AD conversion module PCF8591 based on IIC bus

#include
#include
#define uint unsigned int
#define uchar unsigned char

#define addw 0x90
#define addr 0x91

sbit scl=P2^0;
sbit sda=P2^1;

sbit rs=P2^6;
sbit rw=P2^5;
sbit en=P2^7;

float Ch0value,Ch1value;

void delayms(int i) 
{ int x,y;
for (x=i;x>0;x--)
 for(y=110;y>0;y--); 
}

void usdelay() 
{
_nop_();_nop_();_nop_();
_nop_();_nop_();_nop_(); 
}

void start() //Start signal
{//When the clock line is at a high level, the data line changes from high to low, which is the start signal
sda=1;
usdelay();
scl=1;
usdelay();
sda=0; //The data line changes from high to low, which is the start signal
usdelay();
scl=0;
}

void stop() //End signal
{//When the clock line is at a high level, the data line changes from low to high, which is the end signal
sda=0;
usdelay();
scl=1;
usdelay();
sda=1;
usdelay();
sda=0; //This sentence is optional
scl=0; //This sentence is optional
}

void ack()//应答信号  
{ uchar i;
scl=1;
usdelay(); 
    while((sda==1)&&(i<200))i++;
scl=0;
    usdelay();
}

void Noack() //No response
{
sda=1; //When the clock line is high, the data line is high, which means no response
usdelay();
    scl=1;
usdelay();
scl=0;
    usdelay(); 
}

void send_byte(uchar dat)
{
uchar i;
for(i=0;i<8;i++)
  {   
   scl=0;
   usdelay();
   sda=(bit)(dat&0x80); //Data transmission is from high to low
   //(bit) is the forced conversion command, which changes the data into a one-bit database of either 0 or 1
   usdelay();
   scl=1;
   usdelay();
   dat<<=1;
   }
  scl=0;
  usdelay();
  sda=1;//Release the bus
  usdelay();
}

fly read_byte()
{

uchar i,k;
scl=0; 
usdelay();
sda=1; //Release bus
usdelay();
for(i=0;i<8;i++)
  {
   scl=1;
   usdelay();
   k=(k<<1)|sda;//Judge 8 times, shift 7 times
   scl=0;
   usdelay();   
  }
return k;
}
[page]

uchar read_adc(uchar channel)
{
  uchar temp;
  start();
  send_byte(addw);
  ack();
  send_byte(0x40|channel);
  ack();
  start();
  send_byte(addr);
  ack();
  temp=read_byte();
  Noack();
  stop();
  return temp;

}

void init()
{
  scl=1;
  sda=1;
}
 

/*********1602Program************************/

  void write_com(suchar com)
 {
  rs=0;
  rw=0;
  en=0;
  P0=com;
  delayms(2);
  en=1;
  delayms(2);
  en=0;
  }

void write_dat(uchar dat)
 {
  rs=1;
  rw=0;
  en=0;
  P0=dat;
  delayms(2);
  en=1;
  delayms(2);
  en=0;
  }

void zfc(uchar *p)
{
 while(*p!=0)
 write_dat(*p++);
}

void init_1602()
{
write_com(0x38);
  delayms(2);
write_com(0x0c);
 delayms(2);
write_com(0x06);
 delayms(2);
write_com(0x01);
write_com(0x80);
zfc("Channel 0 :");
write_com(0x80+0x40);
zfc("Channel 1 :");
}

void display()
{
uchar a0,a1,a2, b0,b1,b2;
a0=Ch0value*196/10000;
a1=Ch0value*196%10000/1000;
a2=Ch0value*196%1000/100;

b0=Ch1value*196/10000;
b1=Ch1value*196%10000/1000;
b2=Ch1value*196%1000/100;
write_com(0x80+11);
write_dat(0x30+a0);
write_dat('.');
write_dat(0x30+a1);
write_dat(0x30+a2);
write_dat('V');

write_com(0x80+0x40+11);
write_dat(0x30+b0);
write_dat('.');
write_dat(0x30+b1);
write_dat(0x30+b2);
write_dat('V');

}
void main()
{  
   init_1602();
   init();
    while(1)
{
 Ch0value=read_adc(0);
delayms(50);
Ch1value=read_adc(1);
delayms(50);
 display(); 
}
}