Arduino Yún Sketch Programming - The Hands-on Arduino Yun Manual Lab - page 76

byte adc_value;
byte getADC (byte config)
{
Wire.beginTransmission(PCF8591);
Wire.write(config);
Wire.endTransmission();
Wire.requestFrom(( int ) PCF8591, 2 );
while (Wire.available())
{
adc_value = Wire.read(); //This needs two reads
to get the value.
adc_value = Wire.read();
}
return adc_value;
}
void setup ()
{
Serial.begin( 9600 );
Wire.begin();
Serial.println("ADC Test");
}
void loop ()
{
adc_value = getADC(PCF8591_ADC_CH0);
Serial.println("thermistor: ");
Serial.println(adc_value);
delay( 500 );
adc_value = getADC(PCF8591_ADC_CH1);
Serial.println("photo-voltaic cell: ");
Serial.println(adc_value);
delay( 500 );
adc_value = getADC(PCF8591_ADC_CH3);
Serial.println("potentiometer: ");
Serial.println(adc_value);