I'm using a chain of 15 shiftbrites that I need to flash white based on some delay timing. I'm using non-SPI code because I'm running shiftbrites along with a WAVE shield. The code seems fine as I can get the flashing I want while just providing the green channel with flashing data from an array while the red and blue receive zero values. Once I want to bring another channel into the mix, my chain starts freaking out. The chain of shiftbrites is in a relatively small area and the cable between them are the standard 6 pin leads, so no long runs here. Power is from a little MeanWell wallwart, 9vdc @ 2 amps which is powering the Arduino as well as the shiftbrites.
I have a good multi-meter but no o-scope. My chain freaks out even if I'm only sending a value of 10 to red, green and blue. Wire runs are short, power is good and the code works with green just fine.
Is there some magic to cleaning up the TTL on the shiftbrites, or is a small animal sacrifice in order? Any help is appreciated.
There are two factors that can help with this sort of problem. One is connecting power directly from the supply to a couple of other points on the chain, in this case the end and the middle in addition to the beginning might help a lot. The second factor is supply voltage, 9V is the maximum for ShiftBrites but that doesn't mean you should try to run it that high if you have a choice. For LEDs, lower voltage is better because less power needs to be thrown away as heat. If possible, try using a 6V supply. Someone else reported very good results with a 5V supply, though that is below recommended voltage due to the internal regulator.
Thanks so much. Switched from my 9vdc to a 6vdc and everything smoothed right out. I had tried a 7.4vdc supply earlier in the process but that too caused the string to act erratically so I had given up on the "less voltage" idea. Nice little units BTW. Is there something like a ShiftBar that is a simple breakout board for the ShiftBrites with screw terminals on one side and a header on the other?