So reading this thread has me wondering:http://arduino.cc/forum/index.php/topic,80567.0.htmlwhy would you suggest WS2811 LEDs on an Arduino forum? I would need a newer clocked arduino (uno, leo, teensy3, etc) to just keep up with >50 LEDs. Specifically, something off-brand 'duino compatible with a honking processor.Nobody on that thread mentioned fastSPI, though. Is fastSPI fast enough to handle a 2811 on an 16MHz arduino? 32? 32 with interrupts? Your last post says 500us to latch, but the code says 50us... which the other thread says is impossible/flakey for more than a few leds.I just seems to me like a pretty significant detail to skip, no?
The only issues with length is that at some point you need to add some pull-downs to the data and clock lines at the END of the string, to avoid reflection of the signal.
Read the data sheet on the WS2801. It tells you when/where you need to add the resistors.However, I have run the FastSPI testled sketch on a full 5m reel straight out of the box with no problems what so ever. The only change I made to the sketch was to add the proper dataRate line, which is missing from the sketch. No resistors added, just hook up the four wires, make sure the 4 wires at the end aren't touching anything metal, and turn it on. In fact, I just grabbed two reels, hooked them up in parallel to my Uno, using FastSPI. I only ran one sequence, which is the single color down the whole strip, because it's not hooked up to a high amp power supply:(the freezing that you're seeing, if any, is just the way YouTube processed the video - the chase is smooth with no hiccups.)http://www.youtube.com/watch?v=1XhF-0Tlg_U
The Connection and Driving of Cascading OperationThe transmit the data over long distance by cascading, the WS2801 integrates push-pull output stage with strong driving capability which enables the data and clock can be transmitted up to 6 meters at 2MHz clock frequency.To prevent the reflection, it is necessary to connect a 50? resistor at the data input or output port for impedance match.
Maybe post your sketch so I can see what you're doing ...