interactive led table

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alexthefox

Senior Member
hi everyone, have you saw in youtobe the video of interactive led coffee table? i will try to do by picaxe... what you suggest to do it?

i think it worck by photoresistor and have 2 groups of led shift one to other from fast to slow, with low pwm...

other idea?
 
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alband

Senior Member
That is seriously cool!

It clearly has sections, each with its own controlling PICAXE (or PIC).
I would suspect the random command would be used in small quantities.
The hardest part will be to get the chips to know where they are on the table and where all their LED's are.
It seems to have a graduated pulse using PWM and the brightness from the sensors seems to determine how many are on and how bright.
If you do make this, please put a nice sheet of black acrylic on top of the circuit board, it would look so much cooler.
I think the key is not to be too repetitive and strict, make it all differently and give the formulii some wiggle room.
 
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alexthefox

Senior Member
what i think is to do many board (not to bigger), and on this board put some leds divided in 2 bank. photoresistor on each bank. so when somethink is on the banck it light the led, when no, the light shout down with pwm... if the object is bigger, take 2 board, and leds of 2 boards lights... i thinked in this way...
 
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BeanieBots

Moderator
PWM, PWMout or a sequence of pulsouts can be used.
Even high low can be used.
I did a simulated "arc welder" for a model railway which used "sound" to give the random flickering effect. (it's in the archives somewhere).
Do a forum search on "RGB*", "fader" or "Dimming" to find loads of example code.
 
slimplynth

slimplynth

Senior Member
Needy McGreedy

looking at the first youtube vid with the cat, it looks like it detects the continued presence of an object/organism and reacts by increasing the intensity, thats what struck me the most, especially with the cat.. but maybe thats just the recording.

would it be possible to use these IR LEDs to detect the presence of a hand/cat overhead?

I think it just needs more LEDs :D
 
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nickpatts

Member
the guy states in the comment, it is done with active and passive IR sensing, all done with opamps all analog, no pic chips/etc, also mentioned it does not carry on flashing leds after an object has stopped moving, so placing a cup with start a ripple effect then stop, then react again when the cup is moved. could find anything about how each unit is joined together, but would of thought it would be easy enough when a grid is active to send a signal to its 4 sides to trigger there ripple and so on to other surrounds grid, you would probably want the ripple to get weeker as it moved out to other grids, so a serial count down could be used active grid sends out a serial data '4' surrounding grids pick this up minus 1 and send out to the other grid serial data 3 etc to effect the dimess of the leds.

rambled abit, but seems like a good project, might give it a go myself but use picaxe chips to run each grid.
 
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Jeremy Leach

Senior Member
I think it's great too. I wouldn't underestimate the cost though as I can imagine there are a few hundred components. Plus I expect it uses a fair level of battery juice ! (oh and a chunk of your life wiring it all up and testing it !!)

I like the way it pulses and fades and isn't just dumb on and off - this indicates analog and lots of capacitors to me !! Might not be so easy to get this effect using digital.

I expect a solution could use picaxes but I almost think it's more a case of starting with what you're trying to achieve then finding the best (cheapest, effective, less power-hungry etc) electronic solution.

This sounds really picky, but I think it would be even better if it wasn't so 'blocky' - the LEDs seem like they are arranged into blocks of some sort.

On the LED display side, perhaps one idea would be to create say 8 different PWM signals (somehow) to represent LED just on to LED fully on, then use picaxe(s) as the 'brains' to route the PWM signals to many LEDs via switching ICs. The picaxe(s) hold an internal array of all the LED states and you design algorithms to control the way the LEDs 'interact'. A clever algorithm would give it all a flowing, rippling, analog feel ! This sounds 'possible' to me. 'IF' this worked then it might open the door to all sorts of algorithm variations for different effects, and 'cool' might be an understatement ;)
 
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alexthefox

Senior Member
i think to do some more easy to start the project... in the video (1st maybe) you can see 2 groups of leds (this is what i saw) change one to other, with different pwm...
if i do 1 or more boards, and in every board 1 sensor, when i move something from one board to other, leds, start to light the board where the object is. if the object (cat, glass, bottle) is fix in the position, the light (the sensor is alwais at that value) stay on, when the value of the sensor, change, leds, start to decrease the brightness...

just to start the project, i whant to work with photoresistor (i have in my staff ;) )
 
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alexthefox

Senior Member
i did some test and it very hard to do with photoresistor... i just test cny70 (low range) and it look like what i want... just test with 1 led, but... ok, i must to look to shift the leds
 
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nickpatts

Member
think in another thread someone posted up some day light filtered ir sensors from rapidonline, could just have this sitting side by side with a shielded ir led and anything that reflects in its path willl trigger it off. they also sell a few proximity although overkill for the job and pricey but then you could have the led brightness controlled by how close the object gets to the table...? so as your hands get closer to the grid it gets brighter with ripples comming off of it, you could even go down the line of rgb or coloured led sets and have a fire effect going from yellows into red the closer you get.
 
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alexthefox

Senior Member
so with IR 38Khz PNA4602 sensor, and a pwmout 2 , 25, 53 n(by wizard 38kHz and 50% duty cycle) to drive a led, can i have the result like a ir presence/sensor?
 
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