Previously, I shared two articles demonstrating how to build a Raspberry Pi barcode scanner in C/C++ with Dynamsoft Barcode Reader SDK, and how to optimize the code with thread. The hardware I used only includes Raspberry Pi 2 and Webcam. Now it is time to have fun with GPIO (General-purpose input/output). Assume you want to get rid of the display screen for making a robot with power bank, wheel, and webcam. And you need to use some indicators to monitor the status of barcode recognition. How to make it with GPIO pins and other peripherals?