voicehat

Voice Hat driver for Android Things

This driver exposes peripherals from the VoiceHat to standard Android audio APIs using Android Things.

It allows the user to interact with:

• Pushbutton
• LED
• Max98357A DAC

At this moment the driver has only been tested on the Raspberry Pi 3.

NOTE: these drivers are not production-ready. They are offered as sample implementations of Android Things user space drivers for common peripherals as part of the Developer Preview release. There is no guarantee of correctness, completeness or robustness.

How to use the driver

Gradle dependency

To use the voicehat driver, simply add the line below to your project's build.gradle, where <version> matches the last version of the driver available on jcenter.

dependencies {
    compile 'com.google.android.things.contrib:driver-voicehat:<version>'
}

Sample usage

// import the VoiceHat driver
import com.google.android.things.contrib.driver.voicehat.VoiceHat;

Access Max98357A DAC

The VoiceHat uses the Max98357A chip for audio I/O. To access the DAC, one can use the static method on the VoiceHat. On the VoiceHat, the gain slot pin is not electrically connected.

Max98357A dac = VoiceHat.openDac();

If you are not using the VoiceHat, you can directly construct an instance of this class.

Max98357A dac = new Max98357A("BCM16", "BCM23");
dac.setSdMode(Max98357A.SD_MODE_LEFT);
dac.setGainSlot(Max98357A.GAIN_SLOT_ENABLE);

Integrating Peripherals

You can access the additional peripherals on the VoiceHat: a pushbutton and an LED.

Gpio led = VoiceHat.openLed();
led.setValue(true);

Button button = VoiceHat.openButton();
button.setOnButtonEventListener(new OnButtonEventListener() {
     @Override
     public void onButtonEvent(Button button, boolean pressed) {
         // do something awesome
     }
});

Alternatively you can register an InputDriver for the pushbutton.

Note: If you are going to use the input driver, you will need to include the following permission to your AndroidManifest:

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

// Start voice hat.
UserDriverManager userDriverManager = UserDriverManager.getManager();
ButtonInputDriver buttonInputDriver = VoiceHat.createButtonInputDriver(KeyEvent.KEYCODE_ENTER);
userDriverManager.registerInputDriver(buttonInputDriver);

// Make sure to call `unregisterInputDriver` in the onDestroy() method in your activity

License

Copyright 2017 Google Inc.

Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.