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Capability - Neopixels

Capability Identifier:

https://tildagon.badge.emfcamp.org/capabilities/registry/neopixels/

Provides access to a string of Neopixels.

  1. The leds attribute contains an instance of a neopixel string.
  2. The led_owner attribute marks which app is exclusively controlling the LEDs. This is because the standard approach for stopping patterns does not apply here, as these LEDs are part of independent hexpansions.

Consumers

Iterate over the apps to find all the LED strings. Before you drive them, you must change led_owner. Once you're finished, and you're happy for another app to take over, change led_owner to None.

Do not release ownership between frames of a pattern unless you do not intend to reacquire ownership soon, as otherwise two apps could fight over access.

class LEDColourApp(App):
    # Changes all LEDs on hexpansion to the same colour

    def __init__(self):
        self.color = (0.4, 0, 0.2)
        self.button_states = Buttons(self)

    def update(self, delta):
        led_apps = get_running_apps_by_capability(
            "https://tildagon.badge.emfcamp.org/capabilities/registry/"
            "neopixels/"
        )

        strings = []

        if self.button_states.get(BUTTON_TYPES["CANCEL"]):
            for led_app in led_apps:
                if led_app.led_owner is self:
                    led_app.led_owner = None
            self.minimise()
            return

        for led_app in led_apps:
            if led_app.led_owner is None:
                led_app.led_owner = self
            if led_app.led_owner is self:
                strings.append(led_app.leds)

        for string in strings:
            string.fill(self.color)
            string.write()

Providers

When you instantiate your neopixels, make sure you store them on as an leds attribute. Also, before writing to them, check if the lease is held.

As the hexpansion driver, you may write to the leds when the lease is None. This allows you to differentiate between when you don't mind someone taking over the LEDs, and when you are holding them exclusively:

class FiveRedLedsDriverApp:
    def __init__(self, config=None):
        self.led_owner = None
        self.leds = neopixel.NeoPixel(config.pin[3], 5)

    def update(self, delta):
        if self.led_owner in {None, self}:
            self.leds.fill((1.0, 0.0, 0.0))
            self.leds.write()