Matrix Keypad driver for Android Things

Download

dependencies {
    compile 'com.nilhcem.androidthings:driver-keypad:0.0.3'
}

Usage

String[] rowPins = new String[]{"BCM12", "BCM16", "BCM20", "BCM21"};
String[] colPins = new String[]{"BCM25", "BCM24", "BCM23", "BCM27"};
 
Keypad keypad = new Keypad(rowPins, colPins, Keypad.KEYS_4x4);
// For a 3x4 matrix, you can use the "Keypad.KEYS_3x4" constant. You can also set your own custom keys.
 
keypad.register(new Keypad.OnKeyEventListener() {
    @Override
    public void onKeyEvent(KeyEvent keyEvent) {
        String action = keyEvent.getAction() == KeyEvent.ACTION_DOWN ? "ACTION_DOWN" : "ACTION_UP";
        Log.i(TAG, "onKeyEvent: (" + action + "): " + keyEvent.getDisplayLabel());
    }
});
 
// Don't forget to:
keypad.unregister();
keypad.close();

Alternatively, you can register a KeypadInputDriver with the system and receive KeyEvents through the standard Android APIs:

KeypadInputDriver mInputDriver;

try {
    mInputDriver = new KeypadInputDriver(rowPins, colPins, Keypad.KEYS_4x4);
    mInputDriver.register();
} catch (IOException e) {
    // error configuring keypad...
}

// Override key event callbacks in your Activity:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    Log.i(TAG, "onKeyDown: " + event.getDisplayLabel());
    return true;
}

@Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
    Log.i(TAG, "onKeyUp: " + event.getDisplayLabel());
    return true;
}

// Unregister and close the input driver when finished:

mInputDriver.unregister();
try {
    mInputDriver.close();
} catch (IOException e) {
    // error closing input driver
}

Also, don't forget to add the required permission to your app's manifest file:

<uses-permission android:name="com.google.android.things.permission.MANAGE_INPUT_DRIVERS" />

Schematic

The sample is for a 4x4 Membrane Matrix Keypad, but the library should work for any keypad formats (e.g. 3x4).
We use 1k pull-up resistors for the rows

• Row 1 -> BCM12
• Row 2 -> BCM16
• Row 3 -> BCM20
• Row 4 -> BCM21
• Col 1 -> BCM25
• Col 2 -> BCM24
• Col 3 -> BCM23
• Col 4 -> BCM27

Kudos to

• Polidea for the Polithings numpad12 driver.
• ciromattia for the Fritzing 4x4 membrane matrix keypad.