#Microcontroller# Using pcf8591 to read the voltage value of the potentiometer-EEWORLD

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#include

sbit sda=P2^0;

sbit scl=P2^1;

#define uint unsigned int

#define uchar unsigned char

uchar code table[] ={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xbf,0x40};

//Display codes of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, b, C, d, E, F

//--Define the read and write address of PCF8591--//

#define WRITEADDR 0x90 //write address

#define READADDR 0x91 //read address

void delayms(uint z)

{

int x,y;

for(x=z;x>0;x--)

for(y=110;y>0;y--);

}

void delay()

{ ;; }

void start()

{

sda=1;

delay();

scl=1;

delay();

sda=0;

delay();

}

void stop()

{

sda=0;

delay();

scl=1;

delay();

sda=1;

delay();

}

void respons() //response

{

flying i;

scl=1;

delay();

while((sda==1)&&(i<250))i ;

scl=0;

delay();

}

void write_byte(uchar date)

{

flying i,temp;

temp=date;

for(i=0;i<8;i )

{

temp=temp<<1;

scl=0;

delay();

sda=CY;

delay();

scl=1;

delay();

}

scl=0;

delay();

sda=1;

delay();

}

fly read_byte()

{

flying i,k;

scl=0;

delay();

sda=1;

delay();

for(i=0;i<8;i )

{

scl=1;

delay();

k=(k<<1)|sda;

scl=0;

delay();

}

return k;

}

flying ADC_PCF8591_rd_(flying channel)

{

flying date;

start();

write_byte(0x90);

response();

write_byte(channal);

response();

start();

write_byte(0x91);

response();

date=read_byte();

stop();

return date;

}

void ADC_PCF8591_wt_(uchar date)

{

start();

write_byte(0x90);

response();

write_byte(0x40);

response();

write_byte(date);

response();

stop();

}

//Note: Select AD or DA in the main function and process it

void display(uchar i)

{

float a; int j;

a=i;

a=a*500/256;

j=a;

P2=0xfd;

P0=0xff;

P0=~table[j/100]&0x7f;

delayms(5);

P2=0xfb;

P0=0xff;

P0=~table[j0/10];

delayms(5);

P2=0xf7;

P0=0xff;

P0=~table[j];

delayms(5);

}

void main()

{

uint temp;

sda=1;

delay();

scl=1;

delay();

while(1)

{

temp=ADC_PCF8591_rd_(0x00);

display(temp);

}

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