Notes on ESP32-C3 GPIO – Strapping Pins, Flash Pins, etc

ESP32-C3 is a tiny little chip, which makes every ESP32-C3 GPIO a very valuable resource for hardware designers.

I often design ESP32 based PCBs. ESP32-C3 based PCBs have picked up quite a bit of momentum lately. Instead of reading through the datasheet every time to figure out what GPIOs do what, here is my list of notes that I use to refer to when designing ESP32-C3 schematics. The official documentation contains a Hardware Reference section that can be useful for getting started.

As a general summary, the GPIOs on the ESP32-C3 can be summarized as follows:

• 10 GPIOs – completely flexible
• 2 GPIOs – used for RxD and TxD, may be re-used
• 7 GPIOs – shared with flash, 2 can be saved with DIO external flash, 1 more can be saved with external flash power
• 3 GPIOs – flexible but must be ‘high’ on reset because they are strapping pins