大家好,请教一个问题,Aref使用的外部基准1.024v,取样通道是ADC1,取样电压为0.5v。但是无论取样电压怎么变化,ADC取样回来的值总是1023,请问问题可能出在哪?
unsigned int MCU_ADC_READ(unsigned char channel){
unsigned char Sample_avgCn;
unsigned int ret,tota=1;
ADMUX&=~((1<<MUX0)|(1<<MUX1)|(1<<MUX2)|(1<<MUX3));//Clear MUX bits
ADMUX|=channel;//MUX set
ADCSRA|=(1<<ADSC)|(1<<ADEN);//Start a conversion
while(ADCSRA&(1<<ADSC));//dump first result
ADCSRA|=(1<<ADEN);
for(Sample_avgCn=0;Sample_avgCn<8;Sample_avgCn++){//read 8 times
ADCSRA|=(1<<ADSC);
while(ADCSRA&(1<<ADSC));
ret=ADCL;
ret|=(unsigned int)(ADCH<<8);
tota+=ret;
}
ADCSRA = 0; //Turn OFF internal ADC
return tota>>3;//averaging by 8
}