-up resistor is required when using the SCI
transmitter pin (TxD) because port D pins are configured for wired-OR operation by
the bootloader. In bootstrap mode, the interrupt vectors point to RAM. This allows the
use of interrupts through a jump table. Refer to Freescale application note AN1060,
M68HC11 Bootstrap Mode.
Freescale Semiconductor, Inc...
4.2 On-Chip Memory
The MC68HC11F1 contains 1024 bytes of on-chip RAM and 512 bytes of EEPROM.
The bootloader ROM occupies 256 bytes. The CONFIG register is implemented as a
separate EEPROM byte.
4.2.1 Mapping Allocations
Memory locations for on-chip resources are the same for both expanded and singlechip modes. The 96-byte register block originates at $1000 after reset and can be
placed at any other 4-Kbyte boundary ($x000) after reset by writing an appropriate value to the INIT register. Refer to Figure 4-1, which illustrates the memory map.
The on-board 1024-byte RAM is initially located at $0000 after reset. If RAM and registers are both mapped to the same 4-Kbyte boundary, the first 96 bytes of RAM are
inaccessible (registers have higher priority). Remapping is accomplished by writing
appropriate values to the INIT register.
The 512-byte EEPROM array is initially located at $FE00 after reset when EEPROM
is enabled in the memory map by the CONFIG register. In expanded and special test
modes EEPROM can be placed at any other 4-Kbyte boundary ($xE00) by programming bits EE[3:0] in the CONFIG register to an appropriate value. In single-chip and
bootstrap modes the EEPROM is forced on and cannot be remapped.
In special bootstrap mode, a bootloader ROM is enabled at locations $BF00–$BFFF.
The vectors for special bootstrap mode are contained in the bootloader program. The
boot ROM fills 256 bytes of the memory map even though not all locations are used.
OPERATING MODES AND ON-CHIP MEMORY
4-2
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4.2.2 Memory Map
$0000
x000
1024 BYTES RAM 1
EXT
EXT
x3FF
$1000
y000
EXT
EXT
96-BYTE REGISTER BLOCK 2
y05F
BF00
256 BYTES BOOTSTRAP ROM
BFC0
Freescale Semiconductor, Inc...
BFFF
zD00
zDFF
zE00
256 BYTES RESERVED 4
(SPECIAL TEST MODE ONLY)
512 BYTES EEPROM 5
FFC0
$FE00
EXT
$FFFF
SINGLE
CHIP
EXPANDED
BOOTSTRAP
SPECIAL MODE 3
INTERRUPT
VECTORS
zFFF
FFFF
NORMAL MODE
INTERRUPT
VECTORS
SPECIAL
TEST
NOTES:
1. RAM can be remapped to any 4-Kbyte boundary ($x000). "x" represents the value contained in
RAM[3:0] in the init register.
2. The register block can be remapped to any 4-Kbyte boundary ($y000). "y" represents the value contained in
reg[3:0] in the init register.
3. Special test mode vectors are externally addressed.
4. In special test mode the address locations $zD00–$zDFF are not externally addressable.
"z" represents the value of bits EE[3:0] in the config register.
5. EEPROM can be remapped to any 4-Kbyte boundary ($z000). "z" represents the value contained in
EE[3:0] in the config register.
Figure 4-1 MC68HC11F1 Memory Map
4.2.2.1 RAM
The MC68HC11F1 microcontroller has 1024 bytes of fully static RAM that can be used
for storing instructions, variables, and temporary data during program execution. RAM
can be placed at any 4-Kbyte boundary in the 64 Kbyte address space by writing an
appropriate value to the INIT register.
RAM is initially located at $0000 in the memory map upon reset. Direct addressing
mode can access the first 256 locations of RAM using a one-byte address operand.
Direct mode accesses save program memory space and execution time.
The on-chip RAM is a fully static memory. RAM contents can be preserved during periods of processor inactivity by either of two methods, both of which reduce power consumption.
OPERATING MODES AND ON-CHIP MEMORY
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During the software-based STOP mode, MCU clocks are stopped, but the MCU continues to draw power from VDD. Power supply current is directly proportional to operating frequency in CMOS integrated circuits and there is very little leakage when the
clocks are stopped. These two factors reduce power consumption while the MCU is in
STOP mode.
Freescale Semiconductor, Inc...
To reduce power consumption to a minimum, VDD can be turned off, and the MODB/
VSTBY pin can be used to supply RAM power from either a battery back-up or a second power supply. Although this method requires external hardware, it is very effective. Refer to SECTION 2 PIN DESCRIPTIONS for information about how to connect
the standby RAM power supply. Refer to SECTION 5 RESETS AND INTERRUPTS
for a description of low power operation.
VDD
MAX
690
VDD
4.7 k
VOUT
4.8 V
NiCd
+
TO MODB/VSTBY
OF M68HC11
VBATT
Figure 4-2 RAM Standby MODB/VSTBY Connections
4.2.2.2 Bootloader ROM
The bootloader ROM is enabled at address $BF00–$BFFF during special bootstrap
mode. The reset vector is fetched from this ROM and the MCU executes the bootloader firmware. In normal modes, the bootloader ROM is disabled.
4.2.2.3 EEPROM
The MC68HC11F1 contains 512 bytes of electrically erasable programmable readonly memory (EEPROM). The default location for EEPROM is $FE00–$FFFF. Other
locations can be chosen according to the values written to EE[3:0] in the CONFIG register. In single-chip and bootstrap modes, the EEPROM is forced on and located at the
default position. In these modes, the EEPROM cannot be remapped. In special test
mode, the EEPROM is disabled initially.
4.2.3 Registers
Table 4-1, a summary of registers and control bits, the registers are shown in ascending order within the 96-byte register block. The addresses shown are for default block
mapping ($1000–$105F), however, the register block can be remapped to any 4-Kbyte
page ($x000–$x05F) by the INIT register.
OPERATING MODES AND ON-CHIP MEMORY
4-4
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Table 4-1 Register and Control Bit Assignments
The register block can be remapped to any 4-Kbyte boundary.
Freescale Semiconductor, Inc...
Bit 7
6
5
4
3
2
1
Bit 0
$1000
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
$1001
DDA7
DDA6
DDA5
DDA4
DDA3
DDA2
DDA1
DDA0
PORTA
$1002
PG7
PG6
PG5
PG4
PG3
PG2
PG1
PG0
$1003
DDG7
DDG6
DDG5
DDG4
DDG3
DDG2
DDG1
DDG0
DDRG
$1004
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
PORTB
$1005
PF7
PF6
PF5
PF4
PF3
PF2
PF1
PF0
PORTF
$1006
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
PORTC
$1007
DDC7
DDC6
DDC5
DDC4
DDC3
DDC2
DDC1
DDC0
$1008
0
0
PD5
PD4
PD3
PD2
PD1
PD0
$1009
0
0
DDD5
DDD4
DDD3
DDD2
DDD1
DDD0
DDRD
$100A
PE7
PE6
PE5
PE4
PE3
PE2
PE1
PE0
PORTE
$100B
FOC1
FOC2
FOC3
FOC4
FOC5
0
0
0
CFORC
$100C
OC1M7
OC1M6
OC1M5
OC1M4
OC1M3
0
0
0
OC1M
$100D
OC1D7
OC1D6
OC1D5
OC1D4
OC1D3
0
0
0
OC1D
$100E
Bit 15
14
13
12
11
10
9
Bit 8
TCNT (High)
$100F
Bit 7
6
5
4
3
2
1
Bit 0
TCNT (Low)
$1010
Bit 15
14
13
12
11
10
9
Bit 8
TIC1 (High)
$1011
Bit 7
6
5
4
3
2
1
Bit 0
TIC1 (Low)
$1012
Bit 15
14
13
12
11
10
9
Bit 8
TIC2 (High)
$1013
Bit 7
6
5
4
3
2
1
Bit 0
TIC2 (Low)
$1014
Bit 15
14
13
12
11
10
9
Bit 8
TIC3 (High)
$1015
Bit 7
6
5
4
3
2
1
Bit 0
TIC3 (Low)
$1016
Bit 15
14
13
12
11
10
9
Bit 8
TOC1 (High)
$1017
Bit 7
6
5
4
3
2
1
Bit 0
TOC1 (Low)
$1018
Bit 15
14
13
12
11
10
9
Bit 8
TOC2 (High)
$1019
Bit 7
6
5
4
3
2
1
Bit 0
TOC2 (Low)
$101A
Bit 15
14
13
12
11
10
9
Bit 8
TOC3 (High)
$101B
Bit 7
6
5
4
3
2
1
Bit 0
TOC3 (Low)
$101C
Bit 15
14
13
12
11
10
9
Bit 8
TOC4 (High)
$101D
Bit 7
6
5
4
3
2
1
Bit 0
TOC4 (Low)
$101E
Bit 15
14
13
12
11
10
9
Bit 8
TI4/O5 (High)
$101F
Bit 7
6
5
4
3
2
1
Bit 0
TI4/O5 (Low)
DDRA
PORTG
DDRC
PORTD
$1020
OM2
OL2
OM3
OL3
OM4
OL4
OM5
OL5
TCTL1
$1021
EDG4B
EDG4A
EDG1B
EDG1A
EDG2B
EDG2A
EDG3B
EDG3A
TCTL2
$1022
OC1I
OC2I
OC3I
OC4I
I4/O5I
IC1I
IC2I
IC3I
TMSK1
$1023
OC1F
OC2F
OC3F
OC4F
I4/O5F
IC1F
IC2F
IC3F
TFLG1
$1024
TOI
RTII
PAOVI
PAII
0
0
PR1
PR0
TMSK2
$1025
TOF
RTIF
PAOVF
PAIF
0
0
0
0
TFLG2
$1026
0
PAEN
PAMOD
PEDGE
0
I4/O5
RTR1
RTR0
PACTL
$1027
Bit 7
6
5
4
3
2
1
Bit 0
PACNT
OPERATING MODES AND ON-CHIP MEMORY
TECHNICAL DATA
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Table 4-1 Register and Control Bit Assignments (Continued)
The register block can be remapped to any 4-Kbyte boundary.
Freescale Semiconductor, Inc...
Bit 7
6
5
4
3
2
1
Bit 0
$1028
SPIE
SPE
DWOM
MSTR
CPOL
CPHA
SPR1
SPR0
SPCR
$1029
SPIF
WCOL
0
MODF
0
0
0
Bit 0
SPSR
$102A
Bit 7
6
5
4
3
2
1
Bit 0
SPDR
$102B
TCLR
0
SCP1
SCP0
RCKB
SCR2
SCR1
SCR0
BAUD
$102C
R8
T8
0
M
WAKE
0
0
0
SCCR1
$102D
TIE
TCIE
RIE
ILIE
TE
RE
RWU
SBK
SCCR2
$102E
TDRE
TC
RDRF
IDLE
OR
NF
FE
0
SCSR
$102F
Bit 7
6
5
4
3
2
1
Bit 0
SCDR
$1030
CCF
0
SCAN
MULT
CD
CC
CB
CA
ADCTL
$1031
Bit 7
6
5
4
3
2
1
Bit 0
ADR1
$1032
Bit 7
6
5
4
3
2
1
Bit 0
ADR2
$1033
Bit 7
6
5
4
3
2
1
Bit 0
ADR3
$1034
Bit 7
6
5
4
3
2
1
Bit 0
$1035
0
0
0
PTCON
BPRT3
BPRT2
BPRT1
BPRT0
ADR4
BPROT
$1036
Reserved
$1037
Reserved
$1038
GWOM
CWOM
CLK4X
0
0
0
0
0
$1039
ADPU
CSEL
IRQE
DLY
CME
FCME
CR1
CR0
OPTION
OPT2
$103A
Bit 7
6
5
4
3
2
1
Bit 0
COPRST
$103B
ODD
EVEN
0
BYTE
ROW
ERASE
EELAT
EEPGM
PPROG
$103C
RBOOT
SMOD
MDA
IRV
PSEL3
PSEL2
PSEL1
PSEL0
HPRIO
$103D
RAM3
RAM2
RAM1
RAM0
REG3
REG2
REG1
REG0
INIT
$103E
TILOP
0
OCCR
CBYP
DISR
FCM
FCOP
0
$103F
EE3`
EE2
EE1
EE0
1
NOCOP
1
EEON
TEST1
CONFIG
Reserved
$1040
to
Reserved
$105B
$105C
IO1SA
IO1SB
IO2SA
IO2SB
GSTHA
GSTHB
PSTHA
PSTHB
CSSTRH
$105D
IO1EN
IO1PL
IO2EN
IO2PL
GCSPR
PCSEN
PSIZA
PSIZB
$105E
GA15
GA14
GA13
GA12
GA11
GA10
0
0
CSGADR
$105F
IO1AV
IO2AV
0
GNPOL
GAVLD
GSIZA
GSIZB
GSIZC
CSGSIZ
CSCTL
4.3 System Initialization
Registers and bits that control initialization and the basic operation of the MCU are protected against writes except under special circumstances. The following table lists registers that can be written only once after reset or that must be written within the first 64
cycles after reset.
OPERATING MODES AND ON-CHIP MEMORY
4-6
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Table 4-2 Write Access Limited Registers
Freescale Semiconductor, Inc...
Register
Address
$x024
$x035
$x038
$x039
$x03C
$x03D
Register
Name
Timer Interrupt Mask 2 (TMSK2)
Block Protect Register (BPROT)
System Configuration Options 2 (OPT2)
System Configuration Options (OPTION)
Highest Priority I-bit and Miscellaneous (HPRIO)
RAM and I/O Map Register (INIT)
Must be Written in
First 64 Cycles
Note 1
Note 2
No
Note 3
No
Yes
Write One Time
Only
—
—
Note 4
—
Note 5
Note 6
Notes:
1. Bits 1 and 0 can be written once only in first 64 cycles. When SMOD = 1, these bits can be written any time. All
other bits can be written at any time.
2. Bits can be written to zero (protection disabled) once only in first 64 cycles or at any time in special modes. Bits
can be set to one at any time.
3. Bits 5, 4, 2, 1, and 0 can be written once only in first 64 cycles. When SMOD = 1, bits 5, 4, 2, 1, and 0 can be
written at any time. All other bits can be written at any time
4. Bit 5 (CLK4X) can be written only one time.
5. Bit 4 (IRV) can be written only one time.
6. Can be written once in first 64 cycles after reset in normal modes or at any time in special modes.
4.3.1 Mode Selection
The four mode variations are selected by the logic levels present on the MODA and
MODB pins at the rising edge of RESET. The MODA and MODB logic levels determine
the logic state of SMOD and MDA control bits in the HPRIO register.
After reset is released, the mode select pins no longer influence the MCU operating
mode. In single-chip operating mode, the MODA pin is connected to a logic level zero.
In expanded mode, MODA should be connected to VDD through a pull-up resistor of
4.7 kΩ. The MODA pin also functions as the load instruction register (LIR) pin when
the MCU is not in reset. The open-drain active low LIR output pin drives low during the
first E cycle of each instruction (opcode fetch). The MODB pin also functions as standby power input (VSTBY), which allows RAM contents to be maintained in absence of
VDD. Refer to APPENDIX A ELECTRICAL CHARACTERISTICS for VSTBY voltage
requirements.
Refer to Table 4-3, which is a summary of mode pin operation, the mode control bits,
and the four operating modes.
Table 4-3 Hardware Mode Select Summary
Input Levels
at Reset
MODB
1
1
0
0
Mode
MODA
0
1
0
1
Single Chip
Expanded
Special Bootstrap
Special Test
Control Bits in HPRIO
(Latched at Reset)
RBOOT
SMOD
MDA
0
0
0
0
0
1
1
1
0
0
1
1
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A normal mode is selected when MODB is logic one during reset. One of three reset
vectors is fetched from address $FFFA–$FFFF, and program execution begins from
the address indicated by this vector. If MODB is logic zero during reset, the special
mode reset vector is fetched from addresses $BFFA–$BFFF and software has access
to special test features. Refer to SECTION 5 RESETS AND INTERRUPTS for information regarding reset vectors.
Freescale Semiconductor, Inc...
4.3.1.1 HPRIO Register
Bits in the HPRIO register select the highest priority interrupt level, select whether
bootstrap ROM is present, and control visibility of internal reads by the CPU. After reset, MDA and SMOD select the operating mode.
HPRIO — Highest Priority I-Bit Interrupt and Miscellaneous
RESET:
Bit 7
RBOOT*
0
0
1
0
6
SMOD*
0
0
1
1
5
MDA*
0
1
0
1
4
IRV
0
0
1
1
3
PSEL3
0
0
0
0
2
PSEL2
1
1
1
1
$103C
1
PSEL1
1
1
1
1
Bit 0
PSEL0
0
0
0
0
Single Chip
Expanded
Bootstrap
Special Test
*Reset states of RBOOT, SMOD, and MDA bits depend on hardware mode selection. Refer to Table 4-3.
RBOOT — Read Bootstrap ROM
Set to one out of reset in bootstrap mode. Valid while in special modes only. Can be
read anytime. Can only be written in special modes.
0 = Bootloader ROM disabled and not in map
1 = Bootloader ROM enabled and in map at $BF00–$BFFF
SMOD and MDA — Special Mode Select and Mode Select A
The initial value of SMOD is the inverse of the logic level present on the MODB pin at
the rising edge of reset. The initial value of MDA equals the logic level present on the
MODA pin at the rising edge of reset. These two bits can be read at any time. They can
be written at any time in special modes. Neither bit can be written is normal modes.
SMOD cannot be set once it has been cleared. Refer to Table 4-3.
IRV — Internal Read Visibility
IRV can be written at any time in special modes (SMOD = 1). In normal modes (SMOD
= 0) IRV can be written only once. In expanded and test modes, IRV determines
whether internal read visibility is on or off. In single-chip and bootstrap modes, IRV has
no meaning or effect.
0 = No internal read visibility on external bus
1 = Data from internal reads is driven out the external data bus.
PSEL[3:0] — Priority Select Bits [3:0]
Refer to 5.3.1 Highest Priority Interrupt and Miscellaneous Register.
OPERATING MODES AND ON-CHIP MEMORY
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4.3.2 Initialization
Because bits in the following registers control the basic configuration of the MCU, an
accidental change of their values could cause serious system problems. The protection mechanism, overridden in special operating modes, requires a write to the protected bits only within the first 64 bus cycles after any reset, or only once after each reset.
Table 4-2 summarizes the write access limited registers.
4.3.2.1 CONFIG Register
CONFIG controls the presence and position of the EEPROM in the memory map.
CONFIG also enables the COP watchdog timer.
Freescale Semiconductor, Inc...
CONFIG — System Configuration Register
RESET:
Bit 7
EE3
1
1
P
P
6
EE2
1
1
P
P
5
EE1
1
1
P
P
4
EE0
1
1
P
P
$103F
3
—
1
1
1
1
2
NOCOP
P
P(L)
P
P(L)
1
—
1
1
1
1
Bit 0
EEON
1
1
P
0
Single Chip
Bootstrap
Expanded
Special Test
P indicates a previously programmed bit. P(L) indicates that the bit resets to the logic
level held in the latch prior to reset, but the function of COP is controlled by DISR bit
in TEST1 register.
The CONFIG register consists of an EEPROM byte and static latches that control the
start-up configuration of the MCU. The contents of the EEPROM byte are transferred
into static working latches during reset sequences. The operation of the MCU is controlled directly by these latches and not by CONFIG itself. In normal modes, changes
to CONFIG do not affect operation of the MCU until after the next reset sequence.
When programming, the CONFIG register itself is accessed. When the CONFIG register is read, the static latches are accessed.
These bits can be read at any time. The value read is the one latched into the register
from the EEPROM cells during the last reset sequence. A new value programmed into
this register cannot be read until after a subsequent reset sequence. Unused bits always read as ones.
In special test mode, the static latches can be written directly at any time. In all modes,
CONFIG bits can only be programmed using the EEPROM programming sequence,
and are neither readable nor active until latched via the next reset. Refer to 4.4.3 CONFIG Register Programming.
EE[3:0] — EEPROM Mapping Control
EE[3:0] select the upper four bits of the EEPROM base address. In single-chip and
bootstrap modes, EEPROM is forced to $FE00–$FFFF regardless of the value of
EE[3:0].
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Table 4-4 EEPROM Mapping
EE[3:0]
EEPROM Position
0000
$0E00 – $0FFF
0001
$1E00 – $1FFF
0010
$2E00 – $2FFF
0011
$3E00 – $3FFF
0100
$4E00 – $4FFF
0101
$5E00 – $5FFF
0110
$6E00 – $6FFF
0111
$7E00 – $7FFF
1000
$8E00 – $8FFF
1001
$9E00 – $9FFF
1010
$AE00 – $AFFF
1011
$BE00 – $BFFF
1100
$CE00 – $CFFF
1101
$DE00 – $DFFF
1110
$EE00 – $EFFF
1111
$FE00 – $FFFF
Bit 3 — Not implemented
Always reads one
NOCOP — COP System Disable
0 = COP system enabled (forces reset on time-out)
1 = COP system disabled
Bit 1 — Not implemented
Always reads one
EEON — EEPROM Enable
In single-chip modes EEON is forced to one (EEPROM enabled).
0 = 512 bytes of EEPROM is disabled from the memory map
1 = 512 bytes of EEPROM is present in the memory map
4.3.2.2 INIT Register
The internal registers used to control the operation of the MCU can be relocated on 4Kbyte boundaries within the memory space with the use of INIT. This 8-bit special-purpose register can change the default locations of the RAM and control registers within
the MCU memory map. It can be written only once within the first 64 E-clock cycles
after a reset. It then becomes a read-only register.
INIT — RAM and I/O Mapping Register
RESET:
Bit 7
RAM3
0
6
RAM2
0
5
RAM1
0
4
RAM0
0
$103D
3
REG3
0
2
REG2
0
1
REG1
0
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REG0
1
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RAM[3:0] — RAM Map Position
These four bits, which specify the upper hexadecimal digit of the RAM address, control
position of RAM in the memory map. RAM can be positioned at the beginning of any
4-Kbyte page in the memory map. Refer to Table 4-5.
REG[3:0] — 128-Byte Register Block Position
These four bits specify the upper hexadecimal digit of the address for the 128-byte
block of internal registers. The register block is positioned at the beginning of any 4Kbyte page in the memory map. Refer to Table 4-5.
Freescale Semiconductor, Inc...
Table 4-5 RAM and Register Mapping
RAM[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Location
$0000–$03FF
$1000–$13FF
$2000–$23FF
$3000–$33FF
$4000–$43FF
$5000–$53FF
$6000–$63FF
$7000–$73FF
$8000–$83FF
$9000–$93FF
$A000–$A3FF
$B000–$B3FF
$C000–$C3FF
$D000–$D3FF
$E000–$E3FF
$F000–$F3FF
REG[3:0]
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
Location
$0000–$005F
$1000–$105F
$2000–$205F
$3000–$305F
$4000–$405F
$5000–$505F
$6000–$605F
$7000–$705F
$8000–$805F
$9000–$905F
$A000–$A05F
$B000–$B05F
$C000–$C05F
$D000–$D05F
$E000–$E05F
$F000–$F05F
When the memory map has the 96-byte register block mapped at the same location
as RAM, the registers have priority and the lower 96 bytes of RAM are inaccessible.
No harmful conflicts occur due to a hardware resource priority scheme. On-chip registers have the highest priority of all on-chip resources, followed by on-chip RAM, bootstrap ROM, and on-chip EEPROM.
4.3.2.3 OPTION Register
The 8-bit special-purpose OPTION register sets internal system configuration options
during initialization. In single-chip and expanded modes (SMOD = 0), IRQE, DLY, FCME, and CR[1:0] can be written only once and only in the first 64 cycles after a reset.
This minimizes the possibility of any accidental changes to the system configuration.
In special test and bootstrap modes (SMOD = 1), these bits can be written at any time.
OPTION — System Configuration Options
RESET:
Bit 7
ADPU
0
6
CSEL
0
5
IRQE*
0
4
DLY*
0
$1039
3
CME
0
2
FCME*
0
1
CR1*
0
Bit 0
CR0*
0
*Can be written only once in first 64 cycles out of reset in normal modes or at any time in special modes.
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ADPU — A/D Power-Up
Refer to SECTION 10 ANALOG-TO-DIGITAL CONVERTER.
0 = A/D system disabled
1 = A/D system power enabled
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CSEL — Clock Select
Selects alternate clock source for on-chip EEPROM and A/D charge pumps. On-chip
RC clock should be used when E clock falls below 1 MHz. Refer to SECTION 10 ANALOG-TO-DIGITAL CONVERTER.
0 = A/D and EEPROM use system E clock
1 = A/D and EEPROM use internal RC clock
IRQE — Configure IRQ for Falling Edge-Sensitive Operation
Refer to SECTION 5 RESETS AND INTERRUPTS.
0 = Low level-sensitive operation.
1 = Falling edge-sensitive only operation.
DLY — Enable Oscillator Start-up Delay
Refer to SECTION 5 RESETS AND INTERRUPTS.
0 = The oscillator start-up delay coming out of STOP is bypassed and the MCU resumes processing within about four bus cycles.
1 = A delay of approximately 4000 E-clock cycles is imposed as the MCU is started
up from the STOP power-saving mode.
CME — Clock Monitor Enable
In order to use both STOP and clock monitor, the CME bit must be written to zero before executing STOP, then written to one after recovering from STOP. Refer to SECTION 5 RESETS AND INTERRUPTS.
0 = Clock monitor disabled
1 = Clock monitor enabled
FCME — Force Clock Monitor Enable
When FCME equals one, slow or stopped clocks will cause a clock failure reset. To
use STOP mode, FCME must always equal zero. Refer to SECTION 5 RESETS AND
INTERRUPTS.
0 = Clock monitor follows state of CME bit
1 = Clock monitor enabled and cannot be disabled until next reset
CR[1:0] — COP Timer Rate Select Bits
These control bits determine a scaling factor for the watchdog timer. Refer to SECTION 5 RESETS AND INTERRUPTS.
4.3.2.4 OPT2 Register
The system configuration options 2 register (OPT2) controls three additional system
options.
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OPT2 — System Configuration Options 2
RESET:
Bit 7
GWOM
0
6
CWOM
0
5
CLK4X
0
4
—
0
$1038
3
—
0
2
—
0
1
—
0
Bit 0
—
0
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GWOM — Port G Wired-OR Mode
Refer to SECTION 6 PARALLEL INPUT/OUTPUT.
0 = Port G operates normally.
1 = Port G outputs are open-drain type.
CWOM — Port C Wired-OR Mode
Refer to SECTION 6 PARALLEL INPUT/OUTPUT.
0 = Port C operates normally.
1 = Port C outputs are open-drain type.
CLK4X — 4XOUT Clock Enable
The 4XOUT signal, when enabled, is a buffered XTAL signal and is four times the frequency of the E-clock. This buffered clock is intended to synchronize external devices
with the MCU. Refer to SECTION 2 PIN DESCRIPTIONS.
0 = The 4XOUT pin is driven low.
1 = The 4XOUT signal is driven on the 4XOUT pin.
Bits [4:0] — Not implemented
Always read zero
4.3.2.5 Block Protect Register (BPROT)
BPROT prevents accidental writes to EEPROM and the CONFIG register. The bits in
this register can be written to zero during the first 64 E-clock cycles after reset in the
normal modes. Once the bits are cleared to zero, the EEPROM array and the CONFIG
register can be programmed or erased. Setting the bits in the BPROT register to logic
one protects the EEPROM and CONFIG register until the next reset. Refer to Table
4-6.
BPROT — Block Protect
RESET:
Bit 7
—
0
$1035
6
—
0
5
—
0
4
PTCON
1
3
BPRT3
1
2
BPRT2
1
1
BPRT1
1
Bit 0
BPRT0
1
Bits [7:5] — Not implemented
Always read zero
PTCON — Protect for CONFIG
0 = CONFIG register can be programmed or erased normally
1 = CONFIG register cannot be programmed or erased
BPRT[3:0] — Block Protect Bits for EEPROM
0 = Protection disabled for associated block
1 = Protection enabled for associated block
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Table 4-6 EEPROM Block Protection
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Bit Name
BPRT0
BPRT1
BPRT2
BPRT3
Block Protected
$xE00–$xE1F
$xE20–$xE5F
$xE60–$xEDF
$xEE0–$xFFF
Block Size
32 Bytes
64 Bytes
128 Bytes
288 Bytes
4.4 EEPROM and CONFIG Register
The 512-byte EEPROM array and the single-byte CONFIG register are implemented
with the same type of memory cells. The CONFIG register is a separate address located within the register block rather than in the EEPROM array. Unlike other registers
within the register block, the CONFIG register can only be altered using the EEPROM
programming procedure.
4.4.1 EEPROM
The 512-byte on-board EEPROM is initially located from $FE00 to $FFFF after reset
in single-chip modes. It can be mapped to any other 4-Kbyte boundary by programming bits EE[3:0] in the CONFIG register. The EEPROM is enabled by the EEON bit
in the CONFIG register. Programming and erasing is controlled by the PPROG register.
Unlike information stored in ROM, data in the 512 bytes of EEPROM can be erased
and reprogrammed under software control. Because programming and erasing operations use an on-chip charge pump, a separate external power supply is not required.
Use of the block protect register (BPROT) prevents inadvertent writes to (or erases of)
blocks of EEPROM. The CSEL bit in the OPTION register selects an on-chip oscillator
clock for programming and erasing while operating at frequencies below 1 MHz.
4.4.1.1 EEPROM Programming
An exact register access sequence must be followed to allow successful programming
and erasure of the EEPROM. The following procedures for modifying the EEPROM
and CONFIG register detail the sequence. If an attempt is made to set both EELAT
and EEPGM bits in the same write cycle and this attempt occurs before the required
write cycle with the EELAT bit set, then neither bit is set. If a write to an EEPROM address is performed while the EEPGM bit is set, the write is ignored, and the programming operation in progress is not disturbed. If no EEPROM address is written between
the point at which EELAT is set and EEPGM is set, then no program or erase operation
occurs. These safeguards are included to prevent accidental EEPROM changes in
cases of program runaway. If the frequency of the E clock is 1 MHz or less, the CSEL
bit in the OPTION register must be set to select the internal RC clock.
When the EELAT bit in the PPROG register is cleared, the EEPROM can be read as
if it were a ROM. The block protect register has no effect during reads. During EEPROM programming, the ROW and BYTE bits of PPROG are not used.
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Recall that zeros must be erased by a separate erase operation before programming.
The following example of how to program an EEPROM byte assumes that the appropriate bits in BPROT have been cleared and the data to be programmed is present in
accumulator A.
Freescale Semiconductor, Inc...
PROG
LDAB
#$02
EELAT=1, EEPGM=0
STAB
$103B
Set EELAT bit
STAA
$FE00
Store data to EEPROM address
LDAB
#$03
EELAT=1, EEPGM=1
STAB
$103B
Turn on programming voltage
JSR
DLY10
Delay 10 ms
CLR
$103B
Turn off high voltage and set to READ mode
4.4.1.2 EEPROM Bulk Erase
To erase the EEPROM, ensure that the proper bits of the BPROT register are cleared,
then complete the following steps using the PPROG register:
1. Write to PPROG with the ERASE, EELAT, and appropriate BYTE and ROW
bits set.
2. Write to the appropriate EEPROM address with any data. Row erase only requires a write to any location in the row. Bulk erase is accomplished by writing
to any location in the array.
3. Write to PPROG with ERASE, EELAT, EEPGM, and the appropriate BYTE and
ROW bits set.
4. Delay for 10 ms or more, as appropriate.
5. Clear the EEPGM bit in PPROG to turn off the high voltage.
6. Return to step 1 for next byte or row or proceed to step 7.
7. Clear the PPROG register to reconfigure the EEPROM address and data buses
for normal operation.
The following is an example of how to bulk erase the 512-byte EEPROM. The CONFIG
register is not affected in this example. When bulk erasing the CONFIG register, CONFIG and the 512-byte array are all erased.
BULKE
LDAB
#$06
STAB
$103B
Set EELAT bit
ERASE=1, EELAT=1, EEPGM=0
STAB
$FE00
Store any data to any EEPROM address
LDAB
#$07
EELAT=1, EEPGM=1
STAB
$103B
Turn on programming voltage
JSR
DLY10
Delay 10 ms
CLR
$103B
Turn off high voltage and set to READ mode
4.4.1.3 EEPROM Row Erase
The following example shows how to perform a fast erase of large sections of EEPROM and assumes that index register X contains the address of a location in the desired row.
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ROWE
LDAB
#$0E
ROW=1, ERASE=1, EELAT=1, EEPGM=0
STAB
$103B
Set to ROW erase mode
STAB
0,X
Store any data to any address in ROW
LDAB
#$0F
ROW=1, ERASE=1, EELAT=1, EEPGM=1
STAB
$103B
Turn on high voltage
JSR
DLY10
Delay 10 ms
CLR
$103B
Turn off high voltage and set to READ mode
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4.4.1.4 EEPROM Byte Erase
The following is an example of how to erase a single byte of EEPROM and assumes
that index register X contains the address of the byte to be erased.
BYTEE
LDAB
#$16
BYTE=1, ROW=0, ERASE=1, EELAT=1, EEPGM=0
STAB
$103B
Set to BYTE erase mode
STAB
0,X
Store any data to address to be erased
LDAB
#$17
BYTE=1, ROW=0, ERASE=1, EELAT=1, EEPGM=1
STAB
$103B
Turn on high voltage
JSR
DLY10
Delay 10 ms
CLR
$103B
Turn off high voltage and set to READ mode
4.4.2 PPROG EEPROM Programming Control Register
Bits in PPROG register control parameters associated with EEPROM programming.
PPROG — EEPROM Programming Control
RESET:
Bit 7
ODD
0
6
EVEN
0
5
—
0
4
BYTE
0
$103B
3
ROW
0
2
ERASE
0
1
EELAT
0
Bit 0
EEPGM
0
ODD — Program Odd Rows in Half of EEPROM (TEST)
EVEN — Program Even Rows in Half of EEPROM (TEST)
Bit 5 — Not implemented
Always reads zero
BYTE — Byte/Other EEPROM Erase Mode
0 = Row or bulk erase mode used
1 = Erase only one byte of EEPROM
ROW — Row/All EEPROM Erase Mode (only valid when BYTE = 0)
0 = All 512 bytes of EEPROM erased
1 = Erase only one 16-byte row of EEPROM
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Table 4-7 EEPROM Erase Mode Control
BYTE
0
0
1
1
ROW
0
1
0
1
Action
Bulk Erase (All 512 Bytes)
Row Erase (16 Bytes)
Byte Erase
Byte Erase
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ERASE — Erase/Normal Control for EEPROM
Can be read or written any time.
0 = Normal read or program mode
1 = Erase mode
EELAT — EEPROM Latch Control
Can be read or written any time. When EELAT equals one, writes to EEPROM cause
address and data to be latched.
0 = EEPROM address and data bus configured for normal reads
1 = EEPROM address and data bus configured for programming or erasing
EEPGM — EEPROM Program Command
Can be read any time. Can only be written while EELAT = 1.
0 = Program or erase voltage switched off to EEPROM array
1 = Program or erase voltage switched on to EEPROM array
4.4.3 CONFIG Register Programming
Because the CONFIG register is implemented with EEPROM cells, use EEPROM procedures to erase and program this register. The procedure for programming is the
same as for programming a byte in the EEPROM array, except that the CONFIG register address is used. CONFIG can be programmed or erased (including byte erase)
while the MCU is operating in any mode, provided that PTCON in BPROT is clear. To
change the value in the CONFIG register, complete the following procedure. Do not
initiate a reset until the procedure is complete. The new value will not take effect until
after the next reset sequence.
1. Erase the CONFIG register.
2. Program the new value to the CONFIG address.
3. Initiate reset.
CONFIG — System Configuration Register
RESET:
Bit 7
EE3
1
1
P
P
6
EE2
1
1
P
P
5
EE1
1
1
P
P
4
EE0
1
1
P
P
$103F
3
—
1
1
1
1
2
NOCOP
P
P(L)
P
P(L)
1
—
1
1
1
1
Bit 0
EEON
1
1
P
0
Single Chip
Bootstrap
Expanded
Special Test
P indicates a previously programmed bit. P(L) indicates that the bit resets to the logic
level held in the EEPROM bit prior to reset, but the function of COP is controlled by
DISR bit in TEST1 register.
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For a description of the bits contained in the CONFIG register refer to 4.3.2.1 CONFIG
Register.
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4.5 Chip Selects
The function of the chip selects is to minimize the amount of external glue logic needed
to interface the MCU to external devices. The MC68HC11F1 has four software configured chip selects that can be enabled in expanded modes. The chip selects for I/O
(CSIO1 and CSIO2) are used for I/O expansion. The program chip select (CSPROG)
is used with an external memory that contains the program code and reset vectors.
The general-purpose chip select (CSGEN) is the most flexible and is used to enable
external devices.
Such factors as polarity, block size, base address and clock stretching can be controlled using the four chip-select control registers. When a port G pin is not used for
chip select functions it can be used for general-purpose I/O.
When enabled, a chip select signal is asserted whenever the CPU makes an access
to a designated range of addresses. Bus control signals and chip select signals are
synchronous with the external E clock signal. For more information refer to Table A–
7. Expansion Bus Timing in APPENDIX A ELECTRICAL CHARACTERISTICS. The
length of the external E clock cycle to which the external device is synchronized can
be stretched to accommodate devices that are slower than the MCU.
4.5.1 Program Chip Select
The program chip select (CSPROG) is active in the range of memory where the main
program exists. Refer to Figure 4-3.
When enabled, the CSPROG is active during address valid time and is an active-low
signal. Although the general-purpose chip select has priority over the program chip select, CSPROG can be raised to a higher priority level by setting the GCSPR bit in
CSCTL register. Bits in CSCTL enable the program chip select and determine its address range and priority level. Bits in CSSTRH select from zero to three clock cycles
of delay.
4.5.2 I/O Chip Selects
The I/O chip selects (CSIO1 and CSIO2) are fixed in size and fill the remainder of the
4-Kbyte block occupied by the register block. CSIO1 is mapped at $x060–$x7FF and
CSIO2 is mapped at $x800–$xFFF, where “x” corresponds to the high-order nibble of
the register block base address, represented by the value contained in REG[3:0] in the
INIT register.
Bits in the CSCTL register determine the polarity of the active state and enable both I/
O chip selects. Bits in CSGSIZ select whether each chip select is active for addressvalid or E-valid time. Bits in CSSTRH select from zero to three clock cycles of delay.
Refer to Figure 4-3.
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$0000
0000
$1000
x000
96-BYTE REGISTER
BLOCK
x05F
$8000
x060
x7FF
x800
xFFF
I/O CHIP SELECT 1
(CSIO1)
PROGRAM CHIP SELECT
(CSPROG)
REMAPPABLE TO
4-KBYTE BOUNDARY
I/O CHIP SELECT 2
(CSIO2)
8000
$C000
Freescale Semiconductor, Inc...
PSIZ[A:B] = 0:0
64K
PSIZ[A:B] = 0:1
32K
C000
$E000
$FE00
$FFFF
PSIZ[A:B] = 1:0
16K
E000
PSIZ[A:B] = 1:1
8K
FFC0
FFFF
FFFF
VECTORS
EXPANDED
MODE
Figure 4-3 Address Map for I/O and Program Chip Selects
4.5.3 General-Purpose Chip Select
The general-purpose chip select (CSGEN) is the most flexible and has the most control bits. Polarity of the active state, E-valid or address-valid timing, size, starting address, and clock delay are all programmable.
A single bit in CSCTL selects a priority between CSGEN and CSPROG. Bits in CSGSIZ select between address valid or E-clock valid timing, determine the polarity of the
active state and the address range of CSGEN. The value contained in the CSGADR
register determines the starting address for CSGEN. Depending on the size selected
for CSGEN, some bits in CSGADR will be invalid (don’t cares). Note that CSGEN is
disabled when a size of zero is selected. Refer to Figure 4-4.
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$0000
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EXP
MODE
ADDR
SPACE
$FFFF
VALID BASE ADDR BITS:
N/A
GSIZA : GSIZB : GSIZC: 0 : 0 : 0
64K
SIZE:
GA15
GA[15:14]
GA[15:13]
GA[15:12]
GA[15:11]
GA[15:10]
GA[15:10]
0:0:1
32K
0:1:0
16K
0:1:1
8K
1:0:0
4K
1:0:1
2K
1:1:0
1K
1:1:1
DISABLED
NOTE: These examples assume a starting address of $0000.
Figure 4-4 Address Map for General-Purpose Chip Select
CSSTRH — Chip Select Clock Stretch Select
RESET:
Bit 7
IO1SA
0
6
IO1SB
0
5
IO2SA
0
4
IO2SB
0
$105C
3
GSTHA
0
2
GSTHB
0
1
PSTHA
0
Bit 0
PSTHB
0
Table 4-8 Chip Select Clock Stretch Control
Bit A
0
0
1
1
Bit B
0
1
0
1
Clock Stretch Selected
None
1 cycle
2 cycles
3 cycles
IO1SA–IO1SB — I/O Chip Select 1 Clock Stretch Select
Refer to Table 4-8.
IO2SA–IO2SB — I/O Chip Select 2 Clock Stretch Select
Refer to Table 4-8.
GSTHA–GSTHB — General-Purpose Chip Select Clock Stretch Select
Refer to Table 4-8.
PSTHA–PSTHB — Program Chip Select Clock Stretch Select
Refer to Table 4-8.
OPERATING MODES AND ON-CHIP MEMORY
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CSCTL — Chip Select Control
RESET:
Bit 7
IO1EN
0
6
IO1PL
0
$105D
5
IO2EN
0
4
IO2PL
0
3
GCSPR
0
2
PCSEN*
—
1
PSIZA
0
Bit 0
PSIZB
0
*PCSEN is set out of reset in expanded modes and cleared in single-chip modes.
IO1EN — I/O Chip Select 1 Enable
0 = CSIO1 is disabled and port G bit 5 is general-purpose I/O.
1 = CSIO1 is enabled and uses port G bit 5.
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IO1PL — I/O Chip Select 1 Polarity Select
0 = CSIO1 active low
1 = CSIO1 active high
IO2EN — I/O Chip Select 2 Enable
0 = CSIO2 is disabled and port G bit 4 is general-purpose I/O.
1 = CSIO2 is enabled and uses port G bit 4.
IO2PL — I/O Chip Select 2 Polarity Select
0 = CSIO2 active low
1 = CSIO2 active high
GCSPR — General-Purpose Chip Select Priority
0 = Program chip select has priority over general-purpose chip select
1 = General-purpose chip select has priority over program chip select
PCSEN — Program Chip Select Enable
This bit is set out of reset in expanded modes and cleared in single-chip modes.
0 = CSPROG disabled and port G bit 7 available as general-purpose I/O
1 = CSPROG enabled out of reset and uses port G bit 7 pin
PSIZA, PSIZB — Program Chip Select Size (A or B)
Table 4-9 Program Chip Select Size Control
PSIZA
0
0
1
1
PSIZB
0
1
0
1
Size (Bytes)
64 K
32 K
16 K
8K
Address Range
$0000–$FFFF
$8000–$FFFF
$C000–$FFFF
$E000–$FFFF
CSGADR — General-Purpose Chip Select Address Register
RESET:
Bit 7
GA15
0
6
GA14
0
5
GA13
0
4
GA12
0
3
GA11
0
2
GA10
0
$105E
1
—
0
Bit 0
—
0
GA[15:10] — General-Purpose Chip Select Base Address
GA[15:10] correspond to MCU address bits ADDR[15:10] and select the starting address of the general-purpose chip select's address range. Which bits are valid depends upon the size selected by GSIZA–GSIZC in CSGSIZ register. Refer to the
following table and to Figure 4-4.
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Table 4-10 General-Purpose Chip Select Starting Address
Size (Bytes)
Valid Starting Address
Bits
None
GA[15:10]
GA[15:11]
GA[15:12]
GA[15:13]
GA[15:14]
GA15
None
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0 K (Disabled)
1K
2K
4K
8K
16 K
32 K
64 K
CSGSIZ — General-Purpose Chip Select Size Control
RESET:
Bit 7
IO1AV
0
6
IO2AV
0
5
—
0
4
GNPOL
0
3
GAVLD
0
$105F
2
GSIZA
1
1
GSIZB
1
Bit 0
GSIZC
1
IO1AV — I/O Chip Select 1 Address Valid
0 = I/O chip select 1 is active during E-clock valid time (E-clock high)
1 = I/O chip select 1 is active during address valid time
IO2AV — I/O Chip Select 2 Address Valid
0 = I/O chip select 1 is active during E-clock valid time (E-clock high)
1 = I/O chip select 1 is active during address valid time
GNPOL — General-Purpose Chip Select Polarity Select
0 = CSGEN is active low
1 = CSGEN is active high
GAVLD — General-Purpose Chip Select Address Valid Select
0 = CSGEN is valid during E-clock valid time (E-clock high)
1 = CSGEN is valid during address valid time
G1SZA–G1SZC — General-Purpose Chip Select Size
Refer to Table 4-11.
Table 4-11 General-Purpose Chip Select Size Control
GSIZA
0
0
0
0
1
1
1
1
GSIZB
0
0
1
1
0
0
1
1
GSIZC
0
1
0
1
0
1
0
1
Size (Bytes)
64 K
32 K
16 K
8K
4K
2K
1K
0 K (Disabled)
OPERATING MODES AND ON-CHIP MEMORY
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Table 4-12 Chip Select Control Parameter Summary
CSIO1
Enable
Valid
Polarity
Size
Start Address
Stretch
IO1EN in CSCTL —
1 = On, off at reset (0)
IO1AV in CSGSIZ —
1 = Address valid, 0 = E valid
IO1PL in CSCTL —
1 = Active high, 0 = Active low
Fixed —
($x060–$x7FF)
$x060 —
“x” is determined by REG[3:0] in INIT
IO1SA–IO1SB in CSSTRH — 0, 1, 2, or 3 E clocks
CSIO2
Enable
Valid
Polarity
Size
Start Address
Stretch
IO2EN in CSCTL —
1 = On, off at reset (0)
IO2AV in CSGSIZ —
1 = Address valid, 0 = E valid
IO2PL in CSCTL —
1 = Active high, 0 = Active low
Fixed —
($x800–$xFFF)
$x800 —
“x” is determined by REG[3:0] in INIT
IO2SA–IO2SB in CSSTRH — 0, 1, 2, or 3 E clocks
Enable
PCSEN in CSCTL —
Valid
Polarity
Size
Fixed (Address valid)
Fixed (Active low)
PSIZA–PSIZB —
in CSCTL
Start Address
Stretch
Fixed (determined by size)
PSTHA–PSTHB in CSSTRH — 0, 1, 2, or 3 E clocks
1 cycle after reset in expanded mode
no delay after reset in all other modes
GCSPR in CSCTL —
1 = CSGEN above CSPROG
0 = CSPROG above CSGEN
CSPROG
Priority
CSGEN
Enable
1 = On, on after reset in expanded modes
off after reset in single-chip modes
0:0 = 64K ($0000–$FFFF)
0:1 = 32K ($8000–$FFFF)
1:0 = 16K ($C000–$FFFF)
1:1 = 8K ($E000–$FFFF)
Set size to 0K to disable —
Valid
Polarity
Size
Start Address
Stretch
1 = CSGEN above CSPROG
0 = CSPROG above CSGEN
GAVLD in CSGSIZ —
Address valid or E valid
GNPOL in CSGSIZ —
Active high or low
GSIZA–GSIZC in CSGSIZ — Refer to Table 4–12
GA[15:10] in CSGADR
GSTHA–GSTHB in CSSTRH — 0, 1, 2, or 3 E clocks
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SECTION 5 RESETS AND INTERRUPTS
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Resets and interrupt operations load the program counter with a vector that points to
a new location from which instructions are to be fetched. A reset causes the internal
control registers to be initialized to a known state. The program counter is loaded with
a known starting address and execution of instructions begins. An interrupt temporarily
suspends normal program execution while an interrupt service routine is being executed. After an interrupt has been serviced, the main program resumes as if there had
been no interruption.
5.1 Resets
There are four possible sources of reset. Power-on reset (POR) and external reset
share the normal reset vector. The computer operating properly (COP) reset and the
clock monitor reset each has its own vector.
5.1.1 Power-On Reset
A positive transition on VDD generates a power-on reset (POR), which is used only for
power-up conditions. POR cannot be used to detect drops in power supply voltages.
A 4064 tcyc (internal clock cycle) delay after the oscillator becomes active allows the
clock generator to stabilize. If RESET is at logical zero at the end of 4064 tcyc, the CPU
remains in the reset condition until RESET goes to logical one.
It is important to protect the MCU during power transitions. To protect data in EEPROM, M68HC11 systems need an external circuit that holds the RESET pin low
whenever VDD is below the minimum operating level. This external voltage level detector, or other external reset circuits, are the usual source of reset in a system. The
POR circuit only initializes internal circuitry during cold starts. Refer to Figure 2–3.
5.1.2 External Reset (RESET)
The CPU distinguishes between internal and external reset conditions by sensing
whether the reset pin rises to a logic one in less than two E-clock cycles after an internal device releases reset. When a reset condition is sensed, the RESET pin is driven
low by an internal device for four E-clock cycles, then released. Two E-clock cycles
later it is sampled. If the pin is still held low, the CPU assumes that an external reset
has occurred. If the pin is high, it indicates that the reset was initiated internally by either the COP system or the clock monitor. It is not advisable to connect an external
resistor capacitor (RC) power-up delay circuit to the reset pin of M68HC11 devices because the circuit charge time constant can cause the device to misinterpret the type of
reset that occurred.
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5.1.3 Computer Operating Properly (COP) Reset
The MCU includes a COP system to help protect against software failures. When the
COP is enabled, the software is responsible for keeping a free-running watchdog timer
from timing out. When the software is no longer being executed in the intended sequence, a system reset is initiated.
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The state of the NOCOP bit in the CONFIG register determines whether the COP system is enabled or disabled. To change the enable status of the COP system, change
the contents of the CONFIG register and then perform a system reset. In the special
test and bootstrap operating modes, the COP system is initially inhibited by the disable
resets (DISR) control bit in the TEST1 register. The DISR bit can subsequently be written to zero to enable COP resets.
The COP timer rate control bits CR[1:0] in the OPTION register determine the COP
time-out period. The system E clock is divided by the values shown in Table 5-1. After
reset, these bits are zero, which selects the fastest time-out period. In normal operating modes, these bits can only be written once within 64 bus cycles after reset.
Table 5-1 COP Timer Rate Selection
CR[1:0]
Divide
E By
215
XTAL = 8.0 MHz Timeout
–0 ms, +16.4 ms
16.384 ms
XTAL = 12.0 MHz
Time-out
–0 ms, +10.9 ms
10.923 ms
XTAL = 16.0 MHz
Time-out
–0 ms, +8.2 ms
8.192 ms
00
01
217
65.536 ms
43.691 ms
32.768 ms
10
219
262.14 ms
174.76 ms
131.07 ms
11
221
E=
1.049 s
699.05 ms
524.29 ms
2.0 MHz
3.0 MHz
4.0 MHz
COPRST — Arm/Reset COP Timer Circuitry
RESET:
Bit 7
7
0
6
6
0
5
5
0
4
4
0
$103A
3
3
0
2
2
0
1
1
0
Bit 0
0
0
Complete the following reset sequence to service the COP timer. Write $55 to COPRST to arm the COP timer clearing mechanism. Then write $AA to COPRST to clear
the COP timer. Performing instructions between these two steps is possible as long
as both steps are completed in the correct sequence before the timer times out.
5.1.4 Clock Monitor Reset
The clock monitor circuit is based on an internal RC time delay. If no MCU clock edges
are detected within this RC time delay, the clock monitor can optionally generate a system reset. The clock monitor function is enabled or disabled by the CME and FCME
control bits in the OPTION register. The presence of a time-out is determined by the
RC delay, which allows the clock monitor to operate without any MCU clocks.
Clock monitor is used as a backup for the COP system. Because the COP needs a
clock to function, it is disabled when the clocks stop. Therefore, the clock monitor system can detect clock failures not detected by the COP system.
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Semiconductor wafer processing causes variations of the RC time-out values between
individual devices. An E-clock frequency below 10 kHz is detected as a clock monitor
error. An E-clock frequency of 200 kHz or more prevents clock monitor errors. Using
the clock monitor function when the E-clock is below 200 kHz is not recommended.
Special considerations are needed when a STOP instruction is executed and the clock
monitor is enabled. Because the STOP function causes the clocks to be halted, the
clock monitor function generates a reset sequence if it is enabled at the time the STOP
mode was initiated. Before executing a STOP instruction, clear to zero the CME bit in
the OPTION register to disable the clock monitor. After recovery from STOP, set the
CME bit to logic one to enable the clock monitor.
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5.1.5 OPTION Register
OPTION — System Configuration Options
RESET:
Bit 7
ADPU
0
6
CSEL
0
5
IRQE*
0
4
DLY*
1
$1039
3
CME
0
2
FCME*
0
1
CR1*
0
Bit 0
CR0*
0
*Can be written only once in first 64 cycles out of reset in normal modes, or at any time in special modes.
ADPU — Analog-to-Digital Converter Power-Up
Refer to SECTION 10 ANALOG-TO-DIGITAL CONVERTER.
CSEL — Clock Select
Refer to SECTION 10 ANALOG-TO-DIGITAL CONVERTER.
IRQE — Configure IRQ for Edge-Sensitive Only Operation
0 = Low level sensitive operation.
1 = Falling edge sensitive only operation.
DLY — Enable Oscillator Start-up Delay
0 = The oscillator start-up delay coming out of STOP is bypassed and the MCU resumes processing within about four bus cycles.
1 = A delay of approximately 4000 E-clock cycles is imposed as the MCU is started
up from the STOP power-saving mode.
CME — Clock Monitor Enable
This control bit can be read or written at any time and controls whether or not the internal clock monitor circuit triggers a reset sequence when the system clock is slow or
absent. When it is clear, the clock monitor circuit is disabled, and when it is set, the
clock monitor circuit is enabled. Reset clears the CME bit.
FCME — Force Clock Monitor Enable
To use STOP mode, the FCME bit must equal zero.
0 = Clock monitor follows the state of the CME bit.
1 = Clock monitor circuit is enabled until next reset
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CR[1:0] — COP Timer Rate Select
The internal E clock is first divided by 215 before it enters the COP watchdog system.
These control bits determine a scaling factor for the watchdog timer. Refer to Table 51.
5.1.6 CONFIG Register
CONFIG — System Configuration Register
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RESET:
Bit 7
EE3
1
1
P
P
6
EE2
1
1
P
P
5
EE1
1
1
P
P
4
EE0
1
1
P
P
$103F
3
—
1
1
1
1
2
NOCOP
P
P(L)
P
P(L)
1
—
1
1
1
1
Bit 0
EEON
1
1
P
0
Single Chip
Bootstrap
Expanded
Special Test
P indicates a previously programmed bit. P(L) indicates that the bit resets to the logic
level held in the latch prior to reset, but the function of COP is controlled by DISR in
TEST1 register.
EE[3:0] — EEPROM Mapping Control
Refer to SECTION 4 OPERATING MODES AND ON-CHIP MEMORY.
Bit 3 — Not implemented
Always reads one
NOCOP — COP System Disable
0 = COP system enabled (forces reset on time-out)
1 = COP system disabled
Bit 1 — Not implemented
Always reads one
EEON — EEPROM Enable
Refer to SECTION 4 OPERATING MODES AND ON-CHIP MEMORY.
5.2 Effects of Reset
When a reset condition is recognized, the internal registers and control bits are forced
to an initial state. Depending on the cause of the reset and the operating mode, the
reset vector can be fetched from any of six possible locations. Refer to Table 5-2.
Table 5-2 Reset Cause, Operating Mode, and Reset Vector
Cause of Reset
POR or RESET Pin
Clock Monitor Failure
COP Watchdog Time-out
Normal Mode Vector
$FFFE, FFFF
$FFFC, FFFD
$FFFA, FFFB
Special Test or Bootstrap
$BFFE, $BFFF
$BFFC, $BFFD
$BFFA, $BFFB
These initial states then control on-chip peripheral systems to force them to known
start-up states, as follows:
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5.2.1 Central Processing Unit
After reset, the CPU fetches the reset vector from the appropriate address during the
first three cycles, and begins executing instructions. The stack pointer and other CPU
registers are indeterminate immediately after reset; however, the X and I interrupt
mask bits in the condition code register (CCR) are set to mask any interrupt requests.
Also, the S bit in the CCR is set to inhibit the STOP mode.
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5.2.2 Memory Map
After reset, the INIT register is initialized to $01, putting the 1024 bytes of RAM at locations $0000 through $03FF, and the control registers at locations $1000 through
$105F. The EE[3:0] bits in the CONFIG register control the location of the 512-byte
EEPROM array.
5.2.3 Parallel I/O
When a reset occurs in expanded operating modes, port B, C, and F pins used for parallel I/O are dedicated to the expansion bus. If a reset occurs during a single-chip operating mode, all ports are configured as general-purpose high-impedance inputs.
NOTE
Do not confuse pin function with the electrical state of the pin at reset.
All general-purpose I/O pins configured as inputs at reset are in a
high-impedance state. Port data registers reflect the port's functional
state at reset. The pin function is mode dependent.
5.2.4 Timer
During reset, the timer system is initialized to a count of $0000. The prescaler bits are
cleared, and all output compare registers are initialized to $FFFF. All input capture registers are indeterminate after reset. The output compare 1 mask (OC1M) register is
cleared so that successful OC1 compares do not affect any I/O pins. The other four
output compares are configured so that they do not affect any I/O pins on successful
compares. All input capture edge-detector circuits are configured for capture disabled
operation. The timer overflow interrupt flag and all eight timer function interrupt flags
are cleared. All nine timer interrupts are disabled because their mask bits have been
cleared.
The I4/O5 bit in the PACTL register is cleared to configure the I4/O5 function as OC5;
however, the OM5–OL5 control bits in the TCTL1 register are clear so OC5 does not
control the PA3 pin.
5.2.5 Real-Time Interrupt (RTI)
The real-time interrupt flag (RTIF) is cleared and automatic hardware interrupts are
masked. The rate control bits are cleared after reset and can be initialized by software
before the real-time interrupt (RTI) system is used.
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5.2.6 Pulse Accumulator
The pulse accumulator system is disabled at reset so that the pulse accumulator input
(PAI) pin defaults to being a general-purpose input pin.
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5.2.7 Computer Operating Properly (COP)
The COP watchdog system is enabled if the NOCOP control bit in the CONFIG register is cleared, and disabled if NOCOP is set. The COP rate is set for the shortest duration time-out.
5.2.8 Serial Communications Interface (SCI)
The reset condition of the SCI system is independent of the operating mode. All transmit and receive interrupts are masked and both the transmitter and receiver are disabled so the port pins default to being general-purpose I/O lines. The SCI frame format
is initialized to an 8-bit character size. The send break and receiver wakeup functions
are disabled. The TDRE and TC status bits in the SCI status register are both set, indicating that there is no transmit data in either the transmit data register or the transmit
serial shift register. The RDRF, IDLE, OR, NF, FE, PF, and RAF receive-related status
bits are cleared.
5.2.9 Serial Peripheral Interface (SPI)
The SPI system is disabled by reset. The port pins associated with this function default
to being general-purpose I/O lines.
5.2.10 Analog-to-Digital Converter
The A/D converter configuration is indeterminate after reset. The ADPU bit is cleared
by reset, which disables the A/D system. The conversion complete flag is cleared by
reset.
5.2.11 System
The EEPROM programming controls are disabled, so the memory system is configured for normal read operation. PSEL[3:0] are initialized with the binary value %0101,
causing the external IRQ pin to have the highest I-bit interrupt priority. The IRQ pin is
configured for level-sensitive operation (for wired-OR systems). The RBOOT, SMOD,
and MDA bits in the HPRIO register reflect the status of the MODB and MODA inputs
at the rising edge of reset. The DLY control bit is set to specify that an oscillator startup delay is imposed upon recovery from STOP mode. The clock monitor system is disabled because CME and FCME are cleared.
5.3 Reset and Interrupt Priority
Resets and interrupts have a hardware priority that determines which reset or interrupt
is serviced first when simultaneous requests occur. Any maskable interrupt can be given priority over other maskable interrupts.
The first six interrupt sources are not maskable. The priority arrangement for these
sources is as follows:
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1. POR or RESET pin
2. Clock monitor reset
3. COP watchdog reset
4. XIRQ interrupt
5. Illegal opcode interrupt
6. Software interrupt (SWI)
The maskable interrupt sources have the following priority arrangement:
1. IRQ
2. Real-time interrupt
3. Timer input capture 1
4. Timer input capture 2
5. Timer input capture 3
6. Timer output compare 1
7. Timer output compare 2
8. Timer output compare 3
9. Timer output compare 4
10. Timer input capture 4/output compare 5
11. Timer overflow
12. Pulse accumulator overflow
13. Pulse accumulator input edge
14. SPI transfer complete
15. SCI system (refer to Figure 5-5)
Any one of these interrupts can be assigned the highest maskable interrupt priority by
writing the appropriate value to the PSEL bits in the HPRIO register. Otherwise, the
priority arrangement remains the same. An interrupt that is assigned highest priority is
still subject to global masking by the I bit in the CCR, or by any associated local bits.
Interrupt vectors are not affected by priority assignment. To avoid race conditions, HPRIO can only be written while I-bit interrupts are inhibited.
5.3.1 Highest Priority Interrupt and Miscellaneous Register
HPRIO — Highest Priority I-Bit Interrupt and Miscellaneous
RESET:
Bit 7
RBOOT*
0
0
1
0
6
SMOD*
0
0
1
1
5
MDA*
0
1
0
1
4
IRV
0
1
0
1
3
PSEL3
0
0
0
0
2
PSEL2
1
1
1
1
$103C
1
PSEL1
0
0
0
0
Bit 0
PSEL0
1
1
1
1
Single Chip
Expanded
Bootstrap
Special Test
*The values of the RBOOT, SMOD, MDA, and IRV reset bits depend on the operating mode selected during powerup. Refer to Table 4–3.
RBOOT — Read Bootstrap ROM
Set to one out of reset in bootstrap mode. Valid while in special modes only. Can be
read any time. Can only be written in special modes. Refer to SECTION 4 OPERATING MODES AND ON-CHIP MEMORY for more information.
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SMOD — Special Mode Select
Can be read any time. Can only be written in special modes (SMOD = 1). Can only be
written to zero. Refer to SECTION 4 OPERATING MODES AND ON-CHIP MEMORY
for more information.
MDA — Mode Select A
Can be read any time. Can only be written in special modes (SMOD = 1). Refer to
SECTION 4 OPERATING MODES AND ON-CHIP MEMORY for more information.
Freescale Semiconductor, Inc...
IRV — Internal Read Visibility
The IRV control bit allows internal read accesses to be available on the external data
bus during operation in expanded modes. In special modes (SMOD = 1), IRV resets
to one (enabled) and can be written any time. In normal modes (SMOD = 0), IRV resets to zero (disabled) and only one write is allowed.
PSEL[3:0] — Priority Select Bits
These bits select one interrupt source to be elevated above all other I-bit-related
sources and can only be written while the I bit in the CCR is set (interrupts disabled).
Table 5-3 Highest Priority Interrupt Selection
PSEL3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
PSEL2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
PSEL1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
PSEL0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Interrupt Source Promoted
Timer Overflow
Pulse Accumulator Overflow
Pulse Accumulator Input Edge
SPI Serial Transfer Complete
SCI Serial System
Reserved (Default to IRQ)
IRQ
Real-Time Interrupt
Timer Input Capture 1
Timer Input Capture 2
Timer Input Capture 3
Timer Output Compare 1
Timer Output Compare 2
Timer Output Compare 3
Timer Output Compare 4
Timer Output Compare 5/Input Capture 4
5.4 Interrupts
The MCU has 18 interrupt vectors that support 22 interrupt sources. The 15 maskable
interrupts are generated by on-chip peripheral systems. These interrupts are recognized when the global interrupt mask bit (I) in the condition code register (CCR) is
clear. The three non-maskable interrupt sources are illegal opcode trap, software interrupt, and XIRQ pin. Refer to Table 5-4, which shows the interrupt sources and vector assignments for each source.
RESETS AND INTERRUPTS
5-8
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Table 5-4 Interrupt and Reset Vector Assignments
Vector Address
Freescale Semiconductor, Inc...
FFC0, C1 – FFD4, D5
FFD6, D7
FFD8, D9
FFDA, DB
FFDC, DD
FFDE, DF
FFE0, E1
FFE2, E3
FFE4, E5
FFE6, E7
FFE8, E9
FFEA, EB
FFEC, ED
FFEE, EF
FFF0, F1
FFF2, F3
FFF4, F5
FFF6, F7
FFF8, F9
FFFA, FB
FFFC, FD
FFFE, FF
Interrupt Source
Reserved
SCI Serial System
• SCI Receive Data Register Full
• SCI Receiver Overrun
• SCI Transmit Data Register Empty
• SCI Transmit Complete
• SCI Idle Line Detect
SPI Serial Transfer Complete
Pulse Accumulator Input Edge
Pulse Accumulator Overflow
Timer Overflow
Timer Input Capture 4/Output Compare 5
Timer Output Compare 4
Timer Output Compare 3
Timer Output Compare 2
Timer Output Compare 1
Timer Input Capture 3
Timer Input Capture 2
Timer Input Capture 1
Real-Time Interrupt
IRQ
XIRQ Pin
Software Interrupt
Illegal Opcode Trap
COP Failure
Clock Monitor Fail
RESET
CCR
Mask Bit
—
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
X
None
None
None
None
None
Local Mask
—
RIE
RIE
TIE
TCIE
ILIE
SPIE
PAII
PAOVI
TOI
I4/O5I
OC4I
OC3I
OC2I
OC1I
IC3I
IC2I
IC1I
RTII
None
None
None
None
NOCOP
CME
None
For some interrupt sources, such as the SCI interrupts, the flags are automatically
cleared during the normal course of responding to the interrupt requests. For example,
the RDRF flag in the SCI system is cleared by the automatic clearing mechanism consisting of a read of the SCI status register while RDRF is set, followed by a read of the
SCI data register. The normal response to an RDRF interrupt request would be to read
the SCI status register to check for receive errors, then to read the received data from
the SCI data register. These two steps satisfy the automatic clearing mechanism without requiring any special instructions.
5.4.1 Interrupt Recognition and Register Stacking
An interrupt can be recognized at any time after it is enabled by its local mask, if any,
and by the global mask bit in the CCR. Once an interrupt source is recognized, the
CPU responds at the completion of the instruction being executed. Interrupt latency
varies according to the number of cycles required to complete the current instruction.
When the CPU begins to service an interrupt, the contents of the CPU registers are
pushed onto the stack in the order shown in Table 5-5. After the CCR value is stacked,
the I bit and the X bit (if XIRQ is pending) are set to inhibit further interrupts. The interrupt vector for the highest priority pending source is fetched, and execution continues
RESETS AND INTERRUPTS
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at the address specified by the vector. At the end of the interrupt service routine, the
return from interrupt instruction is executed and the saved registers are pulled from the
stack in reverse order so that normal program execution can resume. Refer to SECTION 3 CENTRAL PROCESSING UNIT for further information.
Freescale Semiconductor, Inc...
Table 5-5 Stacking Order on Entry to Interrupts
Memory Location
SP
SP – 1
SP – 2
SP – 3
SP – 4
SP – 5
SP – 6
SP – 7
SP – 8
CPU Registers
PCL
PCH
IYL
IYH
IXL
IXH
ACCA
ACCB
CCR
5.4.2 Non-Maskable Interrupt Request (XIRQ)
Non-maskable interrupts are useful because they can always interrupt CPU operations. The most common use for such an interrupt is for serious system problems, such
as program runaway or power failure. The XIRQ input is an updated version of the NMI
input of earlier MCUs.
Upon reset, both the X bit and I bit of the CCR are set to inhibit all maskable interrupts
and XIRQ. After minimum system initialization, software can clear the X bit by a TAP
instruction, enabling XIRQ interrupts. Thereafter, software cannot set the X bit. Thus,
an XIRQ interrupt is a nonmaskable interrupt. Because the operation of the I-bit-related interrupt structure has no effect on the X bit, the internal XIRQ pin remains nonmasked. In the interrupt priority logic, the XIRQ interrupt has a higher priority than any
source that is maskable by the I bit. All I-bit-related interrupts operate normally with
their own priority relationship.
When an I-bit-related interrupt occurs, the I bit is automatically set by hardware after
stacking the CCR byte. The X bit is not affected. When an X-bit-related interrupt occurs, both the X and I bits are automatically set by hardware after stacking the CCR.
A return from interrupt instruction restores the X and I bits to their pre-interrupt request
state.
5.4.3 Illegal Opcode Trap
Because not all possible opcodes or opcode sequences are defined, the MCU includes an illegal opcode detection circuit, which generates an interrupt request. When
an illegal opcode is detected and the interrupt is recognized, the current value of the
program counter is stacked. After interrupt service is complete, reinitialize the stack
pointer so repeated execution of illegal opcodes does not cause stack underflow. Left
uninitialized, the illegal opcode vector can point to a memory location that contains an
illegal opcode. This condition causes an infinite loop that causes stack underflow. The
stack grows until the system crashes.
RESETS AND INTERRUPTS
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The illegal opcode trap mechanism works for all unimplemented opcodes on all four
opcode map pages. The address stacked as the return address for the illegal opcode
interrupt is the address of the first byte of the illegal opcode. Otherwise, it would be
almost impossible to determine whether the illegal opcode had been one or two bytes.
The stacked return address can be used as a pointer to the illegal opcode so the illegal
opcode service routine can evaluate the offending opcode.
Freescale Semiconductor, Inc...
5.4.4 Software Interrupt
SWI is an instruction, and thus cannot be interrupted until complete. SWI is not inhibited by the global mask bits in the CCR. Because execution of SWI sets the I mask bit,
once an SWI interrupt begins, other interrupts are inhibited until SWI is complete, or
until user software clears the I bit in the CCR.
5.4.5 Maskable Interrupts
The maskable interrupt structure of the MCU can be extended to include additional external interrupt sources through the IRQ pin. The default configuration of this pin is a
low-level sensitive wired-OR network. When an event triggers an interrupt, a software
accessible interrupt flag is set. When enabled, this flag causes a constant request for
interrupt service. After the flag is cleared, the service request is released.
5.4.6 Reset and Interrupt Processing
Figure 5-1 and Figure 5-3 illustrate the reset and interrupt process. Figure 5-1 illustrates how the CPU begins from a reset and how interrupt detection relates to normal
opcode fetches. Figure 5-3 is an expansion of a block in Figure 5-1 and illustrates interrupt priorities. Figure 5-5 shows the resolution of interrupt sources within the SCI
subsystem.
RESETS AND INTERRUPTS
TECHNICAL DATA
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HIGHEST
POWER-ON RESET
(POR)
PRIORITY
EXTERNAL RESET
DELAY 4064 E CYCLES
CLOCK MONITOR FAIL
(WITH CME = 1)
COP WATCHDOG TIMEOUT
(WITH NOCOP = 0)
LOAD PROGRAM COUNTER
WITH CONTENTS OF
$FFFE, FFFF (VECTOR FETCH)
Freescale Semiconductor, Inc...
LOWEST
LOAD PROGRAM COUNTER
WITH CONTENTS OF
$FFFC, FFFD (VECTOR FETCH)
LOAD PROGRAM COUNTER
WITH CONTENTS OF
$FFFA, FFFB (VECTOR FETCH)
SET S, X, AND I BITS
IN CCR
RESET MCU
HARDWARE
1A
BEGIN AN INSTRUCTION
SEQUENCE
YES
X BIT IN
CCR SET
?
NO
XIRQ
PIN LOW
?
YES
NO
STACK CPU
REGISTERS
SET X AND I BITS
FETCH VECTOR
$FFE4, FFE5
1B
Figure 5-1 Processing Flow Out of Reset (1 of 2)
RESETS AND INTERRUPTS
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1B
YES
I BIT IN
CCR SET
?
NO
Freescale Semiconductor, Inc...
ANY I BIT
INTERRUPT
PENDING
?
NO
YES
FETCH OPCODE
STACK CPU
REGISTERS
YES
STACK CPU
REGISTERS
SET X AND I BITS
ILLEGAL
OPCODE
?
NO
FETCH VECTOR
$FFE8, FFE9
YES
WAI
?
STACK CPU
REGISTERS
NO
YES
STACK CPU
REGISTERS
SET X AND I BITS
NO
SWI
?
YES
NO
FETCH VECTOR
$FFE6, FFE7
YES
SET I BIT
RTI
?
RESTORE CPU
REGISTERS
FROM STACK
NO
EXECUTE THIS
INSTRUCTION
1A
INTERRUPT
YET
?
RESOLVE INTERRUPT
PRIORITY AND FETCH
VECTOR FOR HIGHEST
PENDING SOURCE
(REFER TO FIGURE 5-2)
START NEXT
INSTRUCTION
SEQUENCE
Figure 5-2 Processing Flow Out of Reset (2 of 2)
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BEGIN
X BIT
IN CCR SET
?
YES
NO
YES
IRQ
?
SET X BIT IN CCR
FETCH VECTOR
$FFF4, FFF5
NO
HIGHEST
PRIORITY
INTERRUPT
?
NO
Freescale Semiconductor, Inc...
XIRQ PIN
LOW
?
YES
FETCH VECTOR
YES
FETCH VECTOR
$FFF2, FFF3
NO
RTII = 1
?
YES
NO
REAL-TIME
INTERRUPT
?
YES
FETCH VECTOR
$FFF0, FFF1
YES
FETCH VECTOR
$FFEE, FFEF
YES
FETCH VECTOR
$FFEC, FFED
YES
FETCH VECTOR
$FFEA, FFEB
YES
FETCH VECTOR
$FFE8, FFE9
NO
IC1I = 1
?
YES
NO
TIMER
IC1F
?
NO
IC2I = 1
?
YES
NO
TIMER
IC2F
?
NO
IC3I = 1
?
YES
NO
TIMER
IC3F
?
NO
OC1I = 1
?
NO
YES
TIMER
OC1F
?
NO
2B
2A
Figure 5-3 Interrupt Priority Resolution (1 of 2)
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Freescale Semiconductor, Inc.
2A
2B
YES
OC2I = 1
?
NO
YES
NO
Freescale Semiconductor, Inc...
YES
FETCH VECTOR
$FFE6, FFE7
YES
FETCH VECTOR
$FFE4, FFE5
YES
FETCH VECTOR
$FFE2, FFE3
YES
FETCH VECTOR
$FFE0, FFE1
YES
FETCH VECTOR
$FFDE, FFDF
YES
FETCH VECTOR
$FFDC, FFDD
YES
FETCH VECTOR
$FFDA, FFDB
YES
FETCH VECTOR
$FFD8, FFD9
NO
OC3I = 1
?
TIMER
OC3F
?
NO
YES
OC4I = 1
?
NO
TIMER
OC4F
?
NO
YES
OC5/IC4I = 1
?
NO
TIMER
OC5/IC4F
?
NO
YES
TOI = 1
?
NO
TIMER
TOF
?
NO
YES
PAOVI = 1
?
NO
YES
PAII = 1
?
NO
YES
SPIE = 1
?
NO
PULSE
ACCUMULATOR
PAOVF
?
NO
PULSE
ACCUMULATOR
PAIF
?
NO
SPIF
OR MODF
?
NO
SCI
(REFER TO FIG 5-3)
?
NO
TIMER
OC2F
?
YES
FETCH VECTOR
$FFD6, FFD7
SPURIOUS INTERRUPT – TAKE IRQ VECTOR
FETCH VECTOR
$FFF2, FFF3
END
Figure 5-4 Interrupt Priority Resolution (2 of 2)
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BEGIN
RDRF = 1
?
YES
NO
OR = 1
?
YES
Freescale Semiconductor, Inc...
NO
RIE = 1
?
YES
NO
TDRE = 1
?
YES
NO
TIE = 1
?
YES
NO
TCIE = 1
?
YES
NO
YES
NO
TC = 1
?
RE = 1
?
TE = 1
?
YES
NO
YES
NO
IDLE = 1
?
NO
YES
ILIE = 1
?
YES
NO
RE = 1
?
YES
NO
NO – VALID SCI
REQUEST
YES – VALID SCI
REQUEST
Figure 5-5 Interrupt Source Resolution Within SCI
5.5 Low Power Operation
Both STOP and WAIT suspend CPU operation until a reset or interrupt occurs. The
WAIT condition suspends processing and reduces power consumption to an intermediate level. The STOP condition turns off all on-chip clocks and reduces power consumption to an absolute minimum while retaining the contents of all 1024 bytes of
RAM.
RESETS AND INTERRUPTS
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5.5.1 WAIT
The WAI opcode places the MCU in the WAIT condition, during which the CPU registers are stacked and CPU processing is suspended until a qualified interrupt is detected. The interrupt can be an external IRQ, an XIRQ, or any of the internally generated
interrupts, such as the timer or serial interrupts. The on-chip crystal oscillator remains
active throughout the WAIT standby period.
Freescale Semiconductor, Inc...
The reduction of power in the WAIT condition depends on how many internal clock signals driving on-chip peripheral functions can be shut down. The CPU is always shut
down during WAIT. While in the wait state, the address/data bus repeatedly runs read
cycles to the address where the CCR contents were stacked. Ensuring that the stack
contents are placed in internal RAM will further reduce power consumption. The MCU
leaves the wait state when it senses any interrupt that has not been masked.
The free-running timer system is shut down only if the I bit is set to one and the COP
system is disabled by NOCOP being set to one. Several other systems can also be in
a reduced power consumption state depending on the state of software-controlled
configuration control bits. Power consumption by the analog-to-digital (A/D) converter
is not affected significantly by the WAIT condition. However, the A/D converter current
can be eliminated by writing the ADPU bit to zero. The SPI system is enabled or disabled by the SPE control bit. The SCI transmitter is enabled or disabled by the TE bit,
and the SCI receiver is enabled or disabled by the RE bit. Therefore the power consumption in WAIT is dependent on the particular application.
5.5.2 STOP
Executing the STOP instruction while the S bit in the CCR is equal to zero places the
MCU in the STOP condition. If the S bit is not zero, the STOP opcode is treated as a
no-op (NOP). The STOP condition offers minimum power consumption because all
clocks, including the crystal oscillator, are stopped while in this mode. To exit STOP
and resume normal processing, a logic low level must be applied to one of the external
interrupts (IRQ or XIRQ) or to the RESET pin. A pending edge-triggered IRQ can also
bring the CPU out of STOP.
Because all clocks are stopped in this mode, all internal peripheral functions also stop.
The data in the internal RAM is retained as long as VDD power is maintained. The CPU
state and I/O pin levels are static and are unchanged by STOP. Therefore, when an
interrupt restarts the system, the MCU resumes processing as if there were no interruption. If reset is used to restart the system a normal reset sequence results where
all I/O pins and functions are also restored to their initial states.
To use the IRQ pin as a means of recovering from STOP, the I bit in the CCR must be
clear (IRQ not masked). The XIRQ pin can be used to wake up the MCU from STOP
regardless of the state of the X bit in the CCR, although the recovery sequence depends on the state of the X bit. If X is set to zero (XIRQ not masked), the MCU starts
up, beginning with the stacking sequence leading to normal service of the XIRQ request. If X is set to one (XIRQ masked or inhibited), then processing continues with
the instruction that immediately follows the STOP instruction, and no XIRQ interrupt
service is requested or pending.
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Freescale Semiconductor, Inc...
Because the oscillator is stopped in STOP mode, a restart delay may be imposed to
allow oscillator stabilization upon leaving STOP. If the internal oscillator is being used,
this delay is required; however, if a stable external oscillator is being used, the DLY
control bit can be used to bypass this start-up delay. The DLY control bit is set by reset
and can be optionally cleared during initialization. If the DLY equal to zero option is
used to avoid start-up delay on recovery from STOP, then reset should not be used as
the means of recovering from STOP, as this causes DLY to be set again by reset, imposing the restart delay. This same delay also applies to power-on reset, regardless
of the state of the DLY control bit, but does not apply to a reset while the clocks are
running.
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SECTION 6 PARALLEL INPUT/OUTPUT
Freescale Semiconductor, Inc...
The MC68HC11F1 MCU has up to 54 input/output lines, depending on the operating
mode. The data bus of this microcontroller is nonmultiplexed. I/O lines are organized
into seven parallel ports. Ports with bidirectional pins have an associated data direction control register. This register (DDRx) contains a data direction control bit for each
bidirectional port line. The following table is a summary of the configuration and features of each port.
Table 6-1 I/O Port Configuration
Port
Port A
Port B
Port C
Port D
Port E
Port F
Port G
Input Pins
—
—
—
—
8
—
—
Output Pins
—
8
—
—
—
8
—
Bidirectional Pins
8
—
8
6
—
—
8
Shared Functions
Timer
High-Order Address
Data Bus
SCI and SPI
A/D Converter
Low-Order Address
Chip Select Outputs
Port pin function is mode dependent. Do not confuse pin function with the electrical
state of the pin at reset. Port pins are either driven to a specified logic level or are configured as high impedance inputs. I/O pins configured as high-impedance inputs have
port data that is indeterminate. The contents of the corresponding latches are dependent upon the electrical state of the pins during reset. In port descriptions, an “I” indicates this condition. Port pins that are driven to a known logic level during reset are
shown with a value of either one or zero. Some control bits are unaffected by reset.
Reset states for these bits are indicated with a “U”.
6.1 Port A
Port A has eight bidirectional I/O pins and shares functions with the timer system.
PORTA — Port A Data
RESET:
Alt. Pin
Func.:
And/or:
$1000
Bit 7
PA7
I
6
PA6
I
5
PA5
I
4
PA4
I
3
PA3
I
2
PA2
I
1
PA1
I
Bit 0
PA0
I
PAI
OC1
OC2
OC1
OC3
OC1
OC4
OC1
IC4/OC5
OC1
IC1
—
IC2
—
IC3
—
PARALLEL INPUT/OUTPUT
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DDRA — Data Direction Register for Port A
RESET:
Bit 7
DDA7
0
6
DDA6
0
5
DDA5
0
4
DDA4
0
$1001
3
DDA3
0
2
DDA2
0
1
DDA1
0
Bit 0
DDA0
0
Freescale Semiconductor, Inc...
DDA[7:0] — Data Direction for Port A
0 = Input
1 = Output
NOTE
To enable PA3 as fourth input capture, set the I4/O5 bit in the PACTL
register. Otherwise, PA3 is configured as a fifth output compare out
of reset, with bit I4/O5 being cleared. If the DDA3 bit is set (configuring PA3 as an output), and IC4 is enabled, writes to PA3 cause edges
on the pin to result in input captures. Writing to TI4/O5 has no effect
when the TI4/O5 register is acting as IC4. PA7 drives the pulse accumulator input but also can be configured for general-purpose I/O,
or output compare. Note that even when PA7 is configured as an output, the pin still drives the pulse accumulator input.
6.2 Port B
Reset state is mode dependent. In single-chip or bootstrap modes, port B pins are
general-purpose outputs. In expanded and test modes, port B pins are high-order address outputs and PORTB is not in the memory map.
PORTB — Port B Data
Bit 7
PB7
S. Chip or
Boot:
PB7
RESET:
0
Expan. or
Test:
ADDR15
$1004
6
PB6
5
PB5
4
PB4
3
PB3
2
PB2
1
PB1
Bit 0
PB0
PB6
0
PB5
0
PB4
0
PB3
0
PB2
0
PB1
0
PB0
0
ADDR14
ADDR13
ADDR12
ADDR11
ADDR10
ADDR9
ADDR8
6.3 Port C
Reset state is mode dependent. In single-chip and bootstrap modes, port C pins are
high-impedance inputs. It is customary to have an external pull-up resistor on lines that
are driven by open-drain devices. In expanded or test modes, port C pins are data bus
inputs/outputs and PORTC is not in the memory map. The R/W signal is used to control the direction of data transfers.
The CWOM control bit in the OPT2 register disables port C's P-channel output drivers.
Because the N-channel driver is not affected by CWOM, setting CWOM causes port
C to become an open-drain-type output port suitable for wired-OR operation. In wiredOR mode, (PORTC bits are at logic level zero), pins are actively driven low by the Nchannel driver. When a port C bit is at logic level one, the associated pin is in a highPARALLEL INPUT/OUTPUT
6-2
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impedance state, as neither the N-channel nor the P-channel devices are active. It is
customary to have an external pull-up resistor on lines that are driven by open-drain
devices. Port C can only be configured for wired-OR operation when the MCU is in single-chip or bootstrap modes.
PORTC — Port C Data
Freescale Semiconductor, Inc...
S. Chip or
Boot:
RESET:
Expan. or
Test:
$1006
Bit 7
PC7
6
PC6
5
PC5
4
PC4
3
PC3
2
PC2
1
PC1
Bit 0
PC0
PC7
I
PC6
I
PC5
I
PC4
I
PC3
I
PC2
I
PC1
I
PC0
I
DATA7
DATA6
DATA5
DATA4
DATA3
DATA2
DATA1
DATA0
DDRC — Data Direction Register for Port C
RESET:
Bit 7
DDC7
0
6
DDC6
0
5
DDC5
0
4
DDC4
0
$1007
3
DDC3
0
2
DDC2
0
1
DDC1
0
Bit 0
DDC0
0
DDC[7:0] — Data Direction for Port C
0 = Input
1 = Output
6.4 Port D
In all modes, port D bits [5:0] can be used either for general-purpose I/O, or with the
SCI and SPI subsystems. During reset, port D pins are configured as high impedance
inputs (DDRD bits cleared).
The DWOM control bit in the SPCR register disables port D’s P-channel output drivers.
Because the N-channel driver is not affected by DWOM, setting DWOM causes port
D to become an open-drain-type output port suitable for wired-OR operation. In wiredOR mode, (PORTD bits are at logic level zero), pins are actively driven low by the Nchannel driver. When a port D bit is at logic level one, the associated pin is in a highimpedance state, as neither the N-channel nor the P-channel devices are active. It is
customary to have an external pull-up resistor on lines that are driven by open-drain
devices. Port D can be configured for wired-OR operation in any operating mode.
PORTD — Port D Data
RESET:
Alt. Pin
Func.:
$1008
Bit 7
—
0
6
—
0
5
PD5
I
4
PD4
I
3
PD3
I
2
PD2
I
1
PD1
I
Bit 0
PD0
I
—
—
SS
SCK
MOSI
MISO
TxD
RxD
PARALLEL INPUT/OUTPUT
TECHNICAL DATA
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Freescale Semiconductor, Inc.
DDRD — Data Direction Register for Port D
RESET:
Bit 7
—
0
6
—
0
5
DDD5
0
4
DDD4
0
$1009
3
DDD3
0
2
DDD2
0
1
DDD1
0
Bit 0
DDD0
0
Bits [7:6] — Not implemented
Always read zero
Freescale Semiconductor, Inc...
DDD[5:0] — Data Direction for Port D
0 = Input
1 = Output
NOTE
When the SPI system is in slave mode, DDD5 has no meaning nor
effect. When the SPI system is in master mode, DDD5 determines
whether bit 5 of PORTD is an error detect input (DDD5 = 0) or a general-purpose output (DDD5 = 1). If the SPI system is enabled and expects any of bits [4:2] to be an input, that bit will be an input
regardless of the state of the associated DDR bit. If any of bits [4:2]
are expected to be outputs that bit will be an output only if the associated DDR bit is set.
6.5 Port E
Port E has eight general-purpose input pins and shares functions with the A/D converter system. When some port E pins are being used for general-purpose input and others are being used as A/D inputs, PORTE should not be read during the sample
portion of an A/D conversion.
PORTE — Port E Data
RESET:
Alt. Pin
Func.:
$100A
Bit 7
PE7
I
6
PE6
I
5
PE5
I
4
PE4
I
3
PE3
I
2
PE2
I
1
PE1
I
Bit 0
PE0
I
AN7
AN6
AN5
AN4
AN3
AN2
AN1
AN0
6.6 Port F
Reset state is mode dependent. In single-chip or bootstrap modes, port F pins are general-purpose outputs. In expanded and test modes, port F pins are low order address
outputs and PORTF is not in the memory map.
PARALLEL INPUT/OUTPUT
6-4
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TECHNICAL DATA
Freescale Semiconductor, Inc.
PORTF — Port F Data
Freescale Semiconductor, Inc...
S. Chip
or Boot:
RESET:
Expan.
or Test:
$1005
Bit 7
PF7
6
PF6
5
PF5
4
PF4
3
PF3
2
PF2
1
PF1
Bit 0
PF0
PF7
0
PF6
0
PF5
0
PF4
0
PF3
0
PF2
0
PF1
0
PF0
0
ADDR7
ADDR6
ADDR5
ADDR4
ADDR3
ADDR2
ADDR1
ADDR0
6.7 Port G
Port G pins reset to high-impedance inputs except in expanded modes where reset
causes PG7 to become the CSPROG output. Alternate functions for port G bits [7:4]
are chip select outputs. All port G bits are bidirectional and have corresponding data
direction bits.
The GWOM control bit in the OPT2 register disables port G's P-channel output drivers.
Because the N-channel driver is not affected by GWOM, setting GWOM causes port
G to become an open-drain-type output port suitable for wired-OR operation. In wiredOR mode, (PORTG bits are at logic level zero), pins are actively driven low by the Nchannel driver. When a port G bit is at logic level one, the associated pin is in a highimpedance state, as neither the N-channel nor the P-channel devices are active. It is
customary to have an external pull-up resistor on lines that are driven by open-drain
devices. Port G can be configured for wired-OR operation in any operating mode.
PORTG — Port G Data
Bit 7
PG7
I
RESET:
Alt. Pin
Func.: CSPROG
$1002
6
PG6
I
5
PG5
I
4
PG4
I
3
PG3
I
2
PG2
I
1
PG1
I
Bit 0
PG0
I
CSGEN
CSIO1
CSIO2
—
—
—
—
DDRG — Data Direction Register for Port G
RESET:
Bit 7
DDG7
0
6
DDG6
0
5
DDG5
0
4
DDG4
0
$1003
3
DDG3
0
2
DDG2
0
1
DDG1
0
Bit 0
DDG0
0
DDG[7:0] — Data Direction for Port G
0 = Input
1 = Output
6.8 System Configuration Options 2
The system configuration options 2 register controls several configuration parameters.
Bit 6, CWOM, is the only bit in this register that directly affects parallel I/O.
PARALLEL INPUT/OUTPUT
TECHNICAL DATA
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6-5
Freescale Semiconductor, Inc.
OPT2 — System Configuration Options 2
RESET:
Bit 7
GWOM
0
6
CWOM
0
5
CLK4X
1
4
—
0
$1038
3
—
0
2
—
0
1
—
0
Bit 0
—
0
GWOM — Port G Wired-OR Mode
0 = Port G operates normally
1 = Port G outputs are open drain
Freescale Semiconductor, Inc...
CWOM — Port C Wired-OR Mode
0 = Port C operates normally
1 = Port C outputs are open drain
CLK4X — 4XOUT Clock Enable
Refer to SECTION 2 PIN DESCRIPTIONS.
Bits [4:0] — Not implemented
Always read zero
PARALLEL INPUT/OUTPUT
6-6
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SECTION 7 SERIAL COMMUNICATIONS INTERFACE
The serial communications interface (SCI) is a universal asynchronous receiver transmitter (UART), one of two independent serial I/O subsystems in the MC68HC11F1
MCU. It has a standard nonreturn to zero (NRZ) format (one start bit, eight or nine data
bits, and one stop bit). Several baud rates are available. The SCI transmitter and receiver are independent, but use the same data format and bit rate.
Freescale Semiconductor, Inc...
7.1 Data Format
The serial data format requires the following conditions:
1. An idle-line in the high state before transmission or reception of a message.
2. A start bit, logic zero, transmitted or received, that indicates the start of each
character.
3. Data that is transmitted and received least significant bit (LSB) first.
4. A stop bit, logic one, used to indicate the end of a frame. (A frame consists of a
start bit, a character of eight or nine data bits, and a stop bit.)
5. A break (defined as the transmission or reception of a logic zero for some multiple number of frames).
Selection of the word length is controlled by the M bit of SCI control register SCCR1.
7.2 Transmit Operation
The SCI transmitter includes a parallel transmit data register (SCDR) and a serial shift
register. The contents of the serial shift register can only be written through the SCDR.
This double buffered operation allows a character to be shifted out serially while another character is waiting in the SCDR to be transferred into the serial shift register.
The output of the serial shift register is applied to TxD as long as transmission is in
progress or the transmit enable (TE) bit of serial communication control register 2
(SCCR2) is set. The block diagram, Figure 7-1, shows the transmit serial shift register
and the buffer logic at the top of the figure.
SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA
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7-1
Freescale Semiconductor, Inc.
TRANSMITTER
BAUD RATE
CLOCK
(WRITE-ONLY)
SCDR Tx BUFFER
DDD1
10 (11) - BIT Tx SHIFT REGISTER
2
1
0
PIN BUFFER
AND CONTROL
L
BREAK—JAM 0's
3
PREAMBLE—JAM 1's
4
JAM ENABLE
5
SHIFT ENABLE
SIZE 8/9
Freescale Semiconductor, Inc...
6
TRANSFER Tx BUFFER
H (8) 7
PD1/
TxD
8
FORCE PIN
DIRECTION (OUT)
TRANSMITTER
CONTROL LOGIC
SCCR1 SCI CONTROL 1
OR
NF
FE
TDRE
TC
RDRF
IDLE
WAKE
M
R8
T8
8
SCSR INTERRUPT STATUS
8
TDRE
TIE
TC
TCIE
SBK
TE
RE
RWU
TIE
TCIE
RIE
ILIE
8
SCCR2 SCI CONTROL 2
SCI Rx
REQUESTS
SCI INTERRUPT
REQUEST
INTERNAL
DATA BUS
Figure 7-1 SCI Transmitter Block Diagram
7.3 Receive Operation
During receive operations, the transmit sequence is reversed. The serial shift register
receives data and transfers it to a parallel receive data register (SCDR) as a complete
word. This double buffered operation allows a character to be shifted in serially while
another character is already in the SCDR. An advanced data recovery scheme distinguishes valid data from noise in the serial data stream. The data input is selectively
sampled to detect receive data, and a majority voting circuit determines the value and
integrity of each bit.
SERIAL COMMUNICATIONS INTERFACE
7-2
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MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
RECEIVER
BAUD RATE
CLOCK
PIN BUFFER
AND CONTROL
PD0/
RxD
DATA
RECOVERY
START
÷16
STOP
DDD0
10 (11) - BIT
Rx SHIFT REGISTER
(8) 7
6
5
4
3
2
1
0
MSB
DISABLE
DRIVER
ALL ONES
M
WAKE-UP
LOGIC
RWU
OR
NF
FE
TDRE
TC
RDRF
IDLE
M
WAKE
8
R8
T8
SCSR1 SCI STATUS 1
SCCR1 SCI CONTROL 1
SCDR Rx BUFFER
(READ-ONLY)
8
RDRF
RIE
IDLE
ILIE
8
SBK
RWU
TE
RE
OR
RIE
TIE
TCIE
RIE
ILIE
Freescale Semiconductor, Inc...
RE
SCCR2 SCI CONTROL 2
SCI Tx
REQUESTS
SCI INTERRUPT
REQUEST
INTERNAL
DATA BUS
Figure 7-2 SCI Receiver Block Diagram
SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA
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7-3
Freescale Semiconductor, Inc.
Freescale Semiconductor, Inc...
7.4 Wakeup Feature
The wakeup feature reduces SCI service overhead in multiple receiver systems. Software for each receiver evaluates the first character of each message. The receiver is
placed in wakeup mode by writing a one to the RWU bit in the SCCR2 register. While
RWU is one, all of the receiver-related status flags (RDRF, IDLE, OR, NF, and FE) are
inhibited (cannot become set). Although RWU can be cleared by a software write to
SCCR2, to do so would be unusual. Normally RWU is set by software and is cleared
automatically with hardware. Whenever a new message begins, logic alerts the sleeping receivers to wake up and evaluate the initial character of the new message.
Two methods of wakeup are available: idle-line wakeup and address-mark wakeup.
During idle-line wakeup, a sleeping receiver awakens as soon as the RxD line becomes idle. In the address-mark wakeup, logic one in the most significant bit (MSB) of
a character wakes up all sleeping receivers.
7.4.1 Idle-Line Wakeup
To use the receiver wakeup method, establish a software addressing scheme to allow
the transmitting devices to direct a message to individual receivers or to groups of receivers. This addressing scheme can take any form as long as all transmitting and receiving devices are programmed to understand the same scheme. Because the
addressing information is usually the first frame(s) in a message, receivers that are not
part of the current task do not become burdened with the entire set of addressing
frames. All receivers are awake (RWU = 0) when each message begins. As soon as
a receiver determines that the message is not intended for it, software sets the RWU
bit (RWU = 1), which inhibits further flag setting until the RxD line goes idle at the end
of the message. As soon as an idle line is detected by receiver logic, hardware automatically clears the RWU bit so that the first frame of the next message can be received. This type of receiver wakeup requires a minimum of one idle-line frame time
between messages, and no idle time between frames in a message.
7.4.2 Address-Mark Wakeup
The serial characters in this type of wakeup consist of seven (eight if M = 1) information
bits and an MSB, which indicates an address character (when set to one, or mark).
The first character of each message is an addressing character (MSB = 1). All receivers in the system evaluate this character to determine if the remainder of the message
is directed toward this particular receiver. As soon as a receiver determines that a
message is not intended for it, the receiver activates the RWU function by using a software write to set the RWU bit. Because setting RWU inhibits receiver-related flags,
there is no further software overhead for the rest of this message.
When the next message begins, its first character has its MSB set, which automatically
clears the RWU bit and enables normal character reception. The first character whose
MSB is set is also the first character to be received after wakeup because RWU gets
cleared before the stop bit for that frame is serially received. This type of wakeup allows messages to include gaps of idle time, unlike the idle-line method, but there is a
loss of efficiency because of the extra bit time for each character (address bit) required
for all characters.
SERIAL COMMUNICATIONS INTERFACE
7-4
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TECHNICAL DATA
Freescale Semiconductor, Inc.
7.5 SCI Error Detection
Three error conditions, SCDR overrun, received bit noise, and framing can occur during generation of SCI system interrupts. Three bits (OR, NF, and FE) in the serial communications status register (SCSR) indicate if one of these error conditions exists.
Freescale Semiconductor, Inc...
The overrun error (OR) bit is set when the next byte is ready to be transferred from the
receive shift register to the SCDR and the SCDR is already full (RDRF bit is set). When
an overrun error occurs, the data that caused the overrun is lost and the data that was
already in SCDR is not disturbed. The OR is cleared when the SCSR is read (with OR
set), followed by a read of the SCDR.
The noise flag (NF) bit is set if there is noise on any of the received bits, including the
start and stop bits. The NF bit is not set until the RDRF flag is set. The NF bit is cleared
when the SCSR is read (with FE equal to one) followed by a read of the SCDR.
When no stop bit is detected in the received data character, the framing error (FE) bit
is set. FE is set at the same time as the RDRF. If the byte received causes both framing and overrun errors, the processor only recognizes the overrun error. The framing
error flag inhibits further transfer of data into the SCDR until it is cleared. The FE bit is
cleared when the SCSR is read (with FE equal to one) followed by a read of the SCDR.
7.6 SCI Registers
There are five addressable registers associated with the SCI. SCCR1, SCCR2, and
BAUD are control registers. SCDR is the SCI data register and SCSR is the SCI status
register. Refer to the BAUD register description as well as the block diagram for the
baud rate generator.
7.6.1 Serial Communications Data Register
SCDR is a parallel register that performs two functions. It is the receive data register
when it is read, and the transmit data register when it is written. Reads access the receive data buffer and writes access the transmit data buffer. Receive and transmit are
double buffered.
SCDR — SCI Data Register
RESET:
Bit 7
R7/T7
I
6
R6/T6
I
$102F
5
R5/T5
I
4
R4/T4
I
3
R3/T3
I
2
R2/T2
I
1
R1/T1
I
Bit 0
R0/T0
I
7.6.2 Serial Communications Control Register 1
The SCCR1 register provides the control bits that determine word length and select
the method used for the wakeup feature.
SCCR1 — SCI Control Register 1
RESET:
Bit 7
R8
I
6
T8
I
5
—
0
$102C
4
M
0
3
WAKE
0
2
—
0
1
—
0
Bit 0
—
0
SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA
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7-5
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R8 — Receive Data Bit 8
If M bit is set, R8 stores the ninth bit in the receive data character.
T8 — Transmit Data Bit 8
If M bit is set, T8 stores the ninth bit in the transmit data character.
M — Mode (Select Character Format)
0 = Start bit, 8 data bits, 1 stop bit
1 = Start bit, 9 data bits, 1 stop bit
Freescale Semiconductor, Inc...
WAKE — Wakeup by Address Mark/Idle
0 = Wakeup by IDLE line recognition
1 = Wakeup by address mark (most significant data bit set)
7.6.3 Serial Communications Control Register 2
The SCCR2 register provides the control bits that enable or disable individual SCI
functions.
SCCR2 — SCI Control Register 2
RESET:
Bit 7
TIE
0
6
TCIE
0
5
RIE
0
$102D
4
ILIE
0
3
TE
0
2
RE
0
1
RWU
0
Bit 0
SBK
0
TIE — Transmit Interrupt Enable
0 = TDRE interrupts disabled
1 = SCI interrupt requested when TDRE status flag is set
TCIE — Transmit Complete Interrupt Enable
0 = TC interrupts disabled
1 = SCI interrupt requested when TC status flag is set
RIE — Receiver Interrupt Enable
0 = RDRF and OR interrupts disabled
1 = SCI interrupt requested when RDRF flag or the OR status flag is set
ILIE — Idle-Line Interrupt Enable
0 = IDLE interrupts disabled
1 = SCI interrupt requested when IDLE status flag is set
TE — Transmitter Enable
When TE goes from zero to one, one unit of idle character time (logic one) is queued
as a preamble.
0 = Transmitter disabled
1 = Transmitter enabled
RE — Receiver Enable
0 = Receiver disabled
1 = Receiver enabled
SERIAL COMMUNICATIONS INTERFACE
7-6
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TECHNICAL DATA
Freescale Semiconductor, Inc.
RWU — Receiver Wakeup Control
0 = Normal SCI receiver
1 = Wakeup enabled and receiver interrupts inhibited
Freescale Semiconductor, Inc...
SBK — Send Break
At least one character time of break is queued and sent each time SBK is written to
one. As long as the SBK bit is set, break characters are queued and sent. More than
one break may be sent if the transmitter is idle at the time the SBK bit is toggled on
and off, as the baud rate clock edge could occur between writing the one and writing
the zero to SBK.
0 = Break generator off
1 = Break codes generated
7.6.4 Serial Communication Status Register
The SCSR provides inputs to the interrupt logic circuits for generation of the SCI system interrupt.
SCSR — SCI Status Register
RESET:
Bit 7
TDRE
1
6
TC
1
5
RDRF
0
$102E
4
IDLE
0
3
OR
0
2
NF
0
1
FE
0
Bit 0
—
0
TDRE — Transmit Data Register Empty Flag
This flag is set when SCDR is empty. Clear the TDRE flag by reading SCSR and then
writing to SCDR.
0 = SCDR busy
1 = SCDR empty
TC — Transmit Complete Flag
This flag is set when the transmitter is idle (no data, preamble, or break transmission
in progress). Clear the TC flag by reading SCSR and then writing to SCDR.
0 = Transmitter busy
1 = Transmitter idle
RDRF — Receive Data Register Full Flag
This flag is set if a received character is ready to be read from SCDR. Clear the RDRF
flag by reading SCSR and then reading SCDR.
0 = SCDR empty
1 = SCDR full
IDLE — Idle Line Detected Flag
This flag is set if the RxD line is idle. Once cleared, IDLE is not set again until the RxD
line has been active and becomes idle again. The IDLE flag is inhibited when RWU =
1. Clear IDLE by reading SCSR and then reading SCDR.
0 = RxD line is active
1 = RxD line is idle
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OR — Overrun Error Flag
OR is set if a new character is received before a previously received character is read
from SCDR. Clear the OR flag by reading SCSR and then reading SCDR.
0 = No overrun
1 = Overrun detected
Freescale Semiconductor, Inc...
NF — Noise Error Flag
NF is set if majority sample logic detects anything other than a unanimous decision.
Clear NF by reading SCSR and then reading SCDR.
0 = Unanimous decision
1 = Noise detected
FE — Framing Error
FE is set when a zero is detected where a stop bit was expected. Clear the FE flag by
reading SCSR and then reading SCDR.
0 = Stop bit detected
1 = Zero detected
Bit 0 — Not implemented
Always reads zero
7.6.5 Baud Rate Register
Use this register to select different baud rates for the SCI system. The SCP[1:0] bits
select the prescaler rate for the SCR[2:0] bits. Together, these five bits provide multiple baud rate combinations for a given crystal frequency. Normally, this register is written once during initialization. The prescaler is set to its fastest rate by default out of
reset, and can be changed at any time. Refer to Table 7-1 and Table 7-2 for normal
baud rate selections.
BAUD — Baud Rate
RESET:
Bit 7
TCLR
0
$102B
6
—
0
5
SCP1
0
4
SCP0
0
3
RCKB
0
2
SCR2
U
1
SCR1
U
Bit 0
SCR0
U
TCLR — Clear Baud Rate Counters (Test)
SCP[1:0] — SCI Baud Rate Prescaler Selects
Refer to the SCI baud rate generator block diagram.
Table 7-1 Baud Rate Prescaler Selection
Prescaler
SCP1
SCP0
0
0
0
1
1
0
1
1
Divide Internal
Clock By
1
3
4
13
4.0
62500
20833
15625
4800
4.9152
76800
25600
19200
5907
Crystal Frequency (MHz)
8.0
12.0
125000
187500
41667
62500
31250
46875
9600
14423
SERIAL COMMUNICATIONS INTERFACE
7-8
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16.0
25000
83332
62500
19200
20.0
312500
104165
78125
24000
MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
RCKB — SCI Baud Rate Clock Check (Test)
SCR[2:0] — SCI Baud Rate Selects
Selects receiver and transmitter bit rate based on output from baud rate prescaler
stage. Refer to the SCI baud rate generator block diagram.
Freescale Semiconductor, Inc...
Table 7-2 Baud Rate Selection
SCR[2:0]
000
001
010
011
100
101
110
111
Divide
Prescaler
By
1
2
4
8
16
32
64
128
4800
4800
2400
1200
600
300
150
75
—
Highest Baud Rate
(Prescaler Output from Previous Table)
19200
76800
312500
19200
76800
312500
9600
38400
156250
4800
19200
78125
2400
9600
39063
1200
4800
19531
600
2400
9766
300
1200
4883
150
600
2441
The prescaler bits, SCP[2:0], determine the highest baud rate, and the SCR[2:0] bits
select an additional binary submultiple (≥1, ≥2, ≥4, through ≥128) of this highest baud
rate. The result of these two dividers in series is the 16X receiver baud rate clock. The
SCR[2:0] bits are not affected by reset and can be changed at any time, although they
should not be changed when any SCI transfer is in progress.
Figure 7-3 and Figure 7-4 illustrate the SCI baud rate timing chain. The prescaler select bits determine the highest baud rate. The rate select bits determine additional divide by two stages to arrive at the receiver timing (RT) clock rate. The baud rate clock
is the result of dividing the RT clock by 16.
SERIAL COMMUNICATIONS INTERFACE
TECHNICAL DATA
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EXTAL
XTAL
OSCILLATOR
AND
CLOCK GENERATOR
(÷4)
÷3
÷4
INTERNAL
BUS
CLOCK
(PH2)
÷13
SCP1:SCP0
0:0
E
0:1
1:0
1:1
AS
Freescale Semiconductor, Inc...
SCR2:SCR1:SCR0
0:0:0
÷2
0:0:1
÷2
0:1:0
÷2
0:1:1
÷16
÷2
1:0:0
÷2
1:0:1
÷2
1:1:0
÷2
1:1:1
SCI
TRANSMIT
BAUD RATE
(1X)
SCI
RECEIVE
BAUD RATE
(16X)
Figure 7-3 SCI Baud Rate Generator Block Diagram
7.7 Status Flags and Interrupts
The SCI transmitter has two status flags. These status flags can be read by software
(polled) to tell when the corresponding condition exists. Alternatively, a local interrupt
enable bit can be set to enable each of these status conditions to generate interrupt
requests when the corresponding condition is present. Status flags are automatically
set by hardware logic conditions, but must be cleared by software, which provides an
interlock mechanism that enables logic to know when software has noticed the status
indication. The software clearing sequence for these flags is automatic — functions
that are normally performed in response to the status flags also satisfy the conditions
of the clearing sequence.
SERIAL COMMUNICATIONS INTERFACE
7-10
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TDRE and TC flags are normally set when the transmitter is first enabled (TE set to
one). The TDRE flag indicates there is room in the transmit queue to store another
data character in the TDR. The TIE bit is the local interrupt mask for TDRE. When TIE
is zero, TDRE must be polled. When TIE and TDRE are one, an interrupt is requested.
Freescale Semiconductor, Inc...
The TC flag indicates the transmitter has completed the queue. The TCIE bit is the local interrupt mask for TC. When TCIE is zero, TC must be polled; when TCIE is one
and TC is one, an interrupt is requested.
Writing a zero to TE requests that the transmitter stop when it can. The transmitter
completes any transmission in progress before actually shutting down. Only an MCU
reset can cause the transmitter to stop and shut down immediately. If TE is written to
zero when the transmitter is already idle, the pin reverts to its general-purpose I/O
function (synchronized to the bit-rate clock). If anything is being transmitted when TE
is written to zero, that character is completed before the pin reverts to general-purpose
I/O, but any other characters waiting in the transmit queue are lost. The TC and TDRE
flags are set at the completion of this last character, even though TE has been disabled.
7.7.1 Receiver Flags
The SCI receiver has five status flags, three of which can generate interrupt requests.
The status flags are set by the SCI logic in response to specific conditions in the receiver. These flags can be read (polled) at any time by software. Refer to Figure 7–4,
which shows SCI interrupt arbitration.
When an overrun takes place, the new character is lost, and the character that was in
its way in the parallel RDR is undisturbed. RDRF is set when a character has been
received and transferred into the parallel RDR. The OR flag is set instead of RDRF if
overrun occurs. A new character is ready to be transferred into RDR before a previous
character is read from RDR.
The NF and FE flags provide additional information about the character in the RDR,
but do not generate interrupt requests.
The last receiver status flag and interrupt source come from the IDLE flag. The RxD
line is idle if it has constantly been at logic one for a full character time. The IDLE flag
is set only after the RxD line has been busy and becomes idle, which prevents repeated interrupts for the whole time RxD remains idle.
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BEGIN
RDRF = 1
?
YES
NO
YES
OR = 1
?
Freescale Semiconductor, Inc...
NO
RIE = 1
?
YES
NO
TDRE = 1
?
YES
NO
TIE = 1
?
YES
NO
TCIE = 1
?
YES
NO
YES
NO
TC = 1
?
RE = 1
?
TE = 1
?
YES
NO
YES
NO
IDLE = 1
?
NO
YES
ILIE = 1
?
NO
YES
RE = 1
?
YES
NO
NO – VALID SCI
REQUEST
YES – VALID SCI
REQUEST
Figure 7-4 Interrupt Source Resolution Within SCI
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SECTION 8 SERIAL PERIPHERAL INTERFACE
The serial peripheral interface (SPI), an independent serial communications subsystem, allows the MCU to communicate synchronously with peripheral devices, such
as transistor-transistor logic (TTL) shift registers, liquid crystal display (LCD) drivers,
analog-to-digital converter subsystems, and other microprocessors. The SPI is also
capable of inter-processor communication in a multiple master system. The SPI system can be configured as either a master or a slave device. When configured as a
master, data transfer rates can be as high as one-half the E-clock rate (2.5 Mbits per
second for a 5-MHz bus frequency). When configured as a slave, data transfers can
be as fast as the E-clock rate (5 Mbits per second for a 5-MHz bus frequency).
8.1 Functional Description
The central element in the SPI system is the block containing the shift register and the
read data buffer. The system is single buffered in the transmit direction and double
buffered in the receive direction. This means that new data for transmission cannot be
written to the shifter until the previous transfer is complete; however, received data is
transferred into a parallel read data buffer so the shifter is free to accept a second serial character. As long as the first character is read out of the read data buffer before
the next serial character is ready to be transferred, no overrun condition occurs. A single MCU register address is used for reading data from the read data buffer and for
writing data to the shifter.
The SPI status block represents the SPI status flags (transfer complete, write collision,
and mode fault) located in the SPI status register (SPSR). The SPI control block represents those functions that control the SPI system through the serial peripheral control register (SPCR).
Refer to Figure 8-1, which shows the SPI block diagram.
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M
MSB
÷4
LSB
÷16 ÷32
READ DATA BUFFER
CLOCK
SELECT
S
M
SCK/
PD4
SPR0
SPE
MSTR
SS/
PD5
DWOM
SPR1
PIN
CONTROL
LOGIC
SPI CLOCK (MASTER)
CLOCK
LOGIC
Freescale Semiconductor, Inc...
MOSI/
PD3
M
S
8-BIT SHIFT REGISTER
DIVIDER
÷2
MISO/
PD2
S
INTERNAL
MCU CLOCK
MSTR
SPE
SPI CONTROL
SPSR SPI STATUS REGISTER
SPR1
SPR0
CPOL
CPHA
MSTR
DWOM
SPE
SPIE
MODF
WCOL
SPIF
SPIE
SPCR SPI CONTROL REGISTER
8
8
SPI INTERRUPT
REQUEST
8
INTERNAL
DATA BUS
Figure 8-1 SPI Block Diagram
8.2 SPI Transfer Formats
During an SPI transfer, data is simultaneously transmitted and received. A serial clock
line synchronizes shifting and sampling of the information on the two serial data lines.
A slave select line allows individual selection of a slave SPI device; slave devices that
are not selected do not interfere with SPI bus activities. On a master SPI device, the
select line can optionally be used to indicate a multiple master bus contention. Refer
to Figure 8-2.
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SCK CYCLE #
1
2
3
4
5
6
7
8
SCK (CPOL = 0)
SCK (CPOL = 1)
SAMPLE INPUT
(CPHA = 0) DATA OUT
MSB
6
5
4
3
2
1
LSB
SAMPLE INPUT
(CPHA = 1) DATA OUT
MSB
6
5
4
3
2
1
LSB
Freescale Semiconductor, Inc...
SS (TO SLAVE)
3
1
3
SS ASSERTED
MASTER WRITES
TO SPDR
FIRST SCK EDGE
4
SPIF SET
5
SS NEGATED
2
2
1
SLAVE CPHA = 1 TRANSFER IN PROGRESS
MASTER TRANSFER IN PROGRESS
SLAVE CPHA = 0 TRANSFER IN PROGRESS
4
5
Figure 8-2 SPI Transfer Format
8.2.1 Clock Phase and Polarity Controls
Software can select one of four combinations of serial clock phase and polarity using
two bits in the SPI control register (SPCR). The clock polarity is specified by the CPOL
control bit, which selects an active high or active low clock, and has no significant effect on the transfer format. The clock phase (CPHA) control bit selects one of two different transfer formats. The clock phase and polarity should be identical for the master
SPI device and the communicating slave device. In some cases, the phase and polarity are changed between transfers to allow a master device to communicate with peripheral slaves having different requirements.
When CPHA equals zero, the SS line must be negated and reasserted between each
successive serial byte. Also, if the slave writes data to the SPI data register (SPDR)
while SS is low, a write collision error results.
When CPHA equals one, the SS line can remain low between successive transfers.
8.3 SPI Signals
The following paragraphs contain descriptions of the four SPI signals: master in slave
out (MISO), master out slave in (MOSI), serial clock (SCK), and slave select (SS).
Any SPI output line must have its corresponding data direction bit in DDRD register
set. If the DDR bit is clear, that line is disconnected from the SPI logic and becomes a
general-purpose input. All SPI input lines are forced to act as inputs regardless of the
state of the corresponding DDR bits in DDRD register.
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8.3.1 Master In Slave Out
MISO is one of two unidirectional serial data signals. It is an input to a master device
and an output from a slave device. The MISO line of a slave device is placed in the
high-impedance state if the slave device is not selected.
Freescale Semiconductor, Inc...
8.3.2 Master Out Slave In
The MOSI line is the second of the two unidirectional serial data signals. It is an output
from a master device and an input to a slave device. The master device places data
on the MOSI line a half-cycle before the clock edge that the slave device uses to latch
the data.
8.3.3 Serial Clock
SCK, an input to a slave device, is generated by the master device and synchronizes
data movement in and out of the device through the MOSI and MISO lines. Master and
slave devices are capable of exchanging a byte of information during a sequence of
eight clock cycles.
There are four possible timing relationships that can be chosen by using control bits
CPOL and CPHA in the serial peripheral control register (SPCR). Both master and
slave devices must operate with the same timing. The SPI clock rate select bits,
SPR[1:0], in the SPCR of the master device, select the clock rate. In a slave device,
SPR[1:0] have no effect on the operation of the SPI.
8.3.4 Slave Select
The slave select (SS) input of a slave device must be externally asserted before a
master device can exchange data with the slave device. SS must be low before data
transactions and must stay low for the duration of the transaction.
The SS line of the master must be held high. If it goes low, a mode fault error flag
(MODF) is set in the serial peripheral status register (SPSR). To disable the mode fault
circuit, write a one in bit 5 of the port D data direction register. This sets the SS pin to
act as a general-purpose output rather than the dedicated input to the slave select circuit, thus inhibiting the mode fault flag. The other three lines are dedicated to the SPI
whenever the serial peripheral interface is on.
The state of the master and slave CPHA bits affects the operation of SS. CPHA settings should be identical for master and slave. When CPHA = 0, the shift clock is the
OR of SS with SCK. In this clock phase mode, SS must go high between successive
characters in an SPI message. When CPHA = 1, SS can be left low between successive SPI characters. In cases where there is only one SPI slave MCU, its SS line can
be tied to Vss as long as only CPHA = 1 clock mode is used.
8.4 SPI System Errors
Two system errors can be detected by the SPI system. The first type of error arises in
a multiple-master system when more than one SPI device simultaneously tries to be
a master. This error is called a mode fault. The second type of error, write collision,
indicates that an attempt was made to write data to the SPDR while a transfer was in
progress.
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When the SPI system is configured as a master and the SS input line goes to active
low, a mode fault error has occurred — usually because two devices have attempted
to act as master at the same time. In cases where more than one device is concurrently configured as a master, there is a chance of contention between two pin drivers. For
push-pull CMOS drivers, this contention can cause permanent damage. The mode
fault mechanism attempts to protect the device by disabling the drivers. The MSTR
control bit in the SPCR and all four DDRD control bits associated with the SPI are
cleared and an interrupt is generated subject to masking by the SPIE control bit and
the I bit in the CCR.
Other precautions may need to be taken to prevent driver damage. If two devices are
made masters at the same time, mode fault does not help protect either one unless
one of them selects the other as slave. The amount of damage possible depends on
the length of time both devices attempt to act as master.
A write collision error occurs if the SPDR is written while a transfer is in progress. Because the SPDR is not double buffered in the transmit direction, writes to SPDR cause
data to be written directly into the SPI shift register. Because this write corrupts any
transfer in progress, a write collision error is generated. The transfer continues undisturbed, and the write data that caused the error is not written to the shifter.
A write collision is normally a slave error because a slave has no control over when a
master initiates a transfer. A master knows when a transfer is in progress, so there is
no reason for a master to generate a write-collision error, although the SPI logic can
detect write collisions in both master and slave devices.
The SPI configuration determines the characteristics of a transfer in progress. For a
master, a transfer begins when data is written to SPDR and ends when SPIF is set.
For a slave with CPHA equal to zero, a transfer starts when SS goes low and ends
when SS returns high. In this case, SPIF is set at the middle of the eighth SCK cycle
when data is transferred from the shifter to the parallel data register, but the transfer
is still in progress until SS goes high. For a slave with CPHA equal to one, transfer begins when the SCK line goes to its active level, which is the edge at the beginning of
the first SCK cycle. The transfer ends in a slave in which CPHA equals one when SPIF
is set.
8.5 SPI Registers
The three SPI registers, SPCR, SPSR, and SPDR, provide control, status, and data
storage functions. Refer to the following information for a description of how these registers are organized.
8.5.1 Serial Peripheral Control
SPCR — Serial Peripheral Control Register
RESET:
Bit 7
SPIE
0
6
SPE
0
5
DWOM
0
4
MSTR
0
$1028
3
CPOL
0
2
CPHA
1
1
SPR1
U
Bit 0
SPR0
U
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SPIE — Serial Peripheral Interrupt Enable
Set the SPE bit to one to request a hardware interrupt sequence each time the SPIF
or MODF status flag is set. SPI interrupts are inhibited if this bit is clear or if the I bit in
the condition code register is one.
0 = SPI system interrupts disabled
1 = SPI system interrupts enabled
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SPE — Serial Peripheral System Enable
When the SPE bit is set, the port D bit 2, 3, 4, and 5 pins are dedicated to the SPI function. If the SPI is in the master mode and DDRD bit 5 is set, then the port D bit 5 pin
becomes a general-purpose output instead of the SS input.
0 = SPI system disabled
1 = SPI system enabled
DWOM — Port D Wired-OR Mode
DWOM affects all port D pins.
0 = Normal CMOS outputs
1 = Open-drain outputs
MSTR — Master Mode Select
0 = Slave mode
1 = Master mode
CPOL — Clock Polarity
When the clock polarity bit is cleared and data is not being transferred, the SCK pin of
the master device has a steady state low value. When CPOL is set, SCK idles high.
Refer to Figure 8-2 and 8.2.1 Clock Phase and Polarity Controls.
CPHA — Clock Phase
The clock phase bit, in conjunction with the CPOL bit, controls the clock-data relationship between master and slave. The CPHA bit selects one of two different clocking
protocols. Refer to Figure 8-2 and 8.2.1 Clock Phase and Polarity Controls.
SPR[1:0] — SPI Clock Rate Selects
These two bits select the SPI clock (SCK) rate when the device is configured as master. When the device is configured as slave, these bits have no effect. Refer to Table
8-1.
Table 8-1 SPI Clock Rates
SPR[1:0]
00
01
10
11
E Clock Frequency at
Divide By
E = 2 MHz
2
1.0 MHz
4
500 kHz
16
125 kHz
32
62.5 kHz
Frequency at
E = 3 MHz
1.5 MHz
750 kHz
187.5 kHz
93.7 kHz
Frequency at
E = 4 MHz
2.0 MHz
1.0 MHz
250 kHz
125 kHz
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Frequency at
E = 5 MHz
2.5 MHz
625 kHz
156.25 kHz
78.125 kHz
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8.5.2 Serial Peripheral Status
SPSR — Serial Peripheral Status Register
RESET:
Bit 7
SPIF
0
6
WCOL
0
5
—
0
4
MODF
0
$1029
3
—
0
2
—
0
1
—
0
Bit 0
—
0
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SPIF — SPI Interrupt Complete Flag
SPIF is set upon completion of data transfer between the processor and the external
device. If SPIF goes high, and if SPIE is set, a serial peripheral interrupt is generated.
To clear the SPIF bit, read the SPSR then access the SPDR. Unless SPSR is read
(with SPIF set) first, attempts to write SPDR are inhibited.
WCOL — Write Collision
Clearing the WCOL bit is accomplished by reading the SPSR followed by an access of
SPDR. Refer to 8.3.4 Slave Select and 8.4 SPI System Errors.
0 = No write collision
1 = Write collision
Bit 5 — Not implemented
Always reads zero
MODF — Mode Fault
To clear the MODF bit, read the SPSR then write to the SPCR. Refer to 8.3.4 Slave
Select and 8.4 SPI System Errors.
0 = No mode fault
1 = Mode fault
Bits [3:0] — Not implemented
Always read zero
8.5.3 Serial Peripheral Data Register
The SPDR is used when transmitting or receiving data on the serial bus. Only a write
to this register initiates transmission or reception of a byte, and this only occurs in the
master device. At the completion of transferring a byte of data, the SPIF status bit is
set in both the master and slave devices.
A read of the SPDR is actually a read of a buffer. To prevent an overrun and the loss
of the byte that caused the overrun, the first SPIF must be cleared by the time a second
transfer of data from the shift register to the read buffer is initiated.
SPDR — SPI Data Register
Bit 7
Bit 7
6
6
$102A
5
5
4
4
3
3
2
2
1
1
Bit 0
Bit 0
SPI is double buffered in and single buffered out.
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SERIAL PERIPHERAL INTERFACE
8-8
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SECTION 9 TIMING SYSTEM
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The M68HC11 timing system is composed of five clock divider chains. The main clock
divider chain includes a 16-bit free-running counter, which is driven by a programmable prescaler. The main timer's programmable prescaler provides one of the four
clocking rates to drive the 16-bit counter. Two prescaler control bits select the prescale
rate.
The prescaler output divides the system clock by 1, 4, 8, or 16. Taps off of this main
clocking chain drive circuitry that generates the slower clocks used by the pulse accumulator, the real-time interrupt (RTI), and the computer operating properly (COP)
watchdog subsystems, also described in this section. Refer to Figure 9-1.
All main timer system activities are referenced to this free-running counter. The
counter begins incrementing from $0000 as the MCU comes out of reset, and continues to the maximum count, $FFFF. At the maximum count, the counter rolls over to
$0000, sets an overflow flag, and continues to increment. As long as the MCU is running in a normal operating mode, there is no way to reset, change, or interrupt the
counting. The capture/compare subsystem features three input capture channels, four
output compare channels, and one channel that can be selected to perform either input capture or output compare. Each of the three input capture functions has its own
16-bit input capture register (time capture latch) and each of the output compare functions has its own 16-bit compare register. All timer functions, including the timer overflow and RTI have their own interrupt controls and separate interrupt vectors.
The pulse accumulator contains an 8-bit counter and edge select logic. The pulse accumulator can operate in either event counting mode or gated time accumulation
mode. During event counting mode, the pulse accumulator's 8-bit counter increments
when a specified edge is detected on an input signal. During gated time accumulation
mode, an internal clock source increments the 8-bit counter while an input signal has
a predetermined logic level.
The real-time interrupt (RTI) is a programmable periodic interrupt circuit that permits
pacing the execution of software routines by selecting one of four interrupt rates.
The COP watchdog clock input (E ÷ 215) is tapped off of the free-running counter
chain. The COP automatically times out unless it is serviced within a specific time by
a program reset sequence. If the COP is allowed to time out, a reset is generated,
which drives the RESET pin low to reset the MCU and the external system. Refer to
Table 9-1 for crystal related frequencies and periods.
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OSCILLATOR AND
CLOCK GENERATOR
(DIVIDE BY FOUR)
AS
E CLOCK
INTERNAL BUS CLOCK (PH2)
PRESCALER
(÷ 2, 4, 16, 32)
SPR[1:0]
SPI
PRESCALER
(÷ 1, 3, 4, 13)
SCP[1:0]
PRESCALER
(÷ 1, 2, 4,....128)
SCR[2:0]
SCI RECEIVER CLOCK
÷16
SCI TRANSMIT CLOCK
Freescale Semiconductor, Inc...
E÷26
PULSE ACCUMULATOR
PRESCALER
(÷ 1, 2, 4, 8)
RTR[1:0]
E÷213
REAL-TIME INTERRUPT
÷4
E÷215
PRESCALER
(÷ 1, 4, 8, 16)
PR[1:0]
TCNT
PRESCALER
(÷1, 4, 16, 64)
CR[1:0]
TOF
FF1
FF2
S
Q
R
Q
S
Q
R
Q
FORCE
COP
RESET
IC/OC
CLEAR COP
TIMER
SYSTEM
RESET
Figure 9-1 Timer Clock Divider Chains
TIMING SYSTEM
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Table 9-1 Timer Summary
4.0 MHz
1.0 MHz
1000 ns
XTAL Frequencies
8.0 MHz
12.0 MHz
16.0 MHz
2.0 MHz
3.0 MHz
4.0 MHz
500 ns
333 ns
250 ns
Main Timer Count Rates
Other Rates
(E)
(1/E)
Control Bits
PR1, PR0
0 0
1 count —
overflow —
1.0 µs
65.536 ms
500 ns
32.768 ms
333 ns
21.845 ms
250 ns
16.384 ms
(1/E)
(216/E)
0 1
1 count —
overflow —
4.0 µs
262.14 ms
2.0 µs
131.07 ms
1.333 µs
87.381 ms
1.0 µs
65.536 ms
(4/E)
(218/E)
1 0
1 count —
overflow —
8.0 µs
524.29 ms
4.0 µs
262.14 ms
2.667 µs
174.76 ms
2.0 µs
131.07 ms
(8/E)
(219/E)
1 1
1 count —
overflow —
16.0 µs
1.049 s
8.0 µs
524.29 ms
5.333 µs
349.52 ms
4.0 µs
262.14 ms
(16/E)
(220/E)
9.1 Timer Structure
Figure 9-2 shows the capture/compare system block diagram. The port A pin control
block includes logic for timer functions and for general-purpose I/O. For pins PA3,
PA2, PA1, and PA0, this block contains both the edge-detection logic and the control
logic that enables the selection of which edge triggers an input capture. The digital level on PA[3:0] can be read at any time (read PORTA register), even if the pin is being
used for the input capture function. Pins PA[6:3] are used for either general-purpose
I/O, or as output compare pins. When one of these pins is being used for an output
compare function, it cannot be written directly as if it were a general-purpose output.
Each of the output compare functions (OC[5:2]) is related to one of the port A output
pins. Output compare one (OC1) has extra control logic, allowing it optional control of
any combination of the PA[7:3] pins. The PA7 pin can be used as a general-purpose
I/O pin, as an input to the pulse accumulator, or as an OC1 output pin.
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TCNT (HI)
PRESCALER–DIVIDE BY
MCU
ECLK
1, 4, 8, OR 16
PR1
TCNT (LO)
16-BIT FREE-RUNNING
COUNTER
PR0
TOI
TAPS FOR RTI, COP
WATCHDOG AND
PULSE ACCUMULATOR
16-BIT TIMER BUS
9
TOF
TO
PULSE
ACCUMULATOR
INTERRUPT REQUESTS
(FURTHER QUALIFIED
BY I-BIT IN CCR)
TMSK1
OC1I
TFLG1
16-BIT COMPARATOR =
TOC1 (HI)
TOC1 (LO)
PIN
FUNCTIONS
8
BIT-7
PA7/
OC1/
PAI
BIT-6
PA6/
OC2/
OC1
BIT-5
PA5/
OC3/
OC1
BIT-4
PA4/
OC4/
OC1
BIT-3
PA3/
OC5/
IC4/
OC1
3
BIT-2
PA2/
IC1
2
BIT-1
PA1/
IC2
1
BIT-0
PA0/
IC3
CFORC
OC1F
FOC1
16-BIT COMPARATOR =
TOC2 (HI)
TOC2 (LO)
7
OC2F
FOC2
OC3I
16-BIT COMPARATOR =
TOC3 (HI)
TOC3 (LO)
6
OC3F
FOC3
OC4I
16-BIT TIMER BUS
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OC2I
16-BIT COMPARATOR =
TOC4 (HI)
TOC4 (LO)
5
OC4F
FOC4
I4/O5I
16-BIT COMPARATOR =
TI4/O5 (HI) TI4/O5 (LO)
16-BIT LATCH CLK
4
OC5
I4/O5F
FOC5
IC4
FORCE
OUTPUT
COMPARE
I4/O5
16-BIT LATCH CLK
TIC1 (HI)
TIC1 (LO)
IC1I
IC1F
IC2I
16-BIT LATCH CLK
TIC2 (HI)
TIC2 (LO)
IC2F
IC3I
16-BIT LATCH CLK
TIC3 (HI)
TIC3 (LO)
IC3F
STATUS
FLAGS
INTERRUPT
ENABLES
PORT A
PIN
CONTROL
Figure 9-2 Capture/Compare Block Diagram
TIMING SYSTEM
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Freescale Semiconductor, Inc.
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9.2 Input Capture
The input capture function records the time an external event occurs by latching the
value of the free-running counter when a selected edge is detected at the associated
timer input pin. Software can store latched values and use them to compute the periodicity and duration of events. For example, by storing the times of successive edges
of an incoming signal, software can determine the period and pulse width of a signal.
To measure period, two successive edges of the same polarity are captured. To measure pulse width, two alternate polarity edges are captured.
In most cases, input capture edges are asynchronous to the internal timer counter,
which is clocked relative to an internal clock (PH2). These asynchronous capture requests are synchronized to PH2 so that the latching occurs on the opposite half cycle
of PH2 from when the timer counter is being incremented. This synchronization process introduces a delay from when the edge occurs to when the counter value is detected. Because these delays offset each other when the time between two edges is
being measured, the delay can be ignored. When an input capture is being used with
an output compare, there is a similar delay between the actual compare point and
when the output pin changes state.
The control and status bits that implement the input capture functions are contained in
the PACTL, TCTL2, TMSK1, and TFLG1 registers.
To configure port A bit 3 as an input capture, clear the DDA3 bit of the DDRA register.
Note that this bit is cleared out of reset. To enable PA3 as the fourth input capture, set
the I4/O5 bit in the PACTL register. Otherwise, PA3 is configured as a fifth output compare out of reset, with bit I4/O5 being cleared. If the DDA3 bit is set (configuring PA3
as an output), and IC4 is enabled, then writes to PA3 cause edges on the pin to result
in input captures. Writing to TI4/O5 has no effect when the TI4/O5 register is acting as
IC4.
9.2.1 Timer Control Register 2
Use the control bits of this register to program input capture functions to detect a particular edge polarity on the corresponding timer input pin. Each of the input capture
functions can be independently configured to detect rising edges only, falling edges
only, any edge (rising or falling), or to disable the input capture function. The input capture functions operate independently of each other and can capture the same TCNT
value if the input edges are detected within the same timer count cycle.
TCTL2 — Timer Control 2
RESET:
Bit 7
EDG4B
0
6
EDG4A
0
$1021
5
EDG1B
0
4
EDG1A
0
3
EDG2B
0
2
EDG2A
0
1
EDG3B
0
Bit 0
EDG3A
0
EDGxB and EDGxA — Input Capture Edge Control
There are four pairs of these bits. Each pair is cleared to zero by reset and must be
encoded to configure the corresponding input capture edge detector circuit. IC4 functions only if the I4/O5 bit in the PACTL register is set. Refer to Table 9-2 for timer control configuration.
TIMING SYSTEM
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9.2.2 Timer Input Capture Registers
When an edge has been detected and synchronized, the 16-bit free-running counter
value is transferred into the input capture register pair as a single 16-bit parallel transfer. Timer counter value captures and timer counter incrementing occur on opposite
half-cycles of the phase 2 clock so that the count value is stable whenever a capture
occurs. The TICx registers are not affected by reset. Input capture values can be read
from a pair of 8-bit read-only registers. A read of the high-order byte of an input capture
register pair inhibits a new capture transfer for one bus cycle. If a double-byte read instruction, such as LDD, is used to read the captured value, coherency is assured.
When a new input capture occurs immediately after a high-order byte read, transfer is
delayed for an additional cycle but the value is not lost.
TIC1–TIC3 — Timer Input Capture
$1010
$1011
$1012
$1013
$1014
$1015
Bit 15
Bit 7
Bit 15
Bit 7
Bit 15
Bit 7
14
6
14
6
14
6
13
5
13
5
13
5
$1010–$1015
12
4
12
4
12
4
11
3
11
3
11
3
10
2
10
2
10
2
9
1
9
1
9
1
Bit 8
Bit 0
Bit 8
Bit 0
Bit 8
Bit 0
TIC1 (High)
TIC1 (Low)
TIC2 (High)
TIC2 (Low)
TIC3 (High)
TIC3 (Low)
TICx not affected by reset.
9.2.3 Timer Input Capture 4/Output Compare 5 Register
Use TI4/O5 as either an input capture register or an output compare register, depending on the function chosen for the PA3 pin. To enable it as an input capture pin, set the
I4/O5 bit in the pulse accumulator control register (PACTL) to logic level one. To use
it as an output compare register, set the I4/O5 bit to a logic level zero. Refer to 9.6
Pulse Accumulator.
TI4/O5 — Timer Input Capture 4/Output Compare 5
$101E
$101F
Bit 15
Bit 7
14
6
13
5
12
4
11
3
$101E, $101F
10
2
9
1
Bit 8
Bit 0
TI4/O5 (High)
TI4/O5 (Low)
The TI4/O5 register pair resets to ones ($FFFF).
9.3 Output Compare
Use the output compare (OC) function to program an action to occur at a specific time
— when the 16-bit counter reaches a specified value. For each of the five output compare functions, there is a separate 16-bit compare register and a dedicated 16-bit comparator. The value in the compare register is compared to the value of the free-running
counter on every bus cycle. When the compare register matches the counter value, an
output compare status flag is set. The flag can be used to initiate the automatic actions
for that output compare function.
TIMING SYSTEM
9-6
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To produce a pulse of a specific duration, write a value to the output compare register
that represents the time the leading edge of the pulse is to occur. The output compare
circuit is configured to set the appropriate output either high or low, depending on the
polarity of the pulse being produced. After a match occurs, the output compare register
is reprogrammed to change the output pin back to its inactive level at the next match.
A value representing the width of the pulse is added to the original value, and then written to the output compare register. Because the pin state changes occur at specific
values of the free-running counter, the pulse width can be controlled accurately at the
resolution of the free-running counter, independent of software latencies. To generate
an output signal of a specific frequency and duty cycle, repeat this pulse-generating
procedure.
There are four 16-bit read/write output compare registers: TOC1, TOC2, TOC3, and
TOC4, and the TI4/O5 register, which functions under software control as either IC4
or OC5. Each of the OC registers is set to $FFFF on reset. A value written to an OC
register is compared to the free-running counter value during each E-clock cycle. If a
match is found, the particular output compare flag is set in timer interrupt flag register
1 (TFLG1). If that particular interrupt is enabled in the timer interrupt mask register 1
(TMSK1), an interrupt is generated. In addition to an interrupt, a specified action can
be initiated at one or more timer output pins. For OC[5:2], the pin action is controlled
by pairs of bits (OMx and OLx) in the TCTL1 register. The output action is taken on
each successful compare, regardless of whether or not the OCxF flag in the TFLG1
register was previously cleared.
OC1 is different from the other output compares in that a successful OC1 compare can
affect any or all five of the OC pins. The OC1 output action taken when a match is
found is controlled by two 8-bit registers with three bits unimplemented: the output
compare 1 mask register, OC1M, and the output compare 1 data register, OC1D.
OC1M specifies which port A outputs are to be used, and OC1D specifies what data
is placed on these port pins.
9.3.1 Timer Output Compare Registers
All output compare registers are 16-bit read-write. Each is initialized to $FFFF at reset.
If an output compare register is not used for an output compare function, it can be used
as a storage location. A write to the high-order byte of an output compare register pair
inhibits the output compare function for one bus cycle. This inhibition prevents inappropriate subsequent comparisons. Coherency requires a complete 16-bit read or
write. However, if coherency is not needed, byte accesses can be used.
For output compare functions, write a comparison value to output compare registers
TOC1–TOC4 and TI4/O5. When TCNT value matches the comparison value, specified pin actions occur.
TIMING SYSTEM
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TOC1–TOC4 — Timer Output Compare
$1016
$1017
$1018
$1019
$101A
$101B
$101C
$101D
Bit 15
Bit 7
Bit 15
Bit 7
Bit 15
Bit 7
Bit 15
Bit 7
14
6
14
6
14
6
14
6
13
5
13
5
13
5
13
5
12
4
12
4
12
4
12
4
$1016–$101D
11
3
11
3
11
3
11
3
10
2
10
2
10
2
10
2
9
1
9
1
9
1
9
1
Bit 8
Bit 0
Bit 8
Bit 0
Bit 8
Bit 0
Bit 8
Bit 0
TOC1 (High)
TOC1 (Low)
TOC2 (High)
TOC2 (Low)
TOC3 (High)
TOC3 (Low)
TOC4 (High)
TOC4 (Low)
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All TOCx register pairs reset to ones ($FFFF).
9.3.2 Timer Compare Force Register
The CFORC register allows forced early compares. FOC[1:5] correspond to the five
output compares. These bits are set for each output compare that is to be forced. The
action taken as a result of a forced compare is the same as if there were a match between the OCx register and the free-running counter, except that the corresponding
interrupt status flag bits are not set. The forced channels trigger their programmed pin
actions to occur at the next timer count transition after the write to CFORC.
The CFORC bits should not be used on an output compare function that is programmed to toggle its output on a successful compare because a normal compare that
occurs immediately before or after the force can result in an undesirable operation.
CFORC — Timer Compare Force
RESET:
Bit 7
FOC1
0
6
FOC2
0
5
FOC3
0
$100B
4
FOC4
0
3
FOC5
0
2
—
0
1
—
0
Bit 0
—
0
FOC[1:5] — Force Output Comparison
When the FOC bit associated with an output compare circuit is set, the output compare
circuit immediately performs the action it is programmed to do when an output match
occurs.
0 = Not affected
1 = Output x action occurs
Bits [2:0] — Not implemented
Always read zero
9.3.3 Output Compare Mask Registers
Use OC1M with OC1 to specify the bits of port A that are affected by a successful OC1
compare. The bits of the OC1M register correspond to PA[7:3].
TIMING SYSTEM
9-8
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OC1M — Output Compare 1 Mask
RESET:
Bit 7
OC1M7
0
6
OC1M6
0
5
OC1M5
0
$100C
4
OC1M4
0
3
OC1M3
0
2
—
0
1
—
0
Bit 0
—
0
OC1M[7:3] — Output Compare Masks
0 = OC1 is disabled.
1 = OC1 is enabled to control the corresponding pin of port A
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Bits [2:0] — Not implemented
Always read zero
9.3.4 Output Compare Data Register
Use this register with OC1 to specify the data that is to be stored on the affected pin
of port A after a successful OC1 compare. When a successful OC1 compare occurs,
a data bit in OC1D is stored in the corresponding bit of port A for each bit that is set in
OC1M.
OC1D — Output Compare 1 Data
RESET:
Bit 7
OC1D7
0
6
OC1D6
0
5
OC1D5
0
$100D
4
OC1D4
0
3
OC1D3
0
2
—
0
1
—
0
Bit 0
—
0
If OC1Mx is set, data in OC1Dx is output to port A bit x on successful OC1 compares.
Bits [2:0] — Not implemented
Always read zero
9.3.5 Timer Counter Register
The 16-bit read-only TCNT register contains the prescaled value of the 16-bit timer. A
full counter read addresses the most significant byte (MSB) first. A read of this address
causes the least significant byte (LSB) to be latched into a buffer for the next CPU cycle so that a double-byte read returns the full 16-bit state of the counter at the time of
the MSB read cycle.
TCNT — Timer Counter
$100E
$100F
Bit 15
Bit 7
14
6
$100E, $100F
13
5
12
4
11
3
10
2
9
1
Bit 8
Bit 0
TCNT (High)
TCNT (Low)
TCNT resets to $0000. In normal modes, TCNT is a read-only register.
9.3.6 Timer Control Register 1
The bits of this register specify the action taken as a result of a successful OCx compare.
TIMING SYSTEM
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TCTL1 — Timer Control 1
RESET:
Bit 7
OM2
0
6
OL2
0
$1020
5
OM3
0
4
OL3
0
3
OM4
0
2
OL4
0
1
OM5
0
Bit 0
OL5
0
OM[2:5] — Output Mode
OL[2:5] — Output Level
These control bit pairs are encoded to specify the action taken after a successful OCx
compare. OC5 functions only if the I4/O5 bit in the PACTL register is clear. Refer to
Table 9-3 for the coding.
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Table 9-2 Timer Output Compare Configuration
OMx
0
0
1
1
OLx
0
1
0
1
Action Taken on Successful Compare
Timer disconnected from output pin logic
Toggle OCx output line
Clear OCx output line to zero
Set OCx output line to one
9.3.7 Timer Interrupt Mask Register 1
Use this 8-bit register to enable or inhibit the timer input capture and output compare
interrupts.
TMSK1 — Timer Interrupt Mask 1
RESET:
Bit 7
OC1I
0
6
OC2I
0
5
OC3I
0
$1022
4
OC4I
0
3
I4/O5I
0
2
IC1I
0
1
IC2I
0
Bit 0
IC3I
0
OC1I–OC4I — Output Compare x Interrupt Enable
If the OCxI enable bit is set when the OCxF flag bit is set, a hardware interrupt sequence is requested.
I4/O5I — Input Capture 4/Output Compare 5 Interrupt Enable
When I4/O5 in PACTL is one, I4/O5I is the input capture 4 interrupt enable bit. When
I4/O5 in PACTL is zero, I4/O5I is the output compare 5 interrupt enable bit.
IC1I–IC3I — Input Capture x Interrupt Enable
If the ICxI enable bit is set when the ICxF flag bit is set, a hardware interrupt sequence
is requested.
NOTE
Bits in TMSK1 correspond bit for bit with flag bits in TFLG1. Ones in
TMSK1 enable the corresponding interrupt sources.
TIMING SYSTEM
9-10
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9.3.8 Timer Interrupt Flag Register 1
Bits in this register indicate when timer system events have occurred. Coupled with
the bits of TMSK1, the bits of TFLG1 allow the timer subsystem to operate in either a
polled or interrupt driven system. Each bit of TFLG1 corresponds to a bit in TMSK1 in
the same position.
TFLG1 — Timer Interrupt Flag 1
RESET:
Bit 7
OC1F
0
6
OC2F
0
$1023
5
OC3F
0
4
OC4F
0
3
I4/O5F
0
2
IC1F
0
1
IC2F
0
Bit 0
IC3F
0
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Clear flags by writing a one to the corresponding bit position(s).
OC1F–OC4F — Output Compare x Flag
Set each time the counter matches output compare x value
I4/O5F — Input Capture 4/Output Compare 5 Flag
Set by IC4 or OC5, depending on the function enabled by I4/O5 bit in PACTL
IC1F–IC3F — Input Capture x Flag
Set each time a selected active edge is detected on the ICx input line
9.3.9 Timer Interrupt Mask Register 2
Use this 8-bit register to enable or inhibit timer overflow and real-time interrupts. The
timer prescaler control bits are included in this register.
TMSK2 — Timer Interrupt Mask 2
RESET:
Bit 7
TOI
0
6
RTII
0
$1024
5
PAOVI
0
4
PAII
0
3
—
0
2
—
0
1
PR1
0
Bit 0
PR0
0
TOI — Timer Overflow Interrupt Enable
0 = TOF interrupts disabled
1 = Interrupt requested when TOF is set to one
RTII — Real-Time Interrupt Enable
Refer to 9.4 Real-Time Interrupt.
PAOVI — Pulse Accumulator Overflow Interrupt Enable
Refer to 9.6.3 Pulse Accumulator Status and Interrupt Bits.
PAII — Pulse Accumulator Input Edge Interrupt Enable
Refer to 9.6.3 Pulse Accumulator Status and Interrupt Bits.
PR[1:0] — Timer Prescaler Select
These bits are used to select the prescaler divide-by ratio. In normal modes, PR[1:0]
can only be written once, and the write must be within 64 cycles after reset. Refer to
Table 9-1 and Table 9-4 for specific timing values.
TIMING SYSTEM
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Table 9-3 Timer Prescaler Selection
PR[1:0]
00
01
10
11
Prescaler
1
4
8
16
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NOTE
Bits in TMSK2 correspond bit for bit with flag bits in TFLG2. Ones in
TMSK2 enable the corresponding interrupt sources.
9.3.10 Timer Interrupt Flag Register 2
Bits in this register indicate when certain timer system events have occurred. Coupled
with the four high-order bits of TMSK2, the bits of TFLG2 allow the timer subsystem to
operate in either a polled or interrupt driven system. Each bit of TFLG2 corresponds
to a bit in TMSK2 in the same position.
TFLG2 — Timer Interrupt Flag 2
RESET:
Bit 7
TOF
0
6
RTIF
0
5
PAOVF
0
$1025
4
PAIF
0
3
—
0
2
—
0
1
—
0
Bit 0
—
0
Clear flags by writing a one to the corresponding bit position(s).
TOF — Timer Overflow Interrupt Flag
Set when TCNT changes from $FFFF to $0000
RTIF — Real-Time (Periodic) Interrupt Flag
Refer to 9.4 Real-Time Interrupt.
PAOVF — Pulse Accumulator Overflow Interrupt Flag
Refer to 9.6 Pulse Accumulator.
PAIF — Pulse Accumulator Input Edge Interrupt Flag
Refer to 9.6 Pulse Accumulator.
Bits [3:0] — Not implemented
Always read zero
9.4 Real-Time Interrupt
The real-time interrupt (RTI) feature, used to generate hardware interrupts at a fixed
periodic rate, is controlled and configured by two bits (RTR1 and RTR0) in the pulse
accumulator control (PACTL) register. The RTII bit in the TMSK2 register enables the
interrupt capability. The four different rates available are a product of the MCU oscillator frequency and the value of bits RTR[1:0]. Refer to Table 9-4, which shows the
periodic real-time interrupt rates.
TIMING SYSTEM
9-12
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Table 9-4 RTI Rate Selection
RTR[1:0]
0 0
0 1
1 0
1 1
E = 1 MHz
8.192 ms
16.384 ms
32.768 ms
65.536 ms
E = 2 MHz
4.096 ms
8.192 ms
16.384 ms
32.768 ms
E = 3 MHz
2.731 ms
5.461 ms
10.923 ms
21.845 ms
E = 4 MHz
2.048 ms
4.096 ms
8.192 ms
16.384 ms
E = X MHz
(213/E)
(214/E)
(215/E)
(216/E)
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The clock source for the RTI function is a free-running clock that cannot be stopped or
interrupted except by reset. This clock causes the time between successive RTI timeouts to be a constant that is independent of the software latencies associated with flag
clearing and service. For this reason, an RTI period starts from the previous time-out,
not from when RTIF is cleared.
Every time-out causes the RTIF bit in TFLG2 to be set, and if RTII is set, an interrupt
request is generated. After reset, one entire RTI period elapses before the RTIF flag
is set for the first time. Refer to the TMSK2, TFLG2, and PACTL registers.
9.4.1 Timer Interrupt Mask Register 2
This register contains the real-time interrupt enable bits.
TMSK2 — Timer Interrupt Mask Register 2
RESET:
Bit 7
TOI
0
6
RTII
0
5
PAOVI
0
4
PAII
0
$1024
3
—
0
2
—
0
1
PR1
0
Bit 0
PR0
0
TOI — Timer Overflow Interrupt Enable
0 = TOF interrupts disabled
1 = Interrupt requested when TOF is set to one
RTII — Real-Time Interrupt Enable
0 = RTIF interrupts disabled
1 = Interrupt requested when RTIF set to one
PAOVI — Pulse Accumulator Overflow Interrupt Enable
Refer to 9.6 Pulse Accumulator.
PAII — Pulse Accumulator Input Edge
Refer to 9.6 Pulse Accumulator.
PR[1:0] — Timer Prescaler Select
Refer to Table 9-4.
NOTE
Bits in TMSK2 correspond bit for bit with flag bits in TFLG2. Ones in
TMSK2 enable the corresponding interrupt sources.
TIMING SYSTEM
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9.4.2 Timer Interrupt Flag Register 2
Bits of this register indicate the occurrence of timer system events. Coupled with the
four high-order bits of TMSK2, the bits of TFLG2 allow the timer subsystem to operate
in either a polled or interrupt driven system. Each bit of TFLG2 corresponds to a bit in
TMSK2 in the same position.
TFLG2 — Timer Interrupt Flag 2
RESET:
Bit 7
TOF
0
6
RTIF
0
$1025
5
PAOVF
0
4
PAIF
0
3
—
0
2
—
0
1
—
0
Bit 0
—
0
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Clear flags by writing a one to the corresponding bit position(s).
TOF — Timer Overflow Interrupt Flag
Set when TCNT changes from $FFFF to $0000
RTIF — Real-Time Interrupt Flag
The RTIF status bit is automatically set to one at the end of every RTI period. To clear
RTIF, write a byte to TFLG2 with bit 6 set.
PAOVF — Pulse Accumulator Overflow Interrupt Flag
Refer to 9.6 Pulse Accumulator.
PAIF — Pulse Accumulator Input Edge Interrupt Flag
Refer to 9.6 Pulse Accumulator.
Bits [3:0] — Not implemented
Always read zero
9.4.3 Pulse Accumulator Control Register
Bits RTR[1:0] of this register select the rate for the RTI system. The remaining bits control the pulse accumulator and IC4/OC5 functions.
PACTL — Pulse Accumulator Control
RESET:
Bit 7
—
0
6
PAEN
0
5
PAMOD
0
4
PEDGE
0
$1026
3
—
0
2
I4/O5
0
1
RTR1
0
Bit 0
RTR0
0
Bit 7 — Not implemented
Always reads zero
PAEN — Pulse Accumulator System Enable
Refer to 9.6 Pulse Accumulator.
PAMOD — Pulse Accumulator Mode
Refer to 9.6 Pulse Accumulator.
TIMING SYSTEM
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PEDGE — Pulse Accumulator Edge Control
Refer to 9.6 Pulse Accumulator.
Bit 3 — Not implemented
Always reads zero
I4/O5 — Input Capture 4/Output Compare
Refer to 9.6 Pulse Accumulator.
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RTR[1:0] — RTI Interrupt Rate Select
These two bits determine the rate at which the RTI system requests interrupts. The
RTI system is driven by an E divided by 213 rate clock that is compensated so it is independent of the timer prescaler. These two control bits select an additional division
factor. Refer to Table 9-5.
9.5 Computer Operating Properly Watchdog Function
The clocking chain for the COP function, tapped off of the main timer divider chain, is
only superficially related to the main timer system. The CR[1:0] bits in the OPTION
register and the NOCOP bit in the CONFIG register determine the status of the COP
function. One additional register, COPRST, is used to arm and clear the COP watchdog reset system. Refer to SECTION 5 RESETS AND INTERRUPTS for a more detailed discussion of the COP function.
9.6 Pulse Accumulator
The MC68HC11F1 MCUs have an 8-bit counter that can be configured to operate either as a simple event counter, or for gated time accumulation, depending on the state
of the PAMOD bit in the PACTL register. Refer to the pulse accumulator block diagram, Figure 9-3.
In the event counting mode, the 8-bit counter is incremented by pulses on an external
pin (PAI). The maximum clocking rate for the external event counting mode is the E
clock divided by two. In gated time accumulation mode, a free-running E-clock ÷ 64
signal drives the 8-bit counter, but only while the external PAI pin is activated. Refer
to Table 9-6. The pulse accumulator counter can be read or written at any time.
TIMING SYSTEM
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PAOVI
PAOVF
1
INTERRUPT
REQUESTS
PAII
PAIF
2
PAOVF
PAIF
PAOVI
PAII
E ÷ 64 CLOCK
(FROM MAIN TIMER)
TFLG2 INTERRUPT STATUS
TMSK2 INT ENABLES
PAI EDGE
PAEN
DISABLE
FLAG SETTING
PA7/
PAI/
OC1
2:1
MUX
INPUT BUFFER
AND
EDGE DETECTOR
PAEN
PEDGE
FROM DATA
DIRECTION
BIT FOR
PORT A PIN 7
PACNT 8-BIT COUNTER
DATA BUS
OUTPUT
BUFFER
FROM
MAIN TIMER
OC1
CLOCK
ENABLE
PAEN
PAMOD
Freescale Semiconductor, Inc...
OVERFLOW
PIN
PACTL CONTROL
INTERNAL
DATA BUS
Figure 9-3 Pulse Accumulator
Table 9-5 Pulse Accumulator Timing
Crystal Frequency
(4∗E)
4.0 MHz
8.0 MHz
12.0 MHz
16.0 MHz
E Clock
(E)
1.0 MHz
2.0 MHz
3.0 MHz
4.0 MHz
Cycle Time
(1/E)
1000 ns
500 ns
333 ns
250 ns
26/E
(64/E)
64 µs
32 µs
21.33 µs
16.0 µs
PACNT Overflow
(16384/E)
16.384 ms
8.192 ms
5.461 ms
4.096 ms
Pulse accumulator control bits are also located within two timer registers, TMSK2 and
TFLG2, as described in the following paragraphs.
9.6.1 Pulse Accumulator Control Register
Four of this register's bits control an 8-bit pulse accumulator system. Another bit enables either the OC5 function or the IC4 function, while two other bits select the rate
for the real-time interrupt system.
TIMING SYSTEM
9-16
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PACTL — Pulse Accumulator Control
RESET:
Bit 7
—
0
6
PAEN
0
5
PAMOD
0
$1026
4
PEDGE
0
3
—
0
2
I4/O5
0
1
RTR1
0
Bit 0
RTR0
0
Bit 7 — Not implemented
Always reads zero
Freescale Semiconductor, Inc...
PAEN — Pulse Accumulator System Enable
0 = Pulse accumulator disabled
1 = Pulse accumulator enabled
PAMOD — Pulse Accumulator Mode
0 = Event counter
1 = Gated time accumulation
PEDGE — Pulse Accumulator Edge Control
This bit has different meanings depending on the state of the PAMOD bit, as shown in
Table 9-6.
Table 9-6 Pulse Accumulator Edge Detection Control
PAMOD
0
0
1
1
PEDGE
0
1
0
1
Action on Clock
PAI falling edge increments the counter.
PAI rising edge increments the counter.
A zero on PAI inhibits counting.
A one on PAI inhibits counting.
Bit 3 — Not implemented
Always reads zero
I4/O5 — Input Capture 4/Output Compare 5
0 = Output compare 5 function enable (No IC4)
1 = Input capture 4 function enable (No OC5)
RTR[1:0] — RTI Interrupt Rate Selects
Refer to 9.4 Real-Time Interrupt.
9.6.2 Pulse Accumulator Count Register
This 8-bit read/write register contains the count of external input events at the PAI input, or the accumulated count. The PACNT is readable even if PAI is not active in gated time accumulation mode. The counter is not affected by reset and can be read or
written at any time. Counting is synchronized to the internal PH2 clock so that incrementing and reading occur during opposite half cycles.
PACNT — Pulse Accumulator Count
Bit 7
Bit 7
6
6
5
5
$1027
4
4
3
3
2
2
1
1
Bit 0
Bit 0
TIMING SYSTEM
TECHNICAL DATA
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9.6.3 Pulse Accumulator Status and Interrupt Bits
The pulse accumulator control bits, PAOVI, PAII, PAOVF, and PAIF are located within
timer registers TMSK2 and TFLG2.
TMSK2 — Timer Interrupt Mask 2 Register
RESET:
Bit 7
TOI
0
6
RTII
0
5
PAOVI
0
4
PAII
0
$1024
3
—
0
2
—
0
1
PR1
0
Bit 0
PR0
0
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TFLG2 — Timer Interrupt Flag 2 Register
RESET:
Bit 7
TOF
0
6
RTIF
0
5
PAOVF
0
4
PAIF
0
$1025
3
—
0
2
—
0
1
—
0
Bit 0
—
0
PAOVI and PAOVF — Pulse Accumulator Interrupt Enable and Overflow Flag
The PAOVF status bit is set each time the pulse accumulator count rolls over from $FF
to $00. To clear this status bit, write a one in the corresponding data bit position (bit 5)
of the TFLG2 register. The PAOVI control bit allows configuring the pulse accumulator
overflow for polled or interrupt-driven operation and does not affect the state of
PAOVF. When PAOVI is zero, pulse accumulator overflow interrupts are inhibited, and
the system operates in a polled mode, which requires that PAOVF be polled by user
software to determine when an overflow has occurred. When the PAOVI control bit is
set, a hardware interrupt request is generated each time PAOVF is set. Before leaving
the interrupt service routine, software must clear PAOVF by writing to the TFLG2 register.
PAII and PAIF — Pulse Accumulator Input Edge Interrupt Enable and Flag
The PAIF status bit is automatically set each time a selected edge is detected at the
PA7/PAI/OC1 pin. To clear this status bit, write to the TFLG2 register with a one in the
corresponding data bit position (bit 4). The PAII control bit allows configuring the pulse
accumulator input edge detect for polled or interrupt-driven operation but does not affect setting or clearing the PAIF bit. When PAII is zero, pulse accumulator input interrupts are inhibited, and the system operates in a polled mode. In this mode, the PAIF
bit must be polled by user software to determine when an edge has occurred. When
the PAII control bit is set, a hardware interrupt request is generated each time PAIF is
set. Before leaving the interrupt service routine, software must clear PAIF by writing to
the TFLG2 register.
TIMING SYSTEM
9-18
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SECTION 10 ANALOG-TO-DIGITAL CONVERTER
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The analog-to-digital (A/D) system, a successive approximation converter, uses an allcapacitive charge redistribution technique to convert analog signals to digital values.
10.1 Overview
The A/D system is an 8-channel, 8-bit, multiplexed-input converter. The AVDD pin is
used to input supply voltage to the A/D converter. This allows the supply voltage to be
bypassed independently. The converter does not require external sample and hold circuits because of the type of charge redistribution technique used. A/D converter timing
can be synchronized to the system E clock, or to an internal resistor capacitor (RC)
oscillator. The A/D converter system consists of four functional blocks: multiplexer, analog converter, digital control, and result storage. Refer to Figure 10-1.
10.1.1 Multiplexer
The multiplexer selects one of 16 inputs for conversion. Input selection is controlled by
the value of bits CD–CA in the ADCTL register. The eight port E pins are fixed-direction analog inputs to the multiplexer, and internal analog signal lines are routed to it.
ANALOG-TO-DIGITAL CONVERTER
TECHNICAL DATA
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10-1
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PE0/
AN0
VRH
8-BIT CAPACITIVE DAC
WITH SAMPLE AND HOLD
PE1/
AN1
VRL
PE2/
AN2
PE3/
AN3
SUCCESSIVE APPROXIMATION
REGISTER AND CONTROL
RESULT
ANALOG
MUX
PE5/
AN5
INTERNAL
DATA BUS
PE7/
AN7
SCAN
MULT
CD
CC
CB
CA
PE6/
AN6
CCF
Freescale Semiconductor, Inc...
PE4/
AN4
ADCTL A/D CONTROL
RESULT REGISTER INTERFACE
ADDR 1 A/D RESULT 1
ADDR 2 A/D RESULT 2
ADDR 3 A/D RESULT 3
ADDR 4 A/D RESULT 4
Figure 10-1 A/D Converter Block Diagram
Port E pins can also be used as digital inputs. Reads of port E pins are not recommended during the sample portion of an A/D conversion cycle, when the gate signal
to the N-channel input gate is on. Because no P-channel devices are directly connected to either input pins or reference voltage pins, voltages above VDD do not cause a
latchup problem, although current should be limited according to maximum ratings.
Refer to Figure 10-2, which is a functional diagram of an input pin.
ANALOG-TO-DIGITAL CONVERTER
10-2
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ANALOG
INPUT
PIN
INPUT
PROTECTION
DEVICE
DIFFUSION AND
POLY COUPLER
≤ 4 kΩ
< 2 pF
+ ~ 20 V
– ~ 0.7 V
*
400 nA
JUNCTION
LEAKAGE
~ 20 pF
DAC
CAPACITANCE
VRL
Freescale Semiconductor, Inc...
* This analog switch is closed only during the 12-cycle sample time.
Figure 10-2 Electrical Model of an A/D Input Pin (Sample Mode)
10.1.2 Analog Converter
Conversion of an analog input selected by the multiplexer occurs in this block. It contains a digital-to-analog capacitor (DAC) array, a comparator, and a successive approximation register (SAR). Each conversion is a sequence of eight comparison
operations, beginning with the most significant bit (MSB). Each comparison determines the value of a bit in the successive approximation register.
The DAC array performs two functions. It acts as a sample and hold circuit during the
entire conversion sequence, and provides comparison voltage to the comparator during each successive comparison.
The result of each successive comparison is stored in the SAR. When a conversion
sequence is complete, the contents of the SAR are transferred to the appropriate result register.
A charge pump provides switching voltage to the gates of analog switches in the multiplexer. Charge pump output must stabilize between 7 and 8 volts, thus a delay of up
to 100 µs must be imposed after setting ADPU before the converter can be used. The
charge pump is enabled by the ADPU bit in the OPTION register.
Power is provided to the A/D converter system through the AVDD and AVSS pins.
10.1.3 Digital Control
All A/D converter operations are controlled by bits in register ADCTL. In addition to selecting the analog input to be converted, ADCTL bits indicate conversion status, and
control whether single or continuous conversions are performed. Finally, the ADCTL
bits determine whether conversions are performed on single or multiple channels.
10.1.4 Result Registers
Four 8-bit registers (ADR1–ADR4) store conversion results. Each of these registers
can be accessed by the processor in the CPU. The conversion complete flag (CCF)
ANALOG-TO-DIGITAL CONVERTER
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10-3
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indicates when valid data is present in the result registers. The result registers are written during a portion of the system clock cycle when reads do not occur, so there is no
conflict.
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10.1.5 A/D Converter Clocks
The CSEL bit in the OPTION register selects whether the A/D converter uses the system E clock or an internal RC oscillator for synchronization. When the A/D system is
operating with the MCU E clock, all switching and comparator functions are synchronized to the MCU clocks. This allows the comparator results to be sampled at relatively
quiet clock times to minimize noise errors.
When E-clock frequency is below 750 kHz, charge leakage in the capacitor array can
cause errors, and the internal oscillator should be used. The RC clock is asynchronous
to the MCU internal E clock. Therefore, when the RC clock is used, additional errors
can occur because the comparator is sensitive to the additional system clock noise.
10.1.6 Conversion Sequence
A/D converter operations are performed in sequences of four conversions each. A
conversion sequence can repeat continuously or stop after one iteration. The conversion complete flag (CCF) is set after the fourth conversion in a sequence to show the
availability of data in the result registers. Figure 10-3 shows the timing of a typical sequence. Synchronization is referenced to the system E clock.
E CLOCK
WRITE
TO
ADCTL
MSB
4
CYCLES
12 E CYCLES
SAMPLE ANALOG INPUT
BIT 6
2
CYC
BIT 5
2
CYC
BIT 4
2
CYC
BIT 3
2
CYC
BIT 2
2
CYC
BIT 1
2
CYC
SUCCESSIVE APPROXIMATION SEQUENCE
LSB
2
CYC
2
CYC
END
REPEAT
SEQUENCE
IF
SCAN = 1
SET
CCF
FLAG
0
CONVERT FIRST
CHANNEL
AND UPDATE ADDR1
32
CONVERT SECOND
CHANNEL
AND UPDATE ADDR2
64
CONVERT THIRD
CHANNEL
AND UPDATE ADDR3
96
CONVERT FOURTH
CHANNEL
AND UPDATE ADDR4
128
E
CYCLES
Figure 10-3 A/D Conversion Sequence
ANALOG-TO-DIGITAL CONVERTER
10-4
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10.2 A/D Converter Power-Up and Clock Select
Bit 7 of the OPTION register controls A/D converter power up. Clearing ADPU removes power from and disables the A/D converter system. Setting ADPU enables the
A/D converter system. Stabilization of the analog bias voltages requires a delay of as
much as 100 µs after turning on the A/D converter. When the A/D converter system is
operating with the MCU E clock, all switching and comparator operations are synchronized to the MCU clocks. This allows the comparator results to be sampled at quiet
times, which minimizes noise errors. The internal RC oscillator is asynchronous to the
MCU clock, so noise affects A/D converter results, which lowers accuracy slightly
while CSEL = 1.
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OPTION — System Configuration Options
RESET:
Bit 7
ADPU
0
6
CSEL
0
5
IRQE*
0
4
DLY*
1
$1039
3
CME
0
2
FCME*
0
1
CR1*
0
Bit 0
CR0*
0
*Can be written only once in first 64 cycles out of reset in normal modes, or at any time in special modes
ADPU — A/D Power-Up
0 = A/D powered down
1 = A/D powered up
CSEL — Clock Select
0 = A/D and EEPROM use system E clock
1 = A/D and EEPROM use internal RC clock
IRQE — Configure IRQ for Edge-Sensitive Only Operation
Refer to SECTION 5 RESETS AND INTERRUPTS.
DLY — Enable Oscillator Start-up Delay
Refer to SECTION 5 RESETS AND INTERRUPTS.
CME — Clock Monitor Enable
Refer to SECTION 5 RESETS AND INTERRUPTS.
FCME — Force Clock Monitor Enable
Refer to SECTION 5 RESETS AND INTERRUPTS.
CR[1:0] — COP Timer Rate Select Bits
Refer to SECTION 5 RESETS AND INTERRUPTS and SECTION 9 TIMING SYSTEM.
10.3 Conversion Process
The A/D conversion sequence begins one E-clock cycle after a write to the A/D control/
status register, ADCTL. The bits in ADCTL select the channel and the mode of conversion.
An input voltage equal to VRL converts to $00 and an input voltage equal to VRH converts to $FF (full scale), with no overflow indication. For ratiometric conversions of this
type, the source of each analog input should use VRH as the supply voltage and be
referenced to VRL.
ANALOG-TO-DIGITAL CONVERTER
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10.4 Channel Assignments
The multiplexer allows the A/D converter to select one of sixteen analog signals. Eight
of these channels correspond to port E input lines, four of the channels are internal
reference points or test functions, and four channels are reserved. Refer to Table 101.
Freescale Semiconductor, Inc...
Table 10-1 A/D Converter Channel Assignments
Channel
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
Channel
Signal
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
Reserved
Reserved
Reserved
Reserved
VRH*
Result in ADRx if
MULT = 1
ADR1
ADR2
ADR3
ADR4
ADR1
ADR2
ADR3
ADR4
—
—
—
—
ADR1
14
VRL*
ADR2
15
(VRH)/2*
ADR3
16
Reserved*
ADR4
*Used for factory testing
10.5 Single-Channel Operation
There are two types of single-channel operation. When SCAN = 0, the first type, the
single selected channel is converted four consecutive times. The first result is stored
in A/D result register 1 (ADR1), and the fourth result is stored in ADR4. After the fourth
conversion is complete, all conversion activity is halted until a new conversion command is written to the ADCTL register. In the second type of single-channel operation,
SCAN = 1, conversions continue to be performed on the selected channel with the fifth
conversion being stored in register ADR1 (overwriting the first conversion result), the
sixth conversion overwriting ADR2, and so on.
10.6 Multiple-Channel Operation
There are two types of multiple-channel operation. When SCAN = 0, the first type, a
selected group of four channels is converted one time each. The first result is stored
in A/D result register 1 (ADR1), and the fourth result is stored in ADR4. After the fourth
conversion is complete, all conversion activity is halted until a new conversion command is written to the ADCTL register. In the second type of multiple-channel operation, SCAN = 1, conversions continue to be performed on the selected group of
channels with the fifth conversion being stored in register ADR1 (replacing the earlier
conversion result for the first channel in the group), the sixth conversion overwriting
ADR2, and so on.
ANALOG-TO-DIGITAL CONVERTER
10-6
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10.7 Operation in STOP and WAIT Modes
If a conversion sequence is in progress when either the STOP or WAIT mode is entered, the conversion of the current channel is suspended. When the MCU resumes
normal operation, that channel is resampled and the conversion sequence is resumed.
As the MCU exits the WAIT mode, the A/D circuits are stable and valid results can be
obtained on the first conversion. However, in STOP mode, all analog bias currents are
disabled and it is necessary to allow a stabilization period when leaving the STOP
mode. If the STOP mode is exited with a delay (DLY = 1), there is enough time for
these circuits to stabilize before the first conversion. If the STOP mode is exited with
no delay (DLY bit in OPTION register = 0), allow 10 ms for the A/D circuitry to stabilize
to avoid invalid results.
10.8 A/D Control/Status Registers
All bits in this register can be read or written, except CCF (bit 7), which is a read-only
status indicator, and bit 6, which always reads as zero. Write to ADCTL to initiate a
conversion. To quit a conversion in progress, write to this register and a new conversion sequence begins immediately.
ADCTL — A/D Control/Status
RESET:
Bit 7
CCF
1
6
—
0
5
SCAN
I
$1030
4
MULT
I
3
CD
I
2
CC
I
1
CB
I
Bit 0
CA
I
CCF — Conversions Complete Flag
A read-only status indicator, this bit is set when all four A/D result registers contain valid conversion results. Each time the ADCTL register is overwritten, this bit is automatically cleared to zero and a conversion sequence is started. In the continuous mode,
CCF is set at the end of the first conversion sequence.
Bit 6 — Not implemented
Always reads zero
SCAN — Continuous Scan Control
When this control bit is clear, the four requested conversions are performed once to
fill the four result registers. When this control bit is set, conversions continue in a
round-robin fashion with the result registers updated as data becomes available.
MULT — Multiple Channel/Single Channel Control
When this bit is clear, the A/D converter system is configured to perform four consecutive conversions on the single channel specified by the four channel select bits CD–
CA (bits [3:0] of the ADCTL register). When this bit is set, the A/D system is configured
to perform a conversion on each of four channels where each result register corresponds to one channel.
ANALOG-TO-DIGITAL CONVERTER
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NOTE
When the multiple-channel continuous scan mode is used, extra care
is needed in the design of circuitry driving the A/D inputs. The charge
on the capacitive DAC array before the sample time is related to the
voltage on the previously converted channel. A charge share situation exists between the internal DAC capacitance and the external
circuit capacitance. Although the amount of charge involved is small,
the rate at which it is repeated is every 64 µs for an E clock of 2 MHz.
The RC charging rate of the external circuit must be balanced against
this charge sharing effect to avoid errors in accuracy. Refer to
M68HC11 Reference Manual (M68HC11RM/AD) for further information.
CD–CA — Channel Selects D–A
Refer to Table 10-2. When a multiple channel mode is selected (MULT = 1), the two
least significant channel select bits (CB and CA) have no meaning and the CD and CC
bits specify which group of four channels is to be converted.
Table 10-2 A/D Converter Channel Selection
Channel Select
Control Bits
CD:CC:CB:CA
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
Channel Signal
Result in ADRx if
MULT = 1
AN0
AN1
AN2
AN3
AN4
AN5
AN6
AN7
Reserved
Reserved
Reserved
Reserved
VRH*
ADR1
ADR2
ADR3
ADR4
ADR1
ADR2
ADR3
ADR4
—
—
—
—
ADR1
1101
VRL*
ADR2
1110
(VRH)/2*
ADR3
1111
Reserved*
ADR4
*Used for factory testing
10.9 A/D Converter Result Registers
These read-only registers hold an 8-bit conversion result. Writes to these registers
have no effect. Data in the A/D converter result registers is valid when the CCF flag in
the ADCTL register is set, indicating a conversion sequence is complete. If conversion
results are needed sooner, refer to Figure 10-3, which shows the A/D conversion sequence diagram.
ANALOG-TO-DIGITAL CONVERTER
10-8
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ADR1–ADR4 — A/D Results
Bit 7
Bit 7
Bit 7
Bit 7
6
6
6
6
5
5
5
5
4
4
4
4
3
3
3
3
2
2
2
2
1
1
1
1
Bit 0
Bit 0
Bit 0
Bit 0
ADR1
ADR2
ADR3
ADR4
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$1031
$1032
$1033
$1034
$1031–$1034
ANALOG-TO-DIGITAL CONVERTER
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10-9
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ANALOG-TO-DIGITAL CONVERTER
10-10
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APPENDIX A ELECTRICAL CHARACTERISTICS
This appendix contains electrical parameters for the MC68HC11F1 microcontroller.
Table A-1 Maximum Ratings
Freescale Semiconductor, Inc...
Rating
Symbol
Value
Unit
Supply Voltage
VDD
– 0.3 to + 7.0
V
Input Voltage
Vin
– 0.3 to + 7.0
V
Operating Temperature Range
MC68HC11F1
MC68HC11F1C
MC68HC11F1V
MC68HC11F1M
TA
TL to TH
0 to + 70
– 40 to + 85
– 40 to + 105
– 40 to + 125
°C
Storage Temperature Range
Tstg
– 55 to + 150
°C
ID
25
mA
Current Drain per Pin*
Excluding VDD, VSS, AVDD, VRH, and VRL
*One pin at a time, observing maximum power dissipation limits.
Internal circuitry protects the inputs against damage caused by high static voltages or
electric fields; however, normal precautions are necessary to avoid application of any
voltage higher than maximum-rated voltages to this high-impedance circuit. Extended
operation at the maximum ratings can adversely affect device reliability. Tying unused
inputs to an appropriate logic voltage level (either GND or VDD) enhances reliability of
operation.
ELECTRICAL CHARACTERISTICS
TECHNICAL DATA
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A-1
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Table A-2 Thermal Characteristics
Characteristic
Symbol
Value
Unit
TJ
TA + (PD x QJA)
°C
Ambient Temperature
TA
User-determined
°C
Package Thermal Resistance (Junction-to-Ambient)
68-Pin Plastic Leaded Chip Carrier
80-Pin Low Profile Quad Flat Pack (LQFP, 1.4 mm Thick)
QJA
50
80
°C/W
°C/W
Total Power Dissipation
PD
PINT + PI/O
K / (TJ + 273°C)
W
Average Junction Temperature
(Note 1)
PINT
IDD x VDD
W
I/O Pin Power Dissipation
(Note 2)
PI/O
User-determined
W
A Constant
(Note 3)
K
PD x (TA + 273°C) +
QJA x PD2
W x °C
Device Internal Power Dissipation
Freescale Semiconductor, Inc...
NOTES:
1 This is an approximate value, neglecting PI/O.
2. For most applications PI/O « PINT and can be neglected.
3. K is a constant pertaining to the device. Solve for K with a known TA and a measured PD (at equilibrium. Use
this value of K to solve for PD and TJ iteratively for any value of TA
ELECTRICAL CHARACTERISTICS
A-2
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Table A-3 DC Electrical Characteristics
VDD = 5.0 Vdc ± 5%, VSS = 0 Vdc, TA = TL to TH, unless otherwise noted
Characteristic
Symbol
Min
Max
Unit
Output Voltage (Note 1)
All Outputs except XTAL
All Outputs Except XTAL, RESET, and MODA
ILoad = ± 10.0 µA
VOL
VOH
—
VDD – 0.1
0.1
—
V
V
VOH
VDD – 0.8
—
V
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Output High Voltage (Note 1)
All Outputs Except XTAL, RESET, and MODA
ILoad = – 0.8 mA, VDD = 4.5 V
Output Low Voltage
ILoad = 1.6 mA
All Outputs Except XTAL
VOL
—
0.4
V
Input High Voltage
All Inputs Except RESET
RESET
VIH
0.7 x VDD
0.8 x VDD
VDD + 0.3
VDD + 0.3
V
V
Input Low Voltage
All Inputs
VIL
VSS – 0.3
0.2 x VDD
V
Ports A, B, C, D, F, G
MODA/LIR, RESET
IOZ
—
±10
µA
Input Leakage Current (Note 2)
IRQ, XIRQ on standard devices
Vin = VDD or VSS
Vin = VDD or VSS
MODB/VSTBY,
XIRQ on EPROM devices
Iin
—
±1
µA
—
±10
µA
Input Current with Pull-Up Resistors
Vin = VIL
lipr
100
500
µA
I/O Ports, Three-State Leakage
Vin = VIH or VIL
Ports B, F, and G
RAM Standby Voltage
Power down
VSB
4.0
VDD
V
RAM Standby Current
Power down
ISB
—
20
µA
PE[7:0], IRQ, XIRQ, EXTAL
Ports A, B, C, D, F, G, MODA/LIR, RESET
Cin
—
—
8
12
pF
pF
—
—
—
90
200
30
pF
pF
pF
Input Capacitance
Output Load Capacitance
All Outputs Except PD[4:1],
4XOUT, XTAL, MODA/LIR
PD[4:1]
4XOUT
Characteristic
Maximum Total Supply Current (Note 3)
RUN:
Expanded Mode
WAIT: (All Peripheral Functions Shut Down)
Expanded Mode
STOP:
No Clocks, Expanded Mode
Maximum Power Dissipation
Expanded Mode
CL
Symbol
IDD
WIDD
SIDD
PD
2 MHz
3 MHz
4 MHz
Unit
27
38
50
mA
15
20
25
mA
50
50
50
µA
149
209
275
mW
NOTES:
1. VOH specification for RESET and MODA is not applicable because they are open-drain pins. VOH specification
not applicable to ports C and D in wired-OR mode.
2. Refer to A/D specification for leakage current for port E.
3. EXTAL is driven with a square wave, and
tcyc = 500 ns for 2 MHz rating;
tcyc = 333 ns for 3 MHz rating;
tcyc = 250 ns for 4 MHz rating;
VIL ≤ 0.2 V; VIH ≥ VDD – 0.2 V; No dc loads.
ELECTRICAL CHARACTERISTICS
TECHNICAL DATA
For More Information On This Product,
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A-3
Freescale Semiconductor, Inc.
CLOCKS/
STROBES
~VDD
VDD – 0.8 V
0.4 V
0.4 V
~VSS
NOM
NOM
70% OF VDD
INPUTS
20% OF VDD
NOMINAL TIMING
~VDD
VDD – 0.8 V
0.4 V
OUTPUTS
~VSS
Freescale Semiconductor, Inc...
DC TESTING
CLOCKS/
STROBES
~VDD
70% OF VDD
20% OF VDD
~VSS
20% OF VDD
SPEC
70% OF VDD
20% OF VDD
INPUTS
SPEC
70% OF VDD
20% OF VDD
VDD – 0.8 V
0.4 V
SPEC TIMING
~VDD
OUTPUTS
~VSS
70% OF VDD
20% OF VDD
AC TESTING
NOTES:
1. Full test loads are applied during all DC electrical tests and AC timing measurements.
2. During AC timing measurements, inputs are driven to 0.4 volts and VDD – 0.8 volts while timing measurements are
taken at the 20% and 70% of VDD points.
Figure A-1 Test Methods
ELECTRICAL CHARACTERISTICS
A-4
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MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
Table A-4 Control Timing
VDD = 5.0 Vdc ± 5%, VSS = 0 Vdc, TA = TL to TH
Characteristic
Symbol
Frequency of Operation
E-Clock Period
Crystal Frequency
External Oscillator Frequency
Freescale Semiconductor, Inc...
Processor Control Setup Time
tPCSU = 1/4 tcyc + 50 ns
2.0 MHz
Min
Max
fo
dc
tcyc
500
fXTAL
—
4 fo
dc
tPCSU
3.0 MHz
Min
Max
2.0
dc
—
333
8.0
—
8.0
dc
175
—
16
1
—
—
Reset Input Pulse Width (Notes 2, 3)
PWRSTL
(To Guarantee External Reset Vector)
(Minimum Input Time;
Can Be Preempted by Internal Reset)
4.0 MHz
Unit
Min
Max
3.0
dc
4.0
MHz
—
250
—
ns
12.0
—
16.0
MHz
12.0
dc
16.0
MHz
133
—
113
—
ns
16
1
—
—
16
1
—
—
tcyc
tcyc
Mode Programming Setup Time
tMPS
2
—
2
—
2
—
tcyc
Mode Programming Hold Time
tMPH
10
—
10
—
10
—
ns
PWIRQ
520
—
353
—
270
—
ns
Interrupt Pulse Width, IRQ Edge-Sensitive Mode
PWIRQ = tcyc + 20 ns
Wait Recovery Startup Time
Timer Pulse Width, Input Capture Pulse Accumulator
Input
PWTIM = tcyc + 20 ns
tWRS
—
4
—
4
—
4
tcyc
PWTIM
520
—
353
—
270
—
ns
NOTES:
1. All timing is shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
2. RESET is recognized during the first clock cycle it is held low. Internal circuitry then drives the pin low for four
clock cycles, releases the pin, and samples the pin level two cycles later to determine the source of the interrupt.
Refer to SECTION 5 RESETS AND INTERRUPTS for further detail.
3. PWRSTL = 8 tcyc minimum on mask set C94R only.
PA[3:0]1
PA[3:0]2
PA71,3
PWTIM
PA72,3
NOTES:
1. Rising edge sensitive input.
2. Falling edge sensitive input.
3. Maximum pulse accumulator clocking rate is E-clock frequency divided by 2.
Figure A-2 Timer Inputs
ELECTRICAL CHARACTERISTICS
TECHNICAL DATA
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A-5
FFFE
ADDRESS
MODA, MODB
RESET
E
EXTAL
VDD
4064 tCYC
FFFE
FFFE
FFFE
FFFE
FFFF
tPCSU
NEW
PC
FFFE
PWRSTL
tMPS
Freescale Semiconductor, Inc...
FFFE
tMPH
FFFE
FFFE
FFFF
NEW
PC
Freescale Semiconductor, Inc.
Figure A-3 POR External Reset Timing Diagram
ELECTRICAL CHARACTERISTICS
A-6
For More Information On This Product,
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MC68HC11F1
TECHNICAL DATA
TECHNICAL DATA
STOP
ADDR + 1
STOP
ADDR
5
ADDRESS
PWIRQ
tSTOPDELAY3
NOTES:
1. Edge Sensitive IRQ pin (IRQE bit = 1)
2. Level sensitive IRQ pin (IRQE bit = 0)
3. tSTOPDELAY = 4064 tCYC if DLY bit = 1 or 4 tCYC if DLY = 0.
4. XIRQ with X bit in CCR = 1.
5. IRQ or (XIRQ with X bit in CCR = 0).
STOP
ADDR + 1
STOP
ADDR
4
ADDRESS
E
IRQ2
OR XIRQ
IRQ1
INTERNAL
CLOCKS
STOP
ADDR + 1
STOP
ADDR + 1
STOP SP…SP–7
ADDR+2
SP – 8
SP – 8
FFF2
(FFF4)
FFF3
(FFF5)
NEW
PC
RESUME PROGRAM WITH INSTR WHICH FOLLOWS THE STOP INSTR
OPCODE
Freescale Semiconductor, Inc...
Freescale Semiconductor, Inc.
Figure A-4 STOP Recovery Timing Diagram
ELECTRICAL CHARACTERISTICS
For More Information On This Product,
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A-7
A-8
WAIT
ADDR
WAIT
ADDR+1
PCL
SP
NOTE: RESET also causes recovery from WAIT.
R/W
ADDRESS
IRQ, XIRQ,
OR INTERNAL
INTERRUPTS
E
SP – 2…SP – 8
STACK REGISTERS
PCH, YL, YH, XL, XH, A, B, CCR
SP – 1
SP – 8
SP – 8…SP – 8
SP – 8
tPCSU
SP – 8
tWRS
Freescale Semiconductor, Inc...
SP – 8
VECTOR
ADDR
VECTOR
ADDR+1
NEW
PC
Freescale Semiconductor, Inc.
Figure A-5 WAIT Recovery from Interrupt Timing Diagram
ELECTRICAL CHARACTERISTICS
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MC68HC11F1
TECHNICAL DATA
TECHNICAL DATA
––
OP
CODE
DATA
NOTES:
1. Edge sensitive IRQ pin (IRQE bit = 1).
2. Level sensitive IRQ pin (IRQE bit = 0).
R/W
NEXT
OP + 1
NEXT
OPCODE
PWIRQ
tPCSU
ADDRESS
IRQ2, XIRQ
OR INTERNAL
INTERRUPT
IRQ1
E
PCL
SP
PCH
SP – 1
IYL
SP – 2
IYH
SP – 3
IXL
SP – 4
IXH
SP – 5
B
SP – 6
A
SP – 7
Freescale Semiconductor, Inc...
CCR
SP – 8
––
SP – 8
VECT
MSB
VECTOR
ADDR
VECT
LSB
VECTOR
ADDR+1
OP
CODE
NEW
PC
Freescale Semiconductor, Inc.
Figure A-6 Interrupt Timing Diagram
ELECTRICAL CHARACTERISTICS
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A-9
Freescale Semiconductor, Inc.
Table A-5 Peripheral Port Timing
VDD = 5.0 Vdc ± 5%, VSS = 0 Vdc, TA = TL to TH
Characteristic
Symbol
Max
3.0 MHz
Min
Max
4.0 MHz
Min
Max
Unit
fo
dc
2.0
dc
3.0
dc
4.0
MHz
tcyc
500
—
333
—
250
—
ns
Peripheral Data Setup Time
(MCU Read of Ports A, C, D, E, G)
tPDSU
100
—
100
—
100
—
ns
Peripheral Data Hold Time
(MCU Read of Ports A, C, D, E, G)
tPDH
50
—
50
—
50
—
ns
Delay Time, Peripheral Data Write
(MCU Write to Port A)
(MCU Write to Ports B, C, D, F, and G
tPWD = 1/4 tcyc + 100 ns)
tPWD
—
—
200
225
—
—
200
183
—
—
200
162
Frequency of Operation (E-Clock Frequency)
E-Clock Period
Freescale Semiconductor, Inc...
2.0 MHz
Min
ns
NOTES:
1. Ports C, D, and G timing is valid for active drive (CWOM, DWOM, and GWOM bits cleared).
2. All timing is shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
MCU READ OF PORT
E
tPDSU
tPDH
PORTS A, C, D, F
tPDSU
tPDH
PORTS B, E, G
Figure A-7 Port Read Timing Diagram
MCU WRITE TO PORT
E
tPWD
PORTS C, D, F
PREVIOUS PORT DATA
NEW DATA VALID
tPWD
PORTS A, B, G
PREVIOUS PORT DATA
NEW DATA VALID
Figure A-8 Port Write Timing Diagram
ELECTRICAL CHARACTERISTICS
A-10
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MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
Table A-6 Analog-To-Digital Converter Characteristics
VDD = 5.0 Vdc ± 5%, VSS = 0 Vdc, TA = TL to TH, 750 kHz ≤ E ≤ 3.0 MHz, unless otherwise noted
Characteristic
Parameter
Min
Absolute
2.0 MHz 3.0 MHz 4.0 MHz Unit
Freescale Semiconductor, Inc...
Max
Max
Max
Resolution
Number of Bits Resolved by A/D Converter
—
8
—
—
—
Bits
Non-Linearity
Maximum Deviation from the Ideal A/D Transfer
Characteristics
—
—
±1
±1
±1
LSB
Zero Error
Difference Between the Output of an Ideal and
an Actual for Zero Input Voltage
—
—
±1
±1
±1
LSB
Full Scale Error
Difference Between the Output of an Ideal and
an Actual A/D for Full-Scale Input Voltage
—
—
±1
±1
±1
LSB
Total Unadjusted Maximum Sum of Non-Linearity, Zero Error, and
Error
Full-Scale Error
—
—
± 1/2
Quantization
Error
Uncertainty Because of Converter Resolution
—
—
± 1/2
± 1/2
± 1/2
LSB
Absolute
Accuracy
Difference Between the Actual Input Voltage and
the Full-Scale Weighted Equivalent of the Binary
Output Code, All Error Sources Included
—
—
±1
±2
±2
LSB
Conversion
Range
Analog Input Voltage Range
VRL
—
VRH
VRH
VRH
V
VRH
Maximum Analog Reference Voltage
(Note 2)
VRL
—
VDD +
0.1
VDD +
0.1
VDD +
0.1
V
VRL
Minimum Analog Reference Voltage
(Note 2)
VSS –0.1
—
VRH
VRH
VRH
V
∆VR
Minimum Difference between VRH and VRL
(Note 2)
3
—
—
—
—
V
Conversion
Time
Total Time to Perform a Single
Analog-to-Digital Conversion:
—
—
32
—
E Clock
Internal RC Oscillator
± 1 1/2 ± 1 1/2
LSB
—
—
—
tcyc
tcyc + 32 tcyc + 32 tcyc + 32 µs
Monotonicity
Conversion Result Never Decreases with an
Increase in Input Voltage and has no Missing
Codes
Zero Input
Reading
Conversion Result when Vin = VRL
00
—
—
—
—
Hex
Full Scale
Reading
Conversion Result when Vin = VRH
—
—
FF
FF
FF
Hex
—
—
12
—
—
12
—
12
—
12
tcyc
µs
Sample
Analog Input Acquisition Sampling Time:
Acquisition Time
E Clock
Internal RC Oscillator
Guaranteed
Sample/Hold
Capacitance
Input Capacitance during Sample PE[7:0]
—
20 (Typ)
—
—
—
pF
Input Leakage
Input Leakage on A/D Pins
—
—
—
—
400
1.0
400
1.0
400
1.0
nA
µA
PE[7:0]
VRL, VRH
NOTES:
1. For fop < 2 MHz, source impedances should equal approximately 10 kΩ. For fop ≥ 2 MHz, source impedances
should equal approximately 5 kΩ – 10 kΩ. Source impedances greater than 10 kΩ affect accuracy adversely because of input leakage.
2. Performance verified down to 2.5 V ∆VR, but accuracy is tested and guaranteed at ∆VR = 5 V ± 10%
ELECTRICAL CHARACTERISTICS
TECHNICAL DATA
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A-11
Freescale Semiconductor, Inc.
Table A-7 Expansion Bus Timing
VDD = 5.0 Vdc ± 5%, VSS = 0 Vdc, TA = TL to TH
Num
Characteristic
Symbol
Frequency of Operation (E-Clock Frequency)
1
Cycle Time
2
Pulse Width, E Low
PWEL = 1/2 tcyc – 20 ns
3
Pulse Width, E High
PWEH = 1/2 tcyc – 25 ns
Freescale Semiconductor, Inc...
4A
4B
tcyc = 1/fo
(Note 2)
E Clock
Rise Time
Fall Time
2.0 MHz
Min
Max
3.0 MHz
4.0 MHz
Min
Max
Min
Max
Unit
fo
dc
2.0
dc
3.0
dc
4.0
MHz
tcyc
500
—
333
—
250
—
ns
PWEL
230
—
147
—
105
—
ns
PWEH
225
—
142
—
100
—
ns
tr
tf
—
—
20
20
—
—
20
18
—
—
20
15
ns
ns
9
Address Hold Time
tAH = 1/8 tcyc – 10 ns
tAH
53
—
32
—
21
—
ns
11
Address Delay Time
tAD = 1/8 tcyc + 40 ns
tAD
—
103
—
82
—
71
ns
12
Address Valid Time to E Rise
tAV = PWEL – tAD
tAV
128
—
65
—
34
—
ns
17
Read Data Setup Time
tDSR
30
—
30
—
20
—
ns
18
Read Data Hold Time
tDHR
0
—
0
—
0
—
ns
19
Write Data Delay Time
tDDW
—
40
—
40
—
40
ns
21
Write Data Hold Time
tDHW = 1/8 tcyc
tDHW
63
—
42
—
31
—
ns
29
MPU Address Access Time
tACCA = tcyc – tf – tDSR – tAD
tACCA
348
—
203
—
144
—
ns
(Note 2)
Write Data Setup Time
tDSW = PWEH – tDDW
tDSW
185
—
102
—
60
—
ns
(Note 2)
tECSD
—
40
—
40
—
40
ns
tECSA
155
—
72
—
40
—
ns
39
50
E Valid Chip Select Delay Time
51
E Valid Chip Select Access Time
tECSA = PWEH – tECSD – tDSR
(Note 2)
52
Chip Select Hold Time
54
Address Valid Chip Select Delay Time
tACSD = 1/4 tcyc + 40 ns
55
Address Valid Chip Select Access Time
tACSA = tcyc – tf – tDSR – tACSD
(Note 2)
tCH
0
20
0
20
0
20
ns
tACSD
—
165
—
123
—
103
ns
tACSA
285
—
162
—
113
—
ns
56
Address Valid to Chip Select Time
tAVCS
10
—
10
—
10
—
ns
57
Address Valid to Data Three-State Time
tAVDZ
—
10
—
10
—
10
ns
NOTES:
1. Input clocks with duty cycles other than 50% affect bus performance.
2. Indicates a parameter affected by clock stretching. Add n(tcyc) to parameter value, where:
n = 1, 2, or 3 depending on values written to CSSTRH register.
3. All timing is shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
A-12
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MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
1
2
3
4B
E
4A
11
12
9
R/W, ADDRESS
17
29
18
Freescale Semiconductor, Inc...
READ DATA
39
19
57
21
WRITE DATA
50
51
52
CS E VALID
56
55
CS AD VALID
54
Figure A-9 Expansion Bus Timing
ELECTRICAL CHARACTERISTICS
TECHNICAL DATA
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A-13
Freescale Semiconductor, Inc.
Table A-8 Serial Peripheral Interface Timing
VDD = 5.0 Vdc ± 5%, VSS = 0 Vdc, TA = TL to TH
Num
1
2
Freescale Semiconductor, Inc...
3
4
5
6
7
Characteristic
Symbol
2.0 MHz
3.0 MHz
4.0 MHz
Min
Max
Min
Max
Min
Max
Unit
Operating Frequency
Master
Slave
fop(m)
fop(s)
dc
dc
1.0
2.0
dc
dc
1.5
3.0
dc
dc
2.0
4.0
MHz
MHz
Cycle Time
Master
Slave
tcyc(m)
tcyc(s)
2.0
500
—
—
2.0
333
—
—
2.0
250
—
—
tcyc
ns
Enable Lead Time
Master
Slave
(Note 2)
tlead(m)
tlead(s)
—
250
—
—
—
240
—
—
—
200
—
—
ns
ns
Enable Lag Time
Master
Slave
(Note 2)
tlag(m)
tlag(s)
—
250
—
—
—
240
—
—
—
200
—
—
ns
ns
Clock (SCK) High Time
Master
Slave
tw(SCKH)m
tw(SCKH)s
340
190
—
—
227
127
—
—
130
85
—
—
ns
ns
Clock (SCK) Low Time
Master
Slave
tw(SCKL)m
tw(SCKL)s
340
190
—
—
227
127
—
—
130
85
—
—
ns
ns
Data Setup Time (Inputs)
Master
Slave
tsu(m)
tsu(s)
100
100
—
—
100
100
—
—
100
100
—
—
ns
ns
Data Hold Time (Inputs)
Master
Slave
th(m)
th(s)
100
100
—
—
100
100
—
—
100
100
—
—
ns
ns
8
Access Time (Time to Data Active from
High-Impedance State)
Slave
ta
0
120
0
120
0
120
ns
9
Disable Time (Hold Time to High-Impedance State)
Slave
tdis
—
240
—
167
—
125
ns
10
Data Valid (After Enable Edge)
tv(s)
—
240
—
167
—
125
ns
11
Data Hold Time (Outputs) (After Enable Edge)
tho
0
—
0
—
0
—
ns
12
Rise Time (20% VDD to 70% VDD, CL = 200 pF)
SPI Outputs (SCK, MOSI, and MISO)
SPI Inputs (SCK, MOSI, MISO, and SS)
trm
trs
—
—
100
2.0
—
—
100
2.0
—
—
100
2.0
ns
µs
Fall Time (70% VDD to 20% VDD, CL = 200 pF)
SPI Outputs (SCK, MOSI, and MISO)
SPI Inputs (SCK, MOSI, MISO, and SS)
tfm
tfs
—
—
100
2.0
—
—
100
2.0
—
—
100
2.0
ns
µs
13
(Note 3)
NOTES:
1. All timing is shown with respect to 20% VDD and 70% VDD, unless otherwise noted.
2. Signal production depends on software.
3. Assumes 200 pF load on all SPI pins.
ELECTRICAL CHARACTERISTICS
A-14
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MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
SS
(INPUT)
SS IS HELD HIGH ON MASTER
1
13
12
13
12
5
SCK (CPOL = 0)
(OUTPUT)
SEE
NOTE
4
5
SCK (CPOL = 1)
(OUTPUT)
SEE
NOTE
4
6
Freescale Semiconductor, Inc...
MISO
(INPUT)
7
MSB IN
BIT 6 - - - -1
11
10 (ref)
MOSI
(OUTPUT)
MASTER MSB OUT
LSB IN
10
11 (ref)
BIT 6 - - - -1
MASTER LSB OUT
13
12
NOTE: This first clock edge is generated internally but is not seen at the SCK pin.
Figure A-10 SPI Master Timing (CPHA = 0)
SS
(INPUT)
SS IS HELD HIGH ON MASTER
1
13
12
5
SCK (CPOL = 0)
(OUTPUT)
SEE
NOTE
4
13
5
SCK (CPOL = 1)
(OUTPUT)
SEE
NOTE
4
12
MISO
(INPUT)
MSB IN
MOSI
(OUTPUT)
BIT 6 - - - -1
11
10 (ref)
MASTER MSB OUT
6
7
LSB IN
10
BIT 6 - - - -1
11 (ref)
MASTER LSB OUT
13
12
NOTE: This last clock edge is generated internally but is not seen at the SCK pin.
Figure A-11 SPI Master Timing (CPHA = 1)
ELECTRICAL CHARACTERISTICS
TECHNICAL DATA
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A-15
Freescale Semiconductor, Inc.
SS
(INPUT)
1
SCK (CPOL = 0)
(INPUT)
12
12
13
3
4
2
5
SCK (CPOL = 1)
(INPUT)
4
8
MISO
(OUTPUT)
Freescale Semiconductor, Inc...
13
5
SLAVE
MSB OUT
6
MOSI
(INPUT)
BIT 6 - - - -1
7
10
MSB IN
9
SEE
NOTE
SLAVE LSB OUT
11
BIT 6 - - - -1
11
LSB IN
NOTE: Not defined but normally MSB of character just received.
Figure A-12 SPI Slave Timing (CPHA = 0)
SS
(INPUT)
1
12
SCK (CPOL = 0)
(INPUT)
4
2
4
8
10
SEE
NOTE
13
SLAVE
BIT 6 - - - -1
MSB OUT
6
MOSI
(INPUT)
3
5
SCK (CPOL = 1)
(INPUT)
MISO
(OUTPUT)
13
5
7
MSB IN
10
12
9
SLAVE LSB OUT
11
BIT 6 - - - -1
LSB IN
NOTE: Not defined but normally LSB of character previously transmitted.
Figure A-13 SPI Slave Timing (CPHA = 1)
ELECTRICAL CHARACTERISTICS
A-16
For More Information On This Product,
Go to: www.freescale.com
MC68HC11F1
TECHNICAL DATA
Freescale Semiconductor, Inc.
Table A-9 EEPROM Characteristics
VDD = 5.0 Vdc ± 10%, VSS = 0 Vdc, TA = TL to TH
Characteristic
Temperature Range
Programming Time
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