adc.c

在winavr上调试的一个adc程序

/*
	主程序 
	adc.c
	硬件:avr-51
	时钟:内部4MHz
	ATmega16
	苏丹 2008－05－19
	studio4.13+winavr071221
    标度变换，1023对应2.49V
*/


#include <avr/io.h>
#include <util/delay.h>

#define uchar unsigned char
#define uint  unsigned int

static uint g_aAdValue[8];	//A/D转换缓冲区
static uchar g_aLed[4];

void IoInit(void)
{
   PORTA&=~_BV(PA0);        //初始化pa0
   DDRC=0xff;
   PORTC=0X00;
   DDRA=0xf0;
   PORTA=0xf0;
}

uint AdcConvert(void)
{
	uchar i;
	uint ret;
	uchar max_id,min_id,max_value,min_value;
	
	ADMUX=0xc0;//内部2.56V参考电压，0通道
	ADCSRA=_BV(ADEN);//使能ADC，单次转换模式
	
	//连续转换8次
	for(i=0;i<8;i++)
	{
		ADCSRA|=_BV(ADSC);
		_delay_us(60);
		while(ADCSRA&_BV(ADSC))
			_delay_us(60);
		ret=ADCL;
		ret|=(uint)(ADCH<<8);
		g_aAdValue[i]=ret;
	}
	ret=0;
	for(i=1;i<8;i++)
		ret+=g_aAdValue[i];
	
	//找到最大和最小值索引	
	ret/=7;
	max_id=min_id=1;
	max_value=min_value=0;
	for(i=1;i<8;i++)
	{
		if(g_aAdValue[i]>ret)
		{
			if(g_aAdValue[i]-ret>max_value)
			{
				max_value=g_aAdValue[i]-ret;
				max_id=i;
			}
		}
		else
		{
			if(ret-g_aAdValue[i]>min_value)
			{
				min_value=ret-g_aAdValue[i];
				min_id=i;
			}
		}
	}
	
	//去掉第一个和最大最小值后的平均值
	ret=0;
	for(i=1;i<8;i++)
	{
		if((i!=min_id)&&(i!=max_id))
			ret+=g_aAdValue[i];     
	}
	if(min_id!=max_id)
		ret/=5;
	else  
		ret/=6;

	ADCSRA=0;//关闭ADC
	
	return ret;
}

int Led_disp(void)
{
    uchar i;
    for(i=0;i<4;i++)
    {
       PORTC=g_aLed[i];
	   PORTA&=~(1<<(i+4));
       _delay_us(1000);
       PORTA=0xf0;
    }
return 0;
}
int NtoBCD(void)
{
    uchar g_aDisplayBuf[16]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};
    uint num;
	uchar aa,bb,cc;
	num=AdcConvert()*10/41;//1024对应2.49V
    aa=num/100;
	bb=(num%100)/10;
	cc=(num%100)%10;
	g_aLed[0]=0x80|g_aDisplayBuf[aa];
    g_aLed[1]=g_aDisplayBuf[bb];
    g_aLed[2]=g_aDisplayBuf[cc];
    g_aLed[3]=0x1c;//显示“v”
return 0;
}
int main(void)
{
    IoInit();
    while(1)
	{
	   NtoBCD(); 
	   Led_disp();
    }
	
}