//pcf8591实现一个电位器的ad转换,通过数码管显示;两个按键控制工作,停止;
遇到的问题是:可以正常开始工作,转动电位器就会偶然导致工作停止,即显示为0(我设置在停止时全显示0);
可以通过按开始键重新工作;
#include<reg52.h>
#include<intrins.h>
#define uchar unsigned char
#define uint unsigned int
uchar code duan[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,
0xbf,0x86,0xdb,0xcf,0xe6,0xed,0xfd,0x87,0xff,0xef};
uchar code we[]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf};
sbit wela=P2^7;
sbit dula=P2^6;
sbit sda=P2^0;
sbit scl=P2^1;
sbit key1=P3^6;
sbit key2=P3^7;
uint temp;
void delay(){;;}
void delayms(uint x)
{
uint i,j;
for(i=x;i>0;i--)
for(j=120;j>0;j--);
}
//数码管
void display(uchar pos,uchar dat)
{
P0=we[pos]; wela=1;wela=0;
P0=duan[dat];dula=1;dula=1;
delayms(5);
}
void display1(uint dat)
{
uchar a,b,c,d;
a=0;
b=dat/100;
c=dat%100/10;
d=dat%10;
display(0,a);
display(1,b+10);
display(2,c);
display(3,d);
}
//初始化
void init()
{
sda=1;delay();
scl=1;delay();
}
//iic
void start()
{
sda=1;delay();
scl=1;delay();
sda=0;delay();
}
void stop()
{
sda=0;delay();
scl=1;delay();
sda=1;delay();
}
void respons()
{
uchar i;
scl=1;delay();
while((sda==1)&&(i<250))i++;
scl=0;delay();
}
void writebyte(uchar dat)
{
uchar i,flag;
flag=dat;
for(i=0;i<8;i++)
{
flag<<=1;
scl=0;delay();
sda=CY;delay();
scl=1;delay();
}
scl=0;delay();
sda=1;delay();
}
uchar readbyte()
{
uchar i,dat;
scl=0;delay();
sda=1;delay();
for(i=0;i<8;i++)
{
scl=1;delay();
dat=(dat<<1)|sda;
scl=0;delay();
}
return dat;
}
//pcf8591
uchar adchange(uchar ctl)
{
uchar dat;
start();
writebyte(0x90);
respons();
writebyte(ctl);
respons();
start();
writebyte(0x91);
respons();
dat=readbyte();
stop();
return dat;
}
uchar keyscan()
{
uchar i;
if(key1==0)
{
delayms(10);
if(key1==0)
{
i=1;
while(!key1);
}
}
if(key2==0)
{
delayms(10);
if(key2==0)
{
i=2;
while(!key2);
}
}
return i;
}
void main()
{
uint m,b;
uchar flag=1;
init();
while(1)
{
if(flag==1)
{
b=(int)adchange(0x01);
m=b*100/51;
display1(m);
if(keyscan()==2)flag=2;
}
if(flag==2)
{
display1(0);
if(keyscan()==1)flag=1;
}
}
}
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