Get Rid of Some Nervous Energy with a DIY Electronic Fidget Cube

The purpose and some initial ideas

When a bout of nervous energy suddenly strike, many people find themselves turning to small fidget toys to release it. In the latest episode of the element 14 Presents series, regular host Katie Dumont wanted to come up with her own version that incorporated several different audio, visual, and tactile experiences into a single entertaining cube. From the very beginning, she planned to incorporate six unique sides that could all be fed from the same power source and not depend on each other in order to function as intended. The cube's faces would also rely on input from the user and provide a rewarding output in response.

Showing the current status

For Dumont's fidget cube's first face, she decided to go with a simple "instant gratification" button that simply toggles on or off a ring of LEDs. In addition to the button, she placed a switch that controls power going to the device and an additional button that must be pressed in order to turn the entire cube on. This same PCB also housed the power management circuitry which takes in power from a lithium polymer battery cell, boosts its voltage, and then divides it amongst the other faces of the cube. When the battery's voltage drops too low, a smaller red LED on the front lights up to alert the user.

Drawing images on an LCD

The fidget cube's second face was quite a bit more complex than the previously described one, since instead of using a few LEDs and a button, this panel featured an LCD, microcontroller, and tiny joystick that can all be used together to draw a picture on the screen. The underside of the PCB contains an AVR64DA32 IC which was responsible for taking in inputs from the 5-direction switch (up, down, left, right, and a vertical press) and plotting dark pixels onto the OLED module. An auxiliary button was then positioned next to the multi-directional one which is used to clear the display.

Playing with logic gates

The third side was probably the most involved, as it not only contains an identical AVR64DA32 microcontroller as used in the previous face, but also has a series of six LEDs that act as a display for a binary counter and several other LEDs that show outputs for various logic gates. For example, not pressing either button on the PCB will cause XNOR, NAND, and NOR to all light up.

Building a case and assembling it all together

With three of the PCB faces completely designed and fabricated, Dumont then moved onto the tedious step of taking each individual component and soldering it by hand to its correct location. Next, she 3D printed a simple case that lets each PCB slot into one side and performed a test fit.

Final result

After loading code onto each microcontroller and testing the boards on their own, the fidget cube was put together and powered on as a whole unit for the first time. As can be seen in element14's video here on YouTube, the three faces of the cube worked exactly as intended, and Dumont plans on eventually designing three more to complete the cube. You can download the design files for this project here on Github or view the bill of materials here on element14's blog post.