Trash Fish is a fun and inventive use of scrap materials, brought to life by Circuit Playground Express!

This glowing mechanical creature is programmed using MakeCode, making it accessible for beginners and easy to adapt. Aside from the electronics, this fish can be created using household materials and requires no soldering.

Other Materials

• Cling wrap or scrap plastic sheet
• Clear packing tape
• Scrap corrugated cardboard
• Hot glue gun +  Hot glue sticks 
• Pipe cleaners
• Plastic straws
• Double sided tape
• Hobby knife
• Bamboo skewers

Getting Familiar

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.

Uploading Code to Circuit Playground Express

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

1) Connect your Circuit Playground Express to your computer using a 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.

Editing the Code

If you'd like to play with this code, click Edit in MakeCode and a new window will open in which you can create your own version.

MakeCode is fun to work with and easy to customize, allowing you to get some great results with just a little trial-and-error.

If you'd like to program your fish to swim faster or slower, you can change the number in the servo write pin A1 block (the further from 90 the faster the servo will spin). You can see in the example below that the fins are programmed to flap quickly when the slide switch on the board is moved right, and move slowly or stop altogether when the switch is moved left.

The rate at which your fish changes color can also be modified by changing the pause value in the forever block.

The circuit for this project is quite simple, just connect the Vout pad on Circuit Playground Express (CPX) to the servo's red wire, the A1 pad to the yellow wire, and the GND pad to the brown wire. 

The alligator clip-to-male jumper wire connectors are great for connecting servo motors to CPX.

Circuit, Simplified

If you'd like to forgo the NeoPixel strip and just create a mechanical swimming fish, you can opt to connect just the servo to your Circuit Playground Express, clipping the alligator clips to pads Vout, A1, and GND.

Powering the Fish

Circuit Playground Express can use a variety of power sources, anywhere between 3V-5V is safe. These compact 400mAh lithium ion polymer batteries are excellent for powering small 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" when you want to power the boat.

Set these fins aside, they will be glued onto the the fish in the final steps. 

Your frame should now be ready to install inside the fish shell!

Finally, bring the two halves of the fish together, enclosing the electronics inside.

Use some large dabs of hot glue around the outside edge to hold the halves together. Glueing a JST extension power switch to the underside of the fish can help make it easy to turn on and off.

Troubleshooting

Problem: My motor doesn't turn!

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".

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

Solutions:

• Be sure you have a Circuit Playground Express.  The Classic will not work with MakeCode.
• 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.  
• With the Circuit Playground 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.