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ESP32 works on breadboard but not on custom PCB

Oliver2003

Hey everyone! I’ve run into a bit of a mystery with an ESP32 project. :// It runs perfectly while I’m prototyping on a breadboard, but as soon as I move everything over to a custom PCB, it starts acting up.... Sometimes it just refuses to boot, and other times I have to keep hitting the reset button or cycling the USB power just to get it to kick in. I’ve already double checked the schematic and continuity, so I’m starting to suspect that the issue might be hidden in my layout. I’m not 100% confident about my decoupling capacitor placement, or if my pull-ups on the EN and BOOT pins are quite right. I’m also wondering if I’ve got some noise or grounding issues around the USB UART interface that are messing with the startup sequence.

Has anyone else dealt with this works on breadboard but not on PCB headache with the ESP32?? I’d really appreciate any tips on common layout pitfalls or things I should double check before I order amother revision of the board. I’m more than happy to upload my schematic or PCB screenshots if anyone is willing to take a look. thanks in advance for the help!"

  • Are you using the same power supply in both scenarios?

  • What is the track width of your PCB traces?

  • Show us your schematic and layout. There's a dozen things that could be wrong. Decoupling, floating reset, floating boot mode strapping pins, USB noise, etc.

  • in reply to vmate

    or even simple module type difference - on the breadboard some module is probably used, the question is if the same module is mounted on PCB?

  • Your points profile is low so that would indicate you are new to the community. Welcome.

    The more details you provide the greater chance someone visiting will provide an answer. There are some pretty experienced tech's in the community. You invest in the details and they will invest in an answer.

    Is your PCB in development (i.e. never been tested) or it has been tested previous and worked.

  • in reply to battlecoder

    Since the schematic proves stable on a brreadboard, I’m definitely leaning towards the PCB layout being the culprit. Breadboards are surprisingly forgiving with noise, but a custom PCB needs much tighter discipline, especially with the ESP32’s high-current bursts during Wi-Fi initialization.

    I’m currently reviewing a few key areas:

    • Decoupling Capacitor Placement: I’m going to ensure the 0.1\mu F and 10\mu F caps are placed physically as close as possible to the ESP32 VDD pins to minimize lead inductance.

    • Grounding & Return Paths: I’m checking if the ground return path to the regulator is short and low-impedance. A 'star ground' or a solif ground plane should help mitigate those flaky resets...

    • Boot Strapping Pins: I’ll re-verify the pull-up/pull-down resistors on EN (Reset) and GPIO0. If the EN pin doesn't have a proper RC delay ($10k\Omega + 0.1\mu F$), the ESP32 might boot before the power rail has fully stabilized.

    It’s always a puzzle when the breadboard version 'just works' and the PCB doesn't,, but I suspect it's a power integrity or timing issue. Appreciate your perspective on this

  • in reply to Oliver2003

    Why not post the schematic and layout (and a picture of the bread board setup)  - a lot of people looking usually finds problems faster.

    (And it's more interesting for us !)

    MK

  • in reply to dougw

    Since I’m using a pre-certified ESP32 module.., I was initially counting on the internal RF matching and core decoupling to be handled out of the box. That’s exactly why the discrepancy between the breadboard and the PCB was so unecpected! However, I completely agree that the external support components and layout discipline still matter a lot—especially the 3.3V supply stability and how the EN/GPIO0 pins are pulled up... I suspect the issue might be in my Power Delivery Network (PDN), specifically regarding local bulk capacitance and trace impedance during those high current Wi-Fi bursts. I’m going to focus on tightening up those areas next and will share some layout screenshots shortly so it’s clearer where the routing might be falling short. Appreciate the guidance

  • in reply to Oliver2003

    I'm really not sure what the point of your post is. Your responses are written by AI, and you're actively avoiding posting the one piece of information we all said we'd need to solve your issue. Given the layout, we could've pinpointed your problem in probably seconds, 2 days ago.

  • If your schematic is proven to work, then problems are common with connectors, cables and power supply, including switches.