at24c64读写程序

// AT24C64 support functions using ATMEGA's TWI
// pin-WP is hard-wired to GND
// fuctions work better outside interrupt routines
// by MXH, 2003/07/30

＃i nclude "DStruct.h"
＃i nclude

// CONSTANTS DEFINITION FOR EEPROM
#define EEADDR 0
#define EEWR 0
#define EERD 1
// TWINT *NOT* set after STOP condition is sent
// check status?
// TWSTO is cleared by hardware
#define TwiStop() TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWSTO)
#define TwiStart() TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWSTA)
#define TWI_STATUS (TWSR & 0xF8)

BYTE byEEWait;

//////////////////////////////////////////////////////////////////////////
// implementation

BOOL EEPStart(BYTE addr, BOOL bWrite)
{
byEEWait = 10; // 90~100ms
poll_ack:
TwiStart();
while (!(TWCR & (1<if ( byEEWait == 0 ){
return FALSE;
}
}
if ((TWI_STATUS != TW_START)&&(TWI_STATUS != TW_REP_START))
goto poll_ack;
//byEEWait = 3; // 20~30ms
// send SLA+R/W
TWDR = addr | bWrite;
TWCR = (1<while (!(TWCR & (1<if( byEEWait == 0 ){
TwiStop();
return FALSE;
}
}
if( EEWR == bWrite ){ // MT mode
//if(TWI_STATUS != TW_MT_SLA_ACK)
switch(TWI_STATUS){
case TW_MT_SLA_ACK:
break;
case TW_MT_SLA_NACK:
goto poll_ack;
default:
TwiStop();
return FALSE;
}
}else{ // MR mode
if(TWI_STATUS != TW_MR_SLA_ACK)
return FALSE;
}
return TRUE;
}

//////////////////////////////////////////////////////////////////////
//
BYTE EEPWrite( WORD uiAddress, WORD uiLen, void *pBuf ) //using 0
{
unsigned int i,j,uiCnt;

if( uiLen == 0 ) return 0;
uiCnt = 0;
// uiEnd = uiAddress + uiLen;
i = uiAddress;
do{
if(!EEPStart(0xA0|EEADDR,EEWR)){ //PollAck() is built-in
return 0;
}
TWDR = (BYTE)((i>>8)&0x00ff); // MSB of address
TWCR = (1<byEEWait = 3; // 20~30ms
while (!(TWCR & (1<if( byEEWait == 0 )
return FALSE;
}
if(TWI_STATUS != TW_MT_DATA_ACK){
return FALSE;
}
TWDR = (BYTE)(i&0x00ff); // LSB of address
TWCR = (1<byEEWait = 3; // 20~30ms
while (!(TWCR & (1<if( byEEWait == 0 )
return FALSE;
}
if(TWI_STATUS != TW_MT_DATA_ACK)
return FALSE;
// write data
for( j=0; j<32; j++ ){
TWDR = ((BYTE*)pBuf)[uiCnt];
TWCR = (1<byEEWait = 3; // 20~30ms
while (!(TWCR & (1<if( byEEWait == 0 )
return FALSE;
}
if(TWI_STATUS != TW_MT_DATA_ACK){
return FALSE;
}
i++;
uiCnt++;
if(( 0 == i%32 )||( uiCnt == uiLen )){
TwiStop();
break;
}
}
}while( uiCnt < uiLen );
// while( !PollAck());
return 1;
}

//////////////////////////////////////////////////////////////////////
//
BYTE EEPRead( WORD uiAddress, WORD uiLen, void *pBuf ）
{
UINT i;

if ( uiLen == 0 ) return 0;
if(!EEPStart(0xA0|EEADDR,EEWR)){ //PollAck() is built-in
return 0; //↑
} // not RD but write device address to the chip
TWDR = (BYTE)(( uiAddress >> 8) & 0x00ff ); //((BYTE*)(&uiAddress))[1]; // MSB of address
TWCR = (1<byEEWait = 3; // 20~30ms
while (!(TWCR & (1<if( byEEWait == 0 )
return FALSE;
}
if (TWI_STATUS != TW_MT_DATA_ACK)
return FALSE;
TWDR = (BYTE)( uiAddress & 0x00ff ); //((BYTE*)(&uiAddress))[0]; // LSB of address
TWCR = (1<byEEWait = 3; // 20~30ms
while (!(TWCR & (1<if( byEEWait == 0 )
return FALSE;
}
if (TWI_STATUS != TW_MT_DATA_ACK)
return FALSE;
if(!EEPStart(0xA0+EEADDR,EERD)){ //PollAck()){
return 0; //↑
}// ??? how to read?
for ( i=0; iTWCR = _BV(TWINT)|_BV(TWEN)|_BV(TWEA);
byEEWait = 3; // 20~30ms
while (!(TWCR & (1<if( byEEWait == 0 )
return FALSE;
}
if (TWI_STATUS != TW_MR_DATA_ACK)
return FALSE;
((BYTE*)pBuf)[i] = TWDR; // EEInByte();
}
TWCR = _BV(TWINT) | _BV(TWEN); // send NACK to indicate final byte
byEEWait = 3; // 20~30ms
while (!(TWCR & (1<if( byEEWait == 0 )
return FALSE;
}
//if (TWI_STATUS != TW_MR_DATA_ACK)
// return FALSE;
((BYTE*)pBuf)[i] = TWDR;
TwiStop();
return 1;
}

附录：
;============================
;STC89C51读写AT24C64汇编程序
;===========================
BITCNT    EQU       42H
SDADR     EQU       40H
SDA       BIT         P0.1
SCL       BIT         P0.0
ORG       0000H
JMP        MAIN
ORG       0100H

MAIN:
MOV      R7,  #01010101B
ACALL   WRITE_AT24C64
ACALL   DELAY
ACALL   READ_AT24C64
MOV      P3,  A
ACALL   DELAY
…
;ACALL  显示、键盘子程序
…
JMP        MAIN    
;=============================
DELAY:
MOV       R6,  #0FFH

DELAY0:
MOV       R5,  #0FFH

DELAY1:              
DJNZ      R5,  DELAY1
DJNZ      R6,  DELAY0
RET
;=============================

WRITE_AT24C64:
ACALL           START                     ;发送起始条件
MOV              A,    #0A0H              ;AT24C64总线地址
ACALL           SENTBYTE                  ;发送AT24C64器件总线地址
JB              F0,  SENDRETURN           ;出错返回
MOV             R0,  #SDADR               ;取存储地址
MOV             A,    @R0
ACALL           SENTBYTE
JB              F0,  SENDRETURN
INC             R0
MOV             A,    @R0
ACALL           SENTBYTE
JB              F0,  SENDRETURN
MOV             A,    R7
ACALL           SENTBYTE                   ;发送一次数据
JB              F0,  SENDRETURN            ;出错返回
ACALL           STOP                       ;发送停止条件

DELAY10:     
MOV             R4,  #30H                  ;延时10mS等待数据写完

DELAY11:
MOV             R3,  #34H
DJNZ            R3,  $
DJNZ            R4,        DELAY11

SENDRETURN:
RET
;=============================
READ_AT24C64:                             ;读AT24C64
ACALL           START                     ;发送IC总线起始条件
MOV             A,    #0A0H
ACALL           SENTBYTE                  ;AT24C64总线地址
JB              F0,  RCVRETURN     　　   ;出错返回
MOV             R0,  #SDADR            　 ;取存储地址
MOV             A,    @R0
ACALL           SENTBYTE                  ;发送AT24C64器件总线地址
JB              F0,  SENDRETURN     　　  ;出错返回
INC             R0
MOV             A,    @R0
ACALL           SENTBYTE                  ;发送AT24C64器件总线地址
JB              F0,  SENDRETURN
ACALL           START                     ;发送IC总线重复起始条件
MOV              A,    #0A0H              ;AT24C64总线地址
SETB            ACC.0                 　  ;取总线读操作数
ACALL           SENTBYTE                  ;发送被控制总线地址
JB              F0,  RCVRETURN       　　 ;出错返回
ACALL           RCVBYTE                   ;接收数据

RCVRETURN:
RET
;===============================
START:
SETB            SDA            ;发送起始条件的数据信号
NOP
SETB            SCL            ;发送起始条件的时钟信号
NOP
CLR             SDA            ;发送起始信号
NOP
CLR              SCL           ;准备发送或接收数据
RET
;===============================
STOP:
CLR        SDA                  ;发送停止条件的数据信号
NOP
SETB       SCL                  ;发送停止条件的时钟信号
NOP
SETB       SDA                  ;发送总线停止信号
NOP
RET
;==============================
SENTBYTE:                         ;送数8位
MOV         BITCNT,#08H

SENTB:
RLC        A           　　        ;要发送的数据左移，发送入位C
MOV        SDA,      C
SETB       SCL                     ;置时钟线为高，通知被控制开始接
收数据位
CLR        SCL                     ;准备接收下一个数据位
DJNZ       BITCNT,SENTB            ;8位没发送完继续发送
SETB       SDA                     ;8位发送完后释放数据线准备收应答位
SETB       SCL                     ;开始接收应答信号
CLR        F0                      ;预先清发送数据出错标志
JNB        SDA,      ACKEND        ;判断是否接收应答信号正常转ACKEND
SETB       F0                      ;未收到应答置位错误标志

ACKEND:
CLR        SCL                     ;发送结束准备下次发送或接收数据
RET
;==============================
RCVBYTE:
SETB        SDA                     ;置数据线为输入方式
MOV         BITCNT,#08H             ;传送的数据长度为8位

RCV:
CLR         SCL                     ;置时钟线为低，准备接收数据
SETB        SCL                     ;置时钟线为高使数据线上数据有效
MOV         C,    SDA
RLC       　A                       ;接收的数据位放入ACC
DJNZ        BITCNT,RCV              ;8位没收完继续接收
CLR    　   SCL                     ;8位接收完置时钟线和数据线
CLR       　SDA
SETB        SDA                     ;接收非应答信号
SETB        SCL                     ;置时钟线为高使应答位有效
SETB        SDA
CLR       　SCL                     ;清时钟线以便发送停止条件
RET
;============================
;显示、键盘子程序
;===========================
END