Don’t Confuse CND and GND on ESP32 Boards

Lately, I’m finally making the move from ESP8266 to ESP32. I resisted it for a while because ESP32 development boards are bigger and more expensive than those for the ’8266, like my long-loved Wemos Mini D1. But a cheap ESP32 board that I used had an obnoxious design quirk.

I was trying to tap 5V¹ from the V_in pin and the adjacent ground pin, but when I did, the board would fail to boot. I couldn’t understand why; I double-checked the pin labels and was sure my connections were in the right spot.

Turns out, what I thought was the ground pin wasn’t labelled GND — it was labelled CND. It’s an SPI pin, one that apparently will interfere with booting.

I have no clue why it’s labelled CND and not CMD (or just SPS). “C” and “G” look way too similar in silkscreen print, and apparently some boards have it straight-up mislabelled as ground. To make it worse, most other boards get this pin layout “right” — GND is adjacent to 5V near the input. I’ll shell out for a better board this time around.