This 3D printed heart beats rhythmically, powered by a servo motor and a Circuit Playground Express board connected to a potentiometer, which allows the user to increase or decrease the heart rate.

This spooky installation is a great introduction to coding with MakeCode and is a fun way to freak out your next guests!

Parts

Materials

In addition to the electronics, for this project you will also need:

• Scrap cardboard
• Hot glue gun
• Scissors and/or hobby knife
• Red panty hose
• Access to a 3D printer

Read on to learn how to build your own!

Power Supply

Circuit Playground Express can use a variety of power sources, anywhere between 3V-5V is safe. This compact 2200mAh lithium ion cylindrical battery is excellent for powering projects like this. 

A set of 3 AAA batteries also provides ample power, if that option is more convenient. If you're using a AAAx3 battery pack, check that the switch on the battery pack is set to "ON".

- OR -

Getting Familiar

This project runs a simple Microsoft MakeCode sketch to control the helmet, and is easy to play with if you want to make changes.

Microsoft MakeCode for Adafruit is a web-based code editor that provides a block editor, similar to Scratch or Code.org, and also a JavaScript editor for more advanced users.

If you've never used the Circuit Playground Express with MakeCode before, this guide is a good place to start.

The Code

The code is shown below. For browser viewing, you may need to enable content. For example, in Chrome, click "Show Embedded Content" as the material is fed not from Adafruit but from Microsoft's MakeCode site.

To download the code, click the download link at the bottom of the window. To edit the code in MakeCode, click the box with arrow icon in the upper right corner of the window.

How to Upload Code

To upload code to Circuit Playground Express, follow these instructions:

1) Connect your Circuit Playground Express to your computer using a known, good data+power micro USB cable and press the small reset button in the center of the board. All the LEDs will flash red briefly, then turn green. Your computer should now show a removable drive called CPLAYBOOT. 

2) Click the Download button in the code window below to download the .UF2 file to your computer.

3) Now drag and drop the .UF2 file onto the CPLAYBOOT drive in your computer's file explorer or finder.

Once the file is dragged onto CPLAYBOOT, the drive will automatically eject itself (your computer may give you a "failed to eject drive correctly" error, you can ignore this). The code is now on your Circuit Playground Express and ready to run!

Note: If you get a drive named CIRCUITPY, no worries! Press the reset button twice to get a flash drive named CPLAYBOOT. The project will not run if copied onto the CIRCUITPY drive as it is for CircuitPython.

What does this code do?

In the forever loop, we tell the pixels to turn red and change their brightness in accordance with the sound level.

The servo is set to rotate at a speed that is set by the position of a potentiometer with 0 being fastest and 90 being a standstill. 

Troubleshooting

Problem: My motor doesn't move!

Solution: Make sure that your Circuit Playground Express is connected to a power source (anywhere between 3V-5V is safe). If you're using a AAAx3 battery pack, check that the switch on the battery pack is set to "ON". If you are using the LiPo battery, be sure it is fully charged using the charger in the Featured Products.

Problem: My Circuit Playground Express doesn't show up as CPLAYBOOT

Solutions:

1. Be sure you have a Circuit Playground Express.  The Circuit Playground Classic will not work with MakeCode.
2. If you get a drive named CIRCUITPY instead, press the reset button twice in succession to get to CPLAYBOOT.
3. Some USB cables are "charge-only" and won't pass data. Try using a different USB cable and try using a different USB port on your computer.  
4. With the Circuit Playground Express plugged into your computer with a micro USB cable, click the small reset button in the center of the board. The lights should all turn green. If they don't, try double-clicking the reset button.

If things still aren't working, head over to the Intro to Circuit Playground Express guide for more suggestions.

More MakeCode!

If you enjoy MakeCode and want to continue exploring you can check out lots more MakeCode projects on the Adafruit Learn System.

The 3D files for this project can be downloaded by clicking the button below.

This design for this project is based on the hollow anatomical heart model created by Brian Locicero.

Print Settings

Each of these quadrants requires some support. This project prints well with the following settings:

• 0.2mm Layer Height / 0.4mm nozzle
• 80mm/s printing speed
• 20% infill
• Supports: Yes

Once the heart pieces are printed, it's time to mount and motorize them! 

For this step in the process you will need some scrap cardboard, scissors/hobby knife, and a hot glue gun. 

Now is a good time to connect your servo motor to Circuit Playground Express and test out its functionality.

Once the base is ready, it's time to prepare the heart for mounting.

At this point, you may want to give your beating heart a place to live. A small box works well to contain the electronics and give a stable platform for the heart as it beats.

This one uses the Adafruit shipping box that came with the parts, but any base or box will do.

That's it, adjust the potentiometer to vary the beating frequency.