pic单片机的i2c应用程序1..docx

PIC 单片机的 I2C 应用程序 1 ; File: an734.asm; data: feb.23.2001; Functionality:;; This code implements the basic functions for an I2C slave device; using the SSP module. All I2C functions are handled in an ISR.; Bytes written to the slave are stored in a buffer. After a number; of bytes have been written, the master device can then read the; bytes back from the buffer.;; Variables and Constants used in the program:;; The st ; File: an734.asm ; data: feb.23.2001 ; Functionality: J ; This code implements the basic functions for an I2C slave device ; using the SSP module. All I2C functions are handled in an ISR. ; Bytes written to the slave are stored in a buffer. After a number ; of bytes have been written, the master device can then read the ; bytes back from the buffer. J ; Variables and Constants used in the program: J ; The start address for the receive buffer is stored in the variable ; 'RXBuffer'. The length of the buffer is denoted by the constant ; value 'RX_BUF_LEN'. The current buffer index is stored in the ; variable 'Index'. ; The following files should be included in the MPLAB project: J ; an734.asm-- Main source code file J ; 16f872.lkr-- Linker script file ; (change this file for the device ; you are using) #include <p16f872.inc> ; Change to device that you are using. ;Constant Definitions #define NODE_ADDR 0x02 ; I2C address of this node ; Change this value to address that ; you wish to use. ; Buffer Length Definition #define RX_BUF_LEN 32 ; Length of receive buffer ; Variable declarations udata WREGsave res 1 STATUSsave res 1 FSRsave res 1 PCLATHsave res 1 Index res 1 ; Index to receive buffer Temp res 1 ; RXBuffer res RX_BUF_LEN ; Holds rec'd bytes from master ; device. ; Vectors STARTUP code nop goto Startup ; nop ; 0x0002 nop ; 0x0003 goto ISR ; 0x0004 PROG code ; Macros memset macro Buf_addr,Value,Length movlw Length ; This macro loads a range of data memory movwf Temp ; with a specified value. The starting movlw Buf_addr ; address and number of bytes ar