Turn your bicycle into a Pokebike with DJ Harrigan’s MKR Zero device
June 16th, 2021—
Within the Pokemon series there exists a special bicycle that plays a little tune when ridden, and this is what element14 Presents’ DJ Harrigan was trying to recreate with his DIY Pokebike project. It has a simple purpose: play a song and increase its volume while accelerating and then decrease the volume and eventually stop playing it once the bike comes to a halt.
The circuit uses an Arduino MKR Zero to handle all of the inputs and outputs, and with an onboard microSD card slot and the ability to output digital I2S audio, playing music is easy. Speed is determined by a Hall effect sensor and magnet pair that sends a pulse whenever the wheel has made a rotation. By tracking how many rotations have been made in a second and seeing the changes between these values, acceleration can be derived.
Harrigan then designed and 3D-printed a simple enclosure that houses all of the circuitry, including a battery pack. The front is shaped like a Pokeball, and it has an illuminated push button that allows for the user to interact with it. Finally, there’s a small speaker at the back connected to an I2S amplifier that takes signals from the MKR Zero and converts them into sound.
With everything assembled and programmed, Harrigan had to make a slight modification as the wires coming from the hall effect sensor were unsightly, so he just made the pushbutton on the front toggle the sound on or off manually. Even though some adjustments were made, the project still turned out well, and you can read more about it on element14.