#include<reg52.h
#include<pcf8591.h>
#define uchar unsigned char
#define uint unsigned int
sbit SCL=P1^7;
sbit SDA=P1^2;
void Delay_4us(void)
{
volatile uchar i=0;
i++,i++,i++,i++,i++,i++,i++,i++;
}
void I2c_Start(void)
{
SDA=1;
Delay_4us();
SCL=1;
Delay_4us();
SDA=0;
Delay_4us();
SCL=0;
Delay_4us();
}
void I2c_Stop(void)
{
SCL=0;
Delay_4us();
SDA=0;
Delay_4us();
SCL=1;
Delay_4us();
SDA=1;
Delay_4us();
}
unsigned char Rcv_Byte(void)
{
unsigned char i,rbyte=0;
for(i=8;i;i--)
{
SCL=1;
Delay_4us();
rbyte=rbyte<<1;
rbyte=rbyte|(SDA);
SCL=0;
}
return rbyte;
}
{
unsigned char i;
for(i=8;i;i--)
{
SDA=(bit)(dat&0x80);
Delay_4us();
SCL=1;
Delay_4us();
SCL=0;
Delay_4us();
dat=dat<<1;
}
}
void I2c_Ack(bit a)
{
SDA=a;
Delay_4us();
SCL=1;
Delay_4us();
SCL=0;
Delay_4us();
SDA=1;
Delay_4us();
}bit Test_Ack(void)
{
bit ack;
SDA=1;
Delay_4us();
SCL=1;
Delay_4us();
ack=SDA;
Delay_4us();
SCL=0;
return ack;
}
bit DAC(unsigned char addr,unsigned char Val)
{
I2c_Start();
Send_Byte(0x90|(addr<<1
if(Test_Ack())return(0);
Send_Byte(0x40);
if(Test_Ack())return(0);
Send_Byte(Val);
if(Test_Ack())return(0);
I2c_Stop();
}
unsigned char ADC(unsigned char addr,unsigned char channel)
{
unsigned char dat=0;
EA=0;
I2c_Start();
Send_Byte(0x90|(addr<<1)|0);
if(Test_Ack())return(0);
Send_Byte(channel);
if(Test_Ack())return(0);
I2c_Stop();
Delay_4us();
I2c_Start();
Send_Byte(0x90|(addr<<1)|1);
if(Test_Ack())return(0);
dat=Rcv_Byte();
I2c_Ack(1);
I2c_Stop();
EA=1;
return(dat);
}
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