esp32-d0wd pcb, can't connect with esptool

anfractuosity
Posts: 4
Joined: Sat Jun 13, 2020 6:57 pm

esp32-d0wd pcb, can't connect with esptool

Postby anfractuosity » Sat Jun 13, 2020 7:07 pm

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!
Attachments
pcb_.jpg
pcb_.jpg (818.83 KiB) Viewed 480 times
schem.png
schem.png (502.95 KiB) Viewed 480 times

ESP_Sprite
Posts: 3937
Joined: Thu Nov 26, 2015 4:08 am

Re: esp32-d0wd pcb, can't connect with esptool

Postby ESP_Sprite » Sun Jun 14, 2020 8:30 am

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?

anfractuosity
Posts: 4
Joined: Sat Jun 13, 2020 6:57 pm

Re: esp32-d0wd pcb, can't connect with esptool

Postby anfractuosity » Sun Jun 14, 2020 12:19 pm

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.
Attachments
scope.jpg
scope.jpg (392.32 KiB) Viewed 422 times

ESP_Sprite
Posts: 3937
Joined: Thu Nov 26, 2015 4:08 am

Re: esp32-d0wd pcb, can't connect with esptool

Postby ESP_Sprite » Mon Jun 15, 2020 10:34 am

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.

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