Interfacing X24C44/45 NOVRAMs Motorola 68HC11 Microcontroller rea

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Interfacing X24C44/45 NOVRAMs Motorola 68HC11 Microcontroller rea

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Applications Staff, July 1992 following code demonstrates Xicor X24C44/45 serial NOVRAMs interfaced Motorola 68HC11 microcontroller family when connected shown Fig. code uses three pins from port implement interface. Additional code found Xicor through Xicor FaxBack system) that will implement interfaces between several other Motorola microcontroller families most Xicor serial devices. Xicor
Interfacing X24C44/45 NOVRAMs Motorola 68HC11 Microcontroller
reached toll free 1-800-258-8864, (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 MOTOROLA (Special Interest Group). Xicor application notes also available through Xicor's FaxBack system (408) 954-1627.
RESET XIRQ MODA MODB 68HC11A8
STORE RECALL X24C44
Figure Interfacing X24C44 68HC11 microcontroller using Port
Xicor, Inc. 1511 Buckeye Drive Milpitas, 95035 (408) 432-8888
AN35-1
Xicor THIS CODE DESIGNED DEMONSTRATE X24C44 COULD INTERFACED 68HC11 MICROCONTROLLER. INTERFACE USES LINES FROM PORT (PD3, PD4, PD5) COMMUNICATE. PINS X24C44 TIED TOGETHER WHICH ALLOWS LESS PORT LINE USED. CODE SHOWN DEMONSTRATES RCL, WREN, READ, WRITE, STORE INSTRUCTIONS. REMAINING INSTRUCTIONS (WRDS ENAS) ISSUED USING SAME ROUTINE OTHER NON-DATA INSTRUCTIONS. PROGRAM ISSUES SEQUENCE INSTRUCTIONS READ CONTENTS ADDRESS STORES SAME VALUE ADDRESS SEQUENCE INSTRUCTIONS FOLLOWS SETS PREVIOUS RECALL LATCH WREN SETS WRITE ENABLE LATCH READ DATA FROM ADDRESS READ WRITE DATA READ DURING STEP WRITTEN ADDRESS RAM'S CONTENTS TRANSFERED EEPROM DATA TRANSFER PERFORMED WITH MOST SIGNIFICANT FIRST. DURING READ WRITE INSTRUCTIONS DATA SEQUENCE INVERTED FROM THAT SHOWN DATA BOOK (D15 SHIFTED FIRST). SKBIT CEBIT DIOBIT DOUT WRDS ENAS WRITE WREN READ DDRD PORTD ADDR INST RWDAT COUNT MASK INDICATING PORTD POSITION MASK INDICATING PORTD POSITION MASK INDICATING PORTD DATA POSITION MASK MAKE DI/O OUTPUT MASK MAKE DI/O INPUT RESET WRITE ENABLE LATCH TRANSFERS FROM EEPROM PLACES PART INTO POWER DOWN MODE WRITE WRITE ENABLE LATCH TRANSFERS FROM EEPROM RAM, RESETS WRITE ENABLE LATCH READ DATA DIRECTION REGISTER PORT ADDRESS PORT LOCATION X24C44 ADDRESS ACCESS INSTRUCTION PART LOCATION X24C44 DATA TRANSFERED COUNTER VARIABLE
RESET VECTOR BEGINNING PROGRAM CODE $FFFE $E000 RESET VECTOR PROGRAM ENTRY POINT
AN35-2
Xicor ****************************** START PROGRAM EXECUTION ****************************** BEGIN: LDAA STAA LDAA STAA LDAA STAA LDAA STAA LDAA STAA LDAA STAA LDAA STAA $E000 #$00FF #$1000 #DOUT DDRD,X #$00 PORTD,X #RCL INST CEHIGH OUTBYT CELOW #WREN INST CEHIGH OUTBYT CELOW #$05 ADDR RDWRD #$09 ADDR WRWRD #STO INST CEHIGH OUTBYT CELOW BEGINNING EXECUTABLE CODE INITIALIZE STACK POINTER INITIALIZE PAGE OFFSET LOCATION MAKE DI/O OUTPUTS INITIALIZE DI/O ZEROS PERFORM RECALL RECALL LATCH
PERFORM WRITE ENABLE WRITE ENABLE LATCH
READ CONTENTS ADDRESS VALUE READ WILL STORED RWDATA WRITE DATA JUST READ INTO ADDRESS PERFORM STORE OPERATION
LOOP UNTIL RESET
WRITE WORD SPECIFIED RWDAT. ADDRESS WRITTEN SPECIFIED ADDR. WRWRD: LDAA LSLA LSLA LSLA ORAA STAA LDAA STAA LDAA STAA CEHIGH ADDR WRITE VALUE RWDATA INTO LOCATION SPECIFIED ADDR JUSTIFY ADDRESS INSTRUCTION
#WRITE INST OUTBYT RWDAT INST OUTBYT RWDAT+1 INST
MASK WRITE INSTRUCTION SEND WRITE INSTRUCTION
SEND UPPER BYTE DATA
AN35-3
Xicor OUTBYT CELOW SEND LOWER BYTE DATA
READ WORD LOCATION SPECIFIED ADDR. DATA READ WILL PLACED RWDAT. RDWRD: LDAA LSLA LSLA LSLA ORAA STAA LDAA STAA LDAA STAA LDAA ANDA LDAA STAA CEHIGH ADDR READ ADDRESS SPECIFIED ADDR JUSTIFY ADDRESS READ
#READ INST SEND7 #DIN DDRD,X CLOCK #$10 COUNT PORTD,X #DIOBIT RWDAT+1 RWDAT CLOCK COUNT BITX #DOUT DDRD,X CELOW
MASK READ INSTRUCTION SEND BITS READ INSTRUCTION MAKE DATA LINE INPUT SEND EIGHTH CLOCK PULSE READ INSTRUCTION PREPARE SHIFT BITS ASSUME GOING ZERO (CLEAR CARRY) READ VALUE MASK BYTE READ LEAVE CARRY FLAG ALONE CARRY ROLL CARRY FLAG INTO DATA WORD SEND CLOCK PULSE LOOP UNTIL BITS READ MAKE DATA LINE OUTPUT BRING
BITX:
NO1:
SEND DATA PART. DATA SENT LOCATED INST. SEND7: LDAA STAA LDAA STAA BSET BCLR #$07 COUNT LOOPO #$08 COUNT INST PORTD,X DIOBIT PORTD,X DIOBIT CLOCK SHIFT BITS READ INSTRUCTION
OUTBYT: LOOPO:
PREPARE SHIFT BITS
JUMP DATA SHOULD SEND DI/O SEND DI/O SEND CLOCK SIGNAL
IS0: IS1:
AN35-4
Xicor ***************** BRING HIGH ***************** CEHIGH: BSET PORTD,X #CEBIT BRING HIGH COUNT LOOPO LOOP UNTIL BITS HAVE BEEN SENT
**************** BRING **************** CELOW: BCLR BCLR PORTD,X DIOBIT PORTD,X #CEBIT BRING DATA LINE BRING
*********************** ISSUE CLOCK PULSE *********************** CLOCK: BSET BCLR PORTD,X SKBIT PORTD,X SKBIT BRING HIGH BRING
AN35-5

Interfacing X24C44/45 NOVRAMs Motorola 68HC11 Microcontroller rea

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