ButtonActivity.java

/**
 * Example of using Button driver for toggling a LED.
 *
 * This activity initialize an InputDriver to emit key events when the button GPIO pin state change
 * and flip the state of the LED GPIO pin.
 *
 * You need to connect an LED and a push button switch to pins specified in {@link BoardDefaults}
 * according to the schematic provided above.
 */
public class ButtonActivity extends Activity {
    private static final String TAG = ButtonActivity.class.getSimpleName();

    private Gpio mLedGpio;
    private ButtonInputDriver mButtonInputDriver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.i(TAG, "Starting ButtonActivity");

        PeripheralManagerService pioService = new PeripheralManagerService();
        try {
            Log.i(TAG, "Configuring GPIO pins");
            mLedGpio = pioService.openGpio(BoardDefaults.getGPIOForLED());
            mLedGpio.setDirection(Gpio.DIRECTION_OUT_INITIALLY_LOW);

            Log.i(TAG, "Registering button driver");
            // Initialize and register the InputDriver that will emit SPACE key events
            // on GPIO state changes.
            mButtonInputDriver = new ButtonInputDriver(
                    BoardDefaults.getGPIOForButton(),
                    Button.LogicState.PRESSED_WHEN_LOW,
                    KeyEvent.KEYCODE_SPACE);
            mButtonInputDriver.register();
        } catch (IOException e) {
            Log.e(TAG, "Error configuring GPIO pins", e);
        }
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_SPACE) {
            // Turn on the LED
            setLedValue(true);
            return true;
        }

        return super.onKeyDown(keyCode, event);
    }

    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_SPACE) {
            // Turn off the LED
            setLedValue(false);
            return true;
        }

        return super.onKeyUp(keyCode, event);
    }

    /**
     * Update the value of the LED output.
     */
    private void setLedValue(boolean value) {
        try {
            mLedGpio.setValue(value);
        } catch (IOException e) {
            Log.e(TAG, "Error updating GPIO value", e);
        }
    }

    @Override
    protected void onDestroy(){
        super.onDestroy();

        if (mButtonInputDriver != null) {
            mButtonInputDriver.unregister();
            try {
                mButtonInputDriver.close();
            } catch (IOException e) {
                Log.e(TAG, "Error closing Button driver", e);
            } finally{
                mButtonInputDriver = null;
            }
        }

        if (mLedGpio != null) {
            try {
                mLedGpio.close();
            } catch (IOException e) {
                Log.e(TAG, "Error closing LED GPIO", e);
            } finally{
                mLedGpio = null;
            }
            mLedGpio = null;
        }
    }
}