ESP32 Forum

Hello,

I am trying to make a custom pcb to drive an LCD using an ESP32 S3R8 chip. I read that you can program it directly using USB,which is what i am trying to use instead of UART. My question is, does this work on a brand new chip or do i need to flash something to it using uart first?

I am attaching my schematic for review if it is good enough, for it to go into download mode so i can at least flash it. I will connect it to USB via external cables on K2, not via a USB port.

I also have another question if there is a problem using GPIO 33 to 37, since the reference design i am folowing, leaves those unconnected, but from what i have read in the documentation, unless your using quadSPI flash, which i am not, those pins can be used normaly

You probably want to remove C42.

You have to flash something to it first. A new chip does not enable USB out of the box. I ran into this very same issue on my new boards.

username wrote: ↑

Sun Jun 30, 2024 7:40 pm

You have to flash something to it first. A new chip does not enable USB out of the box. I ran into this very same issue on my new boards.

That is not true; USB is in the bootloader and when you go into download mode, the chip will respond over USB regardless of what's in the flash. The thing is that with an empty flash, the chip will bootloop, making it a lot harder to get into bootloader mode over the USB interface. The trick is to force GPIO0 low and reset or powercycle the chip; that forces it into bootloader mode and USB should be accessible then.

OK,

I tried my board out and out of the box, the USB worked. The only issue was that when i first pluged it it, the com port kept disapearing ON and OFF every second on windows. After i held the GPIO0 button down and power cycled the board, the com port is recognised fine and i could upload my code onto it. After that the com port appears every time i plug the board into usb and i dont need to press GPIO0 again.

Thanks to everyone for the replies