How to connect USB and PS/2 Keyboards to ESP32 with Rust no_std and std

Have you ever wondered how to connect a PC keyboard to your ESP32 for innovative projects? Whether it’s an old PS/2 keyboard or a modern USB one, this article will show you how to integrate these input devices with your ESP32, using the versatile and powerful Rust programming language. The first part of the article describes Rust no_std solution. Rust std for USB solution is at the end of the article.

Preparing the ESP32-C3

First, let’s tackle the wiring for the ESP32-C3. Detailed in bjoernQ’s GitHub repository, “ps2keyboard-esp32c3”, this setup requires three resistors and is perfectly illustrated in the “Circuit” section. For a reliable and efficient connection, consider the wire-wrap technique recommended by Andreas Spiess in his enlightening video, “#243 Better than Dupont Wires: Wire Wrapping for our Projects”.

For the PS/2 connector, refer to the detailed pinout available in the Wikipedia article, “PS/2 port”, particularly the pinout diagram for the female connector (PS/2 port pinout diagram). Please, keep in mind that the pinout is for the female connector from the front side. For the male connector or the back side of the female connector you need to flip the image.

For USB keyboart you’ll need a USB keyboards support a COMBO PS/2 support (still available in many USB keyboards, allowing them to function as PS/2 devices). You can connect these USB keyboards directly by following the schematics from the Instructables project, “USB to PS/2 Convertor” with “ps2keyboard-esp32c3 schematics”,. Specifically, use this wiring diagram (USB to PS/2 wiring diagram) to integrate into the ESP32-C3 setup. No code changes are needed for this part.

Flashing the ESP32-C3

After setting up the hardware, it’s time to program the ESP32-C3. The software part is handled using the pc-keyboard crate, developed by thejpster’s. Flash your ESP32-C3 with the cargo espflash --release command, and watch as keyboard inputs appear on your console.

Interesting Project Ideas

Now that you have your keyboard connected to the ESP32. Here are some project ideas to get you started:

  • Smart Home Controller: Use the keyboard to control lights, temperature, or other IoT devices in your home.
  • Custom Game Controller: Create a gaming experience by mapping keyboard keys to game controls.
  • Educational Tool: Teach programming or robotics, using the keyboard as an input device for experiments and projects.
  • Artistic Installations: Incorporate the keyboard into interactive art projects or music synthesizers.

Rust std + ESP-IDF with USB support

The text above describes Rust no_std solution. If you’re using Rust std on top of ESP-IDF, you can use direct USB support on ESP32-S3 with USB HID for mouse and keyboard Board Support Package (BSP).