Plasma - problems with v1.19.12

[helgibbons]

See https://forums.pimoroni.com/t/wireless-plasma-kit-issues/21274

I'm getting no lights and hard locks in Thonny when trying to init the LEDs with a Plasma Stick running v1.19.12 MicroPython firmware.

Works fine if I flash the board with v1.19.11.

[helgibbons]

Just tried v1.19.12 on a Plasma 2040 (and a different computer, to rule out Thonny shenanigans!) and that's also exhibiting the same problem.

[Gadgetoid]

I expected something would break, since we moved through a few months of MicroPython updates in a single point release 😬

Frustratingly Plasma had already been optimized to the nth degree for similar problems before, so none of the usual suspects are the problem here.

It doesn't seem to be related to the PIO or State Machine choices, since it freezes with any configuration for me.

And, even weirder, if I supply a buffer that's under-sized it still freezes.

It should be bailing with a ValueError:

pimoroni-pico/micropython/modules/plasma/plasma.cpp

Line 93 in b3edbc4

mp_raise_ValueError("Supplied buffer is too small for LED count!");

At this point it hasn't done anything particularly onerous!

Edit: For posterity here is my test code:

import plasma

print("Here we go!")

buf = bytearray(2)
led_strip = plasma.WS2812(10, 1, 1, 25, color_order=plasma.COLOR_ORDER_RGB, buffer=buf)

print("Hello World")

10 LEDs is 10 * sizeof(WS2812::RGB) or 40 bytes, so a bytearray(2) should definitely cause this class constructor to bail super early.

[Gadgetoid]

Even stranger, this hard-locks:

>>> import plasma
>>> plasma.WS2812()

The first four args are required so this should bail in argument parsing. Something must be wrong with the linkage into the C module

IE: The new MP_DEFINE_CONST_OBJ_TYPE macro must have the wrong function set for the class constructor.

[Gadgetoid]

I don't know whether to laugh or cry:

MP_DEFINE_CONST_OBJ_TYPE(
    PlasmaWS2812_type,
    MP_QSTR_plasma_ws2812,
    MP_TYPE_FLAG_NONE,
    make_new, PlasmaWS2812_print,
    print, PlasmaWS2812_make_new,
    locals_dict, (mp_obj_dict_t*)&PlasmaWS2812_locals_dict
);