ESP32 Forum

Hi,

I just found this forum, after I made my PCB, I wish I'd seen it sooner

With esptool I get the error 'Timed out waiting for packet header' when trying to connect.

I've attached a schematic and pcb photo, I have since added a 10K pull up resistor on GPIO0 to 3.3V, so that the correct logic levels appear to be generated for GPIO0 and EN.

I note:
The tx pin of the esp32 seems to always remain = 3.3V
vdd_sdio pin of the esp32 seems to remain = 0V (which I believe means it's not booting?)

Any advice would be much appreciated!

Thanks!

I can't see anything off in the schematic, and vdd_sio being low indeed indicates problems. Can you see if your oscillator is doing anything?

Thanks a lot for your reply.

I just measured the xtal pins and there definitely seems something weird.

I've not tried to measure an xtal frequency before, but hopefully I've done this correctly, I set AC coupling, and measured pin 3.

This should be the xtal which has been placed - https://www.mouser.co.uk/ProductDetail/ ... daPXWePw==

Pin 1 appeared to be GND level as far as I can tell
Pin 3 seemed to have oscillation, but at ~3MHz, which seems very odd, it also doesn't look like a sine wave.

That looks like something is not working indeed; you'd expect a 40MHz sine wave of some sorts. Either the ESP32 is somehow not enabling the clock oscillator (which would happen if e.g. chip_pu is low) or the crystal is broken somehow. Suggest you look at that bit of the PCB for shorts or breaks as a first thing; maybe replace the crystal or try to inject a clock signal directly if that does not lead to anything.