Compiling firmware for Pico

[mikek88]

I got a Pico-variant that has 16MB instead of the standard 2MB. So I duplicated the standard Pico folder and header file, made the changes and compiled a new uf2. It works fine, but the main.py file does not show up like with the standard Pico firmware. I'm not sure what is wrong. My firmware uf2 is the same size as the standard Pico one.

[scruss]

If you're not too picky about how the board identifies, you can install the pre-built image for the Pico LiPo (16MiB). I've used this on the WeAct 16 MB boards, and it works as expected

[fivdi]

I loaded the PicoLipo 16MB firmware and it, too, doesn't create a main.py file.

To the best of my knowledge, flashing MicroPython firmware onto an RP2040 board will not automatically create a file called main.py.

[mikek88]

But it does. Flashing the official Pico firmware onto my board creates the main.py, which runs, and lights the RGB LED and then lights the standard GP25 LED.

[fivdi]

I think the main.py you are seeing is from previous usage of MicroPython on the board. If you erase the flash on your Pico (see
Resetting Flash memory) and then flash MicroPython onto the board again, I'm almost certain that main.py will no longer be there.

[mikek88]

Yep, you're right. I loaded flash_nuke.uf2, reloaded the official firmware and there was no main.py. I guess the "problem" is that the main.py existed on the 2MB filesystem?...And that the 16MB filesystem couldn't see it? I guess all is fine, I just no longer have that main.py.

[fivdi]

I guess the "problem" is that the main.py existed on the 2MB filesystem?...And that the 16MB filesystem couldn't see it?

This appears to be have been the case.

[jimmo]

If you've previously run 2MiB firmware on this board, this would have created a (2MiB) filesystem, then it's now going to be confused when it goes looking for a 16MiB one with the new firmware.

As long as the filesystem is working, you can just put a new main.py there.

[mikek88]

I think the filesystem is file. I changed the mpconfigboard.h file in /ports/rp2/boards/. When I checked the filesystem via Thonny and using os.statvfs('/') it reports correct info and not the 2MB Pico numbers.

And, yes, I know I can add a new main.py, but I wanted to properly create firmware that was consistent with all of the others.

[mikek88]

@jimmo, Looks like you were right! I thought the filesystem stats being different was all that mattered. It looks like the main.py file existed on the 2MB filesystem and going to a 16MB filesystem changed the structure without losing the file. Though, I've lost the file now, after flash_nuke. lol

[fivdi]

If MicroPython is flashed onto a pristine Pico that has never been flashed before, there will be no file called main.py. To the best of my knowledge this is the same for other RP2040 boards too. What exactly are you expecting to occur? Note that I don't use Thonny and I don't know if it automatically creates a main.py on a Pico. If you are having difficulties, there is an application called flash_nuke.uf2 that can be used to erase the content of the flash on RP2040 boards.

[mikek88]

I don't think it's Thonny that creates the main.py, because the code run immediately after flashing without having run Thonny. I want to duplicate this behavior so that when I create my own firmware and flash it I can see the demo code running.

[fivdi]

I want to duplicate this behavior so that when I create my own firmware and flash it I can see the demo code running.

I'm not really sure what the requirement is. What behaviour do you want to duplicate?

[fivdi]

Remember, after MicroPython is flashed onto a pristine Pico or other RP2040 board that was never flashed before, there is no main.py in directory /. If you are seeing one there, it's because you are flashing MicroPython for at least the second time and the main.py you are seeing was already there from previous usage.

[fivdi]

If needed, a tool like mpremote (see here and here) can be used to copy a file called main.py to your board.

[mattytrentini]

For reference, there is a board definition for the WeAct Studio boards (of which 'Wavgat' is one of the popular manufacturers). It's likely (almost certain?) that this definition will suit your board.

We've added board variants to allow 2/4/8/16MB builds for that board definition (see that link above on how to select the variants).

However, right now, the download manager still needs a change to build board variants for the rp2 port. But you're in luck! The default variant is 16MB so you should be able to use the WeAct Studio pre-built firmware. (After following all the other advice here about resetting the filesystem.)