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Topic: 16x16 RGB Matrix with TLC5940 (Read 1 time) previous topic - next topic

melka

Hi there
I'm making the schematics & boards for my 16x16 RGB matrix using TLC5940.
I initially planned on using 3 TLCs by board, one for each color, as those chips have 16 PWM outputs.
But I saw on JMG's blog that he uses only one, and switchs between the 3 colors on each output.
How can I multiplex my outputs ? I want each PWM to be able to switch between the 3 colors.
Any idea ?
Thanks ^^
http://melka.one.free.fr/blog/
http://www.flickr.com/photos/melkaone/

wayoda

Hi,
Quote
Hi there
I'm making the schematics & boards for my 16x16 RGB matrix using TLC5940.
I initially planned on using 3 TLCs by board, one for each color, as those chips have 16 PWM outputs.
But I saw on JMG's blog that he uses only one, and switchs between the 3 colors on each output.
How can I multiplex my outputs ? I want each PWM to be able to switch between the 3 colors.
Any idea ?
Thanks ^^

Multiplexing the TLC5940? I'm suprised this should be possible. Do you have a link to JMG's Blog?
Eberhard

melka

http://www.upwardnotnorthward.com/2008/03/rgb-monome-clone-update-and-rename.html
http://melka.one.free.fr/blog/
http://www.flickr.com/photos/melkaone/

macegr

I've multiplexed the TLC5940. 1/3 duty cycle is easy, 1/6 is a little harder. Either method requires that you be very conscious of timing.
Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store

melka

Yep, I guess timing would be a bit hard to figure but not impossible
It's on the hardware side that I have a problem, how to switch between the 3 outputs.
http://melka.one.free.fr/blog/
http://www.flickr.com/photos/melkaone/

macegr

I used common-cathode RGB LEDs and a p-channel MOSFET to power each red, green, and blue anode rail.
Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store

Grumpy_Mike

Am I missing something here? The thread title talks of a 16 X 16 matrix and the TLC5940 will only control 16 LEDs. Therefore you will need 16 of these chips and times three for the RGB bit so that's 48 chips you need. The project you pointed out at the start was for a 4X4 RGB LED array. Also the biggest I have seen is an 8X8 RGB array from Sparkfun.
A 16X16 array is 256 LEDs and then for the RGB bit gives 768 individual LEDs
Is this thread misstitled?

macegr

I doubt that...it can be hard to grasp how quickly the scale of a project multiplies. It's easy to throw a number like 16x16 out there. The major suppliers of 16x16 RGB modules use a single large ASIC to control each module.
Unique RGB LED Modules and Arduino shields: http://www.macetech.com/store

Grumpy_Mike

Quote
I doubt that...it can be hard to grasp how quickly the scale of a project multiplies.


It's easy they increase with the square of the number.


So if an ASIC is used as a controller its a bit much expecting an Arduino to cope.

melka

#9
Jun 17, 2008, 08:33 pm Last Edit: Jun 17, 2008, 08:51 pm by melka Reason: 1
In fact, I made a mistake when I wrote the title.
I'm working on a 16x16 RGB leds Matrix, but I'm working on 4x4 modules, with a TLC for each module. And I'll certainly use more than one arduino or switch to another uC later.
Title corrected.

Quote
I used common-cathode RGB LEDs and a p-channel MOSFET to power each red, green, and blue anode rail.

Thanks macegr, I'll check this way ^^
http://melka.one.free.fr/blog/
http://www.flickr.com/photos/melkaone/

julienb

hi!!

melka, any news about that ?

I'm ok for the monome clone arduino-based ( http://www.julienbayle.net/diy/LiveInterface/ ) but I want to upgrade it to 3 colors as you probably want to do.

I have a lot of max7221, a lot of TLC5940 etc
I guess I could use them for that  ;D

julienb
http://www.julienbayle.net

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