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applications and implications, project development

Topic(s) of this week

Hero shots

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Assignments

Individual assignment

Just as a note to what happened this week:
- LCD screen via SPI note working - I2C deadlock and pullup resistors

Propose a final project masterpiece that integrates the range of units covered.

Your project should incorporate:

  • 2D and 3D design
  • Additive and subtractive fabrication processes
  • Electronics design and production
  • Embedded microcontroller interfacing and programming
  • System integration and packaging.

Where possible, you should make rather than buy the parts of your project. See Final Project Requirements for a complete list of requirements you must fulfil. create your BOM (Bill Of Materials).

Tasks

Have you answered these questions?

  • What will it do?
  • Who has done what beforehand?
  • What will you design?
  • What materials and components will be used?
  • Where will they come from?
  • How much will they cost?
  • What parts and systems will be made?
  • What processes will be used?
  • What questions need to be answered?
  • How will it be evaluated?
  • Leave feedback in Nueval that this weekly is ready for evaluation.

Individual assignment

My final project proposal is in the documentation of my final project. As not to duplicate those notes in here, I’ll suffice with links to the relevant part of this documentation and images that are also already in the final project documentation.

Final project masterpiece

My final project is the Marimbatron, a MIDI-based musical instrument that you play with drumsticks and/or mallets. It supports an isomorphic key layout which maintains consistent musical intervals between keys, allowing for the same shapes to be used for chords and scales regardless of the root note. It also supports the traditional piano key layout. See here for more information: 00_marimbatron
The Marimbatron modular designed. Every octave is a fully self-contained module.
In total it consists of 76 fab-made pressure sensors with high-speed readout (200 us to read 19 sensors, 12-bit ADC). This will make it output MIDI data in less than 10ms, so no noticeable latency.

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  • Who has done what beforehand? See 02_prior-works
  • What will you design?
    • Everything :-) Well, maybe not the keycaps. But other than that: all designed by me. So lots of documentation. The Final Project documentation is therefore split into logical parts:
      • The pressure sensor is a fully selfcontained unit and therefore has its own page: 05_pressure-sensor
      • The mechanical design and fabrication documentation can be found here: 06_mechanical
      • The electronics design and fabrication documentation can be found here: 07_electronics
      • The programming of the embedded microcontrollers can be found here: 08_programming
  • What parts and systems will be made?
    • Everything part and subsystem of the Marimbatron will be made and integrated into one fully working unit.
  • What materials and components will be used?
    • Plywood for the fixtures
    • Recycled PLA (from failed 3D prints) for the top sheet
    • Polyurethane, PET sheets, graphite spraypowder for the pressure sensors
    • Flexible PCBs sourced at a PCB house, but also fablab-made using coppertape and Kaptontape
  • Where will they come from?
    • All these materials are sourced from contracted suppliers of our University
  • What processes will be used?
    • The Marimbatron is fully fablab-able and made using the following processes:
      • 2D design
        • most importantly the lasercut fixtures
      • 3D design
        • the sensor molds are 3D designed
      • Additive and subtractive fabrication processes
        • the sensor molds and keycaps are 3D printed
        • the sides are CNC milled
      • Electronics design and production
        • The 4 octave version contains 6 custom PCBs and 76 custom designed flexible PCBs
        • Prototypes of each PCB are milled in the Fablab and fully functional
        • Prototypes of the flexible PCB are cut on the vinylcutter using coppertape on kaptontape
      • Embedded microcontroller interfacing and programming
        • The 4 sensorboards contain a SAMD21J18A Cortex-M0+ microcontroller
        • The mainboard contains a SAMD21E18A Cortex-M0+ microcontroller
      • System integration and packaging
  • What questions were answered?
    • Can I make a fully Fablab-able digital intrument using pressure sensors (meaning can it fully be made in a Fablab, including the pressure sensors)? And yes, I can. Although the I ordered flex-PCBs from a PCB house, I did make the very same design using coppertape-on-kaptontape and that works. The weeding is no fun and I needed a lot, so that’s why I ordered them. I also ordered the sensor PCBs, but again, I also made a fully working sensor PCB using the same design in our Fablab.
  • What worked? What didn’t?
    • The vast majority works. I have a digital marimba that sends MIDI messages, it is pressure sensitive and it is fully Fablab-able. Really the only thing that I couldn’t get to work is the round LCD display. That is most probably due to faulty hardware, so it is on the list for future spirals.

The Bill Of Materials (BOM) including cost overview can be found here: 09_bill-of-material