Neopixel Module Not Available

[JoshuaLowe1002]

Apologies if you're already aware of this bug but it seems the neopixel module does not exist in MicroPython on V2.

Maybe an issue linked to microsoft/pxt-microbit#3415

[microbit-mark]

This module is also requested via micro:bit support in https://support.microbit.org/a/tickets/40468

[martinwork]

@microbit-mark @microbit-carlos Needed for testing "display_and_neopixel.py"

[microbit-carlos]

Yes, this is something we wanted to implement in the CODAL layer, so I've opened lancaster-university/codal-microbit-v2#19.

[jaustin]

The older implementation doesn't co-exist with Bluetooth so I think it does make sense to use the PWM-based one. @finneyj any thoughts on merging that so we can ensure Neopixel in MicroPython? Would it require a dedicated PWM channel?

[finneyj]

Yes, I agree we should build a PWM-based driver codal side. It does require a dedicated PWM peripheral, but I have one reserved for this already, so no problem.

Sam's driver needs a bit of work as I recall to package so that it is memory safe during DMA and double buffers to avoid memory overhead/glitching. I'll happily do that when I get a minute.

[dpgeorge]

Ideally CODAL would expose a single function like neopixel_write(pin, len, buf) that would output the given buf of data on the pin using neopixel encoding.

[microbit-carlos]

NeoPixel support has been added to CODAL: https://github.com/lancaster-university/codal-nrf52/blob/master/inc/neopixel.h
Thanks @finneyj !

[finneyj]

no worries @dpgeorge @microbit-carlos.

Please note this is a blocking call (it will block the calling fiber until playout is complete), but doesn't disable interrupts or anything like that, so shouldn't have any of the side effects associated with the old bit banging implementations.

Under the hood it all runs async, so see here if you prefer it to just run in the background. You just need to flip play() to playAsync():

https://github.com/lancaster-university/codal-nrf52/blob/master/source/neopixel.cpp#L25

https://github.com/lancaster-university/codal-nrf52/blob/master/source/WS2812B.cpp#L129

[dpgeorge]

Thanks @finneyj ! A blocking call is good enough for now.

Implemented on the Python side in 915b6aa, should be compatible with micro:bit v1, and also includes support for RGBW LEDs.

[microbit-carlos]

@microbit-mark @martinwork this should be ready for testing on the next MicroPython release.