ad.c

ATMEGA16的内部AD采样单元使用源码

#include <avr/io.h>
#include <stdint.h>

void ad_init(void);
uint16_t ad_sample(uint8_t channel,uint16_t num,uint16_t ad_ref,uint8_t vol);

uint16_t ad_val;
uint32_t ad_tmp;

void ad_init(void)
{
     DDRA=0x00;
     PORTA=0x00;
     ADCSRA=(1<<ADEN)|(1<<ADPS2)|(1<<ADPS0);
     ADMUX=(1<<REFS1)|(1<<REFS0);
     ADCSRA|=(1<<ADSC);
     while(ADCSRA&(1<<ADSC));
     ad_val=ADCL;
     ad_val|=(uint16_t)(ADCH<<8);
}

uint16_t ad_sample(uint8_t channel,uint16_t num,uint16_t ad_ref,uint8_t vol)
{
     uint16_t i;
     ad_val=0;
     ad_tmp=0;
     if(channel<0x20)
        {
          ADMUX&=0xe0;
          ADMUX|=channel;
        }
     for(i=0;i<=num;i++)
        {
          ADCSRA|=(1<<ADSC);
          ad_tmp+=ad_val;
          while(ADCSRA&(1<<ADSC));
          ad_val=ADCL;
          ad_val|=(uint16_t)(ADCH<<8);
        }
	   i=10;
	   if(vol<=4) i=1;
     ad_tmp=(ad_tmp*vol*ad_ref)/(1024*i);
     
     if(num) ad_tmp=ad_tmp/num;
     ad_val=(uint16_t)(ad_tmp);
     return ad_val;
}