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Wiring ForumWiring HardwareTangible computing › Connecting with Ti's TLC5940

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Connecting with Ti's TLC5940 (Read 14944 times)
05/11/07 at 00:35:33

worksofman   Offline
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Ok, I'm just not seeing the information out there, and I would think the Wiring board is capable....  how would a person connect the wiring board to the TLC 5940?
(pdf info at:  http://www.ti.com/lit/gpn/tlc5940 )

(I'm looking to control many RGB LEDs, and this seems the way to do it, but I'm open to suggestions...)

As far as I'm seeing it, I need 4 pins to do grayscale/pwm control:
sin / Data Input
sclk / serial data shift clock
xlat / data latch
gsclk / reference clock for grayscale pwm control

From a number of the other examples, I believe I see how to do the first three.  So the question, summarized, would be:  how to have two clock signals?


« Last Edit: 05/11/07 at 22:47:12 by worksofman »  
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Reply #1 - 05/12/07 at 03:17:48

barragan   Offline
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hi, yes you can hook up this chip to Wiring, it seems easy to do, there is an example on page 17 of the PDF you sent, that includes cascading of these devices. Clock is generated by pulsing HIGH and LOW the pin you're using as clock so multiple pins can act as clocks. I can see you need one clock pin for GSCLK (grayscale clock) and other pin for the SCLK. You can see the order of the sequences (order which pin goes high or low at which moment in order to write) for the serial interface on page 11. I'll try to get one and test. It will take a few days, but you can give it a try.
There is also this chip already in the libraries: http://wiring.org.co/learning/examples/hello_matrix.html
in the example it is using a matrix, but you could drive individual LEDs with it and cascade them as well.
 
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Reply #2 - 05/12/07 at 05:50:29

worksofman   Offline
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One difference between the 7219 and the 5940 is the 5940's PWM ability (if I'm reading everything correctly on the 7219)- it really makes a difference for my application.  Controllable light fading is a big aspect of my final results... (no "blinky" lights for me, please....), and in my bit of testing, RGB colors are much better with PWM than with changing the voltage.

I'm glad it seems reasonable to do.  I'll try to experiment with it as well.

This is all a great process.  The more I learn, the more I learn there is to learn...

thanks

matthew

 
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Reply #3 - 01/07/08 at 04:54:19

lordrivera   Offline
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I was just trying to work with a TLC5940 as well. Anyone have any good sample code or anything?

Thanks!

worksofman wrote on 05/12/07 at 05:50:29:
One difference between the 7219 and the 5940 is the 5940's PWM ability (if I'm reading everything correctly on the 7219)- it really makes a difference for my application.  Controllable light fading is a big aspect of my final results... (no "blinky" lights for me, please....), and in my bit of testing, RGB colors are much better with PWM than with changing the voltage.

I'm glad it seems reasonable to do.  I'll try to experiment with it as well.

This is all a great process.  The more I learn, the more I learn there is to learn...

thanks

matthew


 
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Reply #4 - 05/08/08 at 07:12:57

lordrivera   Offline
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These codes seem to be the best examples I have found

http://pixelriot.com/pmatp/node/15

https://whatever.metalab.at/user/wizard23/tlc5940/arduino/TLC5940/

im still trying to figure out how to cascade them.
 
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Reply #5 - 05/08/08 at 21:14:56

julienb   Offline
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TLC is a driver for common-anode leds matrix ?
Am i wrong ?

so, I couldn't use it with my sparkfun RGB monome clone  Cry  Cry  Cry  Cry
I have to make it with max7221....

I read many thinks in another post i did:
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1209311743/45#45
i don't know if it could work : 1 max + 24 transistors..
 

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Reply #6 - 05/09/08 at 00:14:42

lordrivera   Offline
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its true, all the led's anode's are common to +3.3v in my tlc5490 circuit. Then each cathode of the led goes to a separate pin of the TLC5940, which must provide switchable current regulated ground for each pin.

i dont see why anode common would prevent you from using the tlc5490 for a monome copy. But the TLC5490 seems to be better suited for dimming your LEDs... Is it true that the monome one seems to me to be mostly on/off switching.

Ive been reading the other 50 LED's possible forum too. Thanks!



 
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Reply #7 - 05/09/08 at 08:47:10

julienb   Offline
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lordrivera wrote on 05/09/08 at 00:14:42:
i dont see why anode common would prevent you from using the tlc5490 for a monome copy. But the TLC5490 seems to be better suited for dimming your LEDs... Is it true that the monome one seems to me to be mostly on/off switching.



sparkfun stuff for monome clone uses common cathode leds (if I understood correctly)

indeed TLC can provide all level and thus all color. not only on/off.
But, for my purpose, discrete levels are very enough.
6 colors possibles theorically:
R, G, B, R+G, R+B, G+B
indeed, I don't really know if R+G or the other composites are very "beautiful" and visible, but for my application, it will be VERY enough
 

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