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Need help with WS2811 / 5050 LEDs


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Hmmm... Running 120 pixels and the LaunchPad from a 3.3V PSU and using RobG's code (here) as-is, I get all red-orange LEDs (a few lighter, yellowish) with no changes.  Running at 5V, I get all white, with just one (first) blue LED. 

 

Same LaunchPad/chip works fine with 30-pixel strip powered at 3.3V via the LaunchPad.

 

Anyone have any ideas?  Timing?

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Are you sure all the connections are good?  The devices will actually run a few colors with only the Gnd and DIN connected.  I ran into an issue with my initial boards until I baked the board a bit on my ceramic cooktop and made sure the device was settled.  In one instance - running off of 3.4v - I got only red, in another instance running at 3.6v, only blue and green worked.  

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Are you sure all the connections are good? The devices will actually run a few colors with only the Gnd and DIN connected.

 

I think so; I tried the dual-larson scanner code @ 3.3V and could see some change going back/forth. Seemed like all the brightness was too high on everything.  I'll double-check tomorrow, though.  Thanks.

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Red-orange suggests low voltage. 3.3V is kind of low for those LEDs, plus 120 of them draw more than 3 amps. Try bumping up to 3.6V

You usually get all white when the '0' is too long. Try this, change 

(d & 0x80) ? (UCB0TXBUF = 0xF0) : (UCB0TXBUF = 0xC0);

to 

(d & 0x80) ? (UCB0TXBUF = 0xF0) : (UCB0TXBUF = 0x80);

 

Also, make sure to uncomment delay.

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I just hooked up my 150 LED board to LP and 5V/3A supply. The example code works as expected.

 

In the process, I have noticed that my 5V supply was about 5.2V. That was after the first LED in the string blew up. Good thing I have spare 5050s. Weird, it's not the first time I have used this setup. Maybe storing it in the cold garage was not a good idea.

 

Also, after setting all LEDs to 100% brightness, LEDs near the end were noticeably dimmer.

As it turns out, the voltage drops pretty rapidly after first few LEDs and goes down to about 3V at the very end (LED # 150.)

That was the 30LEDs/m string, didn't try the 60LEDs/m one.

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