Hi Sebastien, On 12/9/22, Sebastien Lorquet <sebast...@lorquet.fr> wrote: > Hi, > > As an introduction to the RISCV, I would like to use NuttX on my M5stamp > C3U, which I can get for 8 dollars at a local store. > > https://docs.m5stack.com/en/core/stamp_c3u >
This M5stamp C3U uses that ESP32-C3 that is already completely supported on NuttX. So, if your plan was to do a port, you arrived too late in the party :-D > The module does not use a usb serial chip but direct USB connection > (there is a schematic in the bottom of the page). > The USB serial on ESP32-C3 is already support on NuttX mainline too. > I wonder how it works: Is serial on USB supported by an internal > bootloader or does this require firmware support that will disappear > after I flash this board for the first time? > It doesn't require a firmware and normally will not require a host driver because it is a generic USB CDC Serial internal. Espressif create a nice thing that all MCU should have: a USB Serial / JTAG internally integrated in the chip. So, you don't need an external programmer neither an external USB/Serial. Just a USB cable and you can program the chip and get a console interface. You can get more info about it reading the "USB Serial/JTAG Controller" chapter of the ESP32-C3 TRM. BR, Alan
