WS2811 speed

[anon]

Is there a need to run them at such high bit rates?


My test setup had 6m Cat5e at 2800 running ok and will be needing it to run this distance in the real world. I wasn't expecting 6803 to run this distance, but seemed to be ok. This is in the P12R demo mode, which from what I can tell is sending out 25-40 updates a second.

 

[Bevo]

As everybody is finding out it is just best to experiment with their own set ups and see what works best for themselves.


I found that with the longer leads 5 to 8m when I tried to run them at higher speeds over 3000 some strips not all if given a white signal would stay on until powered down. And I could not find a good enough setting that I was happy with so I went with how they were tested by Ed from JS1 and now they seem to be working great in any colour even full white.


So just keep testing until you find the speed you are happy with and if you have to many problems you can always try to use shorter leads and null pixels.

 

[burner]

What was the speed you settled on Bevo? I know that of the 2 sections that are flickering for me, 1 is about 5m with no dead pixes (which I might add this weekend), and the other does have a dead pixel and won't be more than about 2.5-3m on either side, this one only has the first 2-3 pixels flashing when all white (out of a strip of 30 pixels, which then links to another 150 or so pixels).

 

[David_AVD]

Is there a need to run them at such high bit rates?

WS2801 and LPD6803 use a separate clock so the data rate can be slowed down to to almost DC. The WS2811 uses a different data format where the clock is embedded into the data line. This means there is only a range of data speeds where it works.

 

[BradsXmasLights]

I have found that using the ECG-PPX extenders this year has avoided all this distance complications/side effects so far. They are worth every cent!

My 2811's run at 2400 (PIX8 2.0a firmware outputting TM180X)

 

[anon]

Is there a need to run them at such high bit rates?

WS2801 and LPD6803 use a separate clock so the data rate can be slowed down to to almost DC. The WS2811 uses a different data format where the clock is embedded into the data line. This means there is only a range of data speeds where it works.

I understand the differences. My thinking was with 2811 there is probably a low point for a particuar IC implementation where it starts to fall off a cliff. But once you get the bit rate up to the point where it works, going higher would only bring in a greater errors? So best to aim for as low as possible within reason?

 

[David_AVD]

My thinking is that any protocol with specific timing requirements should be run in the middle of the allowable range. Now, how wide that range is will depend on the design and implementation of the chip.

 

[BradsXmasLights]

Regarding side effects of incorrect baud rate, I have found:
Slightly too slow = random flickering/pixels at low brightness / %0 brtightness
Slightly too fast = random flickering at ~70-90% brightness (but perfect at 100% still!)

Voltage drop of any lead in cabling also seems to play a big factor. When i had everything layed out side by side it worked perfect at 2000, but I've finally settled on 1130 now I've mounted 152 pixels along my gutter.

 

[BradsXmasLights]

I have mine on 8 metre cables and may be the reason i require the slowe speed of 1800, but they seem to now be working perfectly. It looks like the length of the cable has a lot to do with it

Hey Eddie - what sort of cable are you using for this 8m lead in?

 

[Kaden]

Hey Eddie - what sort of cable are you using for this 8m lead in?

I am using the 4 core alarm cable, the lead in is over 5m and I need to run at 3000 to avoid white flicker, that string is 170 pixels long.

All the rest of my 2811s run at 3250 (middle of the j1sys recommendation)

 

[fasteddy]

I have mine on 8 metre cables and may be the reason i require the slowe speed of 1800, but they seem to now be working perfectly. It looks like the length of the cable has a lot to do with it

Hey Eddie - what sort of cable are you using for this 8m lead in?

I am using 14/020 4 core security cable

But i suspect i may need to up the data rate a bit from 1800 to more like 2000 to 2200 as im seeing a little flickering when lights are not active.