The f32 is an ultra-compact ESP32 development board designed to mount directly behind a USB-C receptacle. The PCB measures just 9.85 mm x 8.45 mm. It's powered by the ESP32-C3FH4 microcontroller and was created primarily for research and as a bit of a stress test for the ESP32, since it intentionally ignores many standard design guidelines. There's only one exposed GPIO and it is connected to an onboard LED, so most of the development on here would be more catered for wifi/web. To test the f32 an example application was created that users can interact with. The application turns the f32 into a captive portal so when it's powered on it will show up as an open access point that the user can select from available WiFi networks. The user is then automatically sent to the f32's control page where they can interact with some of its basic functionality such as turning on an LED or scanning for surrounding WiFi networks. There's also an "About" page that provides a small overview of the device.

The PCB was designed using DipTrace and manufactured by PCBWay with a board thickness of 0.6mm, min hole size of 0.2mm, and min track/spacing of 4/4mil. At the time of making this it only cost $10.75 for 5 boards shipped! That still blows my mind. PCBWay does also offer assembly services, but I chose to assemble this at home and suffer a bit. This took a bit of trial and error with such small parts, but I decided the best way for me was to ditch the stencil and make flux my best friend.

Complete details with firmware files and steps to build one can be found on the f32 GitHub repo: https://github.com/PegorK/f32