;=======================================        
;PIC16C74B單片機(jī)與AT24C64通訊
;該程序?qū)崿F(xiàn)的功能是：
;將I2C_A,I2C_B.....I2C_K內(nèi)容寫(xiě)入EEPROM中
;同時(shí)在EEPROM中讀出數(shù)據(jù)從新寫(xiě)入各個(gè)寄存器
;=======================================
        LIST  P=16C74B
        #include
        ERRORLEVEL  -302
I2C_A    EQU      0X20    
I2C_B    EQU      0X21
I2C_C    EQU      0X22
I2C_D    EQU      0X23
I2C_E    EQU      0X24
I2C_F    EQU      0X25
I2C_G    EQU      0X26    
REG1     EQU      0X2B
REG2     EQU      0X2C
COUNT    EQU      0X71            ;I2C
BCOUNT   EQU      0X72            ;I2C
TXBUF    EQU      0X73            ;I2C
RXBUF    EQU      0X74            ;I2C
BUSCON   EQU      0X75            ;I2C
BUSSTA   EQU      0X76            ;I2C
I2CBUF   EQU      0X77            ;I2C
SLAVEADDR        EQU    0XA0      ;I2C
DATAADDRH        EQU    0X01      ;I2C
DATAADDRL        EQU    0X00      ;I2C
;---------------------------------------    
;BUSCON
;---------------------------------------    
SLAVE_RW        EQU       7
LAST_BYTE_RX    EQU       6
SLAVE_ACTIVE    EQU       5
TIME_OUT        EQU       4
;---------------------------------------    
;BUSSTA
;---------------------------------------
BUS_BUSY          EQU       7
TX_PROGRESS       EQU       6
RX_PROGRESS       EQU       5
TX_SUCCESS        EQU       4
RX_SUCCESS        EQU       3
FATAL_ERROR       EQU       2    ;SLAVE EEPROM 
ABORT             EQU      1
ACK_ERROR         EQU       0
;---------------------------------------
R_NOT_W  EQU       0           
TRUE     EQU       1
FALSE    EQU       0
SDA      EQU     0X04            ;I2C
SCL      EQU     0X03            ;I2C
;=======================================
        ORG     0X00
        GOTO    START
        ORG     0X20
START   BCF     STATUS,RP1
        BCF     STATUS,RP0
        CLRF    RA
        CLRF    RB
        CLRF    RC
        CLRF    RD
        CLRF    RE      
        BSF     STATUS,RP0
        CLRF    TRISA
        CLRF    TRISB                      
        CLRF    TRISC
        CLRF    TRISD
        CLRF    TRISE
        MOVLW   0X02
        MOVWF   I2C_A
        MOVLW   0X04
        MOVWF   I2C_B
        MOVLW   0X03
        MOVWF   I2C_C
        MOVLW   0X03
        MOVWF   I2C_D
        MOVLW   0X05
        MOVWF   I2C_E
        MOVLW   0X06
        MOVWF   I2C_F
        MOVLW   0X04
        MOVWF   I2C_G
;=======================================        
START1  
        CALL   I2CBUS_INIT
        CALL   REGTOI2CBUF
        CALL   I2CWRITE
        CALL   CLRI2CBUF
        CALL   D10
        CALL   I2CREAD      
        CALL   I2CBUFTOREG
        GOTO   START1
;=======================================    
;CLRI2CBUF
;---------------------------------------
CLRI2CBUF
        BCF        STATUS,RP0
        MOVLW      I2CBUF
        MOVWF      FSR
        MOVLW      0X08
        MOVWF      COUNT
CLRLOOP CLRF       INDF
        INCF       FSR,F
        DECFSZ     COUNT,F
        GOTO       CLRLOOP
        RETURN
;---------------------------------------    
;將各個(gè)REGSTER數(shù)據(jù)寫(xiě)入 I2CBUF 緩沖區(qū)
;---------------------------------------
REGTOI2CBUF
        BCF        STATUS,RP0
        MOVLW      I2CBUF
        MOVWF      FSR
        MOVF       I2C_A,W
        MOVWF      INDF
        INCF       FSR,F
        MOVF       I2C_B,W
        MOVWF      INDF
        INCF       FSR,F
        MOVF       I2C_C,W
        MOVWF      INDF
        INCF       FSR,F
        MOVF       I2C_D,W
        MOVWF      INDF
        INCF       FSR,F
        MOVF       I2C_E,W
        MOVWF      INDF
        INCF       FSR,F
        MOVF       I2C_F,W
        MOVWF      INDF
        INCF       FSR,F
        MOVF       I2C_G,W
        MOVWF      INDF
        RETURN
;---------------------------------------
;將 I2CBUF 緩沖區(qū)數(shù)據(jù)寫(xiě)入各個(gè)REGSTER 
;---------------------------------------        
I2CBUFTOREG
        BCF        STATUS,RP0
        MOVLW      I2CBUF
        MOVWF      FSR
        MOVF       INDF,W
        MOVWF      I2C_A
        INCF       FSR,F
        MOVF       INDF,W
        MOVWF      I2C_B
        INCF       FSR,F
        MOVF       INDF,W
        MOVWF      I2C_C
        INCF       FSR,F
        MOVF       INDF,W
        MOVWF      I2C_D
        INCF       FSR,F
        MOVF       INDF,W
        MOVWF      I2C_E
        INCF       FSR,F
        MOVF       INDF,W
        MOVWF      I2C_F
        INCF       FSR,F
        MOVF       INDF,W
        MOVWF      I2C_G
        RETURN
;=======================================    
;將I2CBUF緩沖區(qū)內(nèi)的數(shù)據(jù)寫(xiě)入EEPROM
;=======================================
I2CWRITE
        CALL       I2CSTART
        BTFSS      BUSSTA,BUS_BUSY
        GOTO       TX_FAIL
        BCF        BUSCON,SLAVE_RW
        CALL       TX_SLAVE_ADDR
        BTFSS      BUSSTA,TX_SUCCESS    ;SUCESSFULL?
        GOTO       TX_FAIL
        CALL       TX_DATA_ADDR
        BTFSS      BUSSTA,TX_SUCCESS
        GOTO       TX_FAIL
        MOVLW      I2CBUF
        MOVWF      FSR
        MOVLW      07
        MOVWF      COUNT
T_BYTE_LOOP
        MOVF       INDF,W
        MOVWF      TXBUF
        CALL       I2CTXB
        BTFSS      BUSSTA,TX_SUCCESS
        GOTO       TX_FAIL
        INCF       FSR,F
        DECFSZ     COUNT,F
        GOTO       T_BYTE_LOOP
        GOTO       TX_PASS
TX_FAIL CALL       I2CSTOP
        BCF        BUSSTA,TX_PROGRESS
        BCF        BUSSTA,TX_SUCCESS
        RETLW      FALSE
TX_PASS
        CALL       I2CSTOP
        BCF        BUSSTA,TX_PROGRESS
        RETLW      TRUE
;---------------------------------------            
;從 EEPROM 中讀出數(shù)據(jù)到 I2CBUF 寄存器
;---------------------------------------
I2CREAD BCF        STATUS,RP0
        BCF        BUSSTA,RX_SUCCESS
        CALL       I2CSTART
        BTFSS      BUSSTA,BUS_BUSY
        GOTO       RX_FAIL
        BCF        BUSCON,SLAVE_RW
        CALL       TX_SLAVE_ADDR
        BTFSS      BUSSTA,TX_SUCCESS   
        GOTO       RX_FAIL
        CALL       TX_DATA_ADDR
        BTFSS      BUSSTA,TX_SUCCESS
        GOTO       RX_FAIL
        CALL       I2CSTART
        BSF        BUSCON,SLAVE_RW
        CALL       TX_SLAVE_ADDR
        BTFSS      BUSSTA,TX_SUCCESS 
        GOTO       RX_FAIL
        BCF        BUSSTA,LAST_BYTE_RX
        MOVLW      I2CBUF
        MOVWF      FSR
        MOVLW      07
        MOVWF      COUNT 
R_BYTE_LOOP
        MOVLW      0X01
        XORWF      COUNT,W
        BTFSC      STATUS,Z
        BSF        BUSSTA,LAST_BYTE_RX
        CALL       I2CRXB
        BTFSS      BUSSTA,RX_SUCCESS
        GOTO       RX_FAIL
        MOVF       RXBUF,W     
        MOVWF      INDF
        INCF       FSR,F
        DECFSZ  COUNT,F
        GOTO       R_BYTE_LOOP 
        GOTO       RX_PASS
RX_FAIL CALL       I2CSTOP
        BCF        BUSSTA,RX_PROGRESS
        BCF        BUSSTA,RX_SUCCESS
        RETLW      FALSE  
RX_PASS CALL       I2CSTOP
           BCF        STATUS,RP0
        BCF        BUSSTA,TX_PROGRESS
        BCF        BUSSTA,RX_PROGRESS
        BSF        BUSSTA,RX_SUCCESS
        RETLW      TRUE
;=======================================        
; I2C 初始化
;=======================================
I2CBUS_INIT
        BCF        STATUS,RP0
        MOVF       RC,W
        ANDLW      0X18
        MOVWF      RC
        CLRF       BUSSTA
        CLRF       BUSCON
        RETURN         
;=======================================    
; 傳送設(shè)備地址
;入口:  BUSCON
;出口:  BUSSTA
;=======================================
TX_SLAVE_ADDR
        BCF        STATUS,RP0
        BCF        BUSSTA,ACK_ERROR
        MOVLW      SLAVEADDR
        MOVWF      TXBUF
        BTFSC      BUSCON,SLAVE_RW
        BSF       TXBUF,R_NOT_W
        CALL       I2CTXB           
        BTFSC      BUSSTA,TX_SUCCESS 
        GOTO       TXADDR_SUCCESS
        CLRWDT
        BTFSS      BUSSTA,ACK_ERROR
        CALL       I2CSTOP
        GOTO       TXADDR_END
TXADDR_SUCCESS
        CLRWDT
TXADDR_END
        RETURN
;=======================================    
;TX_DATA_ADDR   發(fā)送寫(xiě)/讀的地址
;=======================================
TX_DATA_ADDR
        BCF        STATUS,RP0
        MOVLW      DATAADDRH
        MOVWF      TXBUF
        CALL       I2CTXB
        BCF        STATUS,RP0
        BTFSS      BUSSTA,TX_SUCCESS
        GOTO       TX_DATA_ADDR_ERROR
        MOVLW      DATAADDRL
        MOVWF      TXBUF
        CALL       I2CTXB
        BCF        STATUS,RP0
        BTFSS      BUSSTA,TX_SUCCESS
        GOTO       TX_DATA_ADDR_ERROR
        GOTO       TX_DATA_END
TX_DATA_ADDR_ERROR
        BCF        BUSSTA,TX_PROGRESS
        BCF        BUSSTA,TX_SUCCESS
        BSF        BUSSTA,ACK_ERROR
TX_DATA_END
        RETURN
;=======================================    
;向 EEPROM 輸出一個(gè)8位數(shù)據(jù)，并檢測(cè)EEPROM的ACK信號(hào)
;入口:  TXBUF  寄存器
;       BUSSTA 寄存器
;出口:  EEPROM 存儲(chǔ)器
;       BUSSTA 寄存器
 ;======================================    
I2CTXB  BCF        STATUS,RP0
        BSF        BUSSTA,TX_PROGRESS
        BCF        BUSSTA,TX_SUCCESS
        MOVLW      0X08
        MOVWF      BCOUNT
TXLOOP  CLRWDT                
        BSF        STATUS,RP0     
        BCF        TRISC,SCL 
        NOP    
        BCF        TRISC,SDA     
        BCF        STATUS,RP0    
        RLF        TXBUF,F       
        BSF        STATUS,RP0
        BTFSC      STATUS,C
        BSF        TRISC,SDA
        NOP
        BSF        TRISC,SCL
        NOP
        NOP
        BCF        STATUS,RP0
        DECFSZ     BCOUNT,F
        GOTO       TXLOOP
;---------------------------------------
;檢測(cè)是EEPROM否有ACK信號(hào)產(chǎn)生,產(chǎn)生為正常
;檢測(cè)方法:
;   1. 將RC口的SCL.SDA分別設(shè)置為輸出和輸入狀態(tài)
;   2. 延時(shí)2個(gè)指令周期,將SCL設(shè)置為高電平
;   3. 延時(shí)2個(gè)指令周期,檢測(cè)RC口SDA的狀態(tài)
;   4. 如果為高電平,設(shè)置錯(cuò)誤狀態(tài),返回
;   5. 如果為低電平,延時(shí)2個(gè)指令周期后,將RC口SCL設(shè)置為低電平,繼續(xù)執(zhí)行
;---------------------------------------
        BSF        STATUS,RP0
        BCF        TRISC,SCL
        BSF        TRISC,SDA
        NOP
        NOP
        BSF        TRISC,SCL
        NOP
        BCF        STATUS,RP0
        BTFSC      RC,SDA
        GOTO       TX_ERR
        BSF        STATUS,RP0
        BCF        TRISC,SCL
        BCF        STATUS,RP0
        BCF        BUSSTA,TX_PROGRESS
        BSF        BUSSTA,TX_SUCCESS
        BCF        BUSSTA,ACK_ERROR
        GOTO       TX_END
TX_ERR  BCF        BUSSTA,TX_PROGRESS
        BCF        BUSSTA,TX_SUCCESS
        BSF        BUSSTA,ACK_ERROR
TX_END  RETURN
;=======================================
;從EEPROM中讀出 8 位的數(shù)據(jù),并發(fā)送發(fā)送ACK信號(hào)
;入口:  EEPROM  存儲(chǔ)器
;       BUSCON  寄存器
;出口:  RXBUF   寄存器
;       BUSSTA  寄存器
;=======================================
I2CRXB  BCF        STATUS,RP0
        BSF        BUSSTA,RX_PROGRESS
        BCF        BUSSTA,RX_SUCCESS
        MOVLW      0X08
        MOVWF      BCOUNT
RXLOOP  CLRWDT
        BSF        STATUS,RP0
        BCF        TRISC,SCL          ;定義TRISC為輸出
        BSF        TRISC,SDA          ;定義TRISC為輸入       
        NOP              
        NOP
        BSF        TRISC,SCL          ;TRISC輸出高電平
        NOP
        BCF        STATUS,RP0
        BCF        STATUS,C
        BTFSC      RC,SDA             ;原指令為BTFSC TRISC,SDA
        BSF        STATUS,C
        RLF        RXBUF,F
        DECFSZ     BCOUNT,F
        GOTO       RXLOOP
;---------------------------------------
;發(fā)送ACK信號(hào)到EEPROM
;判斷接收的是否為最后一個(gè)字節(jié)
;LAST_BYTE_RX為1,是    SDA發(fā)送一個(gè)高電平,結(jié)束
;LAST_BYTE_RX為0,不是  SDA發(fā)送一個(gè)低電平ACK,繼續(xù)接收
;---------------------------------------
        BSF        STATUS,RP0
        BCF        TRISC,SCL      
        BCF        TRISC,SDA      
        BTFSC      BUSCON,LAST_BYTE_RX      ;檢測(cè)是否是最后一個(gè)字節(jié)
        BSF        TRISC,SDA                ;是最后一個(gè)字節(jié)
        NOP                             ;發(fā)送ACK信號(hào)
        BSF        TRISC,SCL
        NOP
        NOP
        NOP
        NOP
        BCF        TRISC,SCL
        BCF        STATUS,RP0
        BCF        BUSSTA,RX_PROGRESS   
        BSF        BUSSTA,RX_SUCCESS
        RETURN
;=======================================
;I2C 開(kāi)始信號(hào)
;輸入:  無(wú)
;輸出:  BUFSSTA
;=======================================
I2CSTART
        BSF     STATUS,RP0
        BSF     TRISC,SDA    ;1US
        NOP                     ;1US
        BSF     TRISC,SCL       ;1US
        NOP
        NOP
        BCF     TRISC,SDA
        NOP
        NOP
        BCF     STATUS,RP0
        BSF     BUSSTA,BUS_BUSY
        RETURN
;=======================================
;I2C 結(jié)束信號(hào)
;輸入:  無(wú)
;輸出:  BUSSTA
;=======================================
I2CSTOP
        BSF     STATUS,RP0
        BCF     TRISC,SCL
        BCF     TRISC,SDA
        BSF     TRISC,SCL
        NOP
        NOP
        BSF     TRISC,SDA
        NOP
        BCF     STATUS,RP0
        BCF     BUSSTA,BUS_BUSY              
        RETURN
;=======================================
; D10 @
;  clock in 4Mhz
;  delay 10ms
;=======================================    
D10    MOVLW    0X0D        
    MOVWF    REG1
LOOP2    MOVLW    0XFF        
    MOVWF    REG2
LOOP1    DECFSZ    REG2,f
    GOTO    LOOP1
    DECFSZ    REG1,f
    GOTO    LOOP2
    RETURN
;=======================================
I2CERR  CLRWDT
        NOP
        NOP
        NOP
        RETURN 
        END