flickering WS2801

I have an annoying problem with my 25 strand LEDs (WS2801).
the hardware:

• raspberry pi model B overclocked to 800MHz
• dedicated 2A power supply for the pi
• one strand of 25 LEDs with WS2801 (just for 3 sides of the TV)
• one 5 A/5V power supply for the LEDs.

The software:

• Openelec 6.0.3 (clean install, not via OTA)
• Hyperion (last version, installed via HyperCon v 1.02.4/21.05.2016)

The Problem: the LEDs are flickering no matter what content i play. I tried using hyperion mobile app to test and i have the same result: flickering. When i completely desaturate the color and increase the intensity to max, the LEDs are white (as should be) and the flicker appears random on few LEDs (not the entire strand)

My strand's data and clock are directly connected to the pi (3.3V via GPIO). my baudrate is set to 250.000 but i have tried with other values: the lower the baudrate is, the flicker decrease in frequency. The higher the baudate , the flicker frequency increase but the LED's intensity is lower.

I have been successfully using hyperion since openelec 5.0; i have updated openelec with no problems (via OTA) up to the last official version (6.0.3) and no issues with the LEDs. But when i have clean-installed Openelec 7.0 beta3, the flicker appeared. Reverting to Openelec 6.0.3 through clean install, the flicker persists.

1. How can i fix this problem?
2. could be a solution to use Darlington transistor arrays (ULN2003A cip) to amplify data and clock signals from 3.3V to 5V?

Zitat von TPmodding

You use 2 power supplys, right?...Do you connected Ground from the LEDs to the Pi?

yes, everything is grounded. i even used shielded cables.

Zitat von TPmodding

Could you pastebin your config (and for better Support a log too) please

naturlich i can send you my config but i'm quite a nub and i don't know how to generate a log file .
and thank you very much for your help.

and forget to mention: yesterday i tested just for 2 min an old build of openelec - v.5.0 and the rainbow effect from boot was ok - no flicker. Unfortunately i couldn't succed to test a video because the pi was connected to internet an already downloaded the update file to last official version (6.0.3) and it wasn't enough: i accidentally unplugged the pi and guess what: after reboot, he started the update process. :{

Zitat von TPmodding

could you change "rate" : 1000000, and try again

i have tried with this value - no luck. Same result also with other values: 500.000, 250.000, ..., 9600.

i think there is something wrong with the new kernel - something with bad implementation of the GPIOs.

it is quite disappointing and i think i'm ready to change the OS from OPENELEC to OSMC. Is hard to believe that is a hardware problem. 1 year, this setup worked flawless. (sins 1st May 2015 to be precise )

thank you for your suport!
I found the problem: my power supply for the LED's is faulty - couldn't provide constant 5V DC: my power supply has evolved into a ramp signal generator