Z8523008PSG

Z80230/Z85230/L Enhanced Serial Communications Controller Product Specification PS005309-0515 Copyright ©2015 by Zilog®, Inc. All rights reserved. www.zilog.com Warning: DO NOT USE IN LIFE SUPPORT LIFE SUPPORT POLICY ZILOG'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF ZILOG CORPORATION. As used herein Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness. Document Disclaimer ©2015 by Zilog, Inc. All rights reserved. Information in this publication concerning the devices, applications, or technology described is intended to suggest possible uses and may be superseded. ZILOG, INC. DOES NOT ASSUME LIABILITY FOR OR PROVIDE A REPRESENTATION OF ACCURACY OF THE INFORMATION, DEVICES, OR TECHNOLOGY DESCRIBED IN THIS DOCUMENT. Z I L O G A L S O D O E S N O T A S S U M E L I A B I L I T Y F O R I N T E L L E C T U A L P R O P E RT Y INFRINGEMENT RELATED IN ANY MANNER TO USE OF INFORMATION, DEVICES, OR TECHNOLOGY DESCRIBED HEREIN OR OTHERWISE. The information contained within this document has been verified according to the general principles of electrical and mechanical engineering. Z8 is a registered trademark of Zilog, Inc. All other product or service names are the property of their respective owners. PS005309-0515 Z80230/Z85230/L Product Specification iii Revision History Each instance in Revision History reflects a change to this document from its previous revision. For more details, refer to the corresponding pages and appropriate links in the table below. Date Revision Level May 2015 Description Page No 09 Minor update to page 36 Minor update to Copywrite Information 36 June 2009 08 Removed Security Watermark from pages all May 2009 07 Minor update to page 107 107 May 2009 06 system update change only - no technical content revised n/a Mar 2009 05 Updated document to add 3V product information Removed ISO/BSI certification information Figure 1, 7 and 23 changed 5V to Vcc Added Z8523L DC Characteristics Updated Read and Write AC Characteristics Updated System Timing Characteristics Updated General Timing Diagram Ordering Information updated Updated Standard Test Conditions Updatred Table 43 Updated Table 49 - min value Misc June 2008 PS005309-0515 04 ii 2, 13, 76 78 90 98 94 107 75 78 98 Updated as per new template and Style Guide. All Updated Figure 4. 3 September 2007 03 Updated Figure 38 and Implemented Style Guide All November 2002 02 Editorial Updates All August 2001 Original Issue All 01 Revision History Z80230/Z85230/L Product Specification iv Table of Contents Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pins Common to Both Z85230/L and Z80230 . . . . . . . . . . . . . . . . . . . . . . . . Pin Descriptions Exclusive to the Z85230/L . . . . . . . . . . . . . . . . . . . . . . . . . Pin Descriptions Exclusive to the Z80230 . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4 6 6 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Input/Output Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 ESCC Data Communications Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . 15 PS005309-0515 Z80230/Z85230/L Enhancements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-Byte Transmit FIFO Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-Byte Receive FIFO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Write Register 7 PRIME (WR7’) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CRC Reception in SDLC Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TxD Forced High in SDLC with NRZI Encoding When Marking Idle . . . . . . Improved Transmit Interrupt Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DPLL Counter Tx Clock Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Read Register 0 Status Latched During Read Cycle . . . . . . . . . . . . . . . . . Software Interrupt Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fast SDLC Transmit Data Interrupt Response . . . . . . . . . . . . . . . . . . . . . . SDLC FIFO Frame Status Enhancement . . . . . . . . . . . . . . . . . . . . . . . . . . FIFO Enable/Disable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FIFO Read Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FIFO Write Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SDLC Status FIFO Anti-Lock Feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 22 22 23 26 26 26 27 27 28 28 28 30 30 31 31 Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Initializing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Write Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Read Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 32 32 53 Z80230 Interface Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z80230 Write Cycle Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z80230 Read Cycle Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z80230 Interrupt Acknowledge Cycle Timing . . . . . . . . . . . . . . . . . . . . . . . Z85230/L Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z85230/L Read Cycle Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 70 71 71 72 73 Table of Contents Z80230/Z85230/L Product Specification v Z85230/L Write Cycle Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Z85230/L Interrupt Acknowledge Cycle Timing . . . . . . . . . . . . . . . . . . . . . . 74 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standard Test Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z85230/L AC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 75 75 76 76 77 78 87 Z80230/Z85230/L Errata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 IUS Problem Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 IUS Problem Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 RTS Problem Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 RTS Problem Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 Automatic TxD Forced High Problem Description . . . . . . . . . . . . . . . . . . . 102 Automatic TxD Forced High Problem Solutions . . . . . . . . . . . . . . . . . . . . 103 SDLC FIFO Overflow Problem Description . . . . . . . . . . . . . . . . . . . . . . . . 103 SDLC FIFO Overflow Problem Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Default RR0 Value Problem Description . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Default RR0 Value Problem Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Default RR10 Value Problem Description . . . . . . . . . . . . . . . . . . . . . . . . . 104 Default RR10 Value Problem Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 CRC Problem Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 CRC Problem Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z8523L (3.3V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Z85230 (5V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Part Number Suffix Designation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 107 107 108 Customer Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 PS005309-0515 Table of Contents Z80230/Z85230/L Product Specification 1 Pin Descriptions The Enhanced Serial Communication Controller (ESCC) pins are divided into seven functional groups: 1. Address/Data 2. Bus Timing and Reset 3. Device Control 4. Interrupt 5. Serial Data (both channels) 6. Peripheral Control (both channels) 7. Clocks (both channels) Figure 1 on page 2 and Figure 2 on page 2 display the pins in each functional group for both the Z80230 and Z85230/L. The pin functions are unique to each bus interface version in the Address/Data group, Bus Timing and Reset group, and Device Control group. The Address/Data group consists of the bidirectional lines used to transfer data between the CPU and the ESCC (addresses in the Z80230 are latched by AS). The direction of these lines depends on whether the operation is a Read or a Write operation. The Timing and Control groups designate the type of transaction to occur and the timing of the occurrence. The interrupt group provides inputs and outputs for handling and prioritizing interrupts. The remaining groups are divided into Channel A and Channel B groups for: • • • PS005309-0515 Serial Data (Transmit or Receive) Peripheral Control (such as DMA or modem) Input and Output Line for the Receive and Transmit Clocks Pin Descriptions Z80230/Z85230/L Product Specification 2 Data Bus Bus Timing and Reset Control Interrupt D7 TxDA D6 RxDA D5 TRxCA RTxCA D4 SYNCA D3 W/REQA D2 DTR/REQA D1 RTSA D0 CTSA RD WR DCDA Z85230/L A/B TxDB CE RxDB D/C TRxCB INT RTxCB INTACK SYNCB IEI W/REQB DTR/REQB IEO RTSB CTSB DCDB Serial Data Channel Clocks Channel A Channel Controls for modem, DMA and Other Serial Data Channel Clocks Channel Controls for modem, DMA and Other Channel B +VccGND PCLK Figure 1. Z85230/L Pin Functions Data Bus Bus Timing and Reset Control Interrupt AD7 TxDA AD6 RxDA AD5 TRxCA RTxCA AD4 SYNCA AD3 W/REQA AD2 DTR/REQA AD1 RTSA AD0 CTSA AS DS DCDA R/W Z80230 TxDB CS1 RxDB CS0 TRxCB RTxCB INT INTACK SYNCB IEI W/REQB DTR/REQB IEO RTSB CTSB DCDB Serial Data Channel Clocks Channel A Channel Controls for modem, DMA and Other Serial Data Channel Clocks Channel Controls for modem, DMA and Other Channel B +VCCGND PCLK Figure 2. Z80230 Pin Functions PS005309-0515 Pin Descriptions Z80230/Z85230/L Product Specification 3 40 1 Z85230 20 21 D0 D2 D4 D6 RD WR A/B CE D/C GND W/REQB SYNCB RTxCB RxDB TRxCB TxDB DTR/REQB RTSB CTSB DCDB IEO IEI INTACK VCC W/REQA SYNCA RTxCA RxDA TRxCA TxDA N/C 7 6 1 40 39 Z85230/L 17 18 29 28 A/B CE D/C N/C GND W/REQB SYNCB RTxCB RxDB TRxCB TxDB N/C DTR/REQA RTSA CTSA DCDA PCLK DCDB CTSB RTSB DTR/REQB N/C D1 D3 D5 D7 INT IEO IEI INTACK VCC W/REQA SYNCA RTxCA RxDA TRxCA TxDA DTR/REQA RTSA CTSA DCDA PCLK INT D7 D5 D3 D1 D0 D2 D4 D6 RD WR Figure 3 displays the Z85230/L DIP and PLCC pin assignments, respectively. Figure 4 displays the Z80230 DIP and PLCC pin assignments. Z85230 DIP Pin Assignments Z85230/L PLCC Pin Assignments 40 1 Z80230 CTSA DCDA PCLK 20 21 AD0 AD2 AD4 AD6 DS AS R/W CS0 CS1 GND W/REQB SYNCB RTxCB RxDB TRxCB TxDB DTR/REQB RTSB CTSB DCDB Z80230 DIP Pin Assignments IEO IEI INTACK VCC W/REQA SYNCA RTxCA RxDA TRxCA TxDA N/C 6 7 1 40 39 Z80230 17 18 29 28 R/W CS0 CS1 N/C GND W/REQB SYNCB RTxCB RxDB TRxCB TxDB N/C DTR/REQA RTSA CTSA DCDA PCLK DCDB CTSB RTSB DTR/REQB N/C AD1 AD3 AD5 AD7 INT IEO IEI INTACK VCC W/REQA SYNCA RTxCA RxDA TRxCA TxDA DTR/REQA RTSA INT AD7 AD5 AD3 AD1 AD0 AD2 AD4 AD6 DS AS Figure 3. Z85230/L Pin Assignments Z80230 PLCC Pin Assignments Figure 4. Z80230 Pin Assignments PS005309-0515 Pin Descriptions Z80230/Z85230/L Product Specification 4 Pins Common to Both Z85230/L and Z80230 The pin descriptions for pins common to both Z85230/L and Z80230 are provided below: CTSA, CTSB (Clear To Send (Inputs, Active Low))—These pins function as transmitter enables if they are programmed for AUTO ENABLE (WR3 bit 5 is 1), in which case a Low on each input enables the respective transmitter. If not programmed as AUTO ENABLE, the pins may be used as general-purpose inputs. These pins are Schmitt-trigger buffered to accommodate slow rise-time inputs. The ESCC detects pulses on these pins and may interrupt the CPU on both logic level transitions. DCDA, DCDB (Data Carrier Detect (Inputs, Active Low))—These pins function as receiver enables if they are programmed for AUTO ENABLE (WR3 bit 5 is 1); otherwise, they are used as general-purpose input pins. The pins are Schmitt-trigger buffered to accommodate slow rise-time signals. The ESCC detects pulses on these pins and may interrupt the CPU on both logic level transitions. RTSA, RTSB (Request To Send (Outputs, Active Low))—The RTS pins can be used as general-purpose outputs or with the AUTO ENABLE feature. When AUTO-ENABLE is off, these pins follow the inverse state of WR5 bit 1. When used with the AUTOENABLE feature in ASYNCHRONOUS mode, this pin immediately goes Low when WR5 bit 1 is 1. When WR5 bit 0 is 0, this pin remains Low until the transmitter is empty. In Synchronous Data Link Control (SDLC) mode, the RTS pins can be programmed to be deasserted when the closing flag of the message clears the TxD pin, if WR7’ bit 2 is 1, WR10 bit 2 is 0, and WR5 bit 1 is 0. SYNCA, SYNCB (Synchronization (Inputs Or Outputs, Active Low))—These pins can act either as inputs, outputs, or as part of the crystal oscillator circuit. In the ASYNCHRONOUS RECEIVE mode (crystal oscillator option not selected), these pins are inputs similar to CTS and DCD. In this mode, transition on these lines affect the state of the SYNC/ HUNT status bits in Read Register 0 but have no other function. In EXTERNAL SYNCHRONIZATION mode, with the crystal oscillator not selected, these lines also act as inputs. In this mode, SYNC is driven Low, two Rx clock cycles after the last bit of the SYNC character is received. Character assembly begins on the rising edge of the receive clock immediately preceding the activation of SYNC. In the INTERNAL SYNCHRONIZATION mode (MONOSYNC and BISYNC) with the crystal oscillator not selected, these pins act as outputs. These outputs go Low each time a SYNC pattern is recognized, regardless of character boundaries. In SDLC mode, pins switch from input to output when MONOSYNC, BISYNC, or SDLC is programmed in WR4 and SYNC modes are enabled. DTR/REQA, DTR/REQB (Data Terminal Ready/Request (Output, Active Low))— These pins can be programmed (WR14 bit 2) to serve either as general-purpose outputs or as DMA Request lines. When programmed for DTR function (WR14 bit 2 is 0), these outputs follow the inverse of the DTR bit of Write Register 5 (WR5 bit 7). When programmed for REQUEST mode these pins serve as DMA Requests for the transmitter. PS005309-0515 Pin Descriptions Z80230/Z85230/L Product Specification 5 When used as DMA Request line (WR14 bit 2 is 1), the timing for the deactivation request can be programmed in Write Register 7’ (WR7’) bit 4. If this bit is 1, the DTR/REQ pin is deactivated with the same timing as the W/REQ pin. If 0, the deactivation timing of DTR/ REQ pin is four clock cycles, the same as in the Z80C30/Z85C30. W/REQA, W/REQB (Wait/request (Output, Open-drain When Programmed For WAIT Function, Driven High And Low When Programmed For Request Function))—These dual-purpose outputs may be programmed as REQUEST lines for a DMA controller or as WAIT lines to synchronize the CPU to the ESCC data rate. The reset state is WAIT. RxDA, RxDB (Receive Data (inputs, active High))—These inputs receive serial data at standard Transistor-Transistor Logic (TTL) levels. RTxCA, RTxCB (Receive/Transmit Clocks (Input, Active Low))—These pins can be programmed to several modes of operation. In each channel, RTxC may supply the following: • • • Receive clock and/or the transmit clock Clock for the baud rate generator (BRG) Clock for the Digital Phase-Locked Loop These pins can also be programmed for use with the respective SYNC pins as a crystal oscillator. The receive clock may be 1, 16, 32, or 64 times the data rate in ASYNCHRONOUS modes. TxDA, TxDB (Transmit Data (Output, Active High))—These output transmit serial data at standard TTL levels. TRxCA, TRxCB (Transmit/Receive Clocks (Input or Output, Active Low))—These pins can be programmed in several different modes. When configured as an input, the TRxC may supply the receive clock and/or the transmit clock. When configured as an output, TRxC can echo the clock output of the Digital Phase-Locked Loop, the crystal oscillator, the BRG or the transmit clock. PCLK (Clock (Input))—This clock is the master ESCC clock used to synchronize internal signals. PCLK is a TTL level signal. PCLK is not required to have any phase relationship with the master system clock. IEI (Interrupt Enable In (Input, Active High))—IEI is used with IEO to form an interrupt daisy chain when there is more than one interrupt-driven device. A High IEI indicates that no higher priority device has an Interrupt Under Service (IUS) or is requesting an  interrupt. IEO (Interrupt Enable Out (Output, Active High))—IEO is High only if IEI is High and the CPU is not servicing an ESCC interrupt. During an Interrupt Acknowledge Cycle, IEO is also driven Low if the ESCC is requesting an interrupt. IEO can be connected to the next lower priority device’s IEI input, and in this case inhibits interrupts from lower priority devices. PS005309-0515 Pin Descriptions Z80230/Z85230/L Product Specification 6 INT (Interrupt (Output, Open-Drain, Active Low))—This pin activates when the ESCC requests an interrupt. The INT is an open-drain output. INTACK (Interrupt Acknowledge (Input, Active Low))—This pin is a strobe which indicates that an Interrupt Acknowledge Cycle is in progress. During this cycle, the ESCC interrupt daisy chain is resolved. The device can return an interrupt vector that may be encoded with the type of interrupt pending. During the acknowledge cycle, if IEI is High, the ESCC places the interrupt vector on the data bus when RD goes active for the Z85230/ L, or when DS goes active for the Z80230. INTACK is latched by the rising edge of PCLK. Pin Descriptions Exclusive to the Z85230/L The pin description for pins exclusive to Z85230/L is provided below: Pins D7–D0 (Data Bus (Bidirectional, tristate))—These pins carry data and commands to and from the Z85230/L. CE (Chip Enable (Input, Active Low))—This pin selects the Z85230/L for a Read or Write operation. RD ((Read (input, Active Low))—This pin indicates a Read operation and, when the Z85230/L is selected, enables the Z85230/L’s bus drivers. During the Interrupt Acknowledge cycle, RD gates the interrupt vector onto the bus if the Z85230/L is the highest priority device requesting an interrupt. WR (Write (Input, Active Low))—When the Z85230/L is selected, this pin denotes a Write operation, which indicates that the CPU writes command bytes or data to the Z85230/L write registers. Note: WR and RD going Low simultaneously is interpreted as a Reset. A/B (Channel A/Channel B (Input))—This pin selects the channel in which the Read or Write operation occurs. A High selects Channel A and a Low selects Channel B. D/C (Data/Control Select (Input))—This signal defines the type of information trans- ferred to or from the Z85230/L. A High indicates data transfer and a Low indicates a command transfer. Pin Descriptions Exclusive to the Z80230 The pin description for pins exclusive to Z80230 is provided below: AD7–AD0 (Address/Data Bus (Bidirectional, Active High, tristate))—These multi- plexed lines carry register addresses to the Z80230 as well as data or control information to and from the Z80230. R/W (Read/Write (Input, Read Active High))—This pin specifies if the operation to be performed is a Read or Write operation. PS005309-0515 Pin Descriptions Z80230/Z85230/L Product Specification 7 CS0 (Chip Select 0 (Input, Active Low))—This pin is latched concurrently with the addresses on A7-A0 and must be Low for the intended bus transaction to occur. CS1 (Chip Select 1 (Input, Active High))—This second chip select pin must be High before and during the intended bus transaction. DS (Data Strobe (Input, Active Low))—This pin provides timing for the transfer of data into and out of the Z80230. If AS and DS are both Low, this condition is interpreted as a RESET. AS (Address Strobe (Input, Active Low))—Addresses on A7-A0 are latched by the ris- ing edge of this signal. PS005309-0515 Pin Descriptions Z80230/Z85230/L Product Specification 8 Functional Description The architecture of the ESCC is described based on its functionality as a: • Data communications device, which transmits and receives data in a wide variety of protocols • Microprocessor peripheral, in which the ESCC offers valuable features such as vectored interrupts and DMA support The details of the communication between the receive and transmit logic of the system bus are displayed in Figure 5 and Figure 6 on page 9. The features and data path for each of the ESCC A and B channels are identical. For more information on SCC/ESCC and ISCC Family of Products, refer to the respective User Manuals available for download from www.zilog.com. Internal Data Bus to Other Channel WR8 TX FIFO 4 Bytes Internal TXD WR7 WR6 SYNC Register SYNC Register Final Tx MUX Shift Register 20-Bit TX ASYNC SYNC SDLC Zero Insert Transmit MUX and 2 Bit Delay TXD NRZI Encode CRC-SDLC Transmit Clock CRC-Gen From Receiver Figure 5. ESCC Transmit Data Path PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 9 CPU I/O I/O Data Buffer Internal Data Bus Upper Byte (WR13) Time Constant 16 Bit Down Counter BRG Input Status FIFO 10 x 19 Frame Lower Byte (WR12) Time Constant Rx Data FIFO 8 Bytes Deep Rx Error FIFO 8 Bytes Deep BRG Output Div 2 Rec. Error Logic 14 Bit Counter Hunt Mode (BISYNC) DPLL IN SYNC Register and 0 Delete DPLL OUT DPLL Receive Shift Register 3 Bits SYNC CRC Internal TXD RxD 1 Bit MUX NRZI Decode CRC Delay Register (8 Bits) MUX CRC Checker To Transmit Section SDLC-CRC CRC Result Figure 6. ESCC Receive Data Path Input/Output Capabilities System communication to and from the ESCC is accomplished using the  ESCC register set. There are 17 Write registers and 16 Read registers. Many of the features on the ESCC are enabled through a new register in the ESCC: Write Register 7 Prime (WR7’). This new register can be accessed if bit 0 or WR15 is set to 1. Table 1 on page 10 lists the Write registers and a brief description of their functions. Table 2 on page 11 lists the Read Registers. PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 10 Throughout this document the Write and Read registers are referenced with the notations Note: WR for Write Register and RR for Read Register. For example: WR4A – Write Register 4 for Channel A RR3 – Read Register 3 for either or both channels Table 1. ESCC Write Registers Write Register Functions WR0 Command Register; Select Shift Left/Right Mode, Cyclic Redundancy Check (CRC) Initialization, and Resets for Various Modes WR1 Interrupt Conditions, Wait/DMA Request Control WR2 Interrupt Vector, Accessed Through Either Channel WR3 Receive and Miscellaneous Control Parameters WR4 Transmit and Receive Parameters and Modes WR5 Transmit Parameters and Controls WR6 SYNC Character or SDLC Address Field WR7 SYNC Character or SDLC Flag WR7’ SDLC Enhancements Enable, Accessible if WR15 bit D0 is 1 WR8 Transmit FIFO, 4-Bytes Deep WR9 Reset Commands and Master INT Enable, Accessible Through Either Channel WR10 Miscellaneous Transmit and Receive Controls WR11 Clock Mode Control WR12 Lower Byte of BRG Time Constant WR13 Upper Byte of BRG Time Constant WR14 Miscellaneous Controls and Digital Phase-Locked Loop (DPLL) Commands WR15 External Interrupt Control PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 11 Table 2. ESCC Read Registers Register Name Functions RR0 Transmit, Receive, and External Status RR1 Special Receive Condition Status Bits RR2A Unmodified Interrupt Vector RR2B Modified Interrupt Vector RR3A Interrupt Pending Bits RR4 WR4 Mirror, if WR7’ bit D6 equals 1 RR5 WR5 Mirror, if WR7’ bit D6 equals 1 RR6 SDLC Frame LSB Byte Count, if WR15 bit D2 equals 1 RR7 SDLC Frame 10 X 19 FIFO Status and MSB Byte Count, if WR15 bit DS equals 1 RR8 Receive Data FIFO, 8 Bits Deep RR9 WR9 Mirror, if WR7’ bit D6 Equals 1 RR10 Miscellaneous Status Bits RR11 WR11 Mirror, if WR7’ bit D6 Equals 1 RR12 Lower Byte of BRG Time Constant RR13 Upper Byte of BRG Time Constant RR14 WR14 Mirror, if WR7’ bit D6 Equals 1 RR15 WR 15 Mirror, if WR7’ bit D6 Equals 1 There are three modes used to move data into and out of the ESCC: 1. POLLING 2. INTERRUPT (vectored and non-vectored) 3. BLOCK TRANSFER The BLOCK TRANSFER mode can be implemented under CPU or DMA control. POLLING When POLLING, data interrupts are disabled, three registers in the ESCC are automatically updated whenever any function is performed. For example, end-of-frame (EOF) in SDLC mode sets a bit in one of these status registers. The purpose of POLLING is for the CPU to periodically read a status register until the register contents indicate the need that data requires transfer. RR0 is the only register that must be read to determine if data needs to be transferred. An alternative to polling RR0 for each channel is to poll the Interrupt PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 12 Pending register. Status information for both channels resides in one register. Only one register may be read. Depending on its contents, the CPU performs one of the three operations listed below: 1. Write data 2. Read data 3. Continues processing Two bits in the register indicate the requirement for data transfer. INTERRUPT The ESCC INTERRUPT mode supports vectored and nested interrupts. The fill levels at which the transmit and receive FIFOs interrupt the CPU are programmable, allowing the ESCC requests for data transfer to be tuned to the system interrupt response time. Nested interrupts are supported with the interrupt acknowledge (INTACK) feature of the ESCC. It allows the CPU to acknowledge the occurrence of an interrupt, and re-enable higher priority interrupts. Since an INTACK cycle releases the INT pin from the active state, a higher priority ESCC interrupt or another higher priority device can interrupt the CPU. When an ESCC responds to INTACK signal from the CPU, it can place an interrupt vector on the data bus. This vector is written in WR2 and may be read in RR2. To increase the interrupt response time, the ESCC can modify 3 bits in this vector to indicate status. If the vector is read in Channel A, status is not included. If it is read in Channel B, status is included. Each of the six sources of interrupts in the ESCC (Transmit, Receive, and External/Status interrupts in both channels) has 3 bits associated with the interrupt source as listed below: 1. Interrupt Pending (IP) 2. Interrupt Under Service (IUS) 3. Interrupt Enable (IE) If the IE bit is set for a given interrupt source, then that source can request interrupts. However, when the Master Interrupt Enable (MIE) bit in WR9 is reset, no interrupts can be requested. The IE bits are write-only. The other two bits are related to the interrupt priority chain (see Figure 7 on page 13). The ESCC can request an interrupt only when no higher priority device is requesting an interrupt (that is, when IEI is High). If the device in question requests an interrupt, it pulls down INT. The CPU then responds with INTACK, and the interrupting device places a vector on the data bus. PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 13 Peripheral Peripheral IEI A7–A0INT INTACKIEO IEI A7–A0 INTINTACKIEO +VCC Peripheral IEI A7–A0INTINTACK +VCC A7–A0 INT INTACK Figure 7. ESCC Interrupt Priority Schedule The ESCC can also execute an Interrupt Acknowledge cycle using software. Sometimes it is difficult to create the INTACK signal with the necessary timing to acknowledge interrupts and allow the nesting of interrupts. In such cases, interrupts can be acknowledged with a software command to the ESCC. For more information, Z80230/Z85230/L Enhancements on page 22 Interrupt Pending (IP) bits signal a need for interrupt servicing. When an IP bit is 1 and the IEI input is High, the INT output is pulled Low, requesting an interrupt. In the ESCC, if an IE bit is not set, then the IP for that source is never set. The IP bits are read in RR3A. The Interrupt Under Service (IUS) bits signal that an interrupt request is serviced. If IUS is set to 1, all interrupt sources of low priority in the ESCC and external to the ESCC are prevented from requesting interrupts. The internal interrupt sources are inhibited by the state of the internal daisy chain, while lower priority devices are inhibited by setting IEO Low for subsequent peripherals. An IUS bit is set during an Interrupt Acknowledge cycle if there are no higher priority devices requesting interrupt. There are three type of interrupts as listed below: 1. Transmit 2. Receive 3. External/Status Each interrupt type is enabled under program control with Channel A having higher priority than Channel B, and with Transmit, Receive, and External/Status interrupts prioritized in that order within each channel. When the Transmit interrupt is enabled (WR1 bit 1 is 1), the occurrence of the interrupt depends on the state of WR7’ bit 5. If WR7’ bit 5 is 0, the CPU is interrupted when the top byte of the transmit First In First Out (FIFO) becomes empty. If WR7’ bit 5 is 1, the CPU is interrupted when the transmit FIFO becomes completely empty. The transmit interrupt occurs when the data in the exit location of the Transmit FIFO loads into the Transmit Shift Register and the Transmit FIFO becomes completely empty. This condition means that there must be at least one character written to the Tx FIFO for it to become empty. PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 14 When the receiver is enabled, the CPU is interrupted in one of the following three methods: 1. Interrupt on First Receive Character or Special Receive Condition 2. Interrupt on All Receive Characters or Special Receive Conditions 3. Interrupt on Special Receive Conditions Only If WR7’ bit 3 is 1, and the Special Receive Condition is selected, the Receive character occurs when there are four bytes available in the Receive FIFO. This is most useful in synchronous applications as the data is in consecutive bytes. Interrupt on First Character or Special Condition and Interrupt on Special Condition Only are typically used with the BLOCK TRANSFER mode. A special Receive Condition consists of one of the following: • • • • Receiver Overrun Framing error in ASYNCHRONOUS mode EOF in SDLC mode Parity error (optional) The Special Receive Condition interrupt is different from an ordinary receive character available interrupt only by the status placed in the vector during the Interrupt Acknowledge cycle. In Receive Interrupt on First Character or Special Condition mode, an interrupt occurs from Special Receive Conditions any time after the first receive character interrupt. The primary function of the External/Status interrupt is to monitor the signal transitions of the CTS, DCD, and SYNC pins. However, an External/Status interrupt is also caused by any of the following: • • • • • A Transmit Underrun condition A zero count in the BRG A detection of a Break (ASYNCHRONOUS mode) An ABORT (SDLC mode) An End Of Poll (EOP) sequence in the data stream (SDLC LOOP mode) The interrupt caused by the ABORT or EOP sequence has a special feature that allows the ESCC to interrupt when the ABORT or EOP sequence is detected or terminated. This feature facilitates the proper termination of the current message, correct initialization of the next message, and the accurate timing of the ABORT condition by external logic in SDLC mode. SDLC LOOP mode allows secondary stations to recognize the primary station and regain control of the loop during a poll sequence. PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 15 CPU/DMA BLOCK TRANSFER The ESCC provides a BLOCK TRANSFER mode to accommodate CPU/DMA controller. The BLOCK TRANSFER mode uses the WAIT/REQUEST output in conjunction with the WAIT/REQUEST bits in WR1. The WAIT/REQUEST output can be defined as a WAIT line in the CPU BLOCK TRANSFER mode or as a REQUEST line in the DMA BLOCK TRANSFER mode. To a DMA controller, the ESCC REQUEST output indicates that the ESCC is ready to transfer data to or from memory. To the CPU, the WAIT line indicates that the ESCC is not ready to transfer data, thereby requesting the CPU to extend the I/O cycle. The DTR/REQUEST line allows full-duplex operation under DMA control. The ESCC can be programmed to deassert the DTR/REQUEST pin with the same timing as the WAIT/REQUEST pin if WR7’ bit 4 is 1. ESCC Data Communications Capabilities The ESCC provides two independent full-duplex programmable channels for use in any common ASYNCHRONOUS or SYNCHRONOUS data communication protocols (see Figure 8). The channels have identical features and capabilities. Start Parity Stop Data Marking Line Data Marking Line Data Asynchronous SYNC Data Data CRC1 CRC2 Monosync SYNC SYNC Data Data Signal CRC1 CRC2 Data CRC1 CRC2 Information CRC1 CRC2 Bisync Data External Sync Flag Address Control Flag SDLC/HDLC/X.25 Figure 8. Various ESCC Protocols PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 16 ASYNCHRONOUS Mode The ESCC has significant improvements over the standard Serial Communications Controller (SCC). The addition of the deeper data FIFOs provide greater protection against underruns and overruns as well as more efficient use of bus bandwidth. The deeper data FIFOs are accessible regardless of the protocol used and they need not be enabled. For information on these improvements, see Z80230/Z85230/L Enhancements on page 22 Send and Receive allow 5 to 8 bits per character, plus optional Even or Odd parity. The transmitters can supply 1, 1.5, or 2 stop bits per character and can provide break indication. The receiver break-detection logic interrupts the CPU both at the start and at the end of a received break. Reception is protected from spikes by start-bit validation that delays the signal for a length of time equal to one half the time period required to process 1 bit of data after a Low level is detected on the receive data input (RxDA or RxDB pins). If the Low level does not persist (that is, a transient), the character assembly process does not start. Framing errors and overrun errors are detected and buffered together with the character at which they occur. Vectored interrupts allow fast servicing of error conditions. Furthermore, a built-in checking process avoids the interpretation of a framing error as a new start bit. A framing error results in the addition of a delay of one half the amount of time required to process 1 bit of data at the point at which the search for the next start bit begins. Transmit and Receive clock can be selected from any of the several sources. In ASYNCHRONOUS mode, the SYNC pin may be programmed as an input with interrupt capability. SYNCHRONOUS Mode The ESCC supports both byte-oriented and bit-oriented SYNCHRONOUS communication. SYNCHRONOUS byte-oriented protocols are handled in several modes. They enable character synchronization with a 6- or 8-bit SYNC character (MONOSYNC) or a 12-bit or 16-bit synchronization pattern (BISYNC), or with an external sync signal. Leading sync characters are removed without interrupting the CPU. 5- or 7-bit sync characters are detected from 8- or 16-bit patterns in the ESCC by overlapping the larger pattern across multiple incoming sync characters as displayed in Figure 9. 5 Bits SYNC SYNC SYNC Data Data Data Data 8 16 Figure 9. Detecting 5- or 7-Bit Synchronous Characters PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 17 CRC checking for SYNCHRONOUS BYTE-ORIENTED mode is delayed by one character time so that the CPU may disable CRC checking on specific characters. This action permits the implementation of protocols such as IBM BISYNC. Both CRC-16 (X16 + X15 + X2 + 1) and CRC-CCITT (X16 + X12 + X5 + 1) error checking polynomials are supported. Either polynomial may be selected in all synchronous modes. You can preset the CRC generator and checker to all 1s or all 0s. The ESCC also provides a feature that automatically transmits CRC data when no other data is available for transmission. This feature enables high-speed transmissions under DMA control, with no need for CPU intervention at the end of a message. When there is no data or CRC to send in the SYNCHRONOUS mode, the transmitter inserts 6-, 8-, 12-, or 16-bit SYNC characters, regardless of the programmed character length. SDLC Mode The ESCC supports SYNCHRONOUS bit-oriented protocols, such as SDLC and  High-Level Data Link Control (HDLC), by performing automatic flag sending, zero insertion, and CRC generation. A special command is used to abort a frame which is in transmission. At the end of a message, the ESCC automatically transmits the CRC and trailing flag when the transmitter underruns. The transmitter may also be programmed to send an idle line consisting of continuous flag characters or a steady marking condition. If a transmit underrun occurs in the middle of a message, an External/Status interrupt warns the CPU of this status change so that an Abort command can be issued. The ESCC may also be programmed to send an Abort command by itself, in the event of an  underrun, relieving the CPU of the task. The last character of a frame may consist of 1- to 8-bits, allowing reception of frames of any length. The receiver automatically synchronizes on the leading flag of a frame in SDLC or HDLC and provides a synchronization signal on the SYNC pin (an interrupt may also be programmed). The receiver may search for frames addressed by 1-byte or 4-bits within a byte of a user-specified address or for a global broadcast address. Frames not matching either the user-selected address or broadcast address are ignored. The number of address bytes are extended under software control. To receive data, an interrupt can be selected on the first received character, or on every character, or On Special Condition Only (EOF). The receiver automatically deletes all zeros inserted by the transmitter during character assembly. CRC is also calculated and is automatically checked to validate frame transmission. At the end of transmission, the status of a received frame is available in the status registers. In SDLC mode, the ESCC must be programmed to use the CRC-CCITT polynomial, but the generator and checker may be pre-set to all 1s or all 0s. The CRC data is inverted before transmission and the receiver checks against the bit pattern 0001110100001111. PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 18 NRZ, NRZI, or FM coding may be used in any 1X mode. The parity options available in ASYNCHRONOUS mode are also available in SYNCHRONOUS mode. However, parity checking is not normally used for SDLC because CRC checking is more robust. SDLC LOOP Mode The ESCC supports SDLC LOOP mode as well as normal SDLC. In SDLC LOOP mode, a primary controller station manages the message traffic flow on the loop and any number of secondary stations. In SDLC LOOP mode, the ESCC performs the functions of a secondary station. An ESCC operation in regular SDLC mode may act as a controller (see Figure 10). SDLC LOOP mode is selected by setting WR10 bit 1 to 1. Controller Secondary #1 Secondary #2 Secondary #4 Secondary #3 Figure 10. SDLC LOOP mode A secondary station in an SDLC LOOP mode always monitors the messages sent around the loop and passes these messages to the rest of the loop, retransmitting them with a onebit time delay. The secondary station places its own message in the loop only at specific times. The controller indicates that the secondary stations can transmit messages by sending a special character, called EOP, around the loop. The EOP character has a bit pattern 11111110, the same pattern as an Abort character in normal HDLC. This bit pattern is unique and easily recognized, because of the zero insertion in the message. When a secondary station has a message to transmit and recognizes an EOP on the line, it changes the last binary 1 of the EOP to a 0 before transmission. This action changes the EOP into a flag sequence. The secondary station now places its message on the loop and terminates the message with an EOP. Any secondary stations further down the loop with messages to transmit appends their messages to the message of the first secondary station using the same process. Secondary stations without any messages to transmit merely echo the incoming message. All secondary stations are prohibited from placing messages on the loop except upon recognizing an EOP. In SDLC LOOP mode, NRZ, NRZI or FM coding can be used. PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 19 SDLC Status FIFO The ESCC’s ability to receive high speed back-to-back SDLC frames is maximized by a 10-bit deep by 19-bit wide status FIFO buffer. When enabled (through WR15 bit 2 is 1), the storage area enables DMA to continue data transfer into the memory, so that the CPU examines the message later. For each SDLC frame, 14 counter bits and 5 Status/Error bits are stored. The byte count and status bits are accessed through Read Registers, RR6, and RR7. RR6 and RR7 are only used when the SDLC FIFO buffer is enabled. The 10 x 19 status FIFO buffer is separate from the 8-byte receive data FIFO buffer. Baud Rate Generator Each channel in the ESCC contains a programmable BRG. Each generator consists of two 8-bit registers that form a 16-bit time constant, a 16-bit down counter, and a flip-flop on the output, producing a square wave. At start-up, the flip-flop at the output is set High, the value in the time constant register is loaded into the counter, and the count down begins. When the BRG reaches zero, the output toggles, the counter is reloaded with the time constant, and the process repeats. The time constant can be changed at any time, but the new value does not take effect until the counter is loaded again. The output of the BRG may be used as the Transmit clock, the Receive clock, or both. The output can also drive the DPLL. For more information, see Digital Phase-Locked Loop. If the receive clock or the transmit clock is not programmed to come from the TRxC pin, the output of the BRG may be echoed out by the TRxC pin. The following formula relates the time constant to the baud rate. PCLK or RTxC is the clock input to the BRG. The clock mode is 1, 16, 32, or 64, as selected in WR 4 bits 6 and 7. Time Constant = PCLK or RTxC Frequency -2 2(Baud Rate) (Clock Mode) Digital Phase-Locked Loop The ESCC contains a DPLL to recover clock information from a data stream with NRZI or FM encoding. The DPLL is driven by a clock that is nominally 32 (NRZI) or 16 (FM) times the data rate. The DPLL uses this clock, along with the data stream, to construct a clock for the data. This clock is then used as the ESCC receive clock, the transmit clock, or both. When the DPLL is selected as the transmit clock source, it provides a jitter-free clock output. The clock output is the DPLL input frequency divided by the appropriate divisor for the selected encoding technique. For NRZI encoding, the DPLL counts the 32x clock to create nominal bit times. As the 32x clock is counted, the DPLL searches the incoming data stream for edges (either 1 to 0 or 0 to 1). When a transition is detected the DPLL makes a count adjustment (during the next counting cycle), producing a terminal count closer to the center of the bit cell. PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 20 For FM encoding, the DPLL counts from 0 to 32, but with a cycle corresponding to two bit times. When the DPLL is locked, the clock edges in the data stream occurs between counts 15 and 16 and between counts 31 and 0. The DPLL looks for edges only during a time centered on the 15 to 16 counting transition. The 32x clock for the DPLL can be programmed to come from either the RTxC input or the output of the BRG. The DPLL output is programmed to be echoed out the ESCC by the TRxC pin (if this pin is not being used as an input). Data Encoding Data encoding allows the transmission of clock and data information over the same medium. This capability saves the need to transmit clock and data over separate medium as is normally required tor synchronous data. The ESCC provides four different data encoding methods, selected by bits 6 and 5 in WR10. Examples of these 4 encoding methods is displayed in Figure 11. Any encoding method is used in any X1 mode in the ESCC, ASYNCHRONOUS or SYNCHRONOUS. The data encoding selected is active even if the transmitter or receiver is idling or disabled. 1 1 0 0 1 0 Data NRZ NRZI FM1 FM0 Figure 11. Data Encoding Methods Table 3 lists the four encoding methods, their levels, and values. Table 3. Data Encoding Descriptions Code Type Level Value NRZ High Low 1 0 NRZI No Change Change 1 0 PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 21 Table 3. Data Encoding Descriptions (Continued) Code Type Level FM1 (biphase mark) Additional Transition at the Center of the Bit Cell No Additional Transition at the Center of the Bit Cell FM0 (biphase space) Value 1 0 A transition occurs at the beginning of every bit 0 call. A 0 is represented by an additional transition at the center of the bit cell. 1 A 1 is represented by no additional transition at the center of the bit cell. In addition to the four methods, ESCC can be used to decode Manchester (biphase level) data using DPLL in the FM mode and programming the receiver for NRZ data. Manchester encoding always produces a transition at the center of the bit cell. If the transition is 0 to 1, the bit is a 0. If the transition is 1 to 0, the bit is a 1. Auto Echo and Local Loopback The ESCC is capable of automatically echoing everything it receives. This feature is useful mainly in ASYNCHRONOUS modes, but works in SYNCHRONOUS and SDLC modes as well. AUTO ECHO mode (TxD is RxD) is used with NRZI or FM encoding with an additional delay because the data stream is not decoded before retransmission. In AUTO ECHO mode, the CTS input is ignored as a transmitter enable, (although transitions for this input can cause interrupts if programmed to do so). In this mode, the transmitter is actually bypassed and the programmer is responsible for disabling transmitter interrupts and Wait/Request on transmit. The ESCC is also capable of LOCAL LOOPBACK. In this mode the internal transmit data is tied to the internal receive data and RxD is ignored. The CTS and DCD inputs are also ignored as transmit and receive enables. However, transitions on these inputs can cause interrupts. LOCAL LOOPBACK works in ASYNCHRONOUS, SYNCHRONOUS, and SDLC modes with NRZ, NRZI, or FM coding of the data stream. PS005309-0515 Functional Description Z80230/Z85230/L Product Specification 22 Z80230/Z85230/L Enhancements A detailed description of the enhancements to the Z80230/Z85230/L ESCC that differentiate it from the standard SCC is provided below: 4-Byte Transmit FIFO Buffer The ESCC has a 4-byte transmit buffer with programmable interrupt and DMA request levels. It is not necessary to enable the FIFO buffer as it is always available. You can set the Transmit Buffer Empty (TBE) interrupt and DMA Request on Transmit command to be generated either when the top byte of transmit FIFO is empty or only when the FIFO is completely empty. A hardware or channel reset clears the transmit shift register, flushes the transmit FIFO, and sets WR7’ bit 5 to 1. If the transmitter generates the interrupt or DMA request for data when the top byte of the FIFO is empty (WR7’ bit 5 is 0), the system allows for a long response time to the data request without underflowing. The interrupt service routine (ISR) writes 1byte and then tests RR0 bit 2. The DMA Request on Transmit in this mode is set to 0 after each data Write (that is, TBE), RR0 bit 2, is set to 1 when the top byte of the FIFO is empty. WR7’ bit 5 resets to 1. In applications for which the interrupt frequency is important, the transmit ISR can be optimized by programming the ESCC to generate the TBE interrupt only when the FIFO is completely empty (WR7’ bit 5 is 1) and, writing 4 bytes to fill the FIFO. When WR7’ bit 5 is 1, only one DMA request is generated, filling the bottom of the FIFO. However, this may be advantageous for applications where the possible reassertion of the DMA request is not required. The TBE status bit, RR0 bit 2, is set to 1 when the top byte of the FIFO is empty. WR7’ bit 5 is set to1 after a hardware or channel reset. 8-Byte Receive FIFO The ESCC has an 8-byte receive FIFO with programmable interrupt levels. It is not necessary to enable the 8-byte FIFO as it is always available. A hardware or channel reset clears the Receive Shift register and flushes the Receive FIFO. The Receive Character Available interrupt is generated as selected by WR7’ bit 3. The Receive Character Available bit, RR0 bit 0 is set to 1 when at least one byte is available at the top of the FIFO (independent of WR7’ bit 3). A DMA Request on Receive, if enabled, is generated whenever 1 byte is available in the receive FIFO independent of WR7’ bit 3. If more than 1 byte is available in the FIFO, the Wait/Request pin becomes inactive and becomes active when the FIFO is emptied. PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 23 By resetting WR7’ bit 3 to 0, applications which have a long latency to interrupts can generate the request to read data from the FIFO when one byte is available. The application can then test the Receive Character Available bit to determine if more data is available. By setting WR7’ bit 3 to 0, the ESCC can issue an interrupt when the receive FIFO is half full (4 bytes available), allowing the frequency of interrupts to be reduced. If WR7’ bit 3 is 1, the Receive Character Available interrupt is generated when there are 4 bytes available. If the ISR reads 4 bytes during each routine, the frequency of interrupts is reduced. If WR7’ bit 3 is 1 and Receive Interrupt on All Characters and Special Conditions is enabled, the receive character available interrupt is generated when four characters are available. However, when a character is detected to have a special condition, an interrupt is generated when the character is loaded into the top four bytes of the FIFO. Therefore, the Special Condition ISR must be RR1 before reading the data to determine which byte has the special condition. Write Register 7 PRIME (WR7’) A new register, WR7’, has been added to the ESCC to enable the programming of six new features. The format of this register is listed in Table 4. Table 4. Write Register 7 Prime (WR7’) Bit 7 6 5 4 3 2 1 0 R/W W W W /W W W W W Reset 0 0 0 0 0 0 0 0 Note: R = Read W = Write X = Indeterminate Bit Position R/W Value 0 Description 7 W Reserved, must be 0 6 W Extended Read Enable 5 W Transmit FIFO Int Level 4 W DTR/REQ Timing Mode 3 W Receive FIFO Int Level 2 W Auto RTS Deactivation 1 W Auto EOM Reset 0 W Auto Transmit Flag WR7’ is written by first setting Bit 0 of Write Register 15 (WR15 bit 0) to 1 and then accessing WR7. All write commands to register 7 are to WR7’ while WR15 bit 0 is set to PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 24 1. WR15 bit 0 must be reset to 0 to address the SYNC character in register WR7. If bit 6 of WR7’ is set to 1, then WR7’ can be read by performing a read cycle to RR14. The WR7’ features remain enabled until specifically disabled or by a hardware or software reset. Bit 5 is set to 1 and all other bits are reset to 0 after a reset. For applications which use either the Zilog Z8X30SCC or Z80230, these two device types can be identified in software with the following test: 1. Write 01H to Write Register 15 2. Read Register 15 If bit 0 is set to 0, the device is Z8X30SCC. If bit 0 is set to 1, it is a Z80C30. If the device is Z8XC30, a write to WR15 is required before proceeding. If the device is Z80230, all writes to address 7 are to WR7’ until WR15 is set to 0. The WR7 register bits are described below: Bit 7 (Not used) This bit must always be 0. Bit 6 (Extended Read Enable) Setting this bit to 1 enables WR3, WR4, WR5, WR7’ and WR10 to be read by issuing a READ command for RR9 (WR3) RR4, RR5, RR14 (WR7’) and RR11 (WR10), respectively. Bit 5 (Transmit FIFO Interrupt Level) If this bit is set to 1, the TBE interrupt is generated when the transmit FIFO is completely empty. If this bit is set to 0, the TBE interrupt is generated when the top byte of the transmit FIFO is empty. This bit is set following a hardware or channel reset. In DMA REQUEST ON TRANSMIT mode, when using either the W/REQ or DTR/REQ pins, the request is asserted when the Tx FIFO is completely empty if WR7’ bit 5 is set to 1. The request is asserted when the top byte of the FIFO is empty if bit 5 is reset. Bit 4 (DTR/REQ Timing) If this bit is set to 1 and the DTR/REQ pin is used for REQUEST mode (WR14 bit 2 is 1), the deactivation of the DTR/REQ pin is identical to the W/REQ pin as displayed in Figure 12 on page 25. If this bit is reset, the deactivation time is 4TcPc. PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 25 WR D7–D0 Transmit Data WR7 bit 4 =1 DTR/REQ WR7 bit 4 = 0 WAIT/REQ Figure 12. DMA Request on Transmit Deactivation Timing Bit 3 (Receive FIFO Interrupt Level) This bit sets the interrupt level of the receive FIFO. If this bit is set to 1, the receive data available bit is asserted when the receive FIFO is half full (4 bytes available). If this bit is reset to 0, the Receive Data Available interrupt is requested when all bytes are set. For more information, see 8-Byte Receive FIFO on page 22. Bit 2 (Automatic RTS Pin Deassertion) This bit controls the timing of the deassertion of the RTS pin in SDLC mode. If this bit is 1 and WR5 bit 1 is set to 0 during the transmission of an SDLC frame, the deassertion of the RTS pin is delayed until the last bit of the closing flag clears the TxD pin. The RTS pin is pulled High after the rising edge of the transmit clock cycle from the last bit of the closing flag. This action implies that the ESCC must be programmed for Flag on Underrun (WR10 bit 2 is 0) for the RTS pin to deassert at the end of the frame. This feature works independently of the programmed Transmitter Idle state. In SYNCHRONOUS mode other than SDLC, the RTS pin immediately follows the state programmed into WR5 bit 1. When WR7’ bit 2 is set to 0, the RTS follows the state of WR5 bit 1. Bit 1 (Automatic EOM Reset) If this bit is 1, the ESCC automatically resets the Tx Underrun/EOM latch and presets the transmit CRC generator to its programmed preset state (per values set in WR5 bit 2 and WR10 bit 7). Therefore, it is not necessary to issue the Reset Tx Underrun/EOM Latch command when this feature is enabled. Bit 0 (Automatic Tx SDLC Flag) If this bit is 1, the ESCC automatically transmits an SDLC flag before transmitting data. This action removes the requirement to reset the Mark Idle bit (WR10 bit 3) before writing data to the transmitter. PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 26 Historically, the SCC latched the databus on the falling edge of WR. However, as many CPUs do not guarantee that the databus is valid when the WR pin goes Low, Zilog modified the databus timing to allow a maximum delay of 20 nS from the WR signal going active Low to the latching of the databus. CRC Reception in SDLC Mode In SDLC mode, the entire CRC is clocked into the receive FIFO. The ESCC completes clocking in the CRC to allow it to be retransmitted or manipulated software. In the SCC, when the closing flag is recognized, the contents of the receive shift register are immediately transferred to the receive FIFO, resulting in the loss of the last two bits of the CRC. In the ESCC, it is not necessary to program this feature. When the closing flag is detected, the last 2 bits of the CRC are transferred into the receive FIFO. In all other  SYNCHRONOUS mode, the ESCC does not clock in the last 2 CRC bits (same as the SCC). TxD Forced High in SDLC with NRZI Encoding When Marking Idle When the ESCC is programmed for SDLC mode with NRZI data encoding and Mark Idle (WR10 bit 6 is 0, bit 5 is 1, bit 3 is 1), the TxD pin is automatically forced High when the transmitter enters the Mark Idle state. There are several different ways for the transmitter to enter the Idle state. In each of the following cases the TxD pin is forced High when the Mark Idle condition is reached: • • • • • Data, CRC, flag, and Idle Data, flag, and Idle Data, abort (on underrun), and Idle Data, abort (command), and Idle Idle flag and command to Idle Mark The Force High feature is disabled when the Mark Idle bit is set to 0. This feature is used in combination with the automatic SDLC opening flag transmission feature, WR7’ bit 0 is 1, to assure that data packets are formatted correctly. In this case, the CPU is not required to issue any commands. If WR7’ bit 0 is 0, as on the SCC, the Mark Idle bit (WR10 bit 3), is set to 1, to enable flag transmission before an SDLC packet transmits. Improved Transmit Interrupt Handling The ESCC latches the TBE interrupt because the CRC is loaded into the Transmit Shift register even if the TBE interrupt, due at the last data byte, has not been reset. The end of a PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 27 synchronous frame is guaranteed to generate two TBE interrupts even if a Reset Transmit Buffer Interrupt command for the data created interrupt is issued after the CRC interrupt occurs (Time A in Figure 13). Two Reset TBE commands are required. The TxIP latches if the EOM latch resets before the end of the frame. Data Data CRC1 CRC2 Flag TxBE Time A TxIP Bit TxIP 2 TxIP 1 Figure 13. TxIP Latching DPLL Counter Tx Clock Source When the DPLL is selected as the transmit clock source, the DPLL counter output is the DPLL source clock divided by the appropriate divisor for the programmed data encoding format. In FM mode (FM0 or FM1), the DPLL counter output signal is the input frequency divided by 16. In NRZI mode, the DPLL counter output signal is the input clock cycle divided by 32. This feature provides a jitter-free output signal that replaces the DPLL transmit clock output as the transmit clock source. This action has no effect on the use of the DPLL as the receive clock source (see Figure 14). DPLL CLK Input DPLL DPLL Counter DPLL Output to Receiver DPLL Output to Transmitter Input Frequency Divided by 16 (FM0 or FM1) Input Clock Cycle Divided by 32 for NRZI Figure 14. DPLL Outputs Read Register 0 Status Latched During Read Cycle The contents of Read Register 0, RR0 is latched during a Read operation. The ESCC prevents the contents of RR0 from changing during a Read operation. But, the SCC allows the status of RR0 to change while reading the register and may require reading RR0 twice. The contents of RR0 is updated after the rising edge of RD signal. PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 28 Software Interrupt Acknowledge The Z80230/Z85230/L interrupt acknowledge cycle can be initiated using software. If Write Register 9 (WR9 bit 5 is 1), Read Register 2 (RR2) results in an interrupt INTACK cycle, a software acknowledgment causes the INT pin to go High. The IEO pin goes Low. The Interrupt Under Service (IUS) latch is set to the highest priority pending interrupt. When a hardware INTACK signal is desired, a software acknowledge cycle requires that a Reset Highest IUS command be issued in the ISR. If RR2 is read from Channel A, the unmodified vector is returned. If RR2 is read from Channel B, then the vector is modified to indicate the source of the interrupt. The Vector Includes Status (VIS) and No Vector (NV) bits in WR9 are ignored when WR9 bit 5 is set to 1. If the INTACK and IEI pins are not used, they are pulled up to VCC through a resistor  (2.2 k?, typical). Fast SDLC Transmit Data Interrupt Response To facilitate the transmission of back-to-back SDLC frames with a single shared flag between frames, the ESCC allows data for a second frame to be written to the transmit FIFO after the Tx Underrun/EOM interrupt occurs. This feature allows application software more time to write the data to the transmitter while allowing the current frame to conclude with CRC and flag. The SCC required that data not be written to the transmitter until a TBE interrupt is generated after the CRC completed transmission. If data is written to the transmit FIFO after the Transmit Underrun/EOM interrupt is issued but before the TBE interrupt is issued, the Automatic EOM Reset function is enabled (WR7’ bit 1 is 1). Consequently, the commands Reset Tx/Underrun EOM Latch and Reset Tx CRC Generator must never be used. SDLC FIFO Frame Status Enhancement When used with a DMA controller, the ESCC SDLC Frame Status FIFO enhancement maximizes the ESCC’s ability to receive high-speed, back-to-back SDLC messages. It minimizes frame overruns due to CPU latencies in responding to interrupts. The feature (displayed in Figure 15 on page 29) includes: • • • 10-bit deep by 19-bit wide status FIFO 14-bit receive byte counter Control logic The 10 x 19 bits status FIFO is separate from the 8-byte receive data FIFO. When the enhancement is enabled, the status in Read Register 1 (RR1) and byte count for the SDLC frame are stored in the 10- x 19-bit status FIFO. This action allows the DMA PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 29 controller to transfer the next frame into memory while the CPU verifies the previously received frame. Frame Status FIFO Circuitry SCC Status Register RR1 Residue Bits (3) Overrun, CRC Error Byte Counter Reset on Flag Detect Increment on Each Received Character Enable Count in SDLC EOF Signal 14 Bits Status Read Complete 5 Bits FIFO Array 10- by 19- Bits Tail Pointer 4-Bit Counter Head Pointer 4-Bit Counter 4-Bit Comparator Equal Over 5 Bits EOF=1 6 Bits EN 6-Bit MUX 2 Bits 6 Bits RR1 Interface to SCC 8 Bits Bit Bit 7 6 Bits 5-0 FIFO Enable RR6 RR7 5 - 0 + RR6 7-0 14-Bit Byte Counter (16 KB Maximum Count) WR15 Bit 2 Set Enables Status FIFO RR7 Bit 7 FIFO data-available status bit (1 during read) RR7 Bit 7 FIFO Overflow Status Bit (1 on overflow) See Notes:, next. Figure 15. SDLC Frame Status FIFO Notes: 1. All Sent bypasses MUX and equals contents of SCC Status Register. 2. Parity bits bypass MUX and equals contents of SCC Status Register. 3. EOF is set to 1 whenever reading from the FIFO. Summarizing the operation: Data is received, assembled, and loaded into the 8-byte FIFO before transferring to memory by the DMA controller. PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 30 When a flag is received at the end of an SDLC frame, the frame byte count from the 14-bit counter and 5 status bits are loaded into the status FIFO for verification by the CPU. The CRC checker is automatically reset in preparation for the next frame, which starts immediately. Because the byte count and status are saved for each frame, the message integrity can be verified at a later time. Status information for up to ten frames is stored before a status FIFO overrun occurs. If a frame is terminated with an Abort command, the byte count and status is loaded to the status FIFO and the counter is reset for the next frame. FIFO Enable/Disable This FIFO buffer is enabled when WR15 bit 2 is 1 and the ESCC is in the SDLC/HDLC mode. Otherwise, the status register contents bypass the FIFO and transfer directly to the bus interface (the FIFO pointer logic is reset either when disabled or by a channel or power-on reset). When the FIFO mode is disabled, the ESCC is downward-compatible with the NMOS Z8030/Z8530. The FIFO mode is disabled on power-up (WR15 bit 2 set to 0 on reset). The effects of backward compatibility on the register set are that RR4 is an image of RR0, RR5 is an image of RR1, RR6 is an image of RR2, and RR7 is an image of RR3. For information on the added registers, see Read Registers on page 53. The status of the FIFO Enable signal is read at RR15 bit 2. If the FIFO is enabled, the bit is set to 1; otherwise it is reset to 0. FIFO Read Operation When WR15 bit 2 is 1 and the FIFO is not empty, the next read status register RR1 or the additional registers RR7 and RR6, reads the FIFO. Reading status register RR1 causes one location of the FIFO to empty, so status is read after reading the byte count; otherwise the count is incorrect. Before the FIFO underflows, it is disabled. In this case, the multiplexer is switched to allow status to read directly from the status register. In this state, reads from RR7 and RR6 are undefined bit 6 of RR7 (FIFO data available) status data is coming from the FIFO or directly from the status register, because it is set to 1 whenever the FIFO is not empty. Since all status bits are not stored in the FIFO, the All Sent, Parity, and EOF bits bypass the FIFO. The status bits sent through the FIFO are the three Residue Bits, Overrun, and CRC Error. The correct sequence for polling the byte count and FIFO logic is RR7, RR6, then RR1 (reading RR6 is optional). Additional logic prevents the FIFO from emptying by multiple reads from RR1. The read from RR7 latches the FIFO empty/full status bit (bit 6) and steers the status multiplexer to read the ESCC megacell instead of the status FIFO PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 31 (because the status FIFO is empty). The read from RR1 allows an entry to be read from the FIFO (if the FIFO is empty, the logic prevents a FIFO underflow condition). FIFO Write Operation When the end of an SDLC frame is received and the Status FIFO is enabled, the contents of the status and byte-count registers load into the FIFO. The EOF signal increments the FIFO. If the FIFO overflows, the RR7 bit 7 (FIFO overflow) is set, indicating the overflow. This bit and the FIFO control logic is reset by disabling and re-enabling the FIFO control bit (WR15 bit 2). For details about FIFO control timing during an SDLC frame, see Figure 16. 0 F 1 A 2 D 3 D 4 D 5 D 6 7 0 1 2 3 4 5 6 7 0 C C F A D D D D C C F F Internal byte strobe increments counter Internal byte strobe increments counter Do not load counter on first flag. reset byte counter here Reset byte counter, then load counter into FIFO and increment PTR. Reset byte counter, then load counter into FIFO and increment PTR Figure 16. SDLC Byte Counting Detail SDLC Status FIFO Anti-Lock Feature When the Frame Status FIFO is enabled and the ESCC is programmed for Special Receive Condition Only (WR1 bit 4 = bit 3=1), the data FIFO is not locked when a character with EOF status is read.When EOF status is at the top of the FIFO, an interrupt with a vector for receive data is generated. The command Reset Highest IUS must be issued at the end of the ISR regardless of whether an Interrupt Acknowledge cycle was executed (hardware or software). This action allows the DMA to complete the transfer of the received frame to memory, then interrupt the CPU that a frame was completed, without locking the FIFO. Because in the RECEIVE INTERRUPT ON SPECIAL CONDITION ONLY mode the interrupt vector for receive data is not used, it indicates that the last byte of a frame has been read from the receive FIFO. Reading the frame status (CRC, byte count and other status stored in the status FIFO) determines that EOF is not required. When a character with a special receive condition other than EOF is received (receiver overrun or parity), a special receive condition interrupt is generated after the character is read from the FIFO and the receive FIFO is locked until the Error Reset command is issued. PS005309-0515 Z80230/Z85230/L Enhancements Z80230/Z85230/L Product Specification 32 Programming The ESCC contains write registers in each channel that are programmed by the system separately to configure the function of each channel. In the Z85230/L ESCC, the data FIFOs are directly accessible by selecting a High on the  D/C pin. Except WR0 and RR0, programming the write registers requires two write operations and reading a read register requires a write and a read operation. The first Write is to WR0 which contains bits that point to the selected register. If the next operation is a Write the selected write register is written. If the next operation is a read, the selected read register is read. The pointer bits are automatically cleared after the second operation so the next read or write comes from RR0 or goes to WR0. It is not necessary to write 00 to WR0 to access WR0 or RR0. For the Z80230 ESCC, the registers are directly addressable. A command issued to WR0B determines how the ESCC decodes the address placed on the address/data bus at the beginning of a Read or Write cycle. In Shift Right mode the channel select A/B is taken from AD0 and the state of AD5 is ignored. In Shift Left mode, the channel select A/B is taken from AD5 and the state of AD0 is ignored. AD7 and AD6 are always ignored as address bits and the register address itself occupies AD4–AD1. Initializing The software first issues a series of commands to initialize the basic mode of operation. These commands are followed by other commands to qualify conditions within the selected mode. For example, in the ASYNCHRONOUS mode, character length, clock rate, number of stop bits, and even and odd parity is set first. Next, the INTERRUPT mode is set. Finally, the receiver and transmitter are enabled. Write Registers The ESCC contains 16 write registers (17 counting the transmit buffer) in each channel. These write registers are programmed to configure the function of the channel. There are two registers (WR2 and WR9) shared by the two channels, which can be accessed through either of them. WR2 contains the interrupt vector for both channels. WR9 contains the interrupt control bits and reset commands. Register WR7’ can be written to if WR15 bit 0 is 1. Z80X20 Register Access The Z80230 registers are addressed using the address on AD7–AD0 which are latched by the rising edge of AS. The Shift Right/Shift Left bit in the Channel B WR0 controls which PS005309-0515 Programming Z80230/Z85230/L Product Specification 33 bits are decoded to form the register address. This bit is placed in this register to simplify programming when the current state of the Shift right/Shift Left bit is not known. A hardware reset forces SHIFT LEFT mode where the address is decoded from  AD5–AD0. In SHIFT RIGHT mode, the address is decoded from AD4–AD0. The Shift Right/Shift Left bit is written using a command to make the software writing to WR0 independent of the state of the Shift Right/Shift Left bit. While in the SHIFT LEFT mode, the register address is placed on AD4–AD0 and the Channel Select bit A/B, is decoded from AD5. In SHIFT RIGHT mode, the register address is again placed on AD4–AD1 but the Channel Select A/B is decoded from AD0. Since Z80230 does not contain 16 read registers, the decoding of the read registers is not complete; this state is listed in Table 4 on page 23 and Table 5 by parentheses around the register name. These addresses may also be used to access the read registers. The Z80230 contains only one WR2 and WR9; these registers may be written from either channel. SHIFT LEFT mode is used when Channel A and B are programmed differently. Using SHIFT LEFT mode allows the software to sequence through the registers of one channel at a time. The SHIFT RIGHT mode is used when the channels are programmed the same. By incrementing the address, you can program the same data value into both Channel A and Channel B registers. Table 5 lists details of the Z80X30 Register Map in SHIFT LEFT Mode. Table 5. Z80230 Register Map (Shift Left Mode) 80230 80230 WR15 D2=1 80230 WR15 D2=0 WR15 D2=1 WR7’ D6=1 AD5 AD4 AD3 AD2 AD1 Write 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 WR08 WR1B WR2 WR3B RR0B RR1B RR2B RR3B RR0B RR1B RR2B RR3B RR08 RR1B RR2B RR3B 0 0 0 0 0 0 0 0 1 1 1 1 0 0 1 1 0 1 0 1 WR4B WR5B WR6B WR7B (RR0B) (RR1B) RR6B RR7B (RR0B) (RR1B) (RR2B) (RR3B) (WR4B) (WR5B) RR6B RR7B 0 0 0 0 1 1 1 1 0 0 0 0 0 0 1 1 0 1 0 1 WR8B WR9 WR10B WR11B RR8B (RR13B) RR10B (RR15B) RR8B (RR13B) RR10B (RR15B) RR8B (WR3B) RR10B (WR10B) PS005309-0515 Programming Z80230/Z85230/L Product Specification 34 Table 5. Z80230 Register Map (Shift Left Mode) (Continued) 80230 80230 80230 WR15 D2=1 WR15 D2=0 WR15 D2=1 WR7’ D6=1 AD5 AD4 AD3 AD2 AD1 Write 0 0 0 0 1 1 1 1 1 1 1 1 0 0 1 1 0 1 0 1 WR12B WR13B WR14B WR15B RR12B RR13B RR14B RR15B RR12B RR13B RR14B RR15B RR12B RR13B (WR7’B) RR15B 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 WR0A WR1A WR2 WR3A RR0A RR1A RR2A RR3A RR0A RR1A RR2A RR3A RR0A RR1A RR2A RR3A 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 1 0 1 WR4A WR5A WR6A WR7A (RR0A) (RR1A) (RR2A) (RR3A) (RR0A) (RR1A) RR6A RR7A (WR4A) (WR5A) RR6A RR7A 1 1 1 1 1 1 1 1 0 0 0 0 0 0 1 1 0 1 0 1 WR8A WR9 WR10A WR11A RR8A (RR13A) RR10A (RR15A) RR8A (RR13A) RR10A (RR15A) RR8A (WR3A) RR10A (WR10A) 1 1 1 1 1 1 1 1 1 1 1 1 0 0 1 1 0 1 0 1 WR12A WR13A WR14A WR15A RR12A RR13A RR14A RR15A RR12A RR13A RR14A RR15A RR12A RR13A (WR7’A) RR15A Notes: 1. The register names in ( ) are the values read out from that register location. 2. WR15 bit D2 enables status FIFO function (not available on NMOS). 3. WR7’ bit D6 enables extend read function (only on ESCC). PS005309-0515 Programming Z80230/Z85230/L Product Specification 35 Table 6 lists details of the Z80X30 Register Map in SHIFT RIGHT mode. Table 6. Z80X30 Register Map (Shift Right Mode) 80230 80230 80230 WR15 D2=1 WR15 D2=0 WR15 D2=1 WR7’ D6=1 AD4 AD3 AD2 AD1 AD0 Write 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 WR08 WR0A WR1B WR1A RR0B RR0A RR1B RR1A RR0B RR0A RR1B RR1A RR0B RR0A RR1B RR1A 0 0 0 0 0 0 0 0 1 1 1 1 0 0 1 1 0 1 0 1 WR2 WR2 WR3B WR3A RR2B RR2A RR3B RR3A RR2B RR2A RR3B RR3A RR2B RR2A RR3B RR3A 0 0 0 0 1 1 1 1 0 0 0 0 0 0 1 1 0 1 0 1 WR4B WR4A WR5B WR5A (RR0B) (RR0A) (RR1B) (RR1A) (RR0B) (RR0A) (RR1B) (RR1A)) (WR4B) (WR4A) (WR5B) (WR5A) 0 0 0 0 1 1 1 1 1 1 1 1 0 0 1 1 0 1 0 1 WR6B WR6A WR7B WR7A (RR2B) (RR2A) (RR3B) (RR3A) RR12B RR13B RR14B RR15B RR12B RR13B (WR7’B) RR15B 1 1 1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 WR8B WR8A WR9 WR9 RR8B RR8A (RR13B) (RR13A) RR8B RR8A (RR13B) (RR13A) RR8B RR8A (WR3B) (WR3A) 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 1 0 1 WR10B WR10A WR11B WR11A RR10B RR10A (RR15B) (RR15A) RR10B RR10A (RR15B) (RR15A) RR10B RR10A (WR10B) (WR10A) 1 1 1 1 1 1 1 1 0 0 0 0 0 0 1 1 0 1 0 1 WR12B WR12A WR13B WR13A RR12B RR12B RR13B RR13A RR12B RR12B RR13B RR13A RR12B RR12B RR13B RR13A 1 1 1 1 1 1 1 1 1 1 1 1 0 0 1 1 0 1 0 1 WR14B WR14A WR15B WR15A RR12B RR12B RR13B RR13A RR12B RR12B RR13B RR13A (WR7’B) (WR7’B) RR13B RR13A Notes: 1. The register names in ( ) are the values read out from that register location. 2. WR15 bit D2 enables status FIFO function (not available on NMOS). 3. WR7’ bit D6 enables extend read function (only on ESCC). PS005309-0515 Programming Z80230/Z85230/L Product Specification 36 Bits 2–0 of WR0 select registers 0–7. With the Point High command, Registers 8–15 are selected. Table 7 lists details of the Z85230/L Register Map. Table 7. Z85230/L Register Map A/B PNT2 PNT1 PNT0 Write Read 85C30/230 WR15 D2=0 Read 85C30/230 WR15 D2=1 Read WR15 D2=1 WR7’ D6=1 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 WR0B WR1B WR2 WR3B RR0B RR1B RR2B RR3B RR0B RR1B RR2B RR3B RR0B RR1B RR2B RR3B 0 0 0 0 1 1 1 1 0 0 1 1 0 1 0 1 WR4B WR5B WR6B WR7B (RR0B) (RR1B) (RR2B) (RR3B) (RR0B) (RR1B) RR6B RR7B (WR4B) (WR5B) RR6B RR7B 1 1 1 1 0 0 0 0 0 0 1 1 0 1 0 1 WR0A WR1A WR2 WR3A RR0A RR1A RR2A RR3A RR0A RR1A RR2A RR3A RR0A RR1A RR2A RR3A 1 1 1 1 1 1 1 1 0 0 1 1 0 1 0 1 WR4A WR5A WR6A WR7A (RR0A) (RR1A) (RR2A) (RR3A) (RR0A) (RR1A) RR6A RR7A (WR4A) (WR5A) RR6A RR7A With Point High Command 0 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 WR8B WR9 WR10B WR11B RR8B (RR13B) RR10B (RR15B) RR8B (RR13B) RR10B (RR15B) RR8B (WR3B) RR10B (WR10B) 0 0 0 0 1 1 1 1 0 0 1 1 0 1 0 1 WR12B WR13B WR14B WR15B RR12B RR13B RR14B RR15B RR12B RR13B RR14B RR15B RR12B RR13B (WR7’B) RR15B 1 1 1 1 0 0 0 0 0 0 1 1 0 1 0 1 WR8A WR9 WR10A WR11A RR8A (RR13A) RR10A (RR15A) RR8A (RR13A) RR10A (RR15A) RR8A (WR3A) RR10A (WR10A) 1 1 1 1 1 1 1 1 0 0 1 1 0 1 0 1 WR12A WR13A WR14A WR15A RR12A RR13A RR14A RR15A RR12A RR13A RR14A RR15A RR12A RR13A (WR7’A) RR15A Notes: 1. WR15 bit D2 enables status FIFO function (not available on NMOS). 2. WR7’ bit D6 enables extend read function (only on ESCC and 85C30). Table 8 through Table 24 on page 53 list the format of each write register. PS005309-0515 Programming Z80230/Z85230/L Product Specification 37 Table 8. Write Register 0 Bit 7 6 5 4 2 1 0 0 0 0 0 W R/W Reset 3 0 0 0 0 R = Read W = Write X = Indeterminate Bit Position 7, 6 R/W W Value Description 00 01 10 11 Null Code Reset Tx CRC Checker Reset Tx CRC Generator Reset Tx Underrun/EOM Latch 5, 4, 3 000 001 010 011 100 101 110 111 Null Code Point High Reset Ext/Status Interrupts Send Abort (SDLC) Enable Int on Next Rx Character Reset Tx Int Pending Error Reset Reset Highest IUS 2, 1, 0 000 001 010 011 100 101 110 111 000 001 010 011 100 101 110 111 Register 0 Register 1 Register 2 Register 3 Register 4 Register 5 Register 6 Register 7 Register 8 (with Point High) Register 9 (with Point High) Register 10 (with Point High) Register 11 (with Point High) Register 12 (with Point High) Register 13 (with Point High) Register 14 (with Point High) Register 15 (with Point High) For the 80230, bits 1 and 0 are accessible only through Channel B. PS005309-0515 Programming Z80230/Z85230/L Product Specification 38 Table 9. Write Register 1 Bit 7 6 5 4 3 2 1 0 0 X 0 0 W R/W 0 Reset 0 X 0 R = Read W = Write X = Indeterminate Bit Position R/W Value 7 0 1 WAIT/DMA Request Enable Disabled Enabled 0 1 WAIT/DMA Request Function Wait Request 0 1 WAIT/DMA Request on Receive/Transmit Transmit Receive 00 01 10 11 Receive Interrupt Disable Rec Int on First Character or Special Condition Int on all Rx Characters or Special Condition Rx Int on Special Condition Only 6 5 4, 3 Description 2 Parity is Special condition 1 Tx Int Enable 0 Ext Int Enable PS005309-0515 Programming Z80230/Z85230/L Product Specification 39 Table 10. Write Register 2 Bit 7 6 5 4 3 2 1 0 X X X X W R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 V7–Interrupt Vector 6 V6–Interrupt Vector 5 V5–Interrupt Vector 4 V4–Interrupt Vector 3 V3–Interrupt Vector 2 V2–Interrupt Vector 1 V1–Interrupt Vector 0 V0–Interrupt Vector PS005309-0515 Programming Z80230/Z85230/L Product Specification 40 Table 11. Write Register 3 Bit 7 6 5 4 3 2 1 0 X X X 0 W R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position 7, 6 R/W Value 00 01 10 11 Description Rx 5 Bits/Character Rx 7 Bits/Character Rx 6 Bits/Character Rx 8 bits/Character 5 Auto Enable 4 Enter HUNT Mode 3 Rx CRC Enable 2 Address Search Mode (SDLC) 1 Sync Character Load Inhibit 0 Rx Enable PS005309-0515 Programming Z80230/Z85230/L Product Specification 41 Table 12. Write Register 4 Bit 7 6 5 4 3 2 1 0 X 1 X 0 W R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7, 6 00 01 10 11 X1 Clock Mode X16 Clock Mode Z32 Clock Mode X64 Clock Mode 5, 4 00 01 10 11 8-Bit Sync Character 16-Bit Sync Character SDLC Mode (01111110 Flag) External Sync Mode 3, 2 00 01 10 11 Sync Modes Enable 1 Stop Bit/Character 1.5 Stop Bits/Character 2 Stop Bits/Character 0 1 Parity EVEN/ODD Odd Even 1 0 PS005309-0515 Parity Enable Programming Z80230/Z85230/L Product Specification 42 Table 13. Write Register 5 Bit 7 6 5 4 3 2 1 0 0 0 0 X W R/W 0 Reset X X 0 R = Read W = Write X = Indeterminate Bit Position R/W Value 7 6, 5 Description DTR 00 01 10 11 Tx 5 Bits (or less)/Character Tx 7 Bits/Character Tx 6 Bits/Character Tx 8 Bits/Character 4 Send Break 3 Tx Enable 2 0 1 CRC-16/CRC-CCITT CRC-CCITT CRC-16 1 RTS 0 Tx CRC Enable PS005309-0515 Programming Z80230/Z85230/L Product Specification 43 Table 14. Write Register 6 Bit 7 6 5 4 2 1 0 X X X X W R/W Reset 3 X X X X R = Read W = Write X = Indeterminate Description Monosync 8 Bits Monos ync 6 Bits Bisync 16 Bits Bisync 12 Bits SDLC SDLC (Address Range) 7 Sync7 Sync1 Sync7 Sync3 ADR7 ADR7 6 Sync6 Sync0 Sync6 Sync2 ADR6 ADR6 5 Sync5 Sync5 Sync5 Sync1 ADR5 ADR5 4 Sync4 Sync4 Sync4 Sync0 ADR4 ADR4 3 Sync3 Sync3 Sync3 1 ADR3 X 2 Sync2 Sync2 Sync2 1 ADR2 X 1 Sync1 Sync1 Sync1 1 ADR1 X 0 Sync0 Sync0 Sync0 1 ADR0 X Bit Position R/W PS005309-0515 Value Programming Z80230/Z85230/L Product Specification 44 Table 15. Write Register 7 Bit 7 6 5 4 3 2 1 0 X X X X W R/W X Reset X X X R = Read W = Write X = Indeterminate Description Bit Position R/W Value This column contains no data Monosync 8 Monosync 6 Bisync 16 Bits Bits Bits Bisync 12 Bits SDLC Sync7 Sync5 Sync15 Sync11 0 6 Sync6 Sync4 Sync14 Sync10 1 5 Sync5 Sync3 Sync13 Sync9 1 4 Sync4 Sync2 Sync12 Sync8 1 3 Sync3 Sync1 Sync11 Sync7 1 2 Sync2 Sync0 Sync10 Sync6 1 1 Sync1 X Sync9 Sync5 1 0 Sync0 X Sync8 Sync4 0 7 PS005309-0515 Programming Z80230/Z85230/L Product Specification 45 Table 16. Write Register 7’ Bit 7 6 5 4 3 2 1 0 0 0 0 0 W R/W 0 Reset 0 1 0 R = Read W = Write X = Indeterminate Bit Position 7 R/W Value 0 Description Not Used. Must be 0. 6 Extended Read Enable 5 Tx FIFO Int Level 4 DTR/REQ Timing Mode 3 Rx FIFO Int Level 2 Auto RTS Deactivation 1 Auto EOM Reset 0 Auto Tx Flag PS005309-0515 Programming Z80230/Z85230/L Product Specification 46 Table 17. Write Register 8 Bit 7 6 5 4 3 2 1 0 0 0 0 0 W R/W 0 Reset 0 1 0 R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 D7 6 D6 5 D5 4 D4 3 D3 2 D2 1 D1 0 D0 PS005309-0515 Programming Z80230/Z85230/L Product Specification 47 Table 18. Write Register 9 Bit 7 6 5 4 3 2 1 0 W R/W Hardware Reset 1 1 0 0 0 0 X X Channel Reset X X 0 X X X X X R = Read W = Write X = Indeterminate Bit Position 7, 6 R/W Value 00 01 10 11 Description No Reset Channel Reset B Channel Reset A Force Hardware Reset Software INTACK Enable 5 4 0 1 Status High/ Status Low Low High 3 Master Interrupt Enable 2 Disable Lower Chain 1 No Vector 0 Vector Includes Status PS005309-0515 Programming Z80230/Z85230/L Product Specification 48 Table 19. Write Register 10 Bit 7 6 5 4 3 2 1 0 W R/W Hardware Reset 0 0 0 0 0 0 0 0 Channel Reset 0 X X 0 0 0 0 0 R = Read W = Write X = Indeterminate Bit Position R/W Value 7 6, 5 CRC Preset I/O 00 01 10 11 4 NRZ NRZI FM 1 (Transition = 1) FM 0 (Transition = 0) Go Active on Poll 0 1 Mark/Flag Idle Flag Idle Mark Idle 0 1 Abort/Flag on Underrun Flag Abort 3 2 1 Loop Mode 0 0 1 PS005309-0515 Description 6-Bit/8-Bit sync 8-Bit 6-bit Programming Z80230/Z85230/L Product Specification 49 Table 20. Write Register 11 Bit 7 6 5 4 3 2 1 0 W R/W Hardware Reset 0 0 0 0 1 0 0 0 Channel Reset X X X X X X X X R = Read W = Write X = Indeterminate Bit Position R/W Value 7 Description 0 1 RTxC Xtal/No Xtal No Xtal RTxC Xtal 6, 5 00 01 10 11 Receive Clock = RTxC Pin Receive Clock = TRxC Pin Receive Clock = BRG Output Receive Clock = DPLL Output 4, 3 00 01 10 11 Transmit Clock = RTxC Pin Transmit Clock = TRxC Pin Transmit Clock = BRG Output Transmit Clock = DPLL Output 0 1 TRxC Input/Output Output Input 00 01 10 11 TRxC Out = Xtal Output TRxC Out = Transmit Clock TRxC Out = BRG Output TRxC Out = DPLL Output 2 1 PS005309-0515 Programming Z80230/Z85230/L Product Specification 50 Table 21. Write Register 12 Bit 7 6 5 4 3 2 1 0 X X X X W R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description (Lower Byte of Time Constant) 7 TC7 6 TC6 5 TC5 4 TC4 3 TC3 2 TC2 1 TC1 0 TC0 PS005309-0515 Programming Z80230/Z85230/L Product Specification 51 Table 22. Write Register 13 Bit 7 6 5 4 3 2 1 0 X X X X W R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description (Upper Byte of Time Constant) 7 TC15 6 TC14 5 TC13 4 TC12 3 TC11 2 TC10 1 TC9 0 TC8 PS005309-0515 Programming Z80230/Z85230/L Product Specification 52 Table 23. Write Register 14 Bit 7 6 5 4 3 2 1 0 X X X X W R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position 7, 6, 5 R/W Value 000 001 010 011 100 101 110 111 Description (Upper Byte of Time Constant) Null Command Enter Search Mode Reset Missing Clock Disable DPLL Set source - BRG Set Source = RTxC Set FM Mode Set NRZI Mode 4 Local Loopback 3 Auto Echo 2 DTR/Request Generator Source 1 BRG Source 0 BRG Enable PS005309-0515 Programming Z80230/Z85230/L Product Specification 53 Table 24. Write Register 15 Bit 7 6 5 4 3 2 1 0 0 0 0 0 W R/W 1 Reset 1 1 1 R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 Break/Abort Interrupt Enable 6 Tx Underrun/EOM Interrupt Enable 5 CTS Interrupt Enable 4 Sync/Hunt 3 DCD Interrupt Enable 2 SDLC FIFO Enable 1 Zero Count Interrupt Enable 0 WR7’ SDLC Feature Enable Read Registers The ESCC contains ten read registers (eleven, counting the receive buffer RR8) in each channel. Four of these may be read to obtain status information (RR0, RR1, RR10, and RR15). Two registers, RR12 and RR13, are read to learn the BRG time constant. RR2 contains either the unmodified interrupt vector, Channel A, or the vector modified by status information, Channel B. RR3 contains the Interrupt Pending (IP) bits for Channel A. RR6 and RR7 contain the information in the SDLC Frame Status FIFO, but is only read when WR15 bit 2 is 1. If WR7’ bit 6 is 1, Write Registers WR3, WR4, WR5, and WR10 can be read as RR9, RR4, RR5, and RR14, respectively. Table 25 on page 54 through Table 40 on page 69 list the format of the read registers. PS005309-0515 Programming Z80230/Z85230/L Product Specification 54 Table 25. Read Register 0 Bit 7 R/W R Reset X 6 5 4 3 2 1 0 1 X X X 1 0 0 R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 Break/Abort 6 Tx Underrun/EOM 5 CTS 4 Sync/Hunt 3 DCD Interrupt Enable 2 Tx Buffer Empty 1 Zero Count 0 Rx Character Available PS005309-0515 Programming Z80230/Z85230/L Product Specification 55 Table 26. Read Register 1 Bit 7 6 5 4 3 2 1 0 0 1 1 X R R/W 0 Reset 0 0 0 R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 EOF (SDLC) 6 CRC/Framing Error 5 Rx Overrun Error 4 Parity Error 3 Residue Code 0 2 Residue Code 1 1 Residue Code 2 0 All Sent PS005309-0515 Programming Z80230/Z85230/L Product Specification 56 Table 27. Read Register 2 Bit 7 6 5 4 3 2 1 0 X X X X R R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description (Interrupt Vector) 7 V7 6 V6 5 V5 4 V4 3 V3 2 V2 1 V1 0 V0 These bits include status information when read from Channel B. PS005309-0515 Programming Z80230/Z85230/L Product Specification 57 Table 28. Read Register 3 Bit 7 6 5 4 3 2 1 0 X X X X R R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 0 6 0 5 Channel A Rx IP 4 Channel A Tx IP 3 Channel A Ext/Status IP 2 Channel B Rx IP 1 Channel B Tx IP 0 Channel B Ext/Status IP Bits 5, 4, 3, 2, 1 and 0 are always 0 when read from Channel B. PS005309-0515 Programming Z80230/Z85230/L Product Specification 58 Table 29. Read Register 4 Bit 7 6 5 4 3 2 1 0 X X X X R R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7, 6 00 01 10 11 X1 Clock Mode X16 Clock Mode Z32 Clock Mode X64 Clock Mode 5, 4 00 01 10 11 8-Bit Sync Character 16-Bit Sync Character SDLC Mode (01111110 Flag) External Sync Mode 3, 2 00 01 10 11 Sync Modes Enable 1 Stop Bit/Character 1.5 Stop Bits/Character 2 Stop Bits/Character 0 1 Parity EVEN/ODD Odd Even 1 0 Parity Enable This register reflects the contents of RR0 if WR7’ bit 6 is enabled. PS005309-0515 Programming Z80230/Z85230/L Product Specification 59 Table 30. Read Register 5 Bit 7 6 5 4 3 2 1 0 X X X X R R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value 7 6, 5 Description DTR 00 01 10 11 Tx 5 Bits (or less)/Character Tx 7 Bits/Character Tx 6 Bits/Character Tx 8 Bits/Character 4 Send Break 3 Tx Enable 2 0 1 CRC-16/CRC-CCITT CRC-CCITT CRC-16 1 RTS 0 Tx CRC Enable This register reflects the contents of RR1 if WR7’ bit 6 is enabled. PS005309-0515 Programming Z80230/Z85230/L Product Specification 60 Table 31. Read Register 6 Bit 7 6 5 4 3 2 1 0 X X X X R R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 BC7 6 BC6 5 BC5 4 BC4 3 BC3 2 BC2 1 BC1 0 BC0 This register can be accessed only if WR15 bit 2 is 1. If this bit is not enabled this register reflects RR2. PS005309-0515 Programming Z80230/Z85230/L Product Specification 61 Table 32. Read Register 7 Bit 7 6 5 4 3 2 1 0 X X X X R R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value 7 Description 0 1 FOS: FIFO Status Overflow FIFO Overflowed Normal 0 1 FDA: FIFO Data Available Status Reads from FIFO Status Reads from ESCC 6 5 BC13 4 BC12 3 BC11 2 BC10 1 BC9 0 BC8 This register can be accessed only if WR15 bit 2 is 1. If this bit is not enabled this register reflects RR3. PS005309-0515 Programming Z80230/Z85230/L Product Specification 62 Table 33. Read Register 8 Bit 7 6 5 4 3 2 1 0 0 0 0 0 R R/W 0 Reset 0 1 0 R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 D7 6 D6 5 D5 4 D4 3 D3 2 D2 1 D1 0 D0 PS005309-0515 Programming Z80230/Z85230/L Product Specification 63 Table 34. Read Register 9 Bit 7 6 5 4 3 2 1 0 R R/W Hardware Reset 1 1 0 0 0 0 X X Channel Reset X X 0 X X X X X R = Read W = Write X = Indeterminate Bit Position 7, 6 R/W Value 00 01 10 11 5 Description No Reset Channel Reset B Channel Reset A Force Hardware Reset Software INTACK Enable 4 0 1 Status High/Status Low Low High 3 Master Interrupt Enable 2 Disable Lower Chain 1 No Vector 0 Vector Includes Status To access this register WR7’ bit 6 must be enabled. PS005309-0515 Programming Z80230/Z85230/L Product Specification 64 Table 35. Read Register 10 Bit 7 6 5 4 3 2 1 0 0 0 0 0 R R/W 0 Reset 0 1 0 R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 One Clock Missing 6 Two Clocks Missing 5 0 4 Loop Sending 3 0 2 0 1 On Loop 0 0 PS005309-0515 Programming Z80230/Z85230/L Product Specification 65 Table 36. Read Register 11 Bit 7 6 5 4 3 2 1 0 R R/W Hardware Reset 0 0 0 0 0 0 0 0 Channel Reset X X X X X X X X R = Read W = Write X = Indeterminate Bit Position R/W Value 7 6, 5 Description CRC Preset I/O 00 01 10 11 4 NRZ NRZI FM1 (Transition = 1) FM0 (Transition = 0) Go Active on Poll 0 1 Mark/Flag Idle Flag Idle Mark Idle 0 1 Abort Flag on Underrun Flag Abort 3 2 1 Loop Mode 0 0 1 6-Bit/8-Bit Sync 8-Bit Sync 6-Bit Sync To access this register WR7’ bit 6 must be enabled. If this bit is not enabled, this register reflects RR15. PS005309-0515 Programming Z80230/Z85230/L Product Specification 66 Table 37. Read Register 12 Bit 7 6 5 4 3 2 1 0 X X X X R R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description (Lower Byte of Time Constant) 7 TC7 6 TC6 5 TC5 4 TC4 3 TC3 2 TC2 1 TC1 0 TC0 PS005309-0515 Programming Z80230/Z85230/L Product Specification 67 Table 38. Read Register 13 Bit 7 6 5 4 3 2 1 0 X X X X R R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description (Upper Byte of Time Constant) 7 TC15 6 TC14 5 TC13 4 TC12 3 TC11 2 TC10 1 TC9 0 TC8 PS005309-0515 Programming Z80230/Z85230/L Product Specification 68 Table 39. Read Register 14 Bit 7 6 5 4 3 2 1 0 0 0 0 0 R R/W 0 Reset 0 1 0 R = Read W = Write X = Indeterminate Bit Position 7 R/W Value 0 Description Not Used. Must be 0. 6 Extended Read Enable 5 Tx FIFO Int Level 4 DTR/REQ Timing Mode 3 Rx FIFO Int Level 2 Auto RTS Deactivation 1 Auto EOM Reset 0 Auto Tx Flag To access this register WR7’ bit 6 must be enabled. If this bit is not enabled this register reflects RR10. PS005309-0515 Programming Z80230/Z85230/L Product Specification 69 Table 40. Read Register 15 Bit 7 6 5 4 3 2 1 0 X X X X R R/W X Reset X X X R = Read W = Write X = Indeterminate Bit Position R/W Value Description 7 Break/Abort Interrupt Enable 6 Tx Underrun/EOM Interrupt Enable 5 CTS Interrupt Enable 4 Sync/Hunt 3 DCD Interrupt Enable 2 SDLC FIFO Enable 1 Zero Count Interrupt Enable 0 WR7’ SDLC Feature Enable PS005309-0515 Programming Z80230/Z85230/L Product Specification 70 Z80230 Interface Timing Z80230 Write Cycle Timing The Z-Bus compatible ESCC is suited for system applications with multiplexed address/ data buses. Two control signals, AS and DS, are used by the Z80230 to control bus transactions. Additionally, four other control signals (CS0, CS1, RW, and INTACK) control the type of bus transaction that occurs. A bus transaction is initiated by AS. The rising edge latches the register address on the Address/Data bus and the state of INTACK and CS0. In addition to bus transactions, the interrupt section uses the AS to set Interrupt Pending (IP) bits. Therefore, AS must be kept cycling for the interrupt section to function. The Z80230 generates internal control signals in response to a register access. Because AS and DS have no defined phase relationship with PCLK, the circuitry generating these internal control signals provide time for metastable conditions to disappear. This action results in a recovery time related to PCLK. This recovery time applies only to transactions involving the Z80230, and any intervening transactions are ignored. This recovery time is four PCLK cycles, measured from the falling edge of DS for one access to the ESCC, to the falling edge of DS for a subsequent access. Figure 17 displays the Write cycle timing. AS CS0 INTACK A7–A0 Address Data Valid R/W CS1 DS Figure 17. Z80230 Write Cycle Timing PS005309-0515 Z80230 Interface Timing Z80230/Z85230/L Product Specification 71 Z80230 Read Cycle Timing The Read Cycle Timing for the Z80230 is displayed in Figure 18. The register address on A7-A0, as well as the state of CS0 and INTACK, are latched by the rising edge of AS. R/W must be High before DS falls to indicate a Read cycle. The Z80230 data bus drivers are enabled while CS1 is High and DS is Low. AS CS0 INTACK A7–A0 Address Data Valid R/W CS1 DS Figure 18. Z80230 Read Cycle Timing Z80230 Interrupt Acknowledge Cycle Timing The Interrupt Acknowledge cycle timing for the Z80230 is displayed in Figure 19 on page 72. The address on A7-A0 and the state of CS0 and INTACK are latched by the rising edge of AS. However, if INTACK is Low. The address on A7-A0, CS0, CS1, and R/W are ignored for the duration of the interrupt acknowledge cycle. The Z80230 samples the state of INTACK on the rising edge of AS, and AC parameters. Parameters 7 and 8 of Table 45 on page 83, specify the setup and hold time requirements. Between the rising edge of AS and the falling edge of DS, the internal and external daisy chains settle, as specified in parameter 29. A system with no external daisy chain provides the time priority internal to the ESCC. Systems using an external daisy chain must refer to Note 5 of Table 45, for the time required to settle the daisy chain. If there is an interrupt pending in the ESCC, and IEI is High when DS falls, the acknowledge cycle is intended for the ESCC. Consequently, the Z80230 sets the Interrupt Under Service (IUS) latch for the highest priority pending interrupt, and places an interrupt vec- PS005309-0515 Z80230 Interface Timing Z80230/Z85230/L Product Specification 72 tor on A7-A0. WR9 bit 1 is set to 1 to disable the placing of a vector on a bus. The INT pin also goes inactive in response to the falling edge of DS. There is only one DS per interrupt acknowledge cycle. IP bits in the Z80230 are updated by AS, which can delay interrupt requests if the processor does not supply AS strobes during the time in between accesses of the Z80230. AS CS0 A7–A0 Vector DS INTACK IEI IEO INT Figure 19. Z80230 Interrupt Acknowledge Cycle Timing Z85230/L Timing The ESCC generates internal control signals from WR and RD that relate to PCLK. Because PCLK had no defined phase relationship with WR and RD, the circuitry generating the internal control signals provides time for metastable conditions to disappear. This causes a recovery time related to PCLK. The recovery time applies only to bus transactions involving the ESCC. The recovery time required for proper operation is specified PS005309-0515 Z80230 Interface Timing Z80230/Z85230/L Product Specification 73 from the falling edge of WR or RD in the first transaction involving the ESCC, to the falling edge of WR or RD in the second transaction. This time must be at least four PCLKs regardless of which register or channel is accessed. Z85230/L Read Cycle Timing Figure 20 displays Read Cycle timing. Addresses on A/B and D/C and the status on INTACK must remain stable throughout the cycle. The effective RD time reduces if CE falls after RD falls, or if it rises before RD rises. A/B, D/C Address Valid INTACK CE D7–D0 Data Valid RD Figure 20. Read Cycle Timing (Z85230/L) Z85230/L Write Cycle Timing Figure 21 on page 74 displays Write Cycle timing. Addresses on A/B and D/C and the status on INTACK must remain stable throughout the cycle. The effective WR time reduces if CE falls after WR falls, or if it rises before WR rises. In Write Cycle timing, the WR signal returns a High slightly before the Address goes invalid. Because many popular CPUs do not guarantee that the databus is valid when WR is Low, the ESCC no longer requires a valid databus when the WR pin is Low. For more information, see AC characteristics parameter 29 available in Table 47 on page 90. PS005309-0515 Z80230 Interface Timing Z80230/Z85230/L Product Specification 74 A/B, D/C Address Valid INTACK CE D7–D0 Address Valid WR Figure 21. Write Cycle Timing (Z85230/L) Z85230/L Interrupt Acknowledge Cycle Timing Figure 22 displays Interrupt Acknowledge Cycle timing. Between the time INTACK goes Low and the falling edge of RD, the internal and external IEI/IEO daisy chains settle. If there is an interrupt pending in the ESCC and IEI is High when RD falls, the Acknowledge cycle is intended for the ESCC. In this case, the ESCC may be programmed to respond to RD Low by placing its interrupt vector on D7–D0. It then sets the appropriate IUS latch internally. If the external daisy chain is not used, then AC Parameter 38 is required to settle the interrupt priority daisy chain internal to the ESCC. If the external daisy chain is used, follow the equation in AC Characteristics Note 5 (Table 47 on page 90) to calculate the required daisy chain settle time. INTACK RD D7–D0 Vector Figure 22. Interrupt Acknowledge Cycle Timing (Z85230/L) PS005309-0515 Z80230 Interface Timing Z80230/Z85230/L Product Specification 75 Electrical Characteristics Absolute Maximum Ratings Stresses greater than those listed in this section can cause permanent damage to the device. These ratings are stress ratings only. Operation of the device at any condition above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods can affect reliability. VCC Supply Voltage Range –0.3 V to +7.0 V Voltages on All Pins with Respect to GND –0.3 V to VCC +0.3 V Operating Ambient Temperature See Ordering Information on page 107 Storage Temperatures –65º C to +150º C Standard Test Conditions The DC Characteristics and capacitance sections apply for the following standard test  conditions, unless otherwise noted. All voltages reference GND. Positive current flows into the referenced pin. Standard conditions are as follows: • • • PS005309-0515 GND = 0 V T as specified in Ordering Information +4.5V VCC +5.5V" or +3.0 V  VCC +3.6V (Z8523L only) Electrical Characteristics Z80230/Z85230/L Product Specification 76 Figure 23 displays typical test load configurations. +VCC +VCC 2.1K 2.2K From Output Under Test From Output 100pf 50pf 250µA Standard Test Load Open-Drain Test Load Figure 23. Standard and Open-Drain Test Loads Capacitance Table 41 lists the capacitance parameters and contains the symbols and test conditions for each. Table 41. Capacitance Parameters Symbol Parameter CIN Min Max Unit Test Condition Input Capacitance 10 pF COUT Output Capacitance 15 pF Unmeasured Pins Returned to Ground CI/O Bidirectional Capacitance 20 pF Note: f = 1 MHz, over specified temperature range. Miscellaneous Gate count—11,000 for both Z80230 and Z85230/L. PS005309-0515 Electrical Characteristics Z80230/Z85230/L Product Specification 77 DC Characteristics Table 42 lists the DC characteristics for the Z80230/Z85230 device. Table 42. Z80230/Z85230 DC Characteristics Symbol Parameter Min. Typ. Max. Unit 2.2 VCC + 0.3 V – 0.3 0.8 V Condition VIH Input High Voltage VIL Input Low Voltage VOH1 Output High Voltage 2.4 V IOH = – 1.6 mA VOH2 Output High Voltage VCC – 0.8 V IOH = – 250 A VOL Output Low Voltage 0.4 V IOL = +2.0 mA IIL Input Leakage ± 10.0 µA 0.4