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Topic: LED not drawing current (Read 821 times) previous topic - next topic

sneergh

I have 50 (out of a planned total of 80) 60-led strings of Adafruit Neopixels wired together, each one individually powered and grounded. Everything lights up fine until I get to string #48, which suddenly stops, the first pixel flickering weakly green. it appears to be drawing no current. my power supply's input is 5V-60A, with three lines going out into six different bus blocks (three for power, three for ground), with about 25 strings attached to each bus block

I am certain that the string in question works (I've tested it). I also switched out the string leading into it and confirmed that one for working as well. I am certain that all my connections are solid and that my code is fine. Is there some really stupid obvious reason for this? Do I just need a beefier power supply?

larryd

Tell us what the power supply ratings are, show us schematic and show us a image of the wiring.


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No technical PMs.
The last thing you did is where you should start looking.

CrossRoads

48 strings * 60 LEDs * 60mA/LED = 172A.

60A supply sound a little underpowered.

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

sneergh

CrossRoads, that's what I thought because I can't imagine what else it could be, but it seems a little odd that it would poop out right on the first pixel of the 49th string--or is that what you would expect to see for a weak power supply?

CrossRoads

Put a volt meter on the string, see what you're getting. Switching power supplies can shut themselves down when they see an overcurrent condition.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

sneergh

Looks like the voltage is not actually dropping an excessive amount. Power supply doesn't seem to be overheating either. If I set the code to only start lighting strings up about halfway through, the problem persists. Seems like a dataline/software problem at this point but I can't imagine what it would be, my test code is so simple.

Grumpy_Mike

What Arduino are you using?

Quote
Everything lights up fine until I get to string #48,
So at 60 LEDs per strip and three bytes per LED you need 48 * 60 * 3 = 8640 bytes of memory. So a Mega and Uno are running out of memory at this point.

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