ESP32-S3FN8 Custom Board, USB Connection Issues

[trnblm]

I'm having issues with my custom-made board. I'm working with an ESP32-S3FN8 circuit that includes USB connections, reset, and boot buttons.
The main issues are:

When plugging the USB into my Windows machine, I get a "Device description request failed" error and the device gets stuck in a reboot loop
Adding a pull-up resistor to the D+ line stops the loop
Holding the BOOT button while plugging in the USB also prevents the loop by entering bootloader mode
Despite these workarounds, my machine still won't recognize the device

I've tested:
3 boards manufactured by JLCPCB (2 weren't recognized by Windows or Linux)
Multiple USB cables
Continuity between D+ & D- on the ESD protection chip (USBLC6-25C6)
Signal observation with an oscilloscope shows attempted handshaking from the Windows machine, though the waveforms don't look correct (no images available)

[ESP_Sprite]

Just to clarify: an empty flash in an ESP32-S3 will indeed cause it to go into a boot loop; making GPIO0 low will stop that from happening. Adding a resistor to D+ is not encouraged as it will only mask the issue; the internal USB logic will still reset but you're stopping the PC from noticing that.

Aside from that: it doesn't look like there's anything wrong with your setup as far as I can see it. Perhaps check the basics: can your power supply (and LDO or buck converter) deliver the required 500mA? Is your 40MHz crystal oscillating at 40MHz? Does U0TXD have a serial sign-on message on it (@115200 baud) when you reset the chip?

[trnblm]

Hi and thank you for the response. Its the first time building a ESP32-S3 board so If im missing something obvious let me know.

We're just trying to flash it but can't access it through the USB ( GPIO 19 & GPIO 20 )
Do we need to burn the USB_PHY_SEL fuse to be able to flash any firmware onto it? https://docs.espressif.com/projects/esp ... s/dfu.html

Through any other connections than USB on the GPIO19 & GPIO20?

I don't have access to the Oscillioscope to check for the crystal.
Im using the AMS1117-3.3 1A, so yes the power isn't the issue.

I haven't connected U0RXD nor U0TXD because i thought i only needed GPIO19 & GPIO20 for upload of firmware through the USB?

[ESP_Sprite]

You should indeed only need GPIO19&20 to flash the chip, nothing more. (Aside from the basics like a proper power supply, 40MHz crystal, proper bootstrap pins set.) You don't need to set an eFuse; the USB-serial-JTAG is active by default. You don't need to connect U0TXD to anything normally either, but it would be useful to debug whatever is happening here: if the bootstrap message happens at the wrong speed, there's probably something wrong with the crystal, and if it doesn't happen at all, something else is wrong.