void adc_init(void){
  ADCSRA |= ((1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0));  //16Mhz/128 = 125Khz the ADC reference clock
  ADMUX |= (1<<REFS0);              //Voltage reference from Avcc (5v)
  ADCSRA |= (1<<ADEN);              //Turn on ADC
  ADCSRA |= (1<<ADSC);              //Do an initial conversion because this one is the slowest and to ensure that everything is up and running
}

volatile uint16_t read_adc(uint8_t channel){
  ADCW = 0;
  ADMUX &= 0xF0;                    //Clear the older channel that was read
  ADMUX |= channel;                //Defines the new ADC channel to be read
  ADCSRA |= (1<<ADSC);                //Starts a new conversion
  while(ADCSRA & (1<<ADSC));            //Wait until the conversion is done
  return ADCW;                    //Returns the ADC value of the chosen channel
}