Jump to content

LED touchpad


Julian

Recommended Posts

@northernlightX: It should work with any LED. As every LED is a photodiode for it´s own emitted frequency of light, the backscattered light is always the perfect one. So it should theoretically work with any LED.

I only can´t imagine that a controller based on this baby can consist of one PIC. I more think you will need more than one controller. One for the matrix scanning and one for the LCD/MIDI/comm etc. Or you would have to use a DSP (I guess they have in the video, or?).

Anyhow: It would be *** T O O O  C O O O O L *** to have something like that controlling your stuff. Possibilities for such a device are HUGE, I think. :D

Link to comment
Share on other sites

  • 2 weeks later...

:/

Like I thought: Here somebody really went deep in there and managed to get up to 30 LEDs running, but only with a master/slave solution: http://projects.dimension-x.net/archives/35 (In this pic only 8 LEDs are up)

Here is his (not fully implemented) idea of the 30 LED matrix: http://forums.linear1.org/index.php/topic,469.15.html (last page)

This guy uses 2 slaves and 1 master and states out that appr. 4 slaves can be used for appr. 60 LEDs (let´s say 64 just for coolness ;) ). So to have an full 8x8 LED touchpad you are very likely to need 4 slave-PICs (and NOT the cheap ones) and one master PIC for connecting the outer world (MIDI, LCD, perhaps RS232, comm to the slaves and stuff). btw: Funny thing is that the "slave" PICs have not one NOP operation to do as the master PIC has a NOP cycle of appr. 20-50 ms (!!!). ;)

I really really don´t know if this is worth the effort, if you know what I mean. :/ :/ :/

Anyhow STILL very interesting, perhaps there´ll be some solution nobody thought of in the next time... *peeeeerhaps* ...

Greetz for now! :)

Link to comment
Share on other sites

Easy: Yep. At least at the moment.

The human eye appr. has a scanning velocity of 40 ms (25 pics/second). So to bring up a "good" optical result, let's say maximum of 10 ms for a full scanning cycle is ok. For one LED he needs apr. 600 us, so eight LEDs use about 4,8 ms to get scanned.

He stated out to get some 16 ch bi-directional multiplexers in there, the only question is if this does not ruin the scanning speed (16 LEDs would be theoratically 10 ms without the communication with the multiplexer). This salve/master combination actually is something to get it running, but certainly not the last step. A multiplexer will just be more complex to implement, that's the reason it's not there yet. There'll be more, I think & hope.

Man, just thinking about getting in there, too... :) :) :D

I think I will get in touch with him. This topic just got me...

Link to comment
Share on other sites

I was considering the use of a single-dimension LED sensor, EG just a line, not a grid.

Doesn't have to be a straight line either... It could be really useful, think of it for replacement of pots/encoders and LEDrings... You could just have the LEDrings...

Link to comment
Share on other sites

I was considering the use of a single-dimension LED sensor, EG just a line, not a grid.

Doesn't have to be a straight line either... It could be really useful, think of it for replacement of pots/encoders and LEDrings... You could just have the LEDrings...

Wow, that's a pretty cool idea! I have a digital dashboard in my old car, and it would be awesome to recreate the rev-curve in leds on a midibox, which you could operate bij hovering your finger over it! Now I know what I'm going to do with my spare 5mm LED's  8)

Link to comment
Share on other sites

Good news! I just got to know that the whole tuochpad programm was written in Protel Basic up to now!! That means when you go back to pure assembler there are high chances that the time for scanning the matrix will be much less (even with a multiplexer)! Cewl!

So: "LED Touchpad" attached to the "ToDo" list. ;D

Link to comment
Share on other sites

To be honest the last device I programmed was a 8051 one from Siemens (NOT Infineon - right). So that´s quite some time ago. I gotta get back to that and this can take a while. But as I really got many ideas and 80% of them are only functional with a microcontroller, this is a real BIG point for me.

As soon as there are updates, I´ll let you know (can take a while anyhow).

Greetz!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...