[SOLVED] Flash ESP32 WROOM32E on custom PCB

[doglike]

Hi,

I have a custom PCB with a ESP32 WROOM32E module and cannot flash it.

GPIO1 (=Tx) is connected to Rx of CP2102.
GPIO3 (=Rx) is connected to Tx of CP2102.
...and I can see the boot messages...

EN and GPIO0 have pullups.
I pull both LOW, keep GPIO0 LOW and switch EN to HIGH.
--> jumps in download mode

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rst:0x1 (POWERON_RESET), boot:0x5 (DOWNLOAD_BOOT(UART0/UART1/SDIO_FEI_REQ_V2))
waiting for download

2021-03-03_21h09_54.jpg (14.36 KiB) Viewed 4538 times

Then:

Code: Select all

make flash

2021-03-03_22h59_16.jpg (14.28 KiB) Viewed 4538 times

It tries to connect "forever" and then throws a timeout error.

Someone an idea ?

Thanks in advance!



EDIT:
Regarding https://github.com/espressif/esptool/wi ... -Selection
GPIO2, 12, 15 have all pulldowns

[ESP_Minatel]

Hi,

Have you checked the soldering and the signals using an oscilloscope? Is the CP2102 integrated in your PCB design?

[doglike]

Hi,

not measured with oscilloscope, yet, but I rudimentally checked the soldering for shorts etc., but the electrical continuity is fine.

The CP2102 is on an external "flasher" and not part of the PCB. I also tried 3 different CP2102-flashers.
I use only Tx and Rx lines of the CP2102 and I just realized, that the Tx/Rx wires from CP2102--->PCB are about 20-30cm.
Is it possible that the communication is disturbed by interference caused by the long wires ?

I am just wondering, why the boot messages are visible, if there should be any electrical error... ??

Thanks

[ESP_Minatel]

Hi,

Can you try adding a capacitor (100nF to 4.7uF) on the EN pin to GND? Maybe you have some issues on the EN timing on your setup.
It will help if you can share part of your schematic.

[doglike]

EDIT: Solved
I didn't connected the GND of the PCB with the GND of the flasher.

[ESP_Minatel]

Thanks for your feedback!