Thanks @knuxify

Could you please rename to remove the _4MB. We're going to start merging the different flash sizes into single boards with multiple variants. See #8505 where @mattytrentini is adding support for board variants to the rp2 port.

In the meantime though, I don't think this board comes in other sizes, so just renaming it should be all you need to do for this PR. Please also send a corresponding PR to https://github.com/micropython/micropython-media for the board image.

I added the _4MB suffix to match the board file definition in the pico-sdk, there's also a 16MB variant in that repo but it indeed seems that it never reached the market.

Without that, I get this error:

PICO target board is waveshare_rp2040_plus.
CMake Error at /home/knuxify/projects/micropython/lib/pico-sdk/src/boards/generic_board.cmake:22 (message):
  Unable to find definition of board 'waveshare_rp2040_plus' (specified by
  PICO_BOARD):

     Looked for waveshare_rp2040_plus.h in /home/knuxify/projects/micropython/lib/pico-sdk/src/boards/include/boards (additional paths specified by PICO_BOARD_HEADER_DIRS)
     Looked for waveshare_rp2040_plus.cmake in /home/knuxify/projects/micropython/lib/pico-sdk/src/boards (additional paths specified by PICO_BOARD_CMAKE_DIRS)
Call Stack (most recent call first):
  /home/knuxify/projects/micropython/lib/pico-sdk/src/board_setup.cmake:28 (include)
  /home/knuxify/projects/micropython/lib/pico-sdk/src/CMakeLists.txt:15 (include)

Where should I define the PICO_BOARD override?

Where should I define the PICO_BOARD override?

At the start of mpconfigboard.cmake

See e.g. https://github.com/micropython/micropython/blob/master/ports/rp2/boards/W5100S_EVB_PICO/mpconfigboard.cmake

I'll let #10314 supersede this one.

Sorry, I obviously didn't search open pull requests :/ I'll be sure for future PRs....