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Author Topic: Glitching TLC5940  (Read 4332 times)
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No one ever told me you can't just use meter long wires for everything.
Did you ask?

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From where to where exactly did you place those?
From the end of the run to ground. But the whole situation was monitored on a scope as I did it to make sure the wave form edges were not too affected.

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I guess there isn't a simple/relatively cheap alternative for it? (
No not for chasing this.
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I can get my hands on a 15Mhz scope, will that be sufficient? Or will I need something faster?
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That might just about do.
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I'll buy it then. smiley

How am I supposed to measure with it when it's here?
Or can anyone point me a good tutorial?
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Just google:- using an oscilloscope
There are lots.
The trick is not so much making the measurements but understanding what the display is showing you. But you can't begin to start that until you have got one.
Good luck.
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The trick with oscilloscopes is to have a pretty good idea of what "normal" is, then you can spot "abnormal".

Also put aside a few hours to getting the hang of it. Otherwise you might just be measuring line hum and thinking that it is part of your project.
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I re-soldered all the LED's in blocks instead of rows, and hooked up the newly wired breadboards, and everything was fine! No glitching or bugs of whatever..

But then I was trying to hook up the spectrum-shield I have, to make a graphic equalizer, and I accidentally shorted my power supply. Then I replaced all the molten wires, and all the TLC's (just to be sure, they were pretty warm) and hooked everything back up to how it was, and the glitching is back!

I however found that when i tightly grip my 7805, the glitching will be gone. My oscilloscope will arrive somewhere today..

Edit:

Also, before shorting the power supply, I hooked up an arduino to the TLC's without connecting the ground, that's probably what caused the TLC's to become very hot, and that's why I replaced them.

Edit:

The glitching seems to be gone for the moment now.. I moved the board from the ground to against the wall.
« Last Edit: April 05, 2012, 05:40:09 am by Inevitableavoidance » Logged

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I however found that when i tightly grip my 7805, the glitching will be gone.
That implies the regulator has not got enough high frequency suppression. Put a 0.01uF across the input and output terminals as close to the regulator as you can get.
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Put a 0.01uF across the input and output terminals as close to the regulator as you can get.

There are already .1uF caps there, should I replace those or add the .01uF?
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Put a 0.01uF across the input and output terminals as close to the regulator as you can get.
There are already .1uF caps there, should I replace those or add the .01uF?
Add.

High frequency noise is filtered out by lower value caps.  Having multiple caps in parallel improves the frequency response of the de-coupling.
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It's completely working..! (I think)
Thanks a lot everyone! smiley

Conclusion:
Wire everything as compact as possible, add a lot of the right capacitors, and try not to put your breadboards directly above a 100m of (changing) powered wire. smiley

I made a simple snake game for the panel:
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Well done. I must admit I would not have even attempted to do such a thing.
You must be well chuffed as we say in England.  smiley
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We're building a 16x8 LED panel now, as a reading light above a bed. But we'll be using 8 TLC's to control each LED individually instead of per 4. (as an extra test before we start the big one)

The big one will eventually use 20 TLC's and 1280 LED's, so i'm afraid we'll probably encounter more decoupling problems.
I'll keep posting about the process here. smiley
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I'm completely puzzled, I soldered everything together instead of using breadboards.
But it isn't working.

I'm 99% sure that everything is soldered correctly, but after 2 secs of powering the board the last two TLC's go out.
If I repower it imidiately, they stay out, but if I wait like half'n hour, and power the board again, the TLC's will again function for about 2 seconds.

Does anyone know what could possibly cause this?
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I suspect it is that 1% of uncertamcy that is killing you.
Let's face it if it worked on bread board it should work on strip board.
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