We already learned about a traffic light controller. The chapter introduced a road intersection module at the start. A channel relay module is introduced in order to work with AC or high-voltage lamps. We also learned how to expand our Raspberry Pi GPIO. After this, we built a traffic light controller for four road intersections. In the last section, we tried to cascade our traffic controller by connecting several IC MCP23017.
In the next chapter, we will learn to control sensor or actuator devices via Bluetooth from a Raspberry Pi board.
