I wired some some LEDs for a small art project to a DevKitC 4.1 made by espessif, and I find that when I use GPIO18, reflashing the board is more cumbersome.
That is, the LEDs start blinking like crazy when I use idf.py flash, showing that someone else is using the pin, and I need to manually hit the BOOT button to upload, which then works great. Which isn't the end of the world, but I've got a lot of pins free, and I'd rather avoid that.
I'm moving over to the PICO, but I'm also trying to figure out which pins are really used for what. IE, truly safe. In the data sheets and schematics, GPIO18 is labeled for high speed data transfer uses, which I could imagine include the USB, but I've read everything and can't find any data about how the CP2102N might be wired other than TX0 and RX0. Doesn't appear to be connected.
I suppose another possibility is the firmware I'm using is trying to communicate over VSPI, HS1_DATA during a reflash, ( which is what Pin 18 is marked as ), in which case I'd like it to have it stop ( I am using ESP-IDF ). I don't see anything obvious in menuconfig regarding that functionality, and I've looked pretty hard.
Thus in the end:
Are the VSPI / HS1 pins safe to use?
I see pins annotated in various ways, what pins are safest, other than trying them?
( I suppose there is a side question here, which is whether the functionality of USB and the CP2102N is available to programmers after boot, which is actually a good question --- I hadn't been planning on using the USB but I might consider it, now that I've thought of it. )