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读写24LCxx系列的EEPROM的实例程序
;********************************************************
;* *
;* ? PIC16F877A ?I2C Master 家Α???﹃?Α EEPROM ?絛ㄒ祘Α *
;* *
;* 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
＃i nclude
;
;***************************************
; ﹚竡跑计?RAM???
;
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
;
;***************************************
; ﹚竡い耞?既?竟??
w_temp EQU 0x72
status_temp EQU 0x73
pclath_temp EQU 0x74
;
;***************************************
; ﹚竡 I2C ???の竲?
;
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" ?ㄏノ絛ㄒ : 続ノ?钩 PIC16F877 ΤSHARE BANK ?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
;
;----------------------------------------------------------------------
;
;* ???代刚祘Α穦?盢?舱计?(0x40-0x47)糶??RMA0x40-0x47??竚
;* ?ノPage Write?よΑ盢8??じ舱?戈?糶? EEPROM ?
;* 秈︽?篈?盎代EEPROM琌??ЧΘ糶??笆??程?盢?糶
;* ??戈??Sequential Read?よΑ眖EEPROM弄?ㄓ??I2C_SEQU_Bufferい
;
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 $
;
;---------------------------------------------------------
;
;* ???代刚祘Α穦?糶????じ舱?戈?糶? EEPROM い
;* ?秈︽?篈?盎代琌??ЧΘ糶??笆??程?盢?糶
;* ??戈??眖EEPROM弄?ㄓ??I2C_Data既?竟い
;
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
goto ACK_Return ; Ack = 0 ; EEPROM is Ready
_Ack_Hi ; Ack = 1 ; EEPROM is Busy for Write
call Delay_mS ; Delay 500uS for next Ack polling
call RstartI2C ; Send a Repeat Start to I2C
bcf I2C_Ctrl,0 ; Clear for Write Command
movf I2C_Ctrl,W ; Send Slave Address to I2C Bus
call Send_Byte
goto _Ack_Polling
ACK_Return
call StopI2C ; Initial STOP Condition
return
;
;**********************************************************
;* Page Write 1 to 8 Bytes to EEPROM
;*
;* Input:
;* - I2C_Ctrl : Control Byte of EEPROM
;* - I2C_Addr : Location of EEPROM
;* - I2C_Page_Buffer: RAM location of Data
;* - I2C_Page_Length : Data length count
;*
;**********************************************************
;
; Send Command for PAGE WRITE :
; " Start+ 0xA0 + EE_Address + W_Data 0+ .. + W_Data N + Stop "
;
EE_Page_Write
movf I2C_Page_Length,W
btfsc STATUS,Z
return
;
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
;
movf I2C_Addr,W ; Send out the Command
call Send_Byte
;
movlw I2C_Page_Buffer
movwf FSR
_W1 movf INDF,W
call Send_Byte
incf FSR,F
decfsz I2C_Page_Length,F
goto _W1
;
call StopI2C ; Initial STOP Condition
return
;
;
;*******************************************************
;* Write a Byte to EEPROM
;*
;* Input:
;* - I2C_Ctrl : Control Byte of EEPROM
;* - I2C_Addr : Location of EEPROM
;* - I2C_Data : Data to EEPROM
;*
;*******************************************************
;
; Send Command for BYTE WRITE :
; " Start+ 0xA0 + EE_Address + Write_Data + Stop "
;
EE_Byte_Write
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
;
movf I2C_Addr,W ; Send out the Command
call Send_Byte
;
movf I2C_Data,W ; Send out the Data
call Send_Byte
;
call StopI2C ; Initial STOP Condition
return
;
;**********************************************************************
;
; As following subroutines perform commonly used I2C functions.
; You can use these subroutines for your I2C access
;
;**********************************************************************
;
;*** Initial I2Cmodule fot 7-bit I2C Master Mode with 100Kcps @4MHz
;
Init_I2C_Master
BANKSEL TRISC ; Initial PortC,bit 3 & 4 as Input
bsf SCL ; RC3 = SCL , RC4 = SDA
bsf SDA
;
BANKSEL PORTC
bsf SCL ; SCL = Hi
bsf SDA ; SDA = Hi
;
movlw b'00101000' ; I2C Master Mode, Clock Rate: FOSC/(4*SSPADD+1)
movwf SSPCON ;
;
banksel SSPADD
movlw .9 ; This gives 100KHz I2C clock @ 4MHz
movwf SSPADD ; (4MHz/4) / (9+1)= 100KHz
;
movlw b'10000000' ; Disable slew rate control,
movwf SSPSTAT ; and clear status bits
;
movlw b'00000000' ; Set SCL,SDA into Ready status
movwf SSPCON2
;
return
;
;****** Send START condition to bus *******
;
StartI2C ; Initiate the I2C START condition.
banksel SSPCON2
bsf SSPCON2,SEN
goto I2C_Done
;
;****** Send STOP condition to bus *******
;
StopI2C
banksel SSPCON2
bsf SSPCON2,PEN
goto I2C_Done
;
;****** Send RESTART condition to bus *******
;
RstartI2C
banksel SSPCON2
bsf SSPCON2,RSEN
goto I2C_Done
;
;****** Send a Non-Acknowledge status to bus (ACK=1) *******
;
Non_Ack
banksel SSPCON2
bsf SSPCON2,ACKDT ; Set the ACK bit
bsf SSPCON2,ACKEN ; Initiate the NACK sequence.
goto I2C_Done
;
;****** Send an Acknowledge status to bus (ACK=0) *******
;
An_Ack
banksel SSPCON2
bcf SSPCON2,ACKDT ; Clear the ACK bit
bsf SSPCON2,ACKEN ; Initiate the NACK sequence.
goto I2C_Done
;
;****** Send data to I2C bus from Wreg. *******
;
Send_Byte
banksel SSPBUF
movwf SSPBUF
goto I2C_Done
;
;****** Enable I2C Receive for Master Mode *******
;
RecI2C
banksel SSPCON2
bsf SSPCON2,RCEN ; Set the receive enable bit.
goto I2C_Done
;
;****** Check the I2C stage is completed ********
;
I2C_Done
banksel PIR1
btfss PIR1,SSPIF ; Poll for SSPIF
goto $-1
bcf PIR1,SSPIF
return
;
Delay_mS
banksel D_Count
movlw .124 ; Load .5mS Dealy Value
movwf D_Count
_D_mS nop
decfsz D_Count,F
goto _D_mS
return
;
; *********** End Of Program !!!!!
;
end
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