pcf8591 AD光敏电阻转换数码管只显示255 跟着视频写的 没有什么错误的地方呀 但是数码管就只是显示255
以下是代码段
#include <reg52.h>
#include <intrins.h>
#include <stdio.h>
#define uint unsigned int
#define uchar unsigned char
#define PCF8591ADDR 0x90
#define I2cWrite 0
#define I2cRead 1
sbit DU = P2^6;//数码管段选
sbit WE = P2^7;//数码管段选
sbit SCL = P2^1;
sbit SDA = P2^0;
uchar num;//数码管显示的值
bit AckFlag;
//共阴数码管段选表0-9
uchar code SMGduan[]= {0x3F, 0x06, 0x5B, 0x4F, 0x66, 0x6D, 0x7D, 0x07, 0x7F, 0x6F,};
//数码管位选码
uchar code SMGwei[] = {0xfe, 0xfd, 0xfb};
//三位共阴数码管动态显示
void display(uchar i)
{
static uchar wei;
P0 = 0XFF;//清除断码
WE = 1;//打开位选锁存器
P0 = SMGwei[wei];
WE = 0;//锁存位选数据
switch(wei)
{
case 0: DU = 1; P0 = SMGduan[i / 100]; DU = 0; break;
case 1: DU = 1; P0 = SMGduan[i % 100 / 10]; DU = 0; break;
case 2: DU = 1; P0 = SMGduan[i % 10]; DU = 0; break;
}
wei++;
if(wei == 3)
wei = 0;
}
//定时器0初始化
void timer0Init()
{
EA = 1; //打开总中断
ET0 = 1;//打开定时器0中断
TR0 = 1; //启动定时器0
TMOD |= 0X01; //定时器工作模式1，16位定时模式
TH0 = 0xED;
TL0 = 0xFF; //定时5ms
}
void delay(int z)
{
int x,y;
for (x = 114; x; x--)
{
for (y = z; y; y--);
}
}
/****************************************************
IIC通信代码
****************************************************/
void delay5us()
{
_nop_();
}
//I2c起始信号程序
void I2cStart()
{
SCL = 1;
SDA = 1;
delay5us();
SDA = 0;
delay5us();
}
//I2c终止信号程序
void I2cStop()
{
SCL = 0;
SDA = 0;
SCL = 1;
delay5us();
SDA = 1;
delay5us();
}
//I2c主机读从机应答
bit ReadACK()
{
SCL = 1;
delay5us();
if(SDA){ //NOACK
SCL = 0;
return(1);
}else{ //ACK
SCL = 0;
return(0);
}
}
//I2c主机发送应答
void SendACK(bit i )
{
SCL = 0;
if(i) SDA = 1;
else SDA = 0;
SCL = 1;
delay5us();
SCL = 0; //拉低时钟总线
SDA = 1; //释放数据总线
}
void I2cSendByte(uchar DAT)
{
uchar i;
for(i=0;i<8;i++){
SCL = 0;
if(DAT & 0x80)
SDA = 1;
else
SDA = 0;
SCL = 1;
DAT <<=1;
}
SCL = 0; //拉低时钟总线
SDA = 1; //释放数据总线
}
uchar I2cReadByte(){
uchar i,DAT;
for(i=0;i<8;i++){
DAT <<=1;
SCL = 0;
SCL = 1;
if(SDA)
DAT |= 0x01;
}
return (DAT);
}
uchar PCF8591Read(uchar ctrl)
{
uchar DAT;
I2cStart();
I2cSendByte(PCF8591ADDR + I2cWrite); //I2c发送一个字节
if(ReadACK())
AckFlag = 1; //NOACK
else
AckFlag = 0; //ACK
I2cSendByte(ctrl); //I2c发送一个字节
ReadACK();
I2cStart();
I2cSendByte(PCF8591ADDR + I2cRead); //I2c发送一个字节
if(ReadACK())
AckFlag = 1; //NOACK
else
AckFlag = 0; //ACK
DAT = I2cReadByte(); //读一字节
SendACK(1);
I2cStop();
return (DAT);
}
//void AT24c02Write(uchar ADDR,DAT)
//{
// I2cStart();
// I2cSendByte(PCF8591ADDR + I2cWrite); //I2c发送一个字节
// if(ReadACK())
// AckFlag = 1; //NOACK
// else
// AckFlag = 0; //ACK
// I2cSendByte(ADDR); //I2c发送一个字节
// if(ReadACK())
// AckFlag = 1; //NOACK
// else
// AckFlag = 0; //ACK
// I2cSendByte(DAT); //I2c发送一个字节
// if(ReadACK())
// AckFlag = 1; //NOACK
// else
// AckFlag = 0; //ACK
// I2cStop();
//}
void main()//main函数自身会循环
{
timer0Init();//定时器0初始化
while (1)
{
EA = 0; //屏蔽中断
num = PCF8591Read(0);
EA = 1; //开中断
delay(5);
}
}
//定时器0中断函数
void timer0() interrupt 1
{
TH0 = 0xED;
TL0 = 0xFF; //定时5ms
display(num); //数码管显示函数
}
