Using a suite of standard protocols, you can implement compelling accessories that extend Android capabilities in a wide range of Android-powered devices.
Audio accessories
Android supports local on-device audio and remote off-device audio over a wired 3.5 mm headset jack, USB connection, or Bluetooth. Manufacturers should see the headset specifications, while users can learn how to record and play back audio using USB host mode.
Custom accessories
What do you want to connect to your Android device? Alarm clock? Keyboard? Thermostat? Robot? Learn how to connect existing equipment or your own unique hardware to Android using the Android Open Accessory (AOA) protocol.