In this chapter, we went deep into the hardware of our Pi. You learned about the GPIO pin configuration and took a detailed look at how they work in the Read mode as well as the Write mode. Next, we went on to learn how to fine-tune our control over the GPIO pins using the gpio command-line utility.

Finally, we looked at the DHT11 sensor to measure temperature and humidity. We used a supporting C library so that our node code could interface with the sensor and finally wrote a program in JavaScript that printed the temperature and humidity readings to the console.

Our Raspberry Pi now has some sensory capability and has the data it needs to be an IoT device. In the next chapter, you will learn how to expose our sensor readings to the public by integrating with the node server we built in the previous chapter.