main.c

单片机源代码

/*
	Mega8 查询方式 A/D转换测试程序
	main.c
	MCU:atmega8
	编译：WinAVR-20040720
	
	
	芯艺 2004-09-19
*/

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

#define uchar unsigned char
#define uint  unsigned int

static uint g_aAdValue[8];	//A/D转换缓冲区

void IoInit(void);


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_loop_1(60);
		while(ADCSRA&_BV(ADSC))
			_delay_loop_1(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 main(void)
{
	uchar i;
	IoInit();
	
	while(1)
	{
		scanf("%c",&i);
		if(i=='c')
			printf("%d\n",AdcConvert());
	}
}