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Thread: Has WS2811 timing changed?

  1. #1
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    Default Has WS2811 timing changed?

    I've read various comments that together seem to indicate that something is different between older and newer ws2811 timing. I will be surprised to learn that a commodity "jelly bean" part like that had any tweaks or revisions (expecting instead a new part as an addition or replacement).

    Can anyone point me in the right direction (e.g. if different, what are the specs) or confirm that there are no changes?

    Thanks

  2. #2
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    Default Re: Has WS2811 timing changed?

    Hi, yes they have changed. I believe some time ago the stopped making the WS2811 and have been selling us the WS2813 as WS2811s since then. Why? The WS2811 LED PWM was too slow for modern use, it showed up on videos and TV. The old WS2811 had LED PWM at 400 Hz whilst the new WS2811 and the WS2813 have a much faster LED PWM of 2 KHz (5 times faster).

    The biggest difference to us was that the reset time (part of the data that says – you all have new data, change now!) lengthened from 50uS to 280uS meaning that controllers needed new firmware.
    Yes; I here you say but the WS2813 has two data lines and the new WS2811s only have one. Both only need one, but if you want the feature that will bypass a dead pixel, you need to use two, hence if you pay more they will solder two extra wires internally.

    Why mess about like this? Cost, they only need to make one core for the IC / 5050 LEDs and if they solder two sets of data wires it’s a WS2813 / WS2818 and if they only solder one set it’s a WS2811 / WS2812. No brainer really.
    Last edited by Barnabybear; 09-11-2018 at 05:20 PM.

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  4. #3
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    Default Re: Has WS2811 timing changed?

    Thanks for the reply. Not having reliable specs (from IC mfg or final product mfg) makes this more difficult than it need be.

    I still have a hunch that World Semi is not making parts marked as WS2811 that have the higher refresh and longer reset time, rather production of ICs marked as WS2811 has stopped. My presumption is that the pixel manufacturers are now using the updated WS2813 w/out the dead pixel option brought out but still calling the pixels WS2811-based.

    The higher PWM frequency (2 MHz) is not relevant to driving the device (but a nice improvement nonetheless) but the longer reset period is definitely something to notice. I have a custom BeagleBone driver I created that should still work, as long as I have the necessary quiescent time between data refreshes. (I hope I can carve out an extra 1/4 of a millisecond somewhere).

    How does one stay apprised of these changes? Without help from this forum, I'd not have even known to be suspicious of pixels marked WS2811 not following the same timing specs (as poorly and inconsistently as they were published - even by WS themselves) as they always have. That would have been a big time sink to figure out by trial-and-error.

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