In this chapter, we got our I2C-based port expander configured and working, and we experimented with it by connecting a magnetic sensor—one of the most commonly used sensors in security systems. We've also learned how to interact with I2C devices using Bash scripts, and how to read and write data to and from these devices.
In addition, we should now be beginning to understand the various elements and building blocks of a security system, including anti-tamper loops and zones. These are concepts that will prepare us for later on in the book, when we start to piece all of this together and build our final, all-encompassing system.
In the next chapter, we will look at passive infra-red motion detectors, how they work, and how we can connect the wired and wireless types to our home security system. We'll also learn how to create log files based on events using Bash scripts so that we can maintain a history of detector states as they change.
