Problem with Naze32 rev6 / WS2812 LEDS

[Toownky]

I'm building a new quad based on the White sheep frame. It's the first time I'm messing with LEDS and not everything goes according to plan LEDs are more/less working : they light up, but the colors are all messed up. IMHO, it's definitely a serial sync issue but I don't understand why.

My setup :

4 WS2812 LEDS strips, 8 LED each, 1 strip per arm, nothing fancy so far.
LED strips are powered using a separate BEC rated for 1.5A (4 strip x 8 LEDs * 18mA = 576mA, should be OK) and are chained : Naze32 pin5 -> strip 1 DI, strip 1 DO -> strip 2 DI, and so on. I also "chained" the +5V and GND. The DI-DO chaining has be triple checked.

Flight controller is a Naze32 Afro rev6a 10DOF flashed with Cleanflight 1.12.0.

Using PPM (obviously), LED feature turned ON and I tried various LEDs configurations. Sometime colors are almost correct, sometime it's only a huge mess.

Any idea of what is going on here ?

 

[Toownky]

Partially self-response : RTFM

The Cleanflight documentation talk about adding a diode on Vin to drop the input voltage. Don't know if this will work for me but this worth a try.

 

[Craftydan]

Either a diode or a 3.3v regulator.

The WS2812B LEDs have trouble understanding the controler when the data line's voltage (3.3v on the Naze board) is much lower than the power rail. They can work at 5v, but the data "high" needs to be much closer to that.

If the diode doesn't work for you, these are my go-to for UBECs and other voltage regulation on airframes:

http://www.banggood.com/5Pcs-Mini-DC-Adjustable-Power-Supply-Buck-Module-Step-Down-Module-p-952402.html

I buy these by the 10 pack for shop stock, but I play a LOT with electronics.

Keep in mind, you'll have to set the voltage output. 3.5-4v should work fine for the WS2812B's.

BTW, your data line needs to be routed in a single path, but the power does not. If you find that at the lower voltage, the last few are dropping off, it may be due to the path being too long and the voltage dropping as it goes. At 60mA/LED max, an array of these can be power hungry, but this regulator can continuously supply 30 WS2812B's at full bright white. Splitting the power side up, so each boom has it's own direct connection to the regulator will cut the length the power has to travel by a factor of 4.

 

[Toownky]

Thanks for the answer.

The diode does the trick and everything work perfectly now ! My fault for not reading the man pages...
The BEC provides a very nice and stable 5.02V output (on load), and the diode has a 0.52V drop. Not in the 3.5-4V recommended, but small voltage drop is enough make make it work.

Powering the 4 strips in series does not cause any problem for me. Splitting power lines was my first idea, but I went for a single one only the make the built a bit cleaner.