24c02.asm

来自「以i2c总线串行方式读取24c02数据的源码」· 汇编 代码 · 共 94 行

I2C_SDA  EQU P1.6  ; PIN 5
  I2C_SCL  EQU P1.7  ; PIN 6

;=============================================
I2C_WRITE:  ;  WRITE 8 BYTES TO EEROM ; INPUT: A - A*8 = EEROM START ADDR 
  ;  R0 - RAN START ADDR
  ;  USE: C, A, R0, R6, R7

  ACALL I2C_START
  ACALL OUT
  MOV R6, #8
WR_LP:MOV A, @R0
  ACALL OUT
  INC R0
  DJNZ R6, WR_LP
  AJMP I2C_STOP  

;==========================================
I2C_READ:  ;  READ 8 BYTES FROM EEROM ; INPUT: A - A*8 = EEROM START ADDR 
  ;  R0 - RAN START ADDR
  ;  USE: C, A, R0, R6, R7
  
  ACALL I2C_START
  ACALL OUT
  MOV R6, #8
  MOV A, #0A1H; #RDCMD
  ACALL OUTS
BRDLP:
  MOV R7, #8
  SETB I2C_SDA
INLP:  CLR  I2C_SCL
  ACALL DELAY6
  SETB  I2C_SCL
  NOP
  MOV C, I2C_SDA
  RLC A
  DJNZ R7, INLP
  CLR  I2C_SCL
  MOV @R0, A
  INC R0
  DJNZ R6, ACKLP
;;;;----------------------------
I2C_STOP:
  CLR I2C_SDA
  ACALL DELAY5
  SETB I2C_SCL
  ACALL DELAY5
  SETB I2C_SDA
DELAY6:
  NOP
DELAY5:
  NOP
  RET
;;-----------------------------
I2C_START:
  Swap A
  RR A
  MOV R6, A
  MOV A, #0A0H; #WTCMD
  ACALL OUTS
  MOV A, R6
  RET
;-------------------------------  
ACKLP:
  CLR I2C_SDA 
  SETB I2C_SCL
  ACALL DELAY5
  CLR I2C_SCL
  AJMP BRDLP
;=======================
OUTS:
  SETB I2C_SDA  
  SETB I2C_SCL 
  ACALL DELAY5 
  CLR I2C_SDA  
  ACALL DELAY5 
  CLR I2C_SCL  
;========================
OUT:
  SETB C
  MOV R7, #9
OTLP: RLC A
  NOP
  MOV I2C_SDA, C
  NOP
  NOP
  SETB I2C_SCL
  ACALL DELAY5
  CLR  I2C_SCL
  DJNZ R7, OTLP
  RET
;========================
END