/********************
A/D D/A之間轉(zhuǎn)換
********************/
#include<reg52.h>
#define uint unsigned int
#define uchar unsigned char
#define PCF8591 0x90//PCF8591的地址
sbit sda=P2^0;
sbit scl=P2^1;
sbit LS138A=P2^2;//138譯碼器的3位 控制數(shù)碼管的
sbit LS138B=P2^3;
sbit LS138C=P2^4;
uint Ledout[8];//8位數(shù)碼管
uchar AD_change;
uint num0,num1,num2,num3;
uint count;
uchar code table[]={
0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f};//段選
void delay()//執(zhí)行空語(yǔ)句，微秒級(jí)延時(shí)函數(shù)
{;;}
void delay1ms(uint z)//延時(shí)1ms
{
uint x,y;
for(x=z;x>0;x--)
{
for(y=0;y<=110;y++)
{
}
}
}
void init()//初始化狀態(tài)下SCL和SDA都為高電平
{
scl=1;
delay();
sda=1;
delay();
}
void start()//在SCL為高電平時(shí)SDA由高電平到低電平
{
sda=1;
delay();
scl=1;
delay();
sda=0;
}
void respons()
/*
應(yīng)答信號(hào),SCL在高電平期間，SDA被從設(shè)備拉為低電平表示應(yīng)答。
（sda==1）和i<255相與，表示若在一段時(shí)間內(nèi)沒(méi)有從器件的應(yīng)答則主器件
默認(rèn)從器件已經(jīng)收到數(shù)據(jù)而不再等待應(yīng)答信號(hào)
*/
{
uchar i;
scl=1;
delay();
while((sda==1)&&(i<250))
{
i++;
}
scl=0;
delay();
}
void stop()//SCL在高電平期間，SDA一個(gè)上升沿停止信號(hào)
{
sda=0;
delay();
scl=1;
delay();
sda=1;
}
void write_byte(uchar date)//寫(xiě)一個(gè)字節(jié)
{
uchar i,temp;
temp=date;
for(i=0;i<8;i++)
{
temp=temp<<1;
scl=0;//只有在SCL為0期間才允許SDA數(shù)據(jù)線(xiàn)上的狀態(tài)才允許變化
delay();
sda=CY;//PSW的寄存器的CY進(jìn)位標(biāo)志位
delay();
scl=1; //SCL時(shí)鐘信號(hào)為高電平期間數(shù)據(jù)線(xiàn)上的數(shù)據(jù)必須保持穩(wěn)定 delay();
delay();
}
scl=0;
delay();
sda=1;//釋放總線(xiàn)
delay();
}
uchar read_byte()
{
uchar i,k;
scl=0;
delay();
sda=1;//釋放總線(xiàn)
delay();
for(i=0;i<8;i++)
{
scl=1;
delay();
k=(k<<1)|sda;
scl=0;
delay();
}
//delay();here is a bug
return k;
}
void write_address(uchar address,uchar date)
{
start();
write_byte(0x90);
respons();
write_byte(address);
respons();
write_byte(date);
respons();
stop();
}
uchar read_address(uchar address)
{
uchar date;
start();
write_byte(0x90); //10010000 前四位固定 接下來(lái)三位全部被接地了 所以都是0 最后一位是寫(xiě) 所以為低電平
respons();
write_byte(address);
respons();
start();
write_byte(0x91);
respons();
date=read_byte();
stop();
return date;
}
void display()
{
uchar i;
Ledout[0]=table[num0%10000/1000];
Ledout[1]=table[num0%1000/100];
Ledout[2]=table[num0%100/10];
Ledout[3]=table[num0%10];
Ledout[4]=table[num1%10000/1000];
Ledout[5]=table[num1%1000/100];
Ledout[6]=table[num1%100/10];
Ledout[7]=table[num1%10];
for(i=0;i<8;i++)
{
P0=Ledout[i];
switch(i)
{
case 0:LS138A=0; LS138B=0; LS138C=0; break;
case 1:LS138A=1; LS138B=0; LS138C=0; break;
case 2:LS138A=0; LS138B=1; LS138C=0; break;
case 3:LS138A=1; LS138B=1; LS138C=0; break;
case 4:LS138A=0; LS138B=0; LS138C=1; break;
case 5:LS138A=1; LS138B=0; LS138C=1; break;
case 6:LS138A=0; LS138B=1; LS138C=1; break;
case 7:LS138A=1; LS138B=1; LS138C=1; break;
}
delay1ms(2);
}
P0=0x00;
}
void main()
{
init();
AD_change=0;
while(1)
{
switch(AD_change)
{
case 0:num0=read_address(0x41);
break;
case 1:num1=read_address(0x42);
break;
case 2:num2=read_address(0x43);
break;
case 3:num3=read_address(0x40);
break;
case 4:write_address(0x40,num1);
break;
}
if(++AD_change>4)
{
AD_change=0;
}
display();
}
}