ESP32-S2 custom board troubel with serial bootloader

[feurer98]

I created my own board after making the prototype with an ESP-Wroom-32 NucleMCU.
I now decided to use the ESP32-S2 chip for the final board.
See the schematic:

ESP32-S2_V001.pdf

(68.24 KiB) Downloaded 299 times

Unfortunately, when I try to upload the code, it does not work. I have looked at the output of the ROM printing and got no better.
but I get the "ready" only after the upload error "invalid head of packet (0x50)" appears in the console.
ESP toll only reports a TIME OUT after 20-30 sec.

Code: Select all

\0\0\0\x01\x01
ready

Then in the other post I found a graph of IO0 and EN: ESP32.com Topic 8704
My understanding is the same as recorded on this graphic.
However, when measuring the node mcu I got other curves. (second graphic)
The third graph shows the course of IO0 and EN in my own print.


i see the difference between the pictures. but i don't know if which one is the right one. mine definitely isn't.
what is the mistake i made?

ESP32-Wroom.png (24.54 KiB) Viewed 4110 times

ESP32-S2.png (27.79 KiB) Viewed 4110 times

[ESP_Sprite]

The trick with getting into bootloader mode is that the IO0 pin needs to be low when (actually, ever so slightly after) EN goes high. Your trace certainly does not show that. I'm decently sure it's because the part of your trace when IO0 is 3.0V, it's actually supposed to be grounded all the way... possibly some analog-y issue with your reset circuit? You could try replacing R15/R16 with 1K instead of the 10K that is there now, perhaps your transistors aren't fully conducting with 10Ks on the base.

[Chevelle]

The documentation isn't all that obvious but careful attention needs to be paid to the state of the strapping pins. I looks like both GPIO45 and GPIO46 should be low for boot loading. Give that a try.