6x TLC5940 32 rgb leds

I have a working setup of 32 rgb leds, two chips per color. I was wondering if it would be easier to somehow rewrite the library to have 3 S-inputs (one for each color). Or would I have to connect them all together in series and have 0 -31 for red 32 -63 for green and channels 64-92 for blue.

I want to expand it to 192rgb leds but that will require 36 chips but it looks like the code is limited to 16 chips. Is there anyway to expand this?

Thanks in advance!

Which "the code" are you talking about?

How often do you need to update each LED?

I want to expand it to 192rgb leds but that will require 36 chips

The problem here is that cascading so many chips you run into fan out problems, that is the number of inputs any one output can drive. This means you will have to have buffers driving the common lines split up into groups of 10 or so.
One way to get round this is to use multiplexing but the LEDs are dimmer unless they can take more current. This is my project for using 64 RGB LEDs using only three TLC5940s.
http://www.thebox.myzen.co.uk/Hardware/Hexome.html

Is my setup and I I have a rainbow pattern working but after a few minutes it starts flickering as shown here.

I know I should make a function to simplify the code but I"m not that advanced yet.

Thanks Grumpy Mike thats a great idea to control many leds with fewer chips but the information would have to be the same. I guess it would be a trade off.

I slept on it and I think the erratic behavior is because I need a higher current voltage regulator.

but the information would have to be the same.

I don't understand this, the information on the LEDs can be anything you like. The trade off is that they are dimmer because they are multiplexed but you can compensate by using more current through the LED.

I think the erratic behavior is because I need a higher current voltage regulator.

It could be, are they getting hot? Have you got enough decoupling capacitors on the chips, it was hard to see on the video. I would also add a 100uF across the supply as well, close to one of the chips.

The chips themselves were cool to touch but the heatsink on the lm7805 was hot as heck. With the rainbow code it is turning on at least 64 leds on at a time @ 20ma each it pulls more than the 1amp 5v can handle so I have ordered a bunch of LT1083 that can handle the higher amperage.

I will need to build a bunch of power supplies or I was thinking on building 1 power supply with many 5v rails. > Is there such a ~12vac transformer rated at 50amps or something like that?

As for the multiplexing of chips I'm not sure if I fully understand. For simplicity say for bank 1 of leds you want all red so you send the code and enable the anode of bank 1. If you wanted bank 2 of leds all red as well you would just enable the anode line for it and it all works well (maybe a little dimmer). Now lets say you want bank 1 all red and bank 2 all green at the same time. How can they be addressed differently if they are all tied to the same 5940 chips (at the same time)?

the lm7805 was hot as heck. ........ so I have ordered a bunch of LT1083 that can handle the higher amperage.

It will do you no good, the heat it generates will be exactly the same. The only way to make it cooler is to lower the input voltage or put it on a heat sink. See:-
http://www.thebox.myzen.co.uk/Tutorial/Power.html
and
http://www.thebox.myzen.co.uk/Tutorial/Power_Examples.html

Is there such a ~12vac transformer rated at 50amps or something like that?

Yes but there is no way you are up to building a power supply of that size. I would find it a challange.

As for the multiplexing of chips I'm not sure if I fully understand.

You enable a bank and send the data for that bank. Then do it for the next and the next and so on. The code does this and knows nothing about what LEDs are on or off, it just ships the data to the chips. Your working code then only has to bother with setting or clearing bits in the data. So the same chip is outputting different data for each bank that is enabled.

So now I want to use higher power leds for my project such as a 3w rgb led:

This shows how to do it and I figured I'd use a bunch of 2n2222 transistors. It shows the output of the tlc4940 to the emitter and I would have to calculate the base resistor tied to vcc.
http://www.ti.com/lit/an/slva280/slva280.pdf (#3 alternate solution)

I ordered a 40amp 5v power supply which should suffice. Should I assume Beta is 100 for a 2n2222 transistor? If so it looks like I should have a 1ohm resistor for the base for a 400ma red and 1.1ohm for 350ma green/blue. Is that right? Is that ideal or should I bump up the Vcc to 12v or higher? Also in the diagram the show the anode connected to VLED(VGB) will that be the same as Vcc?

I'm now using this project to power side emitting fiber optic and the 3w led works noticeably better. I bought that one 3w led but i'm open for suggestions if there are better ones out there.

All sorts of wrong with that.

  1. You can't run a 3W LED with just a series resistor, you need a constant current source.
  2. A 2n2222 can't handle the current.
  3. That data sheet doesn't show you how to drive high power LEDs.
  4. If you have decoupling problems with a low power LED these get multiplied with high power LEDs.

I happy to say after getting a more powerful power supply the problems I had went away.

So I have followed This post > http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1271193991 for each output and it works great except I have both V1 and V2 tied together as they are both 5V and I do not need an indicator led1.

I keep frying the tlc5940 chips. I have noticed it happens when I unplug/plug it in otherwise when it works it keeps working for a long time. I'm thinking I getting a surge in current somewhere. Should I have a separate 5v supply for just the chips or should I put an inductor/cap on the +5v supply?

I have a 40amp 5v power supply

these peaks are coming out of the shaping amplifier

I hope you are not plugging in a chip with the power on, that will kill most things.
When they go does it get hot?
Is there more than one supply? You should not let an unpowerd chip be connected to a powerd input / output line.

Yeah I noted the order of what I plugged things in and when they fried this morning after I posted. Yeah it gets freaking hot, good thing they are only a few bucks.
Yeah it has a separate 12v supply for the arduino with the grounds connected. I think the finished product will have one plug powering the arduino and have the arduino turn on a relay for the 5v supply to avoid this problem. Awesome thanks for clarifying!

Here is what I have so far > VIDEO0031.mp4 - YouTube and VIDEO0034 - YouTube

3 more board to prototype out and I'll be half way done.

Nice videos, it looks to be comming along well.
If the TLC chip is getting hot I should look at the power calculations in the data sheet. it looks a bit daunting at firse but it breaks down into simple parts. You should not be dissapating much here so try and minimise the current. It is probbly the heat that is killing the device more than the power switching.

The chips seem to do just fine as long as I plug them in the right order with no heat.

I have a bunch of 3w rgb leds with 350ma per led and a HengFu with two 20amp 5v outputs. The r3 resistor I used a 1.5ohm 2watt. I planned on providing 20amps 5v per board which I think should be ok but I don't think my multimeter can handle that kind of current to actually test it to see how much it's pulling. I plan on having up to 6 boards per art piece. While I think it should work i'm not sure if its the best practice. From my understanding I could have a higher voltage power supply for V2 and the extra voltage will just get burned up in the FET. Would that be a better option, or would it just be less efficient?

The chips seem to do just fine as long as I plug them in the right order with no heat

Never ever plug in a chip when the power is on. It is the best way to destroy them.

Ok so I have six of these boards done for a total of 96 outputs. I have tested each of these individually ok. I have hooked it up just as before except a separate power connection for vcc for the chip.

I power on all the chips, wait a few min and they are all fine and cool to touch.

I plug in the arduino that has a different power source with a shared ground and 3 of the chips fry.

So I'm not sure if a wire has came loose in my temporary setup or how to hook this up without frying the chips.

I know they are fried because I hook them up again with only vcc and ground and they are extremly hot.

I can replace the chip, hookup the arduino directly to the board instead of a breakout boards of greyscale clock, blank, etc and the board works ok. I know you said that working with higher powered stuff complicates things but this seems more like a hookup issue than a decoupling issue.

Feel free to ask questions, I feel like this can work but i'm just missing something simple.

I power on all the chips, wait a few min and they are all fine and cool to touch.

This is because they are not doing anything so no heat is generated.

I plug in the arduino that has a different power source with a shared ground and 3 of the chips fry.

Is the code that drives the LEDs running at this point. You should not plug in circuits together with the power attached. Connect it all up and apply the power.

There are three voltage sources. The 5v that powers the chips only, the 5v that powers the output circuits, and the arduino 12v. I'm not sure why it fry's some of the chips while it should work. 50x chips just arrived in the mail, I guess I just have to play around with it.