I have a teensy 3.2 on one end of a staff and two strips of 32 leds on each end of the staff. I have a 4 foot section going from the end of the staff with the teensy connected to the other end hooking up to the leds.
When the long wire is hooked up the section hooked up to the 4 foot section of wire displays correctly, but the side close to the teensy is acting funny.
If I disconnect the 4 foot wire section, the section close to the teensy now works fine. It is something to do with the timing im pretty sure because the section works okay if I disconnect only the clock wire from the 4 foot section.
Any tips? Do I need to have equal length strips? The sketch I am running is adafruit’s pov code.
I’m guessing it’s a power issue. Are you powering the strips individually, or running power through the teensy? Check out the wiring diagram on this guide – the doublestaffs don’t have quite that many LEDs but they do all work fine. (the guide doesn’t use a teensy but the wiring should be the same otherwise) https://learn.adafruit.com/pov-dotstar-double-staff/wiring
Each side has power and everything is wired up correctly. I had a teensy board on each end and it worked fine. I then disconnected one and hooked up the opposite side of the teensy with all 4 wires, power, ground, data, clock. Each side has a li-ion battery which powers the system fine.
The side without the teensy near it works fine so signal loss is not the issue. The side with the teensy near it has issues when the other side is hooked up. I think it noise on the clock line. It displays the image in the first 15 or so leds and then it becomes a mess of colors. Its odd. I may need a resistor or to try grounding the clock line at the bottom of the strips as suggested by people in another forum. Ive never had to do that on my projects. WS2812 strips never had an issue like this in the same configuration.
@Chris_Stock what you are describing is definitely a power issue. Measure how many V you get at the spot where your pixels go all nuts. I’m betting it will be way under 4V
You say you have two batteries, one at each end? You don’t accidently have the two battery’s positives connected together do you? Everything should have grounds connected, but I think you’ll only want data, clock, and ground running from the Teensy end to the other non-Teensy end.
Have you tried reducing the SPI clock to only 12 MHz? APA102 just barely works at the default 24 MHz. Each APA102 “regenerates” the signal for the next, but the bandwidth limits of the APA102’s chip cause the pulse width to change slightly after each LED. Usually problems begin after 100 to 200 LEDs, but long wires (or any number of other factors) could change things.
So when I have the teensy hooked up to the leds next to it and send data from the halfway point of my leds down the 4 ft wire section to the other led section it works better now.
So confusing. Is there anyone that wants to try this out and see if you have the same issue?