[嵌入式]51单片机入门（第六讲）

数字/模拟

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?A/D转换? ?模拟量转数字量

#include <reg52.h>
#include <intrins.h>
#define uchar unsigned char
#define uint unsigned int
sbit wela=P2^7;
sbit dula=P2^6;
sbit adwr=P3^6;
sbit adrd=P3^7;
uchar code table[]={
0x3f,0x06,0x5b,0x4f,
0x66,0x6d,0x7d,0x07,
0x7f,0x6f,0x77,0x7c,
0x39,0x5e,0x79,0x71};
void delay(uint z)
{
	uint x,y;
	for(x=z;x>0;x--)
		for(y=110;y>0;y--);
}
void display(uchar bai,uchar shi,uchar ge)
{
    dula=1;
		P0=table[bai];
		dula=0;
		P0=0xff;
		wela=1;
		P0=0x7e;
		wela=0;
		delay(5);

		dula=1;
		P0=table[shi];
		dula=0;
		P0=0xff;
		wela=1;
		P0=0x7d;
		wela=0;
		delay(5);

		dula=1;
		P0=table[ge];
		dula=0;
		P0=0xff;
		wela=1;
		P0=0x7b;
		wela=0;
		delay(5);
}

void main()
{
		uchar a,A1,A2,A3,adval;
		wela=1;
		P0=0x7f; //置CSAD为0，选通ADCS以后不必再管ADCS
	  wela=0;
	  while(1)
		{
			  adwr=1;
			  _nop_();
			  adwr=0;       //启动A/D转换
			  _nop_();
			  adwr=1;
			  for(a=10;a>0;a--)  
			  {
						display(A1,A2,A3);  //显示程序
			  }
				P1=0xff;   //读取P1口之前先给其全1
				adrd=1;     //选通ADCS
				_nop_();
				adrd=0;      //A/D读
				_nop_();
				adval=P1;   //A/D数据给P1口
				adrd=1;    
				A1=adval/100;
				A2=adval%100/10;
				A3=adval%10;
			
			  
		}
}

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之前显示函数里面 使用的 fe? fd? fb? ? 这里用7? 因为我们要同时保持cs端低电平

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?D/A数模转换

#include <reg52.h>
#define uchar unsigned char
#define uint unsigned int
sbit dula=P2^6;
sbit wela=P2^7;
sbit dawr=P3^6;
sbit dacs=P3^2;
sbit fm=P2^3;
void delay(uint z)
{
	uint x,y;
	for(x=z;x>0;x--)
		for(y=110;y>0;y--);
}

void main()
{
	  uchar val,flag;
	  wela=0;
	  dula=0;
	  dacs=0;
	  dawr=0;
	  P0=0;
	  while(1)
		{
				if(flag==0)
				{
					  val+=5;
					  P0=val;
					  if(val==255)
						{
							  flag=1;
							  fm=0;
							  delay(100);
							  fm=1;
						}
						delay(50);
				}else
				{
					  val-=5;
					  P0=val;
					  if(val==0)
						{
							  flag=0;
							  fm=0;
							  delay(100);
							  fm=1;
						}
						delay(50);
				}
		}
}