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I need to run a 2 meter data cable from an Arduino UNO to a series of 40 RGB LEDs with integrated WS2811 drivers. What kind of cable do I need? Do I need something between the cable and the first rgb LED to "clean up" or enhance the signal?

The 2m cable goes to the first LED only. Between each LED there will be 10~20cm of cable. What cable should I use for that connection?

So absolutely worst case (40 LEDs, all 20cm away from each other), that's 8 meters of cable in total (in practice I think 6-7 meters will be the maximum). Is this doable or will the LEDs misbehave? I know that these LEDs are very timing sensitive because they are sending data to all the LEDs on one line.

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  • \$\begingroup\$ Each LED re-generates the signal, so you only need to worry about the 2-metre part - if that part is fine the rest will also be fine. \$\endgroup\$
    – user253751
    Jan 18, 2017 at 22:36

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The datasheet for the WS2811 driver shows that the IC itself buffers the data sent to the next LED position. They do show 33 Ohm series resistors for impedance matching so make sure you have those.

The most important aspect of selecting a wire size is to be ultra conservative about voltage drops down your wire. Here is a chart that shows the reduction in current for 'power' applications (overkill here but it serves to make the point on size selection).

You might expect from the maximum rating of the WS2811 that you have 3 * 18.5 mA maximum (white) per device, so for 40 drivers you have a maximum current requirement of approximately 2 Amps at your source end. From this current requirement and the chart you could reasonably expect to select a wire gauge size between 26 AWG and 18 AWG depending on how conservative you feel.
A very common size for 'hookup wire' is 22 AWG, and since the current requirement reduces as you move down the string of LEDS, this might be quite adequate for your 2 M run of cable.

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  • \$\begingroup\$ Thanks! I don't fully understand the answer I'm afraid. I'm asking specifically about the data line, but there wont be 2,4A going through the data line right? That would break my Arduino I think :) \$\endgroup\$
    – Erik
    Dec 14, 2016 at 19:32
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    \$\begingroup\$ @Erik. Correct....the data line carries essentially no current so it could be very small. The WS2811 buffers and cleans up the signal between LED drivers so you don't need to do that (other than make sure you have the 33 Ohm resistors in place). You could even run the data line as a twisted pair, though I doubt there is any real noise concern in the application. \$\endgroup\$ Dec 14, 2016 at 20:00
  • \$\begingroup\$ @erik if this answered helped you, don't forget to accept it as the answer. \$\endgroup\$
    – Passerby
    Jan 18, 2017 at 22:37

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