pici2ctest.txt

PIC测试程序, 测试程序, 测试程序

PIC的I2C程序测试程序 

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;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;                   Copyright (C) 1997 by Innovatus
;                        All Rights Reserved.
; This code may be distributed and used freely provided that this
; copyright notice stays intact and that any modifications are noted.
; For more information about Innovatus: http://www.innovatus.com
;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;    File Name: testI2C.asm
;       Author: Alan G. Smith
;      Purpose: This is testing out the I2C code.
;
;+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    LIST P=16f84, F=INHX8M, C=100, N=59

#include "p16f84.inc"

XTAL_FREQ       equ     10000000        ; the crystal frequency we are using
ClkOut          equ     XTAL_FREQ / 4   ; the number of cycles per second

_40uS_Delay set   (ClkOut/250000)
_47uS_Delay set   (ClkOut/212766)
_50uS_Delay set   (ClkOut/200000)

#define SclPin  PORTA, 0                ; Pin for SCL (I2C)
#define SdaPin  PORTA, 1                ; Pin for SDA (I2C)

#define _SCL    TRISA, 0                ; How do we toggle SCL
#define _SDA    TRISA, 1                ; How do we toggle SDA

#define MSB   7
#define LSB   0
#define TRUE  1
#define FALSE 0

InitTrisA       equ     0x07            ; The Initial state to TRIS port A.

#define  Bus_Busy      BusStatus,0
#define  Abort         BusStatus,1
#define  Txmt_Progress BusStatus,2
#define  Rcv_Progress  BusStatus,3
#define  Txmt_Success  BusStatus,4
#define  Rcv_Success   BusStatus,5
#define  Fatal_Error   BusStatus,6
#define  ACK_Error     BusStatus,7

#define  Slave_RW      BusControl,0
#define  Last_Byte_Rcv BusControl,1
#define  SlaveActive   BusControl,2

 CBLOCK     0x0C                        ; I2C Ram needed
   BusStatus                            ; The I2C Status register
   BusControl                           ; The I2C Control register
   I2CBitCount                          ; Number of bits left to send (or receive)
   I2CData                              ; Data (note: This is DESTROYED when sending)
   SlaveAddr                            ; Slave Address
 ENDC

 CBLOCK
   DelayCount                           ; used to figure out precise time delays
 ENDC


   org 0                                 ; Reset Vector
   goto   start                          ; Goto Start

start
   bcf    INTCON, GIE                    ; Turn off interrupts in this critical part of code!
   bcf    STATUS, RP0                    ; Select Page 0 of registers
   movlw  0x0C                           ; Make sure there are 0's on SCL and SDA
   movwf  PORTA                          ; We write 1's to TX since 0 is a start bit
   bsf    STATUS, RP0                    ; Select Page 1 of registers
   movlw  InitTrisA                      ; Load W with the value for TRIS A
   movwf  TRISA                          ; movw the value from W into TRIS A
;*************** DEBUG CODE (let us use LEDs) *******************
   clrf   TRISB
;****************************************************************
   clrf   BusStatus                      ; Let's clear out busStatus before we start
   clrf   BusControl                     ; Let's clear out busControl before we start
;*************** TEST CODE *******************
   clrf   PORTB
main
   movlw  0xB0                           ; address of EEPROM
   movwf  SlaveAddr                      ; move into SlaveAddress register
   call   IsSlaveActive                  ; Check and see if the slave is active
   movlw  0xFF                           ; move FF into w (turn all LED's on)
   btfss  SlaveActive                    ; If the slave is active, leave it
   movlw  0xAA                           ; We didn't find it, turn off half.
   bcf    STATUS, RP0                    ; Select page 0 of registers
   movwf  PORTB                          ; move W to PortB

done                                     ; Game over man!
   goto   done                           ; endless loop

IsSlaveActive
   bcf    Slave_RW                       ; set for write operation
   call   TxmtStartBit                   ; Transmit Start Bit
   call   TxmtSlaveAddr                  ; Transmit Slave Address
   bcf    SlaveActive                    ; Assume not present
   btfss  ACK_Error                      ; skip if NACK, device is not present or not responding
   bsf    SlaveActive                    ; ACK received, device present & listening
   call   TxmtStopBit
   return

#include "i2c_low.asm"

 END