adc.c

Atmega168+HMC1052+OLED开发指南针

#include "common.h"

uint AdcConvert(void)
{
	uchar i,n;
	uint ret;
	uchar max_id,min_id,max_value,min_value;
	ADCSRA=(1<<ADEN)|(1<<ADPS1)|(0<<ADPS0);		//ADC enable, single convertion
	//convert 65 times
	for(i=0;i<65;i++)
	{
		ADCSRA|=_BV(ADSC);
		_delay_loop_1(10);
		//for(n=0;n<50;n++);
		while(ADCSRA&_BV(ADSC));
		_delay_loop_1(10);
		ret=ADCL;
		ret|=(uint)(ADCH<<8);
		g_aAdValue[i]=ret;
	}
	ret=0;
	for(i=1;i<65;i++)
		ret+=g_aAdValue[i];
	ret>>=6;
	//find the max and min mumber	
	//ret/=64;
	/*max_id=min_id=1;
	max_value=min_value=0;
	for(i=1;i<65;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;
			}
		}
	}
	//the average value except the first, max and min numbers.
	ret=0;
	for(i=1;i<65;i++)
	{
		if((i!=min_id)&&(i!=max_id))
			ret+=g_aAdValue[i];
	}
	if(min_id!=max_id)
		ret/=62;
	else
		ret/=63;*/
	ADCSRA=0;	//close the ADC
	return ret;
}