void adc_init(void)

{

   ADCSRA = 0x00;  //禁用ADC

   ADMUX = 0x03;

   ACSR = 0x80;    //禁用模擬比較器

   ADCSRB = 0x00;

   ADCSRA = 0x83;

}

uint read_adc(void)

{

   uint temp = 0;

   ADCSRA |= (1 << ADSC);   //使能AD轉(zhuǎn)換，第一次轉(zhuǎn)換，結(jié)果丟棄

   while((ADCSRA & (1 << ADIF)) == 0); //等待AD轉(zhuǎn)換結(jié)束

   ADCSRA |= (1 << ADIF); //ADIF寫1用來清除ADIF，規(guī)格書上要求的

   ADCSRA |= (1 << ADSC);   //使能AD轉(zhuǎn)換，第二次轉(zhuǎn)換，結(jié)果保留

   while((ADCSRA & (1 << ADIF)) == 0); //等待AD轉(zhuǎn)換結(jié)束

   ADCSRA |= (1 << ADIF);

   temp = ADCL;

   temp |= (int)(ADCH << 8);

   

   return temp;