Interfacing X24C44/45 NOVRAMs 78xx Microcontrollers using Serial Port

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Interfacing X24C44/45 NOVRAMs 78xx Microcontrollers using Serial Port

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Applications Staff, 1992 following code demonstrates Xicor X24C44/45 serial NOVRAMs could interfaced 78xx microcontroller family when connected shown Fig. interface uses 78xx serial port, with PC2/SCK connected serial clock (SK), PC0/TXD connected serial data (DI), PC1/RXD connected serial data (DO), connected chip enable (CE). Additional code found Xicor through Xicor FaxBack system) that will
Interfacing X24C44/45 NOVRAMs 78xx Microcontrollers using Serial Port
implement interfaces between 78xx microcontroller family other Xicor serial devices. Xicor reached toll free 1-800-2588864, (408) area code internationally 1-408-943-0655. Xicor's will support 19.2K baud rate modem parity, words, stop bit, local echo). These listings found (Special Interest Group). Xicor application notes also available through Xicor's FaxBack system (408) 954-1627.
MODE MODE AVSS
STORE
Figure Interfacing X24C44 78xx microcontrollers
Xicor, Inc. 1511 Buckeye Drive Milpitas, 95035 (408) 432-8888
AN08-1
Xicor DESCRIPTION: PURPOSE THIS PROGRAM SHOW NEC78XX ASSEMBLY LANGUAGE PROGRAM XICOR X24C44 NOVRAM. PROCESSOR INTERFACES NOVRAM THROUGH SERIAL PORTS. PC2(SCK) CONNECTED SERIAL CLOCK (SK), PC0(TXD) SERIAL DATA IN(DI), PC1(RXD) SERIAL DATA (DO), INPUT NOVRAM. NOVRAM SUPPORTED COMMANDS WHICH IMPLEMENTED ARE: WREN, READ, STO, WRITE, RCL. MUST SUPPLY SIGNAL WHILE TRANSFERS TAKING PLACE EITHER DIRECTIONS. WHEN NOVRAM SELECTED THERE NEED SIGNAL RUNNING. MAIN SECTION CODE CALLS OTHER MODULES ORDER DEMONSTRATE PROCEDURE FOLLOWED WHEN READING/WRITING DEVICE. CONSTANTS RAM_BASE 0FF00H START INTERNAL ADDR LAST_MEM_LOC 0FFFFH ALLOCATED STACK CE_MASK 0FBH OUTPUT PORT PA_CE_LO 0FBH SIGNAL PA_CE_HI 004H SIGNAL ADDR0_TEST 00DH ADDRESS READ BYTE ADDR1_TEST 001H ADDRESS WRITE BYTE SML_IO 00CH MODE SETTING IO_MODE 020H SERIAL INTERFACE MODE (SMH) SK_SEL 002H INTERNAL CLOCK TSK_TRIG 040H TRIGGER (SMH) RX_EN 008H RECEIVE ENABLE (SMH) TX_EN 004H TRANSMIT ENABLE (SMH) PC_MCC 007H PORT SECONDARY FUNCTION MODE PC_MCC_RXD 001H PORT MASK PC_MCC_OFF 000H PORT MODE PC_MC 002H PORT IDLE CONFIGURATION PC_HI_IDLE 007H PORT PINS IDLE VALUES RI_MASK 002H RECEIVE INTERRUPT MASK TI_MASK 004H TRANSMIT INTERRUPT MASK WRDI_CMD (080H WRITE DISABLE WREN_CMD (084H WRITE ENABLE STO_CMD (081H STORE EEPROM WRITE_CMD (083H WRITE DATA RCL_CMD (085H RECALL EEPROM DATA INTO READ_CMD (087H READ DATA FROM RAM_SEG SAV_BYTE: DSEG
;-NOVRAM_CODE CSEG RESET: PROCESSOR JUMPS HERE AFTER RESET BEGIN STARTUP PROCEDURE 1000H
AN08-2
Xicor BEGIN: CALL CALL CALL CALL CALL SP,LAST_MEM_LOC A,08 MM,A PA,PA_CE_LO A,CE_MASK MA,A PC_TO_IO NV_RECALL D,ADDR0_TEST RDWRD D,ADDR1_TEST WRWRD NV_STORE INITIALIZE DISABLE INTERRUPTS MEMORY CONFIGURATION
UPDATE REGISTER INITIALIZE PORT PORT MOVE DATA EEPROM WORD ADDRESS READ CONTENT NOVRAM LOCATION (EA) WORD WRITE ADDRESS WRITE WORD NOVRAM LOCATION STORE EEPROM
NAME: NV_STORE DESCRIPTION: TRANSFER CONTENT EEPROM FUNCTION: THIS PROGRAM SENDS COMMAND SAVE DATA INTO EEPROM CALLS: OUTBYT INPUT: NONE OUTPUT: NONE REGISTER USAGE: A,PA NV_STORE: A,STO_CMD STORE COMMAND FALL THROUGH NAME: NV_RECALL DESCRIPTION: TRANSFER CONTENT EEPROM FUNCTION: THIS PROGRAM SENDS COMMAND RECALL STORED DATA EEPROM INTO CALLS: OUTBYT INPUT: NONE OUTPUT: NONE REGISTER USAGE: A,PA NV_RECALL: A,RCL_CMD RECALL COMMAND FALL THROUGH NAME: NV_WREN DESCRIPTION: ENABLE WRITE OPERATION NOVRAM EEPROM FUNCTION: THIS PROGRAM SENDS COMMAND ENABLE WRITES STORE OPERATIONS EEPROM CALLS: OUTBYT INPUT: NONE OUTPUT: NONE REGISTER USAGE: A,PA
AN08-3
Xicor NV_WREN: CALL A,WREN_CMD PA,PA_CE_HI OUTBYT PA,PA_CE_LO WRITE ENABLE COMMAND ACTIVATE SEND COMMAND DEACTIVATE
NAME: PC_TO_SIO DESCRIPTION: INIT SERIAL PORT SERIAL PORT FUNCTION: THIS PROGRAM INITIALIZES SERIAL PORT MODE/CONTROL REGISTERS CALLS: NONE INPUT: NONE OUTPUT: NONE REGISTER USAGE: SML, SMH, MKH, PC_TO_SIO: SMH,IO_MODE SK_SEL INIT SERIAL REGISTERS A,SML_IO SML,A MKH,RI_MASK TI_MASK DISABLE INTERRUPTS A,PC_MCC PROGRAM PORT SERIAL MODE MCC,A NAME: PC_TO_IO DESCRIPTION: INIT SERIAL PORT PORT FUNCTION: THIS PROGRAM INITIALIZES SERIAL PORT MODE/CONTROL REGISTERS CALLS: NONE INPUT: NONE OUTPUT: NONE REGISTER USAGE: PC_TO_IO: PC,PC_HI_IDLE SETUP VALUES A,PC_MC PROGRAM PORT PINS MC,A A,PC_MCC_OFF PROGRAM PORT MCC,A NAME: RDWRD DESCRIPTION: READS CONTENT NOVRAM SPECIFIC LOCATION. FUNCTION: THIS PROGRAM SENDS COMMAND READ CONTENT MEMORY LOCATION SPECIFIED REGISTER. CALLS: NV_READ_CMD, INWRD INPUT: ADDRESS WORD OUTPUT: READ VALUE REGISTER USAGE: A,PA
AN08-4
Xicor RDWRD: CALL CALL PA,PA_CE_HI NV_READ_CMD INWRD PA,PA_CE_LO ACTIVATE RECALL DEVICE ADDRESS ISSUE DUMMY WRITE COMMAND DATA FROM NOVRAM DEACTIVATE
NAME: INWRD DESCRIPTION: PACKS INCOMMING NOVRAM DATA INTO WORD FUNCTION: THIS PROGRAM READS PACKS INTO WORD SERIAL INPUT DATA FROM NOVRAM. READ WORD RETURNED (EA) REGISTER. CALLS: INBYT INPUT: OUTPUT: READ WORD RETURN VALUE: NONE REGISTER USAGE: A,EA INWRD: CALL INBYT PACK INTO BYTE BITS FROM NOVRAM EAH,A SAVE HIGH BYTE CALL INBYT PACK INTO BYTE BITS FROM NOVRAM EAL,A SAVE BYTE NAME: NV_READ_CMD DESCRIPTION: SENDS READ COMMAND NOVRAM FUNCTION: THIS PROGRAM SENDS READ COMMAND NOVRAM CALLS: OUTBYT INPUT: ADDRESS RETURN VALUE: NONE REGISTER USAGE: NV_READ_CMD: C,READ_CMD FALL THROUGH NV_CMD_OUT: A,0FH FORM COMMAND ADDRESS BYTE OUTBYT SEND NOVRAM
AN08-5
Xicor NAME: OUTBYT DESCRIPTION: SENDS BYTE NOVRAM FUNCTION: THIS PROGRAM SHIFTS BYTE, FIRST NOVRAM. CALLS: NONE INPUT: BYTE SENT RETURN VALUE: NONE REGISTER USAGE: B,SMH,TXB OUTBYT: CALL PC_TO_SIO INITIALIZE PORT SERIAL PORT SMH,RX_EN TX_EN ENABLE RECEIVER TRANSMITTER TXB,A WRITE OUTPUT BUFFER OUTBYT1: SKIT SKIP NEXT INSTRUCTION BUFFER OUTBYT1 EMPTY, ELSE LOOP PC_TO_IO INITIALIZE PORT PORT NAME: INBYT DESCRIPTION: SERIAL PARALLEL CONVERSION INCOMMING NOVRAM DATA STREAM FUNCTION: THIS PROGRAM READS PACKS INTO BYTE, 8-BITS SERIAL INPUT DATA FROM NOVRAM. READ BYTE RETURNED REGISTER. CALLS: PC_TO_SIO,PC_TO_IO INPUT: NONE RETURN VALUE: READ BYTE REGISTER USAGE: A,B, INBYT: CALL PC_TO_SIO INITIALIZE PORT SERIAL PORT A,PC_MCC PC_MCC_RXD PROGRAM PORT MCC,A DISABLE TRANSMITTER SMH,RX_EN ENABLE RECEIVER SMH,TSK_TRIG MODE ENABLED INBYT1: SKIT SKIP NEXT INSTRUCTION BUFFER INBYT1 FULL ELSE LOOP A,RXB RECEIVED BYTE CALL PC_TO_IO INITIALIZE PORT PORT
AN08-6
Xicor NAME: WRWRD DESCRIPTION: WRITES WORD NOVRAM SPECIFIC LOCATION. FUNCTION: THIS PROGRAM WRITES BYTE (EA) REGISTER NOVRAM LOCATION SPECIFIED REGISTER. CALLS: NV_WRITE_CMD, OUTBYT INPUT: WORD ADDRESS, DATA WRITE OUTPUT: NONE REGISTER USAGE: WRWRD: CALL NV_WREN SEND NOVRAM WRITE ENABLE COMMAND PA,PA_CE_HI ACTIVATE CALL NV_WRITE_CMD ISSUE WRITE COMMAND A,EAH HIGH BYTE DATA CALL OUTBYT SEND BYTE A,EAL BYTE DATA CALL OUTBYT SEND BYTE PA,PA_CE_LO DEACTIVATE NAME: NV_WRITE_CMD DESCRIPTION: SENDS WRITE COMMAND NOVRAM FUNCTION: THIS PROGRAM CREATS WRITE COMMAND SEQUENCE TRANSMITS NOVRAM. CALLS: OUTBYT INPUT: BYTE ADDRESS RETURN VALUE: NONE REGISTER USAGE: NV_WRITE_CMD: C,WRITE_CMD NV_CMD_OUT SEND COMMAND NOVRAM
AN08-7

Interfacing X24C44/45 NOVRAMs 78xx Microcontrollers using Serial Port

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