/* 51系列單片機(jī)在使用時(shí)，有時(shí)需要模擬I2C總線， */
/* 這里舉出一個(gè)實(shí)例（讀寫串行EEPROM芯片at2402） */
/************************************************************************/
/* Name:AT24C02存儲(chǔ)器的讀寫程序,用到I2C總線,含相對(duì)獨(dú)立的I2C總線讀寫函數(shù) */
/* Language: C51單片機(jī)編程語言 */
/* Platform: Win98,Intel Celeron 433 Processor,偉福仿真器，仿真8751 */
/* Author: StephenZhu javasdk@163.com */
/* Date: 2003年5月21日,5月22日,5月29日 */
/* Version: 1.1.1 */
/* Others: None */
/************************************************************************/
#include<string.h>
#include<reg52.h>
#include<intrins.h>
#define DELAY_TIME 60 /*經(jīng)實(shí)驗(yàn)，不要小于50！否則可能造成時(shí)序混亂*/
#define TRUE 1
#define FALSE 0
sbit SCL=P1^7;/*假設(shè)由P1.7和P1.6控制*/
sbit SDA=P1^6;
/********** Function Definition 函數(shù)定義 ************/
void DELAY(unsigned int t) /*延時(shí)函數(shù)*/
{
while(t!=0)
t--;
}
void I2C_Start(void)
{
/*啟動(dòng)I2C總線的函數(shù)，當(dāng)SCL為高電平時(shí)使SDA產(chǎn)生一個(gè)負(fù)跳變*/
SDA=1;
SCL=1;
DELAY(DELAY_TIME);
SDA=0;
DELAY(DELAY_TIME);
SCL=0;
DELAY(DELAY_TIME);
}
void I2C_Stop(void)
{
/*終止I2C總線，當(dāng)SCL為高電平時(shí)使SDA產(chǎn)生一個(gè)正跳變*/
SDA=0;
SCL=1;
DELAY(DELAY_TIME);
SDA=1;
DELAY(DELAY_TIME);
SCL=0;
DELAY(DELAY_TIME);
}
void SEND_0(void) /* SEND ACK */
{
/*發(fā)送0，在SCL為高電平時(shí)使SDA信號(hào)為低*/
SDA=0;
SCL=1;
DELAY(DELAY_TIME);
SCL=0;
DELAY(DELAY_TIME);
}
void SEND_1(void)
{
/*發(fā)送1，在SCL為高電平時(shí)使SDA信號(hào)為高*/
SDA=1;
SCL=1;
DELAY(DELAY_TIME);
SCL=0;
DELAY(DELAY_TIME);
}
bit Check_Acknowledge(void)
{
/*發(fā)送完一個(gè)字節(jié)后檢驗(yàn)設(shè)備的應(yīng)答信號(hào)*/
SDA=1;
SCL=1;
DELAY(DELAY_TIME/2);
F0=SDA;
DELAY(DELAY_TIME/2);
SCL=0;
DELAY(DELAY_TIME);
if(F0==1)
return FALSE;
return TRUE;
}
void WriteI2CByte(char b)reentrant
{
/*向I2C總線寫一個(gè)字節(jié)*/
char i;
for(i=0;i<8;i++)
if((b<<i)&0x80)
SEND_1();
else
SEND_0();
}
char ReadI2CByte(void)reentrant
{
/*從I2C總線讀一個(gè)字節(jié)*/
char b=0,i;
for(i=0;i<8;i++)
{
SDA=1; /*釋放總線*/
SCL=1; /*接受數(shù)據(jù)*/
DELAY(10);
F0=SDA;
DELAY(10);
SCL=0;
if(F0==1)
{
b=b<<1;
b=b|0x01;
|
| | | | 作者： 瘋子海 2005-7-4 21:54 回復(fù)此發(fā)言 | |
|
| 2 | 【例程】51系列單片機(jī)模擬I2C總線 | | }
else
b=b<<1;
}
return b;
}
/**********以下為讀寫24c02的函數(shù)**********/
void Write_One_Byte(char addr,char thedata)
{
bit acktemp=1;
/*write a byte to mem*/
I2C_Start();
WriteI2CByte(0xa0);
acktemp=Check_Acknowledge();
WriteI2CByte(addr);/*address*/
acktemp=Check_Acknowledge();
WriteI2CByte(thedata);/*thedata*/
acktemp=Check_Acknowledge();
I2C_Stop();
}
void Write_A_Page(char *buffer,char addr)
{
bit acktemp=1;
bit wrtmp;
int i;
/*write a page to at24c02*/
I2C_Start();
WriteI2CByte(0xa0);
acktemp=Check_Acknowledge();
WriteI2CByte(addr);/*address*/
acktemp=Check_Acknowledge();
for(i=0;i<7;i++)
{
WriteI2CByte(buffer[i]);
if(!Check_Acknowledge())
{
I2C_Stop();
}
}
I2C_Stop();
}
char Read_One_Byte(char addr)
{ bit acktemp=1;
char mydata;
/*read a byte from mem*/
I2C_Start();
WriteI2CByte(0xa0);
acktemp=Check_Acknowledge();
WriteI2CByte(addr);/*address*/
acktemp=Check_Acknowledge();
I2C_Start();
WriteI2CByte(0xa1);
acktemp=Check_Acknowledge();
mydata=ReadI2CByte();
acktemp=Check_Acknowledge();
return mydata;
I2C_Stop();
}
void Read_N_Bytes(char *buffer,char n,char addr)
{
bit acktemp=1;
int i=0;
/*read 8 bytes from mem*/
I2C_Start();
WriteI2CByte(0xa0);
acktemp=Check_Acknowledge();
WriteI2CByte(addr);/*address*/
acktemp=Check_Acknowledge();
I2C_Start();
WriteI2CByte(0xa1);
acktemp=Check_Acknowledge();
for(i=0;i<n;i++)
{
buffer[i]=ReadI2CByte();
if(i!=n-1)
SEND_0(); /*發(fā)送應(yīng)答*/
else
SEND_1(); /*發(fā)送非應(yīng)答*/
}
I2C_Stop();
}
void main()
{
int i;
char mybyte;
char myarray[8];
char myarray2[8];
char rdarray[16];
for(i=0;i<8;i++)
{
myarray[i]=i;
myarray2[i]=i+0x08;
}
Write_One_Byte(0x20,0x28);
Write_A_Page(myarray,0x10);
Write_A_Page(myarray2,0x18);
mybyte=Read_One_Byte(0x20);
Read_N_Bytes(rdarray,16,0x10);
}
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66821730(技術(shù)支持)
