Simulated Tachometer

Ever since I was a kid, I’ve loved cars — the sound of the engine, the feeling of movement, and the way everything seemed alive. I always wanted to bring that experience to life in my own way. Building a simulated engine let me combine that childhood passion with hands-on creativity, using technologies like MQTT to connect different parts and make the system feel truly interactive and alive.

Tools:

1. Laser Cutter
2. Computer (For programing)

Supplies:

1. LED Matrix - Link
2. Raspberry pi pico - Link
3. Breadboard - Link
4. AdaFruit Matrix Portal S3 - Link
5. 1/4 Inch Baltic Birch
6. Super Glue
7. USB-C power brick
8. USB-C to USB-C Cord
9. Lego
10. Key Lock switch - Link
11. Potentiometer (Wiring included) - Link
12. Jumper Cables to Aligator Clips - Link

To Setup the Matrix Portal and Pico, follow the instructions on the Adafruit website. Alternatively, for more visual learners, Prof G, Boston College Professor, has a great setup tutorial for a Adafruit Circuit Playground Blue-fruit. Follow this video, but instead of installing for the Circuit Playground, install the for the Matrix Portal. Additionally, it may be helpful to install other programs like Circup, to ensure all necessary libraries are up to date and available. (Link to installation tutorial here)

1. Go to Adafruit io and make an account
2. Navigate to the dashboard pane and create new dashboard
3. Once created, hit cog in the right side of screen then "Create New Block"
4. Choose the text box, and then create a new feed called "text_box"
5. then hit continue, and it should appear on your dashboard

*note: I already had this setup, so the parts will already be there for me in the video. But this should take you through the steps*

For more requests per minute from Adafruit IO, you can upgrade to the Adafruit subscription service.

This code works with MQTT protocol to send and receive data from a dashboard. Pico handles the engine "inputs" like the accelerometer and the ignition, while the matrix portal handles the display. Along with the code files attached each of your devices will need to have a settings.toml file set up to your local network and Adafriuit IO Username and key, which can be found when you click the yellow key icon on the Adafruit Io website.

I cant attach a .toml file, so you will have to make one but I have uploaded a screen shot of what it should look like. It must be called settings.toml or else the code will not work.

To add all of the libraries to your device, save the code onto your pico/matrix then open your code editor and in the terminal write the command "circup install -a". This will install all the needed libraries for you.

*Note: if you do not have Adafruit premium, I commented a line for you to replace in my matrix code with, so you do no throttle the Adafruit website.*

Pico

Potentiometer

1. Red (Power) --> 3V
2. White --> GP26
3. Black --> Ground

Key (does not matter which wire only that one touches ground and one signal)

1. GP16 (one alligator clip on one nub on the bottom)
2. Ground (the other alligator clip on the other nub)

LED Strip

1. Red (Power) --> VBUS / 5V
2. White --> GP2
3. Black --> Ground

Matrix

For power, screw down the wires provided with the display to their respective spots on the Matrix Portal:

1. Power: red - 5V
2. Ground: black - and

Then plug that connection into the middle port on the display with the label VOC GND under it. Congrats! you have power! For Data, take the Matrix portal and use the underside connection port, and plug that into the HUB75 port on the display. Congrats! you have data!

Because this was somewhat of a childhood dream of mine, I thought it would be fun to build this out of Legos, as they were what my toy cars would be made out of. These laser cut files will house both the pico and matrix portal, however, as they were not part of my project. If you are to build them, assemble with super glue and then mount the electronics inside.

If you are building with legos, assemble your containers with room for wiring in mind and then some minimal movement.

Place all electronics inside, and plug them in!

Thank you for following my Instructable, I hope you enjoy!