MIDI Project - Progress

February 8, 2021
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Tangible Interaction

1 Circuit Design

As planned last week, the first thing I did was to change codes so as to enable chords. I separated the detection phase and sending-message phase apart so that Arduino can trigger more than one notes at the same time.

Here is the new code. Below is the effect of new code.

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The diameter of the enclosure I used was less than 20 cm. So I had to move the circuit to PCB to make it more compact.

Here is the PCB.

Testing video of the PCB board can be seen below.

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2 Panel Design

I spent tons of time just to drill standard holes on cardboard to let the light go through holes. However, it was way to hard to drill holes in exact same size and it was extremely time-consuming. I missed the quick and nice laser cutter SO MUCH. To fasten the speed, I decided to hollow out the cardboard and covered another piece of plastic paper above where I can easily drill holes. It still cost me more than 3 hours to measure and cut holes.

The round panel

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I put the PCB board below and tried to cover the holes by black dots drawn by markers on a plastic wrap. It was, however, too transparent to block the light going through. So I changed the material to plasticene.

Inner structure (still testing)

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3 Next Steps

I didn't add the supplementary light yet, but there are still lots of improvements to be done.

Note: * means required next steps.

  1. Problem: Supplementary light not provided.
    Solution: (1)* Add bright and stable light on the device; (2)* add a potentiometer as light sensor calibrator to adjust the sensitivity to light.
  2. Problem: Notes not sensitive to be triggered when the panel is spinning.
    Possible Reasons: (1) holes are not aligned with the light sensors. (2) could be the problem with code (need testing); (3)light sensors are too far away from the hole.
    Solution: (1)*Change lazy susan; (2) double check and test the code.
  3. Problems: It is not stable when spinning. & lazy susan is too big.
    Solution: (1)* change lazy susan.

I bought a new lazy susan which had different structure from the one I used now. It enabled me to put the pcb board in the middle so that the board can get close to the round panel.

New lazy susan
The PCB board is 5cm wide. So it's good to fit into the inner diameter.
Inner structure of the MIDI box
  • Next, I need to fix all the problems above, and start to build the second prototype using new lazy susan. Since the new lazy susan won't arrive till next Wednesday, I need to fix code problems first and use cardboards to represent the size and shape of new lazy susan. And then wait to make the second true prototype.
  • And I bought steel bearing balls to replace the role of plasticine. Hope it arrive soon.

4 Questions

  1. How to build a stable cylinder using cardboard?
  2. How to drill holes well and quickly?

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