51 MCU drives I2C (24C02) assembly language program-EEWORLD

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;Program description: Write the contents of 55h~58h inside the MPU to 24c02 via the I2C bus from external interrupt 0, and then read the written contents to

;MPU internal data memory 60H~~63H

SCL EQU P1.1

SDA EQU P1.0

org 0000h

jmp begin

org 0003H

ljmp write

org 0013H

ljmp read

;Main program

begin:

mov 55H,#41H

mov 56h,#42h

MOV 57h,#43H

MOV 58H, #44H

mov tcon,#0

setb ex0

setb ex1

setb of

main:

nop

jmp main

;**********************************************************

;Program to read 24C02 data

read:

ACALL START ; start signal

MOV A,#0A0H ; send the slave address

ACALL SEND ;Send control word

ACALL ACKI; receive response

JC OUTEND ; No response, transfer to end

MOV A,#00H; Set the internal address of the slave device to be read

ACALL SEND

ACALL ACKI

JC OUTEND

ACALL START ; start signal

ORL A,#0A1H; Set the control word and prepare to receive

ACALL SEND ;Send control word

ACALL ACKI

JC OUTEND

MOV R2,#4 ; Prepare to receive the number of bytes of data

MOV R1,#60H ; The received byte is stored at address 60H in the master device

IN0:

ACALL REV ; receive a byte

ACALL ACKO; the host sends a response signal to 24C02

MOV @R1,A ; store the received data in the storage unit

INC R1

DEC R2

CJNE R2,#1,IN0 ; Determine whether it is the last received byte

ACALL REV ;Receive the last byte

ACALL ACKN;

MOV @R1,A ; store the received data in the storage unit

OUTEND:

ACALL STOP ;Stop signal

jnb p3.3,$

rarely

;**********************************************************

;Program to write 24C02 data

write:

LCALL START ; start signal

MOV A,#0A0H; set control word, ready to send

ACALL SEND ;Send control word

ACALL ACKI ;Receive acknowledgment

JC WRITEEND ; The slave device does not respond, and the transfer ends

MOV A,#00H ; Set the internal address of the slave device

ACALL SEND ;Send the internal address

ACALL ACKI

JC WRITEEND

MOV R2,#4; Set the number of bytes to send

MOV R1,#55H ;Header address of data to be sent in the master device

OUT1:

MOV A,@R1

ACALL SEND; send data

ACALL ACKI;

JC WRITEEND

INC R1

DJNZ R2,OUT1 ;Sending is not finished, continue sending

WRITEEND:

ACALL STOP ;Stop signal

jnb p3.2,$; prevent further interruption

rarely

;********************************************************

;********************

;I2C simulation program

; Start signal

START:

CLR SCL

SETB SDA

ACALL DELAY

SETB SCL

ACALL DELAY

CLR SDA

ACALL DELAY

CLR SCL

RIGHT

; Stop signal:

STOP:CLR SCL

CLR SDA

ACALL DELAY

SETB SCL

ACALL DELAY

SETB SDA

ACALL DELAY

RIGHT

; Receive a byte

REV: MOV R0,#08H

REV0: SETB SCL

LCALL DELAY

MOV C,SDA

RLC A

CLR SCL

LCALL DELAY

DJNZ R0,REV0

RIGHT

; Send a byte

SEND:

MOV R0, #08H

CLR SCL

SEND0:

RLC A

MOV SDA,C

SETB SCL

ACALL DELAY

CLR SCL

DJNZ R0,SEND0

SETB SDA

RIGHT

; Receive an acknowledge bit:

AKI:

SETB SCL

ACALL DELAY

MOV C,SDA

CLR SCL

RIGHT

; Send a receive acknowledge bit

ACKO:

CLR SDA

ACALL DELAY

SETB SCL

ACALL DELAY

CLR SCL

ACALL DELAY

SETB SDA

ACALL DELAY

RIGHT

;Send a non-receive receive acknowledge bit

ACKN:

SETB SDA

ACALL DELAY

SETB SCL

ACALL DELAY

CLR SCL

ACALL DELAY

DELAY:

NOP

RIGHT

END

Reference address：51 MCU drives I2C (24C02) assembly language program

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