Getting Started with Netduino

Analog Inputs

You have learned how to sense the value of a digital input (with a state of true or false). That works great for pushbuttons and open/close sensors, but the world is full of in-between values.

To measure real-world values like temperature, humidity, light levels, or the position of a knob, you need an analog input. With Netduino, analog sensors output a voltage from 0V to 3.3V. The Netduino’s analog inputs translate these voltages into a range of values (typically 0 through 1023). Using analog inputs, you can discern a temperature value in degrees, the volume you should play music at, or even particular shades of color.

Measuring Voltage

The MakerShield has an integrated potentiometer (like a volume knob). A potentiometer has three pins: one for an input voltage (such as 3.3V), another for ground (0V), and one that is connected to the wiper inside the potentiometer. You connect one of the Netduino’s analog pins to the wiper. When the potentiometer’s knob is turned, the output voltage varies (from 0V at one side, 1.65V in the middle, and 3.3V turned all the way). The changes are linear; as a result, you can measure the position of the knob based on its output voltage.

You can read this voltage in your Netduino app and change program behavior based on its value. In this section, you’ll build an app to read the analog values, and then you’ll change the blinking speed of one of the MakerShield’s LEDs to follow the potentiometer’s position.

First, write the code. Create a new ...