How to programme ESP32-S3 after I set its CPU frequency to 10MHz?

[HKPhysicist]

Dear ESP32 Technical Support and Experts,
I own a board built upon ESP32-S3-WROOM-1-N16R8. I can run any application which I want it to as long as I set the CPU frequency equal to or higher than 80MHz.

Yesterday, I tested my board with a bugless sketch and compiled it at 80MHz CPU frequency. As usual, this combination worked well.

Then, I compiled the same sketch at 10MHz CPU frequency. Compilation was successful and the board was reset.

However, the USB serial port of my board disappeared and did not come up any more!!!

I did press the RESET button, BOOT button and any combination of them and these do not help.

Please help me to repair it again!

Thank you very much!

My IDE is Arduino v2.3.6 for Windows, official arduino-esp32 board manager.
Hardware: ESP32-S3-WROOM-1-N16R8

deep sleep esp32.png (50.7 KiB) Viewed 476 times

[Sprite]

Yeah, USB-jtag-serial needs the BPLL running and I imagine running the CPU at 10MHz disables that. You probably can regain control by holding the BOOT button and unplugging/replugging the board (assuming it's powered from USB).

[lbernstone]

Note that the radio also cannot operate at cpu speeds under 80MHz, so those low rates are not particularly useful.

[HKPhysicist]

Yeah, USB-jtag-serial needs the BPLL running and I imagine running the CPU at 10MHz disables that. You probably can regain control by holding the BOOT button and unplugging/replugging the board (assuming it's powered from USB).

This is the core part of my board. I did remove the battery, press the BOOT button and then replug the USB cable. Nothing has improved. Please advice.

main buttons.jpg (1.15 MiB) Viewed 448 times

[Sprite]

I don't know what to say: if you keep GPIO0 low and make EN low and high, the ESP32 should boot into bootloader mode. I'd suggest checking your board schematic to see if the buttons do that.

[HKPhysicist]

I don't know what to say: if you keep GPIO0 low and make EN low and high, the ESP32 should boot into bootloader mode. I'd suggest checking your board schematic to see if the buttons do that.

Yes, my board's manufacturer marks GPIO0 as FLASH.

Then, I follow the official procedure to regain control of my board.