Touch-based synthesizer is a wiring nightmare

[Jane] wrote in to let us know about the touch-based synthesizer she and her classmates just built. They call it the ToneMatrix Touch, as it was inspired by a flash application called ToneMatrix. We’re familiar with that application as it’s been the inspiration for other physical builds as well.

A resistive touch screen in the surface glass of the device provides the ability to interact by tapping the cells you wish to turn on or off. Below the glass is a grid of LEDs which represent sound bits in the looping synthesizer track. Fifteen shift registers drive the LED matrix, with the entire system controlled by an ATmega644 microcontroller. Although the control scheme is very straight forward, the jumper wires used to connect the matrix to the shift registers make for a ratsnest of wireporn that has been hidden away inside the case. Check out the demonstration video after the break to see what this looks like and sounds like when in use.

Comments

  1. chango says:

    Is it still an LED matrix if each LED gets its own driver? Also the parallax coming from the big gap between the touch panel and the array looks like it could be problematic. The software looks pretty slick tho.

  2. evilspoons says:

    I’m surprised and happy for them that it works with that giant nest of wiring. However, my criticism is that when they’re playing with it in the demo video the actions it takes (notes it plays, whatever) don’t seem even remotely related to where the user touches the screen. Is it supposed to be random or is the touch panel just not being read accurately?

  3. Joe says:

    Umm, as stated above… Wouldn’t it be much more impressive if it actually did something in relation to the person touching it?

  4. That's my hand. says:

    The touchpad gets polled at regular intervals, toggling the grid location. If you move your hand too fast it won’t pick up on every “press”, and if you move your hand too slowly the grid location gets toggled on and then off before the next sequence. It takes a little while to get used to the timing.

    The yellow LEDs turn off for the corresponding coordinate so the user knows if a touch has been picked up.

    The mapping is a little off since we last calibrated, and the touchpad can slide underneath so the coordinates aren’t perfect, but it’s pretty accurate.

  5. Caleb says:

    From the look of the video it is responding to touch input properly, it just has a very slow update rate. Look at the LEDs around the edges, they match the position of her finger but only update and clock in the position at 1hz or so.

  6. Elias says:

    As other said the touch interface seems to respond very badly.
    Also, I’m afraid it sounds like crap too so something more senseful with maybe a bit of reverb and blending between the individual notes could work for a contraption like this.

  7. zool says:

    while the outside seems to correspond, the inside does not, or rather not in the way the flash version it’s based off of does

    seems like something that could be fixed in software
    i don’t think the touch screen is the problem,

    i don’t think you really need a touch screen for this, buttons are fine,
    it’s like a monome
    or if you want cheap, a bliptronic 5000

    http://www.thinkgeek.com/electronics/musical-instruments/c4e1/

  8. marto says:
  9. Bogdan says:

    It’s a real shame to wire those leds like that. I would rather spend 5 hours of thinking of a better solution and 1 for working than 6 for implementing the most obvious time consuming solution.
    But in this case… led matrices are like…. standard thing.

  10. svofski says:

    Just call the mess of wires an art piece and all criticism regarding the inefficiency of solution becomes irrelevant.

    > i don’t think you really need a touch screen for this, buttons are fine
    touch screens are cheaper that buttons. besides, imagine, how would it look if they wired each button in the same manner they have wired the leds?

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