In this chapter we will be focusing on building a real-time physical computing system using BeagleBone board. We will be interfacing an LM35 temperature sensor module with BeagleBone Black in this chapter in order to understand how a sensor can be interfaced with BeagleBone board to make the system interact with the physical world. We will be getting ambient temperature as analog input readings from the physical world around the sensor, and coding the BeagleBone board to make the LEDs connected to the BeagleBone board to light it up in different colors, depending on the temperature levels measured by the sensor. So, by end of this chapter, you will have built an interactive physical computing system using BeagleBone board where it outputs LED indications based on the temperature measured. The contents of the chapter are divided into the following topics: