Without further ado : here is the latest update in the ir photodiode based flat multi touch screen project

Ir_MultiTouch Prototype 2 from mark “ckaos” on Vimeo.

More info and another video after the break

-Some pictures of the prototype: (it’s 8*10 cm )-As you can see , even with “only” 40 photodiodes, it was a bit of scary to solder



Ir_MultiTouch Prototype 2 Reactivity from mark “ckaos” on Vimeo.

More info:


  • I use a staggered grid configuration for the layout of the photodiodes
  • I use a 74hc238 chip for two columns of photodiodes
  • The photodiodes are powered sequentially
  • And even more info:
    1. the setup is/will be endligten based/dsi (it works) although i cheated in this video i just inverted the data from the “IR Shadow” of my hand ( i accidentally ripped off the wiring from the IR Leds earlier today 🙁 but if anyone wants proof i have a video of the V1 prototype working with endlighten)
    2. the endlighten will be used both as IR Diffuser AND back-light, although that requires some more adjustment to work smoothly with this prototype (using an op-amp amongst other things ), but i can confirm it works.
    3. the whole system is about 4-5 cm thick (including screen , box, everything)
    4. the sensor matrix itself is about 1cm thick


  • this data is then sent to openCV for blob detection
  • I developed my own experimental tracker for processing , using openCV ( the tracked blobs are surrounded in green, on the right side of the screen)
  • in the videos above , it runs at 120fps although it might not seem that way since my camera doesn’t film that fast

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One thought on “Ir Multitouch Prototype 2

  • January 8, 2018 at 05:22

    Can you share me the instruction or arduino code Mr.?


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