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Topic: Ws2812b umbrella problem (Read 213 times) previous topic - next topic

nervusvagus

Dec 01, 2018, 11:06 pm Last Edit: Dec 01, 2018, 11:08 pm by nervusvagus
I tried connecting 8 x ws2812b strips of 50cm length to an umbrella in parallel, somehow it didnt work. The IN of the led strips are at the top of the umbrella, all are connected parallel from this top part. The strips light up but the code of rainbow animation using fastled doesnt work, just frozen.

Im using an Arduino Nano, powering them from a powerbank (works for up to 5meter single strip). I used a single 470ohm resistor for all 8 strips for data line. Im tempted to solder 8 x 470ohm resistors to all data lines but its a lot of work with little chance of that being the issue.. I guess asking here seemed a better idea...

I had noticed in previous experiments with lpd8806 strips that if I run through a single strip initially then I can create parallel outs off from the end of this strip and all ran fine. So I tried that again, running a single ws2812b to the top and then connecting all the strips to the out of this single one... aaand it didnt work.

Anyone know what the problem might be?

PaulRB

#1
Dec 02, 2018, 11:06 am Last Edit: Dec 02, 2018, 11:14 am by PaulRB
I would start by disconnecting 7 of the strips. Does the 8th strip work correctly? Swap in one of the 8 strips in turn to confirm each works when connected by itself. Then reconnect more strips, one by one, and test after each. When it starts to fail, try replacing the 470R with 220R.

If you cannot get more than, say, 4 strips to run at once, then you may need to either use a second Arduino pin to send data to the remaining strips, or build a small buffer circuit using a 74hc04 or similar. Alternatively, connect all 8 strips in a chain. This will mean connecting the Arduino to strip #1 only, and running an extra wire back up the umbrella from the end of strip#1 to the start of strip #2 and so on. Software changes might also be required if it's important that every strip does the same pattern. But this would also allow more complex patterns where the 8 strips don't appear identical.

Grumpy_Mike

Quote
I used a single 470ohm resistor for all 8 strips for data line. Im tempted to solder 8 x 470ohm resistors to all data lines but its a lot of work with little chance of that being the issue.
I think it stands a lot of chance of it being the issue.
Anyway connecting each strip to a different pin has a lot more potential for great anamation that them all showing the same thing.

nervusvagus

I did disconnect all pins in the end, so yeah, was either the resistors missing or, I used a bigger fully charged powerbank and that did it.

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