Pulse Width Modulation (PWM) is a one-wire, one-way communication protocol. Both Android Things developer kits have two PWM outputs -this is one case where Arduino has the upper hand- but we will see how to overcome that limitation in the next chapter. The Rainbow HAT uses one of them for the piezo buzzer and exposes the other via the pins on the HAT. We will take advantage of this setup by using some of the hardware of the Rainbow HAT for our examples.
Arduino has a lot more PWM outputs than Android Things. We'll see how to work around that in the next chapter.
And as usual, since we will be using peripherals, we need to make sure that the USE_PERIPHERAL_IO permission is being declared in our manifest:
<uses-permission android:name="com.google.android.things.permission.USE_PERIPHERAL_IO"/>
We will start by learning...