LED格式化输出

操作小记

#include <reg52.h>
#include <stdio.h>
// LED显示0~9
code unsigned char ZiMu[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f};
// 显存
static unsigned char VideoRam[8];
unsigned char CurrentPos=0;

// 设置当前游标位置
void SetPos(unsigned char pos)
{
	CurrentPos=pos;
}

// reset
void Clear(void)
{
	unsigned char i;
	for(i=0;i<8;i++)
		VideoRam[i]=0x00;
	CurrentPos=0;
}

//显示字符
char ShowChar(unsigned char ch)
{
	if((ch>='0')&&(ch<='9'))
		VideoRam[CurrentPos++]=ZiMu[ch-0x30];
	else if(ch==' ')
		VideoRam[CurrentPos++]=0x00;
	else if(ch=='-')
		VideoRam[CurrentPos++]=0x40;
	else if(ch=='.')
		VideoRam[CurrentPos-1]+=0x80; 
	else if(CurrentPos>7)
		CurrentPos=0;

	return ch;
}

//初始化定时器
void InitTimer0(void)
{
	TMOD=0x21;//T1:mode 2,reload; T0:mode 1,16bit counter
	ET0=1;//enable T0 interrupt
	TL0=(65536-3000)%256;//3ms interrupt
	TH0=(65536-3000)/256;
	TR0=1;
	EA=1;
}

//扫描显示
static void ScanSeg(void)
{
	static unsigned char LedNum=7;
	P2=P2&0xe3|(LedNum<<2);
	P0=VideoRam[7-LedNum];
	if(LedNum>0)
		LedNum=	LedNum-1;
	else
		LedNum=7;
}

//定时器中断函数
void Timer0(void) interrupt 1
{
	TL0=(65536-3000)%256;//3ms interrupt
	TH0=(65536-3000)/256;
	ScanSeg();
}

//重写putchar()函数
char putchar(char ch)
{
	return ShowChar(ch);
}

void main(void)
{
	float f1=0.67;
	InitTimer0();

	SetPos(1);
	/*
	ShowChar('2');
	ShowChar('-');
	ShowChar(' ');
	ShowChar('3');
	ShowChar('.');
	ShowChar('4');
	*/
	//printf("%c",0x31); //00110001 -> 1+ 16+32 = 49 -->1
	printf("%5.3f", f1);
	while(1);
}

附录

格式化输出

%f: float
%lf: double
%ld: long int
%d: int
-------------
%.2lf: 保留两位小数
%5.3lf: 输出宽度为5位 保留3位小数