I trawled the ESP-IDF uart.c / uart.h for some time and could not figure out what the right way is, to get a true/false answer to the question "are there any remaining untransmitted characters in the tx buffer or the UART hardware FIFO". I explicitly do not want a blocking send or flush call; I want...

I understand the the PSU selection is by jumper. The question at hand is, once the board is jumpered for external 5V supply and powered up, is it safe to plug in the USB connection for flashing and JTAG access, or is there any risk of conflict with the supplies.

Simple question: is it electrically safe to have the WROVER-KIT 4.1 board, being powered by an external 5V supply, while also connected to USB for JTAG debugging? I have some other devboards that don't have an explicit jumper connection to select the 5V supply source, and at least one of them has a ...