You can now write your first truly embedded program. In a time-honored tradition, this program,
BlinkingLed, which is the embedded equivalent of
HelloWorld, makes an LED blink.
In Figure 2-1, the large box indicates a Netduino Plus, which has a blue LED—labeled LED on the board—that can be controlled from an application program. This LED is connected to a general-purpose input/output (GPIO) pin of the microcontroller. Most microcontrollers have a number of such GPIO pins, each of which can be configured as digital input or digital output. A digital output might be connected to an LED, as in our example; a digital input might be connected to a switch or button.
Figure 2-1. Architecture of BlinkingLed