Assistant Candy Dispenser

Ok Google, give me Candy!

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What you need

• Rasperry PI board (Pi 3/Pi 2/Pi Zero);
• USB Webcam;
• A Candy Dispenser;
• Servo
• Optionally: some candies :)

How to Install

Assistant Candy Dispenser is based on GassistPi, a project that enables Google Assistant and other additional features on Raspberry PI Boards. We decided to use it because it's faster to configure and provides a good starting point to hack on the Assistant Platform using the official Assistant SDK.

Before starting, please configure a working instance of GassistPi following the instructions here. We tested this on GassistPI v2.0 and a Raspberry Pi 3.

Customize trigger invocation

Once you've configured GassistPi, you need to make some changes to its scripts. By default, GassistPi already supports a few commands that will enable PIN on Raspberry to control a led or a servo. For example, if you say:

Ok Google, trigger servo 90

Assistant will rotate the servo connected to your board by 90 degrees (default PIN for servo control is GPIO 27, but you can change this as well in actions.py.

We're going to change the invocation word from trigger to give me (the complete phrase will be "Give me a candy".

To do so, open the main.py script and add a new invocation on the event receiver:

 for event in events:
            process_event(event, assistant.device_id)
            usrcmd=event.args
            if 'give me'.lower() in str(usrcmd).lower():
                assistant.stop_conversation()
                Action(str(usrcmd).lower())

Add a new action "give me a candy"

Now that you have the custom trigger "give me", we need to create a new action as well that will control our servo. To make this happen, open the actions.py file.

You'll notice there's a method already written to control the servo. In fact, with SetAngle(angle) you can automatically control a servo connected to GPIO 27. If you need to change the pin, just edit the pin declaration at the top of the script:

# Servo pin declaration
GPIO.setup(27, GPIO.OUT)
pwm=GPIO.PWM(27, 50)
pwm.start(0)

Now, you need to declare your custom action. In the GPIO Device Control section, add a new condition:

def Action(phrase):
	if 'a candy' in phrase:
            # Do something

At this point, Assistant will automatically trigger your function when it recognizes Give me a Candy as voice input.

In our case we needed the opening angle to be at least 135 degrees to release the candies. After that, we wait 1 second for the candies to go out and then we close the hatch to stop the candies flow.

We can also add something the Assistant will say using the say() API.

Our code implementation is:

def Action(phrase):
    if 'a candy' in phrase:
            say("Here is your candy!!")
            SetAngle(135)
            time.sleep(1)
            SetAngle(0)

Wiring

Connect servo's three wires to 5V, Ground and GPIO27.

Example

We've provided our full main.py and action.py files for reference.

Sweet hacking!

Made by 2 Coffees 1 Tea(m) at GDG Bari.