Yes I've done that and I get normal logs. The same ESP32 chip flashes normally with a usb-ftdi module, so the issue is either the XIAO board, or the USB drivers which their BSP provides

Oh that makes sense :) . Yes I always burn the fuse for flash voltage because my chip uses eMMC driver. I posted the same question on Stack Overflow here https://stackoverflow.com/questions/71982301/emulate-cp210x-usb-ftdi-chip-using-samd21 Another user had success using the same steps I used. I thi...

@chewarga I am sure the chip is in bootloader mode. I very often use a usb-ftdi module to flash my bare ESP32s, and this is the same log I always receive
`rst:0x1 (POWERON_RESET),boot:0x27 (DOWNLOAD_BOOT(UART0/UART1/SDIO_REI_REO_V2))`
the next line of the log explicitly says
`waiting for download`

Also if I should delete this and repost in a different section of the forum let me know

Is it possible to pass flags to esptool.py to fix the baud rate throughout the transaction, and/or limit the way it passes data, perhaps to slow it down, so the Arduino libraries can handle the transfer more easily?

It's also strange that, although my terminal emulator (Cool Term) establishes communication with the SAMD21, the esp-idf monitor does not.

My command is idf.py -p /dev/cu.usbmodemFA131 -b 115200 monitor

The monitor runs, but does not get any logs back from the ESP32, via the SAMD21.

I have a SAMD21 devboard which I would like to use to flash my ESP32 WROVER module. My computer connects to the SAMD21 via usb, and I can use it to receive logs from my ESP32 over a UART connection. Unfortunately when I run esptool.py, the connection fails, I get a timeout waiting for packet header ...

Amazing, thanks so much @ullixesp, I will try this out!

yes i burned the fuses for 3.3v flash.
I have the 16MB flash version of the WROVER-B.

I am using an ESP32 WROVER-B module on a custom PCB.
Does this look like it could be a power issue?