Anyone got any suggestions on how to reduce noise/crosstalk when using the parallel output

Archive FastLED Archive
,
1

Anyone got any suggestions on how to reduce noise/crosstalk when using the parallel output setups on a Teensy 3.1 with WS2812 leds?

I’m using the WS2811_PORTC configuration for parallel output on 4 channels, pins 15, 22, 23 and 9. It works, mostly, but occasionally I’ll get a flicker of noise across the outputs. Its not awful, but its enough to be distracting occasionally. I’m currently avoiding the issue by driving the 4 outputs with separate controllers but this results in a max framerate of 61fps while parallel output gets me up to 112fps, which is definitely preferable.

I’ve currently got the outputs going through a SN74HCT245N level shifter then into some screw terminals and from there out to my LEDs, which currently have one standard 3 pin connector plug before the LEDs themselves. Could I add some resistors before the screw terminals perhaps? If so, what values?

2

I’m of the mindset your not dealing w/ crosstalk … got access to an oscilloscope? Can you disable 3 outputs in code and confirm the flicker goes away?

3

Well its not so much a flicker, as a flash of incorrect data across the LEDs…but sadly no scope so i can’t debug this easily. I’ll try removing the outputs and see if that helps.

4

don’t disable the code driving the outputs in the event its a timing issue …

5

right, i’ll keep writing to my massive array, i’ll just reduce the number of outputs passed to the parallel controller.

6

If you want to experiment with resistors use a 220 Ohm pot and try different settings. Typical values are between 60 and 180 Ohm.