PIC单片机的I2C读写程序

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* PIC的I2C读写程序 *
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TITLE " TWO WIRE/I2C BUS INTERFACE WITH PIC16C5x "
;
LIST P=16C54
;
;*****************************************************************************
;** Two wire/I2C Bus READ/WRITE Sample Routines of Microchip's
;** 24Cxx / 85Cxx serial CMOS EEPROM interfacing to a
;** PIC16C54 8-bit CMOS single chip microcomputer
;** Revsied Version 2.0 (4/2/92).
;**
;** Part use = PIC16C54-XT/JW
;** Note: 1) All timings are based on a reference crystal frequency of 2MHz
;** which is equivalent to an instruction cycle time of 2 usec.
;** 2) Address and literal values are read in octal unless otherwise
;** specified.
;
;
; Program: I2CBUS.ASM
; Revision Date:
; 12-12-95 Compatibility with MPASMWIN 1.30
;
;**********************************************************************
;
;*****************************************************************************
;
;-----------------------------------------------------------------------------
; Files Assignment
;-----------------------------------------------------------------------------
;
PC EQU 2 ; Program counter
STAT EQU 3 ; PIC status byte
FSR EQU 4 ; File Select Register
RA EQU 5 ; Port A use to select device address
RB EQU 6 ; RB7 = SDA, RB6 = SCL
;
STATUS EQU 08 ; Status register
FLAG EQU 09 ; Common flag bits register
EEPROM EQU 0A ; Bit buffer
ERCODE EQU 0B ; Error code (to indicate bus status)
ADDR EQU 10 ; Address register
DATAI EQU 11 ; Stored data input register
DATAO EQU 12 ; Stored data output register
SLAVE EQU 13 ; Device address (1010xxx0)
TXBUF EQU 14 ; TX buffer
RXBUF EQU 15 ; RX buffer
COUNT EQU 16 ; Bit counter
;
TIMER0 EQU 18 ; Delay timer0
TIMER1 EQU 19 ; Delay timer1
;
;
;-----------------------------------------------------------------------------
; Bit Assignments
;-----------------------------------------------------------------------------
;
; Status bits
;
Z EQU 2
C EQU 0
;
; FLAG Bits
;
ERR1 EQU 0 ; Error flag
;
; Instruction Destination Bits
;
F EQU 1
W EQU 0
;
; EEPROM Bits
;
DI EQU 7 ; EEPROM input
DO EQU 6

; EEPROM output
;
; I2C Device Bits
;
SDA EQU 7 ; RB7, data in/out
SCL EQU 6 ; RB