TLC5940/Uno interface problem

No. The I ref and V ref are based on a resistor connected from V- of the op amp to GND. ( in the schematic on page 8. ) So the voltage reference for the op amp that controls the current is provided by the voltage drop across the Rref (the 2k ). So as I pointed out before , the WORSE CASE is NO RESISTOR to GND, bringing the voltage to lowest point. The Opposite of WORST CASE is 2K RESISTOR TO +5V which should limit the current to ZERO . (I think; that's just a guess). You know that NO current was SUNK by LEDS because they NEVER LIT UP. IF THEY HAD ALL LIT UP SUPER BRIGHT FOR AN INSTANT AND THEN GONE DARK, then that would be bad, but that never happened. I can't see why connecting R(IREF) to +5V would damage the chip. If I am right, it should work when you get it wired correctly. You need to replace at least a few of the RGB leds with ordinary red leds first to do the test. We need to eliminate the RGBs from the equation.

Are you saying it STILL DOESN'T WORK after correcting the resistor ? (and the chip doesn't get hot ?)

Thanks very much for your patience. I got rid of the pre-made jumper wires and replaced them with 22 AWG homemade jumper wires like the ones from the TLC5930 to the RGBs, and all three TLCs work just fine. TheRGBs were part of the problem, they weren't seated very well and after adjusting them, they worked. I learned something out of this "goat rope" thanks to you and your sharing of your expertise.

So you are confirming that my analysis of the mis-wired )R(ref) resistor to +5V instead of ground resulting in zero current , rather than maximum current was correct because NOT ONE of the chips were damaged ? Did you replace any of the RGBs with standard RED leds to test the chip as I suggested ? If you were going to write a FINAL ASSEMBLY CHECKLIST for other users for the TLC5940 what would it say ?

You can have a lot of fun with a 328P and TLC5940's. See the video ~1/2 down here https://www.kickstarter.com/projects/954220292/the-infinity-clock-all-digital-analog-clock?ref=live ClocKore Circuit Board

Yes, raschemmel, you were absolutely correct. The RGB leds were not damaged in any way. I removed all male/male jumper wires and replaced them with my own 22 AWG solid wire jumpers. These fit more snugly in the breadboard, making for better contact. Yes, I started to change out the RGBs with standard RED leds. After I replaced the first RED, I re-set the Uno, and the RED led lighted. So I re-seated the remaining RGBs. As I did each one, it would light up, as I went down the row. In a The first thing I would say is, If one is having problems with the chip, get on this forum and ask for help.

Also, be very careful with the wiring. Thanks again for your patience and your help.

Now do you see why I said this back in Reply#16 ? (We are on Reply#25 now)

Do you have any other leds (ordinary red ) that you can substitute before you tear down the circuit just to rule out the RGB leds ?

Then I mentioned it again in Reply#20:

If I am right, it should work when you get it wired correctly. You need to replace at least a few of the RGB leds with ordinary red leds first to do the test. We need to eliminate the RGBs from the equation.

Next time, I will follow the suggestions of you and others who know a whole lot more about this than I do. Once again, thanks for all you help.