以汇编语言完成读写24LCxx系列的EEPROM的实例

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

*

;*    以 PIC16F877A 為I2C Master 模式存取一串列式 EEPROM 的範例程式 *

;*                                            *

;* Written by:  Richard Yang                            *

;*              Sr. Corporate Application Engineer         *

;*              Microchip Technology Inc.            *

;* Date:        Oct. 2nd '2002                        *

;* Revision: 1.00                                *

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

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

; This source code provides a demonstration of the MSSP peripheral

; on the PIC16F87x MCU.  

;

;

;***********      The subroutines for EEPROM      *****************

;

; EE_Random_Read ; EEPROM Random address Read from EEPROM

; EE_SEQU_Read ; EEPROM Sequential Read form EEPROM

; EE_Ack_Check ; Polling current status of EEPROM 

; EE_Page_Write ; Page Write function for EEPROM

; EE_Byte_Write ; Write a byte to EEPROM with address setting

;

;***********      The subroutines for I2C      *****************

;

; Init_I2C_Master ; Initial I2C Module for Master Mode , 7-bit address

; StartI2C ; Send a START Condition !!

; StopI2C ; Send s STOP Condition

; RstartI2C ; Send a Repeat Start conditional to I2C

; Non_Ack ; Send a Non-acknowledge signal to I2C

; An_Ack ; Send a acknowledge signal to I2C

; Sebd_Byte ; Send a byte to I2C bus

; RecI2C ; Enable Read a byte form slave device

; I2C_Done : Wait the I2C completed the currect process

;

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

list p=16f877a

#include

;

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

;       定義變數在RAM的位址

;

  CBLOCK 0x20

I2C_Ctrl  

I2C_Addr

I2C_Data

I2C_Page_Length

D_Count

ENDC

cblock 0x40

I2C_Page_Buffer:8

I2C_SEQU_Buffer:8

endc

;

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

;       定義中斷的暫存器位址

w_temp EQU 0x72

status_temp EQU 0x73

pclath_temp EQU 0x74 

;

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

;       定義 I2C 的位址及腳位

;

EEPROM_CMD equ 0xA0 ; Device adress of Slave Point

EE_Read equ .1

EE_Write equ .0

;

#define SCL PORTC,3 ; I2C SCL pin

#define SDA PORTC,4 ; I2C SDA pin

;

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

; Locates startup code @ the reset vector

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

Reset_Addr

org 0x00

nop

goto Main_Init

;

org 0x04

goto ISR 

;

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

;**** The Start Address of ISR is 0x004

;**** "PUSH" & "POP" 的使用範例 : 適用於像 PIC16F877 有SHARE BANK 的PIC

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

ISR

Push movwf   w_temp            ; save off current W register contents

movf STATUS,w          ; move status register into W register

movwf status_temp        ; save off contents of STATUS register

movf PCLATH,W

movwf pclath_temp

;  

;        Put your interrupt code here

;

Pop movf pclath_temp,W

movwf PCLATH

movf    status_temp,w    ; retrieve copy of STATUS register

movwf STATUS            ; restore pre-isr STATUS register contents

swapf   w_temp,f

swapf   w_temp,w          ; restore pre-isr W register contents

;

retfie                    ; return from interrupt

;----------------------------------------------------------------------

Main_Init   

pagesel Init_I2C_Master ; Set PAGE to PCLATH Register 

    call    Init_I2C_Master ; Init the MSSP for I2C Master 

;

    banksel I2C_Ctrl

movlw EEPROM_CMD ; Load EEPROM command address @ 0xA0

movwf I2C_Ctrl

;

;

Main

;

;----------------------------------------------------------------------

;

;* 以下的測試程式會先將一組數字(0x40-0x47)寫入到RMA0x40-0x47的位置      

;* 再用Page Write的方式將8個位元組的資料寫到 EEPROM 後                  

;* 進行狀態的偵測EEPROM是否已完成寫入的動作，最後將剛寫                   

;* 入的資料以Sequential Read的方式從EEPROM讀出來放在I2C_SEQU_Buffer中     

;

Test_Page_RW

movlw 0x08

movwf I2C_Page_Length

movlw I2C_Page_Buffer

_Fill_RAM movwf FSR

movwf INDF

incf FSR,W

decfsz I2C_Page_Length,F

goto _Fill_RAM

;

Test_Page_Write

; banksel I2C_Ctrl

movlw EEPROM_CMD ; Load EEPROM command address @ 0xA0

movwf I2C_Ctrl

movlw 0x10 ; Select EEPROM location at 0x00

movwf I2C_Addr

movlw .8

movwf I2C_Page_Length

call EE_Page_Write

;

call EE_Ack_Check

;

banksel I2C_Ctrl

movlw EEPROM_CMD ; Load EEPROM command address @ 0xA0

movwf I2C_Ctrl

movlw 0x10

movwf I2C_Addr

movlw .8

movwf I2C_Page_Length

call EE_SEQU_Read

;

goto $

;

;---------------------------------------------------------

;

;* 以下的測試程式會先寫入一個位元組的資料寫到 EEPROM 中                

;* 再進行狀態的偵測是否已完成寫入的動作，最後將剛寫                            

;* 入的資料再從EEPROM讀出來放在I2C_Data暫存器中                       

;

Test_1byte_RW

banksel I2C_Ctrl

movlw EEPROM_CMD ; Load EEPROM command address @ 0xA0

movwf I2C_Ctrl

movlw 0x00 ; Select EEPROM location at 0x00

movwf I2C_Addr

movlw 0xAA ; Write data 0x5A to location 0x00 of EEPROM

movwf I2C_Data

call EE_Byte_Write

;

Test2 call EE_Ack_Check ; Polling Acknowledge for next access

;

banksel I2C_Data

movlw 0x00 ; Clear I2C data buffer

movwf I2C_Data

;

Test3

banksel I2C_Ctrl

movlw EEPROM_CMD ; Load EEPROM command address @ 0xA0

movwf I2C_Ctrl

movlw 0x00

movwf I2C_Addr

call EE_Random_Read

;

goto $

;

;

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

;*           Random Read a Byte from EEPROM          

;*

;* Input:

;*  - I2C_Ctrl : Control Byte of EEPROM  

;*    - I2C_Addr : Location of EEPROM  

;* Output:

;*    - I2C_Data : Read Data from EEPROM  

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

;

; Send Command for RANDOM READ : 

; " Start+ 0xA0 + EE_Address + ReStart + 0xA1 + Read_Data + NAck + Stop "

;

EE_Random_Read

  call StartI2C ; Set SSPCON2.SEN

;

bcf I2C_Ctrl,0 ; set for write Command

movf I2C_Ctrl,W ; Send Slave Address to I2C Bus

call Send_Byte 

;

movf I2C_Addr,W ; Send out the Rendom address of EEPROM  

call Send_Byte 

;

call RstartI2C ; Send a Repeat Start to I2C

;

bsf I2C_Ctrl,0 ; set for Read Command

movf I2C_Ctrl,W ; Send Slave Address to I2C Bus

call Send_Byte 

;

call RecI2C ; Enable I2C Receive 

;

BANKSEL SSPBUF

movf SSPBUF,W ; Save to I2C_Data First !!

movwf I2C_Data

call Non_Ack ; Initial NACK Response !!

call StopI2C ; Initial STOP Condition 

return

;

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

;*                Sequential Read from EEPROM          

;*

;* Input:

;*  - I2C_Ctrl : Control Byte of EEPROM  

;*    - I2C_Addr : Start Location of EEPROM

;* - I2C_Page_Length : How many byte need to read  

;* Output:

;*    - I2C_SEQU_Buffer : Sequential Read Data buffer 

;*  

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

;

; Send Command for RANDOM READ : 

; " Start+ 0xA0 + EE_Address + ReStart + 0xA1 + Read_Data + NAck + Stop "

;

EE_SEQU_Read

  call StartI2C ; Set SSPCON2.SEN

;

bcf I2C_Ctrl,0 ; set for write Command

movf I2C_Ctrl,W ; Send Slave Address to I2C Bus

call Send_Byte 

;

movf I2C_Addr,W ; Send out the Rendom address of EEPROM  

call Send_Byte 

;

call RstartI2C ; Send a Repeat Start to I2C

;

bsf I2C_Ctrl,0 ; set for Read Command

movf I2C_Ctrl,W ; Send Slave Address to I2C Bus

call Send_Byte 

;

movlw I2C_SEQU_Buffer

movwf FSR

;

_Sequ_Loop call RecI2C ; Enable I2C Receive 

BANKSEL SSPBUF

movf SSPBUF,W ; Save to I2C_Data First !!

movwf INDF

incf FSR,F

decfsz I2C_Page_Length,F

goto _Cont_Read

goto _End_Read

_Cont_Read call An_Ack

goto _Sequ_Loop

;

_End_Read call Non_Ack ; Initial NACK Response !!

call StopI2C ; Initial STOP Condition 

return

;

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

;*              EEPROM Acknowledge Polling

;*           

;*    --  The routine will polling the ACK  

;*           response from EEPROM     

;*  --  ACK=0 return  

;* --  ACK=1 send Restart & loop check

;*  

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

;

EE_Ack_Check

  call StartI2C ; Set SSPCON2.SEN

bcf I2C_Ctrl,0 ; Clear for Write Command

movf I2C_Ctrl,W ; Send Slave Address to I2C Bus

call Send_Byte 

_Ack_Polling

BANKSEL SSPCON2

btfss SSPCON2,ACKSTAT ; Check ACKSTAT bit , 0 = ACK , 1 = NACK