Android Things Quick Start Guide by Raul Portales

Author:Raul Portales
Language: eng
Format: epub, pdf
Tags: COM067000 - COMPUTERS / Hardware / General, COM025000 - COMPUTERS / Expert Systems, COM046070 - COMPUTERS / Operating Systems / Linux
Publisher: Packt Publishing
Published: 2018-08-31T13:53:59+00:00

public static Button openButton(String pin) throws IOException {

return new Button(pin, BUTTON_LOGIC_STATE);

}

Since we are using a driver, this step is very simple; the only thing the meta driver hides from us is the logic state of the buttons. Since they are capacitive, they are pressed when the GPIO is low (which is the reverse of normal press buttons). This is the equivalent of the active type we saw with inputs in the previous section.

So, if we just put everything together, we can just collapse it on a single line:

buttonA = Button(BoardDefaults.buttonA, Button.LogicState.PRESSED_WHEN_LOW)

And then, just for completeness, we add a new value to the BoardDefaults object for the pin where the button is connected:

val buttonA: String

get() = when (Build.DEVICE) {

DEVICE_RPI3 -> "BCM21"

DEVICE_IMX7D_PICO -> "GPIO6_IO14"

else -> throw IllegalStateException("Unknown Build.DEVICE ${Build.DEVICE}")

}

Let's take the example of the previous chapter that used a button and an LED and see how it will look when we completely remove the abstraction for the Rainbow HAT:

class ButtonDriverActivity : Activity() {

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