Skip to content


Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time

Google Assistant SDK Demo: Mocktails Mixer

Make a DIY robotic mocktails mixer with the Google Assistant built in.

Google teamed up with innovation studio Deeplocal to create the Google Assistant SDK: Mocktails Mixer — a DIY robotic home bartender that whips up your favorite mixed drinks at your command and serves you a splash of small talk while you wait.


Project Information

  • Estimated time to assemble: 15 hours
  • Difficulty: Intermediate
  • Cost: About $570


  • Voice-controlled drink ordering (and chitchat!)
  • Modular design allows you to customize your Mixer to include as many ingredients and drink combinations as you choose
  • A model and inspiration for other projects that integrate the Google Assistant SDK

What You’ll Find

  • diagrams/
  • hardware/
    • cad/
    • laser-cut/
    • photos/
    • bill of materials
  • software/
    • arduino/
    • rpi/
    • gcf/
    • agent zip

What You'll Need

Before you get started, you should have a basic knowledge of soldering. You should also have access to a laser cutter. You can find all of the parts we used, along with the exact quantity, supplier, cost, and links to purchase here. Note: In general, we used parts that were readily available, but on the expensive side. This build could be completed with less expense if parts are sourced on Amazon/Alibaba or if lower quality parts are used. Note: All materials used in this build are rated as “food safe.” Liquid does not come in contact with any material that is not food grade safe.

Tools needed for the build are listed below:

  • Hand drill
  • Rubber mallet or hammer
  • Screwdriver set
  • X-ACTO knife
  • Soldering Iron
  • Wire cutters
  • Wire strippers
  • Scissors
  • Hex Key Set
  • Wrench Set

Building the Mixer Body

Step 1: Laser Cutting

Laser cut all 2D profiles into the acrylic sheets.

Note: DFXs are all in inches. Please scale according to input of laser cutter. See attached drawings for design guidance.

  • A. Top Panel- ¼ inch thick
  • B. Bottle Capture Panel- ¼ inch thick
  • C. Lid Capture Panel- ¼ inch thick
  • D. Drip Panel- ¼ inch thick
  • E. Pump-Relay Control Panel- ¼ inch thick
  • F. Pour Panel- ¼ inch thick
  • G. Bottom Panel- ¼ inch thick
  • H. Inside Side Panel- ¼ inch thick
  • I. Outside Side Panel-¼ inch thick
  • J. Inside Side Button Panel-¼ inch thick
  • K. Outside SIde Button Panel- ¼ inch thick
  • L. Front Panel- ¼ inch thick
  • M. Rear Panel- ¼ inch thick
  • N. Cup Indicator Panel- 1/16 inch thick
  • O. Arduino Top Plate- 1/16 inch thick
  • P. Arduino Bottom Plate- 1/16 inch thick
  • Q. Speaker Diffusion Level
  • R. Speaker Clear Level 16th- 1/16 inch thick
  • S. Speaker Black Level 8th- ⅛ inch thick
  • T. Speaker Black Level 8th 1- ⅛ inch thick
  • U. Speaker Black Level 4th 1- ¼ inch thick

Step 2: Assemble Bottle Holder Sub

Attach Top Panel with Bottle Capture Panel together with #10-32 x 1/2 inch length button socket cap and #10-32 x 1 inch length ¼ OD standoff.

On the other side, with Lid Capture Panel use 10-32 x ¾ inch length button socket cap fasteners (Optional - Double sided tape can be used to attach the Lid Capture Panel to the bottom of the Bottle Capture Panel).

Note: There is a ¼ inch overhang on the Top Panel. Rear panels are flush with the exception of the tabs.

Step 3: Assemble Pump and Relay Control Panel Sub

Note: To ensure pump tubing is food grade safe, please replace with Tygon Clear PVC tubing 3/32 inch ID x 5/32 inch OD (Hardness rating is “Soft” and durometer is 65A). The durometer is imperative to pump and tube life. This can be found on McMaster-Carr.

Install Food Grade Pump Tubing.

Remove cover from pumps by depressing snaps on both sides of pump head. Remove tubing that was placed in during shipment. Place food grade tubing into pump allowing 3 inches to remain outside the inlet and outlet of the pump. Also, be careful to not puncture the tubing when installing around the rollers.

Attach Pumps.

Use Pump/Relay Control Panel and attach the Peristaltic Pumps to the eight 1.10 inch diameter holes located on the panel. Use a #2-56 x ½ inch length Phillips pan head machine screw and corresponding nut to fasten the pumps to the acrylic. Place a #8 black rubber washer between the pump and acrylic to reduce vibration.

Attach Relays.

Attach the Beef Cake Relays directly above each pump on the Pump/Relay Control Panel. There will be a 4 bolt hole pattern. Use the #2-56 x ⅜ inch length ⅛ inch OD standoffs (Optional - You can use #2-56 x 1/2 inch length Phillips pan head machine screw and corresponding nut instead of the standoffs.) with number #2 washers underneath each hole before the standoff. Fasten each corner with a #2-56 x 5/32 inch length Phillips pan head machine screw. Note that the red led must be positioned toward the top of the acrylic sheet. Use a #2-56 x ⅜ inch length pan head Phillips machine screw and fasten relays from other side of acrylic.

Tip: When attaching the fasteners, washers and standoffs to the relays, allow them to be loose. This will help with easy alignment to the corresponding holes on the acrylic than retighten fasteners on relays.

Attach the Arduino and Amp Mount.

Place the arduino between the Arduino Top Plate and Arduino Bottom Plate. Also, place 4 #8 rubber washers in between to help keep the spacing of the board even. Using the #8-32 ¼ inch hex 3/8 length standoffs secure the assembly together with a #8-32 nut.

The 2 holes located on the Arduino Bottom Plate are for the Amp. Place 2 #2-56 ⅜ inch length ⅛ inch OD standoffs in place with corresponding #2-56 ⅛ inch length Phillips pan head machine screw. Use 2 more #2-56 x ⅛ inch length Phillips pan head machine screws to secure amp to mount.

Attach Raspberry Pi to Drip Panel.

Attach the Raspberry Pi to the underside of the Drip Panel. In the correct orientation, the board will be flipped upside down and the large hole will be towards the back left corner. Attach the board with 4 #2-56 X 5/32 inch length Phillip pan head machine screws to 4 #2-56 X ⅜ inch length ⅛ OD standoffs. This sub-assembly will attach to the four corresponding holes in the Drip Panel. Use another four #2-56 X 3/8 inch length Phillip pan head machine screws through the acrylic to the standoffs.

Wiring the Electrical System

Electrical System Overview

For a clearer view of the wiring diagram download the fritzing file.


The electrical system of the Mocktails Mixer uses two control systems. The first is a Raspberry Pi, which handles all of the communication with the Google Assistant SDK. The second is an Arduino Micro that controls the pumps and LEDs. Both of these systems are connected to each other over serial. The Raspberry Pi sends commands to the arduino about what lights and pumps to turn on and the Arduino executes them.

Outside of these two controllers, the Mocktails Mixer has four major hardware systems. They are Power, the Pumping system, Lights, and Audio.


The power system controls the flow of electricity in the Mixer. However, the Mixer uses two different voltages: 12V for the pumps and 5V for the other hardware. You can handle this by using a step-down voltage regulator or a dual-voltage power supply. These are both adequate for the basic build of the Mixer, but if you want to add extra flair (like more LEDs), you may need to use two separate power supplies. Our instructions and BOM use two power supplies.

Note: For safety, we recommend placing the power supply in an external enclosure to keep 110V away from the liquids in the mixer.


In this version of the Mocktails Mixer, we used eight (8) peristaltic pumps. These are rated and recommended for use at 12V, but you can run them up to 24V if you find that the pumps are running too slow. The pumps are all individually switched by a relay controlled by the Arduino Micro.


For visual feedback, we added an LED ring to the Mixer. We used the Adafruit Neopixel. It is very easy to wire and add additional rings, plus the library is easy to use. These draw a decent amount to amperage, so if you want to add more to your build, you will need to size your 5V power supply accordingly.


Last but not least, we used a USB Microphone to speak with the Assistant that is connected directly to the Raspberry Pi. The speaker is connected to the amplifier on the Arduino’s mounting plate. The amplifier is connected to the Raspberry Pi via a 3.5 mm headphone jack.

Electrical System Wiring Instructions

Step 4: Wire the Power Supplies

To wire the power supply, first connect the AC Lines to their terminals (Black to L or Load, White to N or Neutral, Green to Ground). Next, connect the DC power lines to power supplies. Note: To make the wiring easier to follow, we used red wire for all the 12V lines and green for all of the 5V lines. We kept the all of the Ground wires black because all devices will need to share Ground in order to communicate. Note: We also recommend using a lower gauge wire (12 or 14 gauge), for the DC power lines moving from the power supply to the terminal block or the wire nut, then using a higher gauge (20 to 24 gauge) for all of the other lines.

Step 5: Wire the Pumps and Relays

Before we start to wire the pumps and relays, first assemble the relays. We used the Sparkfun Beefcake relays for this build and the assembly instructions for them can be found here. We like them because they are easy to use and readily available—but cheaper alternatives are available. Next, mount all of the pumps and relays to Pump-Relay Control Panel.

Now we are ready to wire the pumps and relays. First connect the 5V lines to the 5V Terminal on the relays. We daisy chained the lines across the relays to reduce the amount of wires going to the main 5V terminal.

Similarly to the 5V power, connect the Ground wires to the GND terminals on the relays, also daisy chaining them. Next, connect the control lines from the CTRL terminal on their respective pins on the Arduino. To make connecting the control lines to the Arduino easier, we waited until they were all plugged in before we mounted the Arduino; this way we could still read the pin locations on the back or reset the Arduino if necessary.

The pin-outs for the Arduino are:

  • Pump 1 Relay to Pin 2
  • Pump 2 Relay to Pin 3
  • Pump 3 Relay to Pin 4
  • Pump 4 Relay to Pin 5
  • Pump 5 Relay to Pin 7
  • Pump 6 Relay to Pin 8
  • Pump 7 Relay to Pin 9
  • Pump 8 Relay to Pin 10

Note: Do Not use Pin 6 to trigger a relay. We reserved that pin to control the lights because it is the PWM pin on the Arduino.

To provide power to the pumps, connect the 12V lines to the COM terminal on the relay (also daisy-chained), then connect the Positive (red) terminal of the pump to the NO terminal on the relay.

Finally, to wrap it all up, connect the Ground lines to the Negative terminal on the pump. Since the four pumps on the right side of the Mixer are mounted in reverse, we need to change the rotation of the pump to also be reversed. To do this, we just switch the Ground line to the Positive terminal and the Power line from the relay to the Negative terminal.

Step 6: Wire the LEDs

Wiring the NeoPixel LED ring is very easy. Just solder our data line from PIN 6 on the Arduino to the DIN pin, then connect our 5V line to 5V and the Ground line to GND. If you would like to add more LED rings, all you need to do is wire the DOUT from the first ring to the DIN of the next ring. Then, just connect the 5V and grounds on both rings together.

Step 7: Wire the Audio

Since the microphone is USB controlled, there is no wiring necessary. However, the speaker needs to be hooked up to the Amp, then to the Raspberry Pi.

First, complete the assembly of the amplifier, by soldering the headers and terminal block to the board. Next, we’ll connect the Ground line to the Ground pin on the amp, then the 5V Line to the 2-5V pin on the amplifier. Using the audio cable with the 3.5 mm jack, connect the positive line to the A+ pin, then connect the negative line to the A- pin. If your cable has a ground cable, connect it to the Ground pin as well. Now all we need to do is connect the speaker. Connect the speaker’s positive and negative wires to their respective terminal on the amp. Slight interference can occur on the speaker, because of this we recommend you add a capacitor between the A+ and A- pins.

Final Connections

To power the Raspberry Pi, connect a Ground line to a ground pin on the Pi, then connect a 5V line to the 5V in on the Pi.

To activate the Assistant, there is a button on the side for you to push. To wire this button, connect the COM terminal to the 3.3V Out on the Raspberry Pi. Then, connect the NO terminal on the button to the button’s respective GPIO (in our case GPIO 7). For a cleaner signal, connect a resistor between the NO terminal and Ground.

Double check the wiring. Trace all of them from each piece of hardware to their source. Once you feel good about the wiring, go ahead and power up the system. The Raspberry Pi should have a red power light visible and the Arduino should have a blue power light visible as well.

Building the Mixer Body Continued

Step 8: Assemble Pump Control Center Sub

Assemble Pump/Relay Control Panel between Drip Panel and Pour Panel with corresponding tabs and slots on each sheet of acrylic. Make sure the pumps and relays that face the front of the unit are in front of the pour holes in the center pour plate. Use 10-32 standoffs and 10-32 fasteners to bring the sub-assembly together. A #10-32 X ½ inch length of all thread will be used to bring the #10-32 X 2 inch length standoff and #10-32 X 3 inch length standoffs together.

Step 9: Assemble Side Panel Sub

Attach Outside Side Panel to Inside Side Panel using the #8-32 binding posts (Optional - You can omit these from the build. They help with holding the side panels together while assembling). The flat side of the binding post should face the Inside Side Panel. Six of the binding posts will be used per Side Assembly. Repeat with Inside Side Button Panel and Outside Side Button Panel. The side panel assembly with the button will be on the right side of the unit when looking at the unit from the front.

Step 10: Assemble Cup Indication on Bottom Panel

Attach Cup Indicator Panel to Bottom Panel with #8-32 Low Profile Binding Barrels. (Optional - Cup indicator helps a user where to place their cup but is not necessary in the assembly).

Step 11: Bring all the Sub-Assemblies Together

Begin by laying a Side Assembly on its face with slots facing upwards. This will allow for easy installation of the other components.

Attach Bottle Holder Sub-Assembly to the top of the Side Panel Assembly by aligning the slots. Note that the tabs in the rear must face the rear of the unit.

Next, attach the Pump/Relay Control Panel Sub-Assembly right below the Bottle Holder Sub-Assembly, noting that the tabs will align like before. Note that the pumps must be facing towards the front of the unit and the electric motor faces the rear. The front of the unit can be determined by the amount of space between the slots and the edge of Side Panels—the larger gap indicates the front of the unit.

Attach the Bottom Panel to the last two remaining slots towards the bottom of the Side Panel Assembly.

Attach the other Side Panel Assembly, mating all tabs and slots. Use the #10-32 X 1 inch length button socket cap and corresponding square nuts to secure the unit. There are six of these per side.

Rotate the unit 180 degrees and fasten the other six fasteners. Tip: Be careful when rotating the unit and make sure to firmly hold the two side panel assemblies together. A second person may be helpful here.

Step 12: Cut and Fit Fluid Delivery Tubes to Length and Install

Begin by taking the ¼ inch OD tubing (food safe) and run it from each pump up through the holes in the Drip Panel. Leave an additional 8-10 inches of extra tubing to easily remove a bottle.

Next using the tube connectors run the ¼ inch OD tubing (food safe) from the pump outlet to the pour holes in the center of the Pour Panel. The tubes will fit snuggly in each of the 8 holes. They are made to have a slight interference fit.

Step 13: Assembly Speaker Sub

Assemble speaker panels together through the Front Panel with #4-40 X 1.25 inch length Phillips head machine screws and corresponding nuts. Layer the Speaker Sub Assembly in the following order as pictured below.

Step 14: Attach Front Panel to Unit

Attach Front Panel to unit with 10-32 x ¾ inch length button socket cap and corresponding square nuts. There are two of these that hold the panel in place. Tip: Use a piece of Painters tape to hold the square nuts in place until fasteners grab. Tape can be removed after through the bottle holes.

Step 15: Attach Rear Panel to Unit

Align the Rear Panel with the corresponding slots and tabs on the rear of the unit. Once again, use the #10-32 x ¾ inch length button socket cap and respective square nuts.

Bottle Build

Step 16: Cut hole in bottle seal

Use an X-ACTO knife to carefully cut a round hole in the center of the bottle cap seal.

Step 17: Drill hole for tube connectors

Using a 0.15-inch diameter drill bit, drill two holes across from each other in the center of the lid. You can use an X-ACTO knife to deburr the edges around the hole.

Remove any loose debris after drilling. These holes will be used to attach the tube connectors.

Step 18: Attach Tube Connectors

Apply two rubber washers to each of the tube connectors.

Use a hammer and socket head to press fit the connector into the lid. You will hear an audible click when the connector is seated properly. This process will help ensure no leaking occurs.

Step 19: Attach Tubing and Check Valve

Cut a 2-inch length of ¼-inch OD tubing and attach it to the connector on the outside of the lid as pictured below.

Next, attach the check valve to the end of this tubing. Note the flow of valve going into the bottle. Air can only go in and liquid cannot come out.

Step 20: Place Bottle Assembly into Unit

Fill bottles with desired liquid, and before flipping over, attach the ¼ OD food safe tubing coming from the pumps to the open connection on the bottle.

Once this is done, carefully flip bottle over into one of the bottle holding locations.

Programming the Mixer

Mixer Programming Overview: How do the RPi and Assistant SDK communicate with the pumps?

  • The user presses the physical button to start the Google Assistant and speaks a drink request into the microphone.
  • The local Python application picks up the speech and transmits it to for processing using the Assistant SDK.
  • The agent parses the input, determines its context and intent, and processes the request.
  • For a drink request:
    • The agent uses a webhook to process the request.
      • The webhook is an external URL endpoint existing as a Google Cloud Function and written in Node.js.
      • Requests can also be fulfilled natively on the platform.
    • The webhook receives the make_drink intent and specific drink entity from the request, publishes the relevant info over a Pub/Sub route, and returns the response text for the user.
    • The local Python application receives and parses the Pub/Sub message, calculates how many seconds each relay should be turned on, and transmits those commands to the Arduino via serial.
    • The Arduino uses its GPIO to control the relays and dispense the drink.

Step 21: Create a Google Cloud Platform Project

  • Create a new project from the Google Developers Console
  • Locate your project ID in the dashboard and note for later use. (Read here for help)
  • Enable the Pub/Sub API and create a topic named "MocktailsMixerMessages" (Read here for help)

Step 22: Create Google Cloud Function

  • Clone the repository to your local machine.
  • Update “your-google-project-id” on line 7 of software/gcf/index.js.
  • Create a zip file including only package.json and index.js from the software/gcf/ directory.
  • Navigate to the Cloud Functions Console in a browser.
  • Ensure the correct project is selected in the dropdown at the top of the page.
  • Click “Create Function.”
  • Fill out the form with the following info:
    • Name: apiai-webhook
    • Region: (choose region nearest to your location)
    • Memory allocated: 128 MB
    • Timeout: 60 seconds
    • Trigger: HTTP trigger (Note HTTP trigger URL for later use)
    • Source code: ZIP upload
    • ZIP file: (choose ZIP file created above)
    • Stage bucket: (choose a bucket)
    • Function to execute: webhook
    • Click “Create”

Step 23: Set up an agent

Tip: You may want to review the Actions on Google developer guide for an introduction to conversational user interfaces.

  • Sign into the console.
  • From the agents page, click “Create Agent.”
  • Give your agent a name. Select “Private” and click “Save.”
  • Navigate to the Agent Fulfillment page.
  • Flip the enabled toggle on, enter the HTTP trigger URL from the Google Cloud Function in the URL field, and click “Save.”
  • Navigate to the Agent Settings page.
  • Select the “Export and Import” tab and click the “Import from ZIP” button.
  • Select the file from the cloned repository and import.
  • Navigate to the Agent Integrations page:
    • Flip the “Actions on Google” integration on and fill out the form.
    • Select “Authorize” and then “Preview.” Note: Previews are only available for a period of time. Use “Deploy” to register your conversation action with Google. The registration process can take one to two weeks. Read more here.
    • Test your agent on the Google Home Web Simulator.
  • Create an SD card with Raspbian Jessie with Pixel.
    • Download the compressed image and decompress the file. (This should result in YYYY-MM-DD-raspbian-jessie.img)
    • Insert 8GB+ microSD card into computer.
    • On a Mac, open Terminal and perform the following:
      • Find the correct disk using the command $ diskutil list. You’re looking for the entire disk i.e. /dev/diskN.
      • Unmount the disk using the command $ diskutil unmountDisk /dev/diskN.
      • Write the image to the disk using the command $ sudo dd bs=1m if=/path/to/YYYY-MM-DD-raspbian-jessie.img of=/dev/rdiskN. (Note the additional “r” in the output file path. Be patient - there is no feedback for this command and it can take several minutes. WARNING: $ sudo dd is a very powerful command so double-check you have the correct disk.)
      • When the image has been written, eject the microSD card and insert it into your Raspberry Pi.
    • For Windows instructions, see here
    • For Linux instructions, see here

Step 24: Follow steps in Getting Started with the Raspberry Pi and Python.

  • Before section “Connect to the Raspberry Pi via SSH,” you must enable SSH.
    • On a Mac, perform the following using Terminal:
      • Change directory to the root of the microSD card: $ cd /Volumes/boot
      • Create an empty SSH file with no extension: $ touch ssh
  • In section “Configure a new Python virtual environment”, we used Python 3.
  • Before section “Configure and Test the Audio,” plug in a USB microphone and 3.5mm speaker to your Raspberry Pi.

Step 25: Install Additional Raspberry Pi Libraries

  • Change directory: $ cd /home/pi/
  • Install RPi.GPIO: $ env/bin/pip3 install RPi.GPIO
  • Install python pubsub: $ env/bin/pip3 install google-cloud-pubsub
  • Install PySerial: $ python -m pip install pyserial --upgrade
  • Install PyAudio: $ python -m pip install pyaudio

Step 26: Clone code repository on RPi and move files into correct location

  • Change directory: $ cd /home/pi/
  • Clone repository: $ git clone
  • Update the PUBSUB_PROJECT_ID in mocktailsmixer/software/rpi/
  • Copy files into embedded assistant directory: $ cp -r mocktailsmixer/software/rpi embedded-assistant-sdk-python/googlesamples/

Step 27: Prepare Arduino

  • Load sketch onto board.
  • Connect to Raspberry Pi via USB.

Step 28: Run system

  • Ensure you are still in the Python virtual environment. If not: $ cd && source env/bin/activate.
  • Change directory: $ cd /home/pi/embedded-assistant-sdk-python
  • Run the auth_helper to create an authorization file: $ python -m googlesamples.rpi.auth_helpers --client-secrets /home/pi/client_secret_*.json.
  • Run the system $ python -m googlesamples.rpi.

Step 29: Configure your own drinks

  • Using the web console, update the agent’s @drink entity and make_drink intent to reflect the drink names.
  • On your Raspberry Pi, update the DRINK_SIZE, MENU and NUM_BOTTLES variables in bartender/

Step 30: Troubleshooting

  • If the LEDs or relays are not working, check the SER_DEVICE variable in bartender/

Example Transcript

(User presses physical button.)

User: Tell Mocktails Mixer to make me a cherry bomb.

Assistant: Coming right up. While I make your drink, would you like to hear the weather or your fortune?

User: How about the weather?

Assistant: What is your ZIP code?

User: 15212.

Assistant: The weather in Pittsburgh, PA is 75 degrees and sunny.

Cleaning Your Mixer

  • After use, empty your bottles from earlier contents and rinse with water.
  • Fill each bottle with water and run Mixer to clean lines of any residue that may be left behind. This will keep the Mixer clean and ready for the next time you change liquids.
  • Run the Mixer pumps until no liquid can be seen coming out. This will ensure no liquid is left in the lines.
  • Remove bottles from Mixer and allow them to dry after rinsing them out.
  • Periodically check all hoses and connections to prevent leaks from developing.


Make a DIY Robotic Mocktails Mixer Powered by the Google Assistant SDK







No releases published


No packages published