ESP32 Forum

Hello Greetings!

I recently made a custom PCB using ESP32-C3 MCU and not the SOC. Due to size constraints I did not include the external flash chip that is show on the schematics of SOC.

So my question is does ESP32-C3 needs that external flash chip? Or it can function even without it?

The SoC is the chip itself; I imagine you mean you're not using a module (like an ESP32-C3-Wroom) but rather the chip itself? If so, that does need flash to function, however you can get ESP32 chips with integrated flash. Specifically, the ESP32-C3Fx4 chips have 4MiB of built-in flash.

I'm not sure which version of ESP32-C3 has been used on my PCB since I got it assembled from my PCB fabricator. By ESP32-C3Fx4, do you mean ESP32-C3FN4 Like this:

https://www.mouser.in/ProductDetail/Esp ... MnMQ%3D%3D

My design uses the MCU and not the SOM. I have also attached my schematics for you to have a clear picture of the situation

Yes, the ESP32-C3FN4 (like in that Mouser link) would work (although you'd probably want an 100nF from Vdd_spi to gnd for stability), a plain ESP32-C3 would not.

Right now, I'm not able to upload code to my PCB from Arduino IDE.

Using ESP32-C3FN4 instead of ESP32-C3 would solve my problem?

If your problem is only the lack of flash, then yes, it would solve the issue.

How would I know if that's the only problem? The hardware is pretty tiny and if I have to change or replace the IC it is going to be a very difficult task. So I need to know if that's the case or is there anything else

Crazy electron wrote: ↑

Wed Feb 15, 2023 9:41 am

How would I know if that's the only problem? The hardware is pretty tiny and if I have to change or replace the IC it is going to be a very difficult task. So I need to know if that's the case or is there anything else

Well, the schematic you posted seems incomplete, so I can't say if there's any other issues with it. You could e.g. have my colleagues review it if you're willing to send them everything. However, even then there's no saying if that's the only problem you will run into: we may overlook something and we can't see your physical PCBs, your soldering etc; issues with that can also cause non-working hardware. All I can tell you is that not having any flash is a showstopper for sure; without that your setup will never work.

I have shared the complete schematics and how it seems incomplete?
What else would you like me to share? I can share all the required documents. Please let me know so I can provide you the details.
The PCB is assembled by the PCB fabricator, so I'm guessing there won't be problem with that.

Please check if power supply is not less than 500 mA. Add RC not only R at CHIP_EN, add a pull-up at GPIO2, add a series inductor 24 nH at XTAL_P, use ESP32-C3F chip and add 1 uF at VDD_SPI.
Then schematic should be basically correct, layout should be designed following hardware guidelines and module reference designs, next you could try to run the board.
But pay attention to what Sprite said, whatever the design looks OK, real tests should be carried out to finally prove the functionality.
BTW, what we provide in the hardware design guidelines, both schematic and layout, is the simplest circuit to work well, it is better not to remove any part.