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Program won't run ESP32

Posted: Wed Jan 07, 2026 11:14 am
by delcari
I've designed a custom PCB for the ESP32-S3-WROOM module and am having issues running the program. I have successfully flashed the board multiple times with code variations and settings to identify what the issue truly is. I'm unable to receive serial output or even set one of the pins high. I have tested with a multimeter to verify, so I believe it is a boot issue.
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kicad_6SsOmCYFVg.png (96.18 KiB) Viewed 370 times
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kicad_nbLBROqtuY.png (49.87 KiB) Viewed 370 times
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I am a bit of an amateur in a bit of a rush, this is my first custom ESP32 PCB so please outline any obvious flaws or potential mistakes thanks :)

Re: Program won't run ESP32

Posted: Thu Jan 08, 2026 1:41 am
by Sprite
First of all: remove C13. That capacitor will lead to issues with the chip going into download mode on power-on.

Secondly, when you say you don't get serial output, what exactly are the symptoms?

Re: Program won't run ESP32

Posted: Thu Jan 08, 2026 9:28 am
by delcari
Sprite, thank you for your time and assistance, removal of that capacitor completely resolved all the problems I was having, it must've just been stuck in a download mode loop. May I ask the reason it did cycle with that capacitor in place? I'm very happy 😊

Re: Program won't run ESP32

Posted: Fri Jan 09, 2026 12:00 am
by Sprite
The issue is that if you power it on, the capacitor will be empty, and until the 10K resistor can fully charge it, the voltage level on it will read as '0' putting the chip into download mode.