Code to convert ADC readings to actual Voltage.

ADCtoVoltage.device.nut

function getPin9Voltage() 
{
    // Returns value in volts, between 0.0 and 3.3

    local voltage = hardware.voltage();
    local reading = hardware.pin9.read();
    return (reading / 65535.0) * voltage;
}

function sample()
{
    server.log("The voltage on Pin 9 is:" + getPin9Voltage());
    imp.wakeup(1.0, sample);
}

// Set up imp Pin 9 as an analog input

hardware.pin9.configure(ANALOG_IN);

// Start sampling the voltage on Pin 9

sample();