void config_adc() { ADMUX = 0; /* AVCC with external capacitor at AREF pin */ ADMUX |= (1 << REFS0); ADCSRA = 0; // Set the ADC prescaler to 128 for a 16MHz clock, giving an ADC clock of 125kHz ADCSRA |= (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); } void init_adc() { ADCSRA |= (1 << ADEN); // Enable ADC ADCSRA |= (1 << ADIE); // Enable ADC interrupts }