I grabbed the M5Stack Cardputer a couple weeks ago and had a few ideas kicking around for what to build and finally decided on this project. It’s a tiny $30 gadget, smaller than a deck of cards with a little display and an ESP32-S3 microcontroller inside. I wanted to see if I could turn it into a self-contained tool, something that didn’t need a laptop or a terminal running in the background and that’s how Wi-Fi Sentinel came together: a pocket-sized wireless scanner that powers on, scans nearby networks, and shows everything right on its own screen in real time.

No setup menus, no cables, nothing to launch on a computer. Just turn it on and watch networks pop up on a color-coded display: green for strong signals, yellow for medium ones and red for the faint signals. It’s simple, small and surprisingly capable for something that costs less than dinner.

I wanted this to be more hands-on than a typical script. The idea was to make it fully autonomous, keep the info easy to read on a tiny screen and squeeze as much as possible out of limited hardware. Along the way, I ended up learning a ton about IoT development, real-time automation, and how to get creative when resources are tight.

The Wi-Fi Sentinel runs on MicroPython using UIFlow2 APIs for the display and Wi-Fi scanning. The Cardputer ships with MicroPython firmware already baked in, so you can write Python code, drop it on the device, and it just runs — no compiling, no custom firmware needed. The code fires up the Wi-Fi module, scans for networks, shows each SSID with its signal strength and a color status, then refreshes automatically every few seconds. The whole thing fits in just a few dozen lines.

Right now, Wi-Fi Sentinel sticks to scanning and visualization, but there’s a lot of room to grow. It could log data for signal mapping, add timestamps and GPS for location tracking, or even throw alerts when unknown networks appear. What started as a small project has already sparked bigger ideas in security automation and portable systems.

The whole project is open source on GitHub for anyone curious about IoT hardware, MicroPython scripting, or real-time wireless analysis. It’s a tiny device with big ambitions and this is just the start.