addsub.c

单片机开发板源程序适合初学者 第二部分DA转换输出

/*实验名称：按加减键实现内部加减 0.01
  功能：数码显示0.20---2.00
  作者：http://www.mcuprog.com
        05-02-01
*/
#include <reg51.h>
//LCD的口线
sbit E=P2^2;
sbit RW=P2^1;
sbit RS=P2^0;	

unsigned char dpbl,ledbai,ledshi,ledge,keytime;
unsigned char bdata myflag;
sbit keybit = myflag^0;

void time0(void);
void keyscan(void);
void Delay(unsigned int t);
void SendCommandByte(unsigned char ch);
void SendDataByte(unsigned char ch);
void InitLcd(void);
void dispdpbl(void);

void main(void)
{
	InitLcd();
	myflag=0x00;
	dpbl=0;
	keytime=4;		//20MS扫一次按键
	SendCommandByte(0x80);
	Delay(2);
	SendDataByte('S');
	SendDataByte('U');
	SendDataByte('M');
	SendDataByte(':');
	TH0=0xee;		//定时5MS
	TL0=0x00;
	TMOD=0x01;
	TR0=1;
	IT0=1;
	IE=0x83;
	while(1)
	{}	
}	

void int0_1(void) interrupt 0
{
	dpbl++;				//每进一次下降沿中断，变量计数加1
}
void time0(void) interrupt 1
{
	TH0=0xee;
	TL0=0x00;
	if(keytime--==0)
	{keytime=0x04;P1=0xff;keyscan();
	ledbai=(dpbl/100)|0x30;
	ledshi=((dpbl%100)/10)|0x30;
	ledge=(dpbl%10)|0x30;
	dispdpbl();
	}
}  

void keyscan(void)
{
	if(P1==0xfe)
	{
		if(keybit==0)
		{keybit=1;dpbl=0;}
	}
	else
	{
		keybit=0;
	}
	P1=0xff;
}

void Delay(unsigned int t)   // delay 40us
{
 for(;t!=0;t--) ;
}
//=============================================
void SendCommandByte(unsigned char ch)
{
   RS=0;
   RW=0;
   P0=ch;
   E=1;
    Delay(1);
   E=0;
   Delay(100);  //delay 40us
}
//-------------------------------------------------------
void SendDataByte(unsigned char ch)
{  RS=1;
   RW=0;
   P0=ch;
   E=1;
       Delay(1);
   E=0;
   Delay(100); //delay 40us
}
//-------------------------------------------------
void InitLcd(void)
{SendCommandByte(0x30);
 SendCommandByte(0x30);
 SendCommandByte(0x30);
 SendCommandByte(0x38);	//设置工作方式
 SendCommandByte(0x0c); //显示状态设置
 SendCommandByte(0x01); //清屏
 SendCommandByte(0x06); //输入方式设置
}

void dispdpbl(void)
{
	SendCommandByte(0x85);
	SendDataByte(ledbai);
	SendDataByte(ledshi);
	SendDataByte(ledge);
	
}