Wrong times for WS2811? (NeoEsp32RmtSpeedWs2811)

[XYZLassi]

Hi,

i use a WS2811 strip with a wemos lolin32 lite board and the default values do not work for me:

const static DRAM_ATTR uint32_t RmtBit0 = Item32Val(300, 950);
const static DRAM_ATTR uint32_t RmtBit1 = Item32Val(900, 350);
const static DRAM_ATTR uint16_t RmtDurationReset = FromNs(300000); // 300us

What are these values because I found two data sheets with two different times:

WS2811.pdf
WS2811_V1_4.pdf

The following settings work for me:

const static DRAM_ATTR uint32_t RmtBit0 = Item32Val(500, 2000);
const static DRAM_ATTR uint32_t RmtBit1 = Item32Val(1200, 1300);
const static DRAM_ATTR uint16_t RmtDurationReset = FromNs(60000); // 60us

I would like to create a pull request, but I don't know where the old values come from.

[Makuna]

I have an official spec sheet that is different; but similar except for one value. T1L is supposed to be 200ns-420ns. The ones you sent don't make sense as they generate a pulse width (total time of both and high and low) that varies dramatically from bit 0 to a bit 1.

I have tested this on official WS2811 chips and it works; but these chips come from China, the companies change things from batch to batch and clones are made that don't match specs. Do you have a link to where you got them?

Did you try the values from the spec sheets you have to see if they work? I ask as the ones you list don't match any spec sheet for any chip I know of. They are similar to first generation LEDs (big through hole LED with integrated chip). These are the 400Kbps leds and there are methods for those specifically. See Neo400KbpsMethod and NeoEsp32RmtSpeed400Kbps.

[XYZLassi]

Here the link:
https://de.aliexpress.com/item/2000165819.html
I bought them 2-3 years ago.

The methods NeoEsp32RmtSpeed400Kbps and Neo400KbpsMethod works not for me. Only the posted times work.
The times correspond to the first datasheet (WS2811.pdf). I have not tested the 800kps mode of the chip.

Is Worldsemi not the official manufacturer of WS2811, if not then who is?
I can't find a data sheet that gives your times, did they determine them experimentally?

Maybe there was a version with the values, but it is no longer produced.

[Makuna]

My spec sheets are from WorldSemi directly.
WS2811_--_201709_V1.1_17101018593714.pdf

Products from China may come with "clone" parts, so no, your strips may not have chips from WorldSemi or the batch you got they "changed" the specs.

+-50us is not achievable for the implementations of most the Arduinos supported by this library.

[XYZLassi]

He Makuna,

your data sheet is version 1.1 from 2017. I posted version 1.4 and the current datasheet from Adafruit (https://www.adafruit.com/product/1378).
I would say we need an implementation for 1.1, 1.4 and a the Adafruit version.

My IC is a Worldsemi WS2811 20180522 with the Adafruit spec.

[Makuna]

So I did some testing with a newer WS2811 chip. It not only supports the old protocol, it also supported every other one this library works with as long as the reset time was long enough. So the newest WS2811 are VERY flexible in the timing.

This still doesn't solve the issue of updating the WS2811 method as I need to maintain backward compatibility with older chips; but it does mean newest chips won't care. In the specific case listed above, there is no easy answer than to try another method.

Maybe adding a WS2811Alt Method for your case?