# Handle Commands

> [!WARNING]
> **Warning:** The Google Assistant Library for Python is deprecated as of June 28th, 2019. Use the [Google Assistant Service](https://developers.google.com/assistant/sdk/guides/service/python) instead.

<br />

Follow these instructions to execute custom code on your device in
response to commands from the Google Assistant.

## Run the sample

Now that you defined a trait and updated the model, check to make
sure the Google Assistant is sending back an On/Off command for the appropriate
query.

```
googlesamples-assistant-hotword --device-model-id my-model
```

Try the following query:

*Ok Google, turn on.*

You should see the following statements in the console output. If you don't, see
the [troubleshooting instructions](https://developers.google.com/assistant/sdk/guides/library/troubleshooting#traits).

    ON_RECOGNIZING_SPEECH_FINISHED:
      {'text': 'turn on'}
    ON_DEVICE_ACTION:
      {'inputs': [{'payload': {'commands': [{'execution': [{'command': 'action.devices.commands.OnOff',
      'params': {'on': True}}], 'devices': [{'id': 'E56D39D894C2704108758EA748C71255'}]}]},
      'intent': 'action.devices.EXECUTE'}], 'requestId': '4785538375947649081'}
    Do command action.devices.commands.OnOff with params {'on': True}

You will find where these statements are printed in the source code.

## Get the source code

You are now ready to start your own project:

```
git clone https://github.com/googlesamples/assistant-sdk-python
```

## Find the command handler

The `hotword.py` file in the sample code uses the SDK to send requests and
receive responses from the Google Assistant.

```
cd assistant-sdk-python/google-assistant-sdk/googlesamples/assistant/library
```

```
nano hotword.py
```

Search for the following handler definition:

    def process_event(event):

Currently, this function prints out every Device Action event name and any
parameters with the following line:

    print('Do command', command, 'with params', str(params))

This code handles the command `action.devices.commands.OnOff`. This
command is part of the [OnOff](https://developers.google.com/assistant/sdk/reference/traits/onoff)
trait schema. Currently, this code just prints output to the console. You can
modify this code to do whatever you want on your
project. Add the following block under the `print` command in `process_event()`.

```python
print('Do command', command, 'with params', str(params)) # Add the following:
if command == "action.devices.commands.OnOff":
    if params['on']:
        print('Turning the LED on.')
    else:
        print('Turning the LED off.')
```

Run your modified source code directly to see the output.

```
python hotword.py --device-model-id my-model
```

Use the same query as before:

*Ok Google, turn on.*

If you [connected an LED](https://developers.google.com/assistant/sdk/guides/library/python/extend/install-hardware)
to the Raspberry Pi, keep reading to learn how to light the LED in response to
the OnOff command. If you did not, skip the next section to learn how to
add more [traits and handlers](https://developers.google.com/assistant/sdk/guides/library/python/extend/add-trait-and-handler).

## Next steps - Raspberry Pi

Now that you know how to handle the incoming command, modify the sample code
to light an LED. This will require some additional hardware if you are using the
Raspberry Pi.

### Import the GPIO package

To simplify software access to the General Purpose Input/Output (GPIO) pins on
the Raspberry Pi, install the [RPi.GPIO](https://pypi.python.org/pypi/RPi.GPIO)
package in the virtual environment.

```
pip install RPi.GPIO
```

### Modify the sample

Open the `hotword.py` file.

```
nano hotword.py
```

In the `hotword.py` file, import the [RPi.GPIO](https://sourceforge.net/p/raspberry-gpio-python/wiki/BasicUsage)
module to control the GPIO pins on the Pi. Place the following statement near the
other `import` statements:

    import RPi.GPIO as GPIO

Modify the code to set the output pin initially to the low logic state. Do this
in the `main()` function, before processing events:

```python
with Assistant(credentials, device_model_id) as assistant:
    events = assistant.start()

    device_id = assistant.device_id
    print('device_model_id:', device_model_id)
    print('device_id:', device_id + '\n')
    GPIO.setmode(GPIO.BCM)
    GPIO.setup(25, GPIO.OUT, initial=GPIO.LOW)
        ...
```

> [!NOTE]
> **Note:** This sample uses the `GPIO.BCM` option, which refers to pins by their Broadcom [numbering](https://pinout.xyz). BCM 25 refers to physical pin 22 on the Raspberry Pi 3.

Modify the code you added in `process_event()`. When the on command is received,
set the pin to the high logic state. When the off command is received, set the
pin to the low logic state.

```python
if command == "action.devices.commands.OnOff":
    if params['on']:
        print('Turning the LED on.')
        GPIO.output(25, 1)
    else:
        print('Turning the LED off.')
        GPIO.output(25, 0)
```

Save your changes and close the file.

### Run the sample

Run the modified sample code.

```
python hotword.py --device-model-id my-model
```

Use the same query as before. The LED should turn on.

That's just the beginning. Learn how to add more [traits and handlers](https://developers.google.com/assistant/sdk/guides/library/python/extend/add-trait-and-handler).