Chapter 3. Blinking External LEDs

In the previous chapter we programmed onboard LEDs on BeagleBone using BoneScript APIs. As BeagleBone is an embedded device, it can be used in an environment where a keyboard, mouse and monitor might not be available. Rather, most of the times embedded boards do not have these devices. Typical input and output components of embedded boards are LEDs and push-buttons. LEDs can be used as the output device to represent information, for example the board may turn an LED on when there is high system load and turn it off when the system load is low. So, by looking at LEDs we get information about if the system is under high load or not. That is why it is important to program LEDs on BeagleBone so that we can send information as output via LEDs where the monitor is absent. In this chapter, we will continue to program LEDs. We will connect external LEDs and blink them using our BoneScript program. To achieve this, we need to learn about GPIO on BeagleBone.

Here are the topics that will be covered in this chapter:

• What is GPIO?
• BeagleBone GPIO map
• Blinking external LED circuit setup
• Program to blink external LED
• Dancing external LEDs circuit setup
• Program to dance external LEDs