Analog Inputs
Unlike digital input pins which can only read high or low, analog pins can read a range of voltage levels. Micro-controllers based on 3.3V can read voltages anywhere between zero and 3.3V. In contrast to digital input pins that are 5V tolerant; the maximum applied voltage for analog input must not exceed 3.3V (for higher voltages a voltage divider or an op-amp circuit can be used).
Using a Light Sensor to Demonstrate Analog Input
This example uses a light sensor. Its output voltage varies with light intensity -- the darker the light the higher the voltage output. The following code requires the Microsoft.SPOT.Hardware assembly. Consult the Developers' Guide or the product manual for specific channels.
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
public class Program
{
public static void Main()
{
AnalogInput lightSensor = new AnalogInput((Cpu.AnalogChannel)Cpu.AnalogChannel.ANALOG_7);
double lightSensorReading = 0;
while (true)
{
lightSensorReading = lightSensor.Read();
Debug.Print(lightSensorReading.ToString());
Thread.Sleep(500);
}
}
}