[ESP32-S2] Using USB and an external PSU at the same time?

[jgalt91]

Hi,
I have an ESP32-S2 Saola dev board and I need to upload the sketches/code through USB, as I need the ADCs (so can't enable Wifi to do OTA updates). I also have multiple leds that require external PSU, so I will have a power supply providing power to all the circuit and to the ESP32-S2 aswell (5V through the 5V pin).

My plan is to cut the 5V lane of a USB cable (so only D+, D-, GND) to send the code while being powered by the PSU throught the 5V pin. Will that work or I need to program it through RX and TX pins with a USB to Serial TTL converter (not using the 5V lane, only data and ground)?

Thanks in advance

[ESP_Sprite]

Looking at the schematics, you might actually be able to get away without a cut USB cable. There's a Schottky diode between the 5V and USB 5V lines, so there's no possibility of backfeeding the USB line. You do need to be careful that the board will present 5V to your power supply when it is off and USB is plugged in; you could use a second Shottky diode to stop that from happening if you're unsure if this is OK.

[jgalt91]

Great thanks for clarifying.