Charles Giguere's GPIOViewer Library Gives You "X-Ray Vision" Into Espressif ESP32-Based Projects

Maker Charles Giguere has designed a tool which aims to make it easier to troubleshoot projects built around Espressif ESP32 microcontrollers: an on-device web page providing live readouts of each pin on the board — in a 50kB Arduino library.

"It's like having X-ray vision," Giguere claims of his creation, "and if you're, like me, facing challenges in your microcontroller project, sometimes feeling overwhelmed, this tool is a game changer you don't want to miss. I developed it for my own use, but now I'm thrilled to share it with you as an easy to use library."

The tool in question is the GPIOViewer, an Arduino library which installs on an Espressif ESP32-based development board and provides an on-device web server accessible from any browser. Once accessed, the tool displays an image of the board in use — along with the status of every general-purpose input/output (GPIO) pin.

"The GPIOViewer [library] saves time and eliminates the guesswork," Giguere claims, "helping you to focus on the creative aspects of your project. Once the GPIOViewer finishes its initialization it will print a URL in the serial monitor: this is your golden ticket. Copy that URL, paste it in your your browser, and voila: you're now watching the live action of your pins on your screen. Any device with a browser can become your GPIO monitoring station."

In its current release, the GPIOViewer library adds 50kB to a project — saving space by pulling down the required board imagery from a remote server rather than storing it locally. So far, the library supports 19 ESP32-based development boards, ranging from the compact Seeed Studio XIAO ESP32-C3 to the Espressif ESP32-VROOM-32D 38-pin variant — with a "generic view" if your particular model isn't yet supported.

The GPIOViewer library is available, with full source code, on the project's GitHub repository, under the permissive MIT license; a video demo is available on YouTube.