LED strip

As we have done in previous chapters, let's remove the dependency of the Rainbow HAT meta driver and add only the driver that we need. In the case of the RGB LED strip, that driver is called driver-apa102:

dependencies {
    implementation 'com.google.android.things.contrib:driver-apa102:+'
}

And, as we have been doing so far, let's use a BoardDefaults object to be able to run our code independently of the developer kit pinout naming:

val spiBus: String
    get() = when (Build.DEVICE) {
        DEVICE_RPI3 -> "SPI0.0"
        DEVICE_IMX7D_PICO -> "SPI3.1"
        else -> throw IllegalStateException("Unknown Build.DEVICE ${Build.DEVICE}")
    }

There are a couple of important things to note here. First is that the exposed SPI bus on the Raspberry Pi is called 0, while the iMX7D one is 3. It is also important to note...