How Can I Make a Wearable Metronome?

CPX, also known as the Circuit Playground Express, is a design board that consists of processors, different sensors, LEDs, USBs, and more. This year, I was challenged to make wearable technology combined with embroidery and coding with the CPX. This project implemented our prevalent use and dependence on technology which can make our lives more convenient and efficient. With only 5 simple steps, let me show you how to make a wearable metronome with the CPX.

• Cotton blend fabric (15cm x 7.5cm)
• Neoprene fabric (7.5cm x 7.5cm)
• Binder clip - to support the fabric when sewing (*optional)
• Needle
• Thread
• Pair of scissors
• CPX
• Small batteries (AAA): 3 & Battery pact
• Adapter (*may or may not be used)
• Pencil/Erasable pen

To start making a wristband, we have to sew the ends of the cotton blend fabric. With a 5cm width and a 7.5cm length, the embroidery involves a backstitch.

• How do we do a backstitch?
• After threading the needle, poke the needle up from the back of the fabric.
• Then, poke the needle down to the fabric of the starting point.
• From the starting point, poke the needle up from the back of the fabric. But this time, the needle should poke 0.3cm apart from the first insertion point.
• Repeat this process several times until you reach the end of the fabric.
• When reaching the end-line, tie the knot of the thread to make it steady.
• Repeat the above processes four 4 times on every 4 sides.

*During the stitching process, you can use a binder clip to stabilize your fabric*

After finishing making a wristband, start sewing a back pocket to keep the CPX battery.

• With the same backstitch technique explained in Step 1, sew only 3 sides.
• The top of the side is left unsewn to provide a space to place the CPX battery.

After finishing sewing both the wristband and the back pocket, the CPX needs to be sewn opposite of where the pocket is sewn. As we are not applying a tactile technique in the CPX, the thread does not have to be conductive.

• How do we sew a CPX?
• Firstly, the CPX will be sewn through the holes by poking a needle from the back to the front several times for each hole.
• Then, alternatively sewing the needle back and forth will make the CPX steady in the wristband.

As the CPX is attached to the wristband, the next step is to generate a CPX code from the website, Makecode. The website provides a code for making a metronome in the CPX, however, there are more options that can improve the metronome.

• How do we make the code for a CPX that works as a metronome?
• By placing the loops code ('forever') with music codes ('playing tone' & 'resting'), the beats of the metronome can be generated with ease.

EX) forever(function () {

music.setVolume(255)

light.showRing(

`red pink purple blue yellow red pink purple blue yellow`

)

light.setBrightness(200)

music.playTone(466, music.beat(BeatFraction.Quarter))

music.rest(music.beat(BeatFraction.Half))

music.rest(music.beat(BeatFraction.Quarter))

music.playTone(466, music.beat(BeatFraction.Quarter))

music.rest(music.beat(BeatFraction.Half))

music.rest(music.beat(BeatFraction.Quarter))

music.playTone(466, music.beat(BeatFraction.Quarter))

music.rest(music.beat(BeatFraction.Half))

music.rest(music.beat(BeatFraction.Quarter))

music.playTone(466, music.beat(BeatFraction.Half))

music.rest(music.beat(BeatFraction.Half))

})

• To change the tempos, you have to add another block from the input codes ('On {button A/B} {click}'), to give access to buttons that can alternatively provide two different kinds of metronome tempos.

EX) input.buttonA.onEvent(ButtonEvent.Click, function () {

music.changeTempoBy(-20)

})

• In this case, I changed the tempos with a 40 (bpm) gap.

*To improve your metronome, there are optional codes such as color lighting.*

• What do we do after making a code for the CPX?
• After finishing making the code for the CPX, connect the CPX to your laptop either with or without an adaptor.
• Download the code, and move the file to the disc (CPLAYBOOT) that appears on the screen.
• Then, the code is finally on your CPX!

After finishing all the steps above until Step 4, you can additionally add decoration around the CPX with embroidery skills. In this case, I sewed patterns of music notes since the project is related to music. For the music notes, a satin stitch is employed.

• Then, how do we do a satin stitch?
• Before starting sewing, outline the design with a pencil or an erasable pen.
• Then, start sewing by taking the needle down straight across the starting point.
• Next, bring the needle up to where you have started, near where the needle came up on the previous step.
• Take the needle down straight across from where you have sewn in step 3.
• Repeat these processes several times and the stitching can be fully filled up.

Coming to this step, the project is finally complete!

The wearable metronome CPX allows us to challenge ourselves to implement technology and our embroidery skills. This is just the start of how many innovations are made and in fact, you can try making your own wearable tech applications that are more sophisticated and efficient in our daily lives.