neopixel/ws2812 timings

[microbit-carlos]

There is a wide range of ws2812 LEDs with slightly different timings and the CODAL version in the MicroPython v.2.1.1 release doesn't work with all of them:

• ws2812 timing is incorrect when using HARDWARE_NEOPIXEL lancaster-university/codal-microbit-v2#294

This has been fixed in CODAL's PR lancaster-university/codal-nrf52#47, but to do a low-risk v2.1.2 release we can apply the patch directly to v2.1.1 as done in: v2.1.1...0697c6d

[microbit-carlos]

Okay, so I could not successfully trigger a new docker build of the MicroPython builds we have in https://github.com/microbit-foundation/micropython-build-env, because some pinned dependencies don't seem to be available in the ubuntu package repositories.
I'll need to look into that issue and fix it in a future date, but in the meantime I've created a v2.1.2 build by using the docker image created as part of the v2.1.1 build.

I was hoping to be able to checkout the v2.1.x-branch, and re-build with only those changes, but for some reason that didn't triggering re-compilation for the codal-nrf52 files and ended up with a build with the only change being the version string.

Nevertheless, doing a clean build worked correctly, and there wasn't significant changes in the build output (sometimes, even with small changes, the compiler applies optimisation levels differently and/or moves things around, when so a binary/hex comparison is not easy).

The final hex output only contains 4 changes, so that made it really easy to verify everything else should be exactly the same. Which is important as I was hoping to be able to avoid having to run a lot of manual tests.

The v2.1.2 hex file can be downloaded from the GitHub release https://github.com/microbit-foundation/micropython-microbit-v2/releases/tag/v2.1.2 and will be added to the Python Editor soon.

The changes in the hex file are:

• A change at address 0x29900:
  
  • From the map file, is for the neopixel_send_buffer function, makes sense ✅.

    .text._Z20neopixel_send_bufferRN5codal3PinEPKhi
                    0x0000000000029880       0x84 /home/micropython-microbit-v2/lib/codal/build/libcodal-nrf52.a(neopixel.cpp.o)
                    0x0000000000029880                neopixel_send_buffer(codal::Pin&, unsigned char const*, int)
    .text._ZN5codal19allocate_peripheralEPv
                    0x0000000000029904       0x3c /home/micropython-microbit-v2/lib/codal/build/libcodal-nrf52.a(peripheral_alloc.cpp.o)
                    0x0000000000029904                codal::allocate_peripheral(void*)
    

• Another change at address 0x53A50, where we can clearly see the change from WS2812B_LOW and WS2812B_HIGH (neopixel_ws2812b_timing.patch):
  
  • This is the codal::WS2812B::pull() method, also expected ✅.

    .text._ZN5codal7WS2812B4pullEv
                    0x0000000000053a24       0x9c /home/micropython-microbit-v2/lib/codal/build/libcodal-nrf52.a(WS2812B.cpp.o)
                    0x0000000000053a24                codal::WS2812B::pull()
    .text._ZN5codal7WS2812B5_playEPKvib
                    0x0000000000053ac0       0x30 /home/micropython-microbit-v2/lib/codal/build/libcodal-nrf52.a(WS2812B.cpp.o)
                    0x0000000000053ac0                codal::WS2812B::_play(void const*, int, bool)
    

• The other two changes are strings changed as a result of updating the version number (0697c6d) ✅:
  • A change in the string micro:bit v2.1.2+0697c6d on 2023-10-30; MicroPython v1.18 on 2023-10-30:
    
  • And a change in the string MicroPython v1.18 on 2023-10-30; micro:bit v2.1.2 with nRF52833:
    

[microbit-carlos]

@dpgeorge @jimmo v2.1.2 of MicroPython for micro:bit V2 has been deployed to https://python.microbit.org

[jimmo]

Thanks @microbit-carlos!! :)