The Google Assistant project aims at deploying Google Assistant on a DragonBoard410c by 96Boards. Recently, Google released a software development kit (SDK) which allows third party developers to build their own Google Assistant on hardware of their choice. The SDK lets us add features such as hotword detection, voice control and natural language processing to devices of our choice. In this project we will make our own version of Google Assistant using a DragonBoard 410c, a USB mic and speakers.

By the end of this project you should be able to interface an external microphone as well as bluetooth speaker with the DragonBoard, create and configure a Google Developer Project on Google Cloud Platform (a developer project basically gives your device, a DragonBoard in this case, access to the Google Assistant API), use and understand gRPC bindings.

Google just released the SDK a few months ago so that the Assistant can be implemented on a wide range of platforms. So as 96Boards enthusiasts, it is essential that we test it out on one of the boards. It would be a great learning process and nothing beats the feeling of having a fully working project in your hands.

• 1) Hardware
  • 1.1) Hardware requirements
  • 1.2) Hardware setup
• 2) Software
  • 2.1) Operating System
  • 2.2) Requirements
  • 2.3) Software Dependencies
• 3) Configure Developers project
• 4) Account settings
• 5) Integrating Google Assistant onto DragonBoard
• 6) Troubleshooting

• Dragonboard 410c
• 96Boards Compliant Power Supply
• USB Microphone
• USB/Bluetooth Speakers

• Make sure the DragonBoard is powered off
• Connect the USB Mic on the USB Port
• Connect I/O devices (Monitor, Keyboard, etc...)
• Power on your DragonBoard 410c with 96Boards compliant power supply
• When the system starts, open Bluetooth Manager and turn on the Bluetooth. Click on search so that the DragonBoard can start scanning for nearby devices. Once the device appears, right click on it and select pair. Finally, after pairing, click on connect.
• To make sure the microphone and speakers are connected successfully, go to Application Menu -> Sound & Video -> PulseAudio Volume Control and check the input and output devices.

• Linaro Debian based OS (latest)

• For the first part of the project, we won't be installing any packages. All you will be needing is a Google Account.

First, we will begin with updating the already available packages and install the newer versions of packages we have. Run the following commands to do the same.

$ sudo apt-get update
$ sudo apt-get upgrade

The reference code provided by Google is written in Python, so install the latest version of Python. PIP is basically a package manager which is used to install packages that are written in Python. A virtual environment allows creation of isolated environments to download dependencies that are required for a project.

$ sudo apt-get install python3
$ python -m pip install virtualenv
$ virtualenv venv
$ source venv/bin/activate
$ python -m pip install --upgrade pip
$ python -m pip install --upgrade pip setuptools

gRPC is a modern open source high performance RPC framework that can run in any environment. This framework is supports bidirectional audio streaming. You can find more documentation on gRPC here.

$ python -m pip install grpcio
$ python -m pip install grpcio-tools

So these are all the packages we will be using for this application. Now let’s take a look at the final step which allows us to implement the application onto the DragonBoard.

Follow these instructions in order to configure a Developer Project.

• Go to the the projects page on Google Cloud Platform and create a new project.
• In the API manager page search for the Google Assistant API and Enable it.
• Now we will create an OAuth Client ID. Select ‘Others’ and provide a product name and proceed to save. After you click on create, it will generate a dialog box with the client ID and secret. Next to the clientID, click on the download button and save the .json file in working directory of the DragonBoard.

You can find the video in the Images folder.

Open the Activity Controls Page and ensure that all of these switches are turned on. We will need each of these for the proper functioning of the project.

• Web and App Activity
• Location History
• Device Information
• Voice and Audio Activity

Google has provided a sample code which we will be using for our project. Run the following commands in order to clone the sample project repository and move the code into a new directory called new-project.

$ git clone https://github.com/googlesamples/assistant-sdk-python
$ cp -r assistant-sdk-python/google-assistant-sdk/googlesamples/assistant/grpc new-project
$ cd new-project

To proceed, we need to authorize our device to talk to the Google Assistant using the Google Account. The Assistant SDK uses OAuth 2.0 access tokens to authorize your device to connect with the Assistant. First, we install the authorization tool. Then run the tool using the json file that was downloaded earlier. Make sure the path to the json file is correct.

$ pip install --upgrade google-auth-oauthlib[tool]
$ google-oauthlib-tool --client-secrets path/to/client_secret_XXXXX.json --scope https://www.googleapis.com/auth/assistant-sdk-prototype --save --headless
Install the final two dependencies.
$ sudo apt-get install portaudio19-dev libffi-dev libssl-dev
$ pip install --upgrade -r requirements.txt

The directory contains a python file called audio_helpers.py. The code basically records an audio clip for five seconds and plays it back.

$ python audio_helpers.py

Finally, run the push to talk sample. The sample records a voice query after a keypress and plays back the Google Assistant's answer:

python -m pushtotalk

This helps us do a simple speaker and microphone test, just to make sure that the hardware is functional.

$ speaker-test -t wav
$ arecord --format=S16_LE --duration=5 --rate=16000 --file-type=raw out.raw
$ aplay --format=S16_LE --rate=16000 --file-type=raw out.raw

If there is an error that says a certain package is missing, check the path of the imported packages in the code and make sure they are in the right place.

Finally, if you are experiencing choppy audio or any discontinuities in the responses, these commands should help. They basically adjust the sound device’s block size. The appropriate size depends on the hardware so you may have to try more than one to get it right. For example 0,1024, 2048, 3200, 4096.

$ python pushtotalk.py --audio-block-size=0