OctoWS2811 Adaptor: documentation clarification

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mercyful

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Hello,
I am using Teensy 3.2 and the OctoWS2811 Adaptor board, and I am hitting the usual powersupply/ground problems of any hardware newbie like me will hit with any great than 320 leds strips.

I still need to understand exactly what is the meaning of what the documentation of the WS2811 Adaptor states here:

"If Teensy 3.2 will be powered by the LED strip power supply, 5V and ground wires should be run together with the CAT6 cables and connected to the +5V and GND pads on the adaptor boards""


Can someone explain this sentence with a simple wiring diagram?

I guess it is something like this ugly ascii art:

Code:
powersupplyV+       o------- >OctoWS2811Adaptor 5V   
powersupplyground o-------> OctoWS2811Adaptor GND
Then Ethernet CAT5/6 cable out of the Adaptor is connected to the led strips like this:

Code:
eth data                 o------> DI led strip
eth ground             o------>  GND led strip
and also the powersupply is connected to the led strip, like this:

Code:
powersupplyground o----->  GND led strip
powersupplyV+       o-----> 5v led strip
Where's my error (a part trying without proper knowledge?) ?

Thanks a lot!

p.s. i am using a powersupply 5V 20Amps, that should be fine for 320 leds I hope.
 
The powers Supply should be fine for what you are doing, your wiring plan is on track.

Key thing with the gnds is that the LEDs make lots of switching noise on the 5V power which you don't want in in your data lines, but you also need your data to be arriving with the right potential with respect to the gnd on the LEDs. So your setup should be right with seperate power to Teensy+octo, data and gnd going to the strip and the main LED power runs to the strips.

Would ask what size wire you are running for this all? The ~6Amps max current draw will need reasonable though not huge wires. A check for this, and the wiring above is to get the multimeter out and clip/fasten the black lead to the negative of your power supply. Then measure various points:
Gnd on Octo board
Gnd on input of each strip
Gnd on far end of each strip

5V out on PSU
5V in on Teensy
5V in on each strip
5V at far end of strip

All of these should be within 0.25V of your PSU levels (and ideally exactly the same), if they are not then you need to work out what is going on. Common problem is needing to add wires feeding current into the strip every couple of meters because the strip can't carry the current without loss.

Second problem mode is around power supply and rate of change. It may be that it can provide 20Amps, but can't change fast enough to cope with LEDs.

Testing for this sort of thing is done by turning on one pixel at 1,1,1 brightness (or as low as is visible) and running it down each strip. If you can't get a single dim pixel to work then you have a signal problem, if a single dim pixel works, try all pixels to 1,1,1, then step up to a steady high brightness on a single colour (possibly repeating the power check). Note that 33% brightness on white is a harsher current draw then 100% of a single colour because PWM will on some intervals be drawing maximum as they beat together, even at low average draw. If you have a scope try monitoring for ripple on the power supply. Adding filter caps wherever you inject power into the strip can help if power is unstable, but too many can mean your power supply struggles to start as it charges them all. What you especially want to avoid is overshooting, since neither the LEDs nor the Teensy will cope well with > 5.5V so you really don't want that, even if the strips work eventually something will go bang.
 
Thanks a lot for the answer!
With your information i think I determined that the problem is a signal problem, because:
1) i have 4 (four) led strips with 80 leds each; the strips are bought from Gree-Leds: http://www.gree-leds.com/productshow.asp?ArticleID=Y0YY52S0YX ; each strip is connected with the provided connector similar to this one: http://images4.shopmadeinchina.com/20160223/605/210301605/67896789188100.jpg
2) I am running as you proposed a basic test with one dim led turned on for each strip (that is 4 leds turned on in total), color is the weakest possible one, i.e. RGB=(1/255,1/255,1/255); the turn on led is running along the strip at 100millisecond/led speed;
3) two strips works perfectly (the ones connected to ORANGE and BLUE wires of ETH cable), the other two (the ones connected to the BROWN and GREEN wires) have the first led stable RED, and some random blinking each few seconds in random position with random color;
3bis) Note that I can shuffle the connections (i am using the connectors shown above) between strips and signal lines (coming out of the ETH cable), and the ones connected to the BROWN or GREEN do not work, hence the strips are not faulty, the problem must lie between the connectors and the powersupply/OctoWS2811Adapter;
4) i measured as you proposed the voltage, there is not voltage drop at all with this setup (I tried with full brightness, it dropped to 4.7, but that is another problem :) )
5) each strip is connected (GND and DI) to the ethernet CAT 5 (not CAT 6) coming out of the WS2811 adaptor.
6) for power and GND I am using #22 wires or better, except for the wires for the connectors carrying the DI and GND to the strip, they are slightly below that (gotta check asap);

Hence the signal problem could be caused by:
A) CAT 5 cable? I am not using CAT 6 cable... that could be highly the issue;
B) the thin wires at connectors? Althought they carry only GND and DI, I have to try with proper wire greater than #22 also for those i believe;

Thanks for any further help/insight!
 
My first thought is that you are having some sort of wiring issue. Simple check is to grab the blink example and a multimeter And work through your problem outputs having changed the delay to 3000

https://www.pjrc.com/store/octo28_adaptor.html

LEDS won't work but the multimeter should show a clean 5V/0V steps. If you have access to a scope you can skip that step but aim is one way or another to confirm you have solid 5V.

Another test for single strips is using the fastled or neopixel pointed at the single strip pins.
 
Sorted out what the problem is: the TouchScreen.h library I am using is leveraging pin 7 and 8 too (as OctoWS2811 does too!).
As soon as i removed this pin conflict, i am able to drive 4 led strips with OctoWS2811 :)
This is the reason why the strips connected to signals #1(pin 2) and #2(pin 14) always worked, while the ones connected to #3(pin 7) and #4(pin 8) never did!
Thanks for your help!
 
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