ESP32 WROOM 32 halts booting process

[zapp123]

Hi there.

I think i have a bit of a strange issue and i cannot for the life of me figure out the cause.

I have created a PCB which i have soldered my esp32wroom devboard onto.

This is the dev board in question - https://99tech.com.au/product/esp32-devkit-30u/

When i plug the USB in, i get a solid red LED and nothing more. If i try press the reset button while checking the serial monitor, nothing

The same goes for the boot button, it seems to do nothing and nothing shows up on the serial monitor.

HOWEVER, if my finger is anywhere near the "EN" pin on the esp32, i can see the serial monitor go crazy and it keeps printing the power reset message endlessly. if i press the boot button while doing this i can see it change from SPI_FAST_FLASH_BOOT into DOWNLOAD_BOOT

This does nothing though, if i try upload a sketch, it gets stuck on "connecting....." and then fails.

It seems the device is stuck while booting.

FYI, my custom PCB does not connect any pins from the DeV board, in fact, it does not even connect the "EN" pin to anything, it is just used to secure the Devboard to my PCB.

I am using the following GPIO pins as touch sensors which are just exposed pads on my custom PCB:

GPIO2
GPIO12
GPIO13
GPIO14
GPIO15
GPIO27
GPIO32
GPIO33

I have also run traces to a plug for so i can attach a eink paper display, however the display is not connected as of yet. I have used the following pins for the corresponding purposes

GPIO04 - BUSY
GPIO16 - RST
GPIO17 - DC
GPIO05 - CS
GPIO18 - CLK
GPIO23 - DIN

NOTE: Keep in mind these last ones arent really connected to anything at the moment. there is a plug terminal soldered to the board but i have not actually connected anything to that plug so they are essentially open at the moment

i have attached my schematic as an image below. the "ESP LEFT SIDE" and "ESP RIGHT SIDE" are both headers which are soldered to the board, which the ESP is then soldered to.

ESP Help.png (885.75 KiB) Viewed 15733 times

Thanks in advance

[wangnick]

Hi @zapp123

Do you have a second DEV board that is as of now still not soldered onto your PCB? If yes, does it exhibit the same problems?

Note that GPIO2 and GPIO5 are part of the ESP32 "GPIO-STRAPPING" mechanism. Due to this, and due to the "GPIO-STRAPPING" effects on the ESP32 boot, on the regular DEV board schematics GPIO2 is pulled to GND by 10k and GPIO4 is pulled to 3V3 by 10k.

In any case I suggest you reverse engineer the schematics of your particular DEV board. Besides the USB-to Serial chip you will find normally only a couple of resistors, a few capacitors, often two transistors for the DTR/RTS to EN/IO0 business, a LED or two, and a linear voltage regulator.

In fact, you could as well replicate those components onto your PCB, and go for just an ESP32-WROOM-32 module to put onlo your PCB instead of a full DEV board ...

KR, Sebastian