Hey,
Hoping for some clarification here. I’m looking to use the OctoWS2811 board with a Teensy 3.6 to drive some 24V LED Strips using some FastLED code I’ve already been prototyping. Specifically, I’m connecting 2 WS2811 strips that are 1, 800 LEDS each. The part that I’m unclear on, is power for the data signal. The OctoWS2811 will get me from the Teensy’s 3.3V to 5V, but I could use some help figuring out if I need to do some level shifting to get that 5V up to 24V. If so, I’ve seen some posts in my initial research suggesting the use of a mosfet or some TIP42 transistors. Any help pointing me in the right direction here would be much appreciated. Happy to provide further details if needed too.
No, the data signal will still he 5v. Also with a single strip being 1800 leds long, it will take 54ms to write a single frame of data - capping you at under 20fps…
Thanks for the reply Daniel. To see if I have this right… I can power my OctoWS2811/Teensy 3.6 from its USB port, connect my two 24V power supplies to each end of the led strip and connect ground of all three together? I don’t need to add anything else into that circuit to account for the data signal being 5V and the leds 24V? My main concern is any damage caused to the strip.
In terms of fps, I’m going to try maintaining that many leds as one strip for now as the animation I’m programming is a pretty slow movement of the light moving down the strip. If I’m not satisfied with the results then I’ll split it up to lengths that work. The strip will be forming a large circle, so I’m hoping to keep all the wiring to one point if I can.
@Jeff_Howard If I understand you correctly, you’re going to be using two 24V power supplies. The grounds of those and the ground of the MCU should all be connected as you stated. The +24V lines from the two power supplies should not be connected though. Your ground can be connected all the way around the circle. The +24V lines from each supply should only go half way around and not connect to the other.
Thanks @marmil . I didn’t go in to those details but should have. I was planning to supply power as you’ve outlined, with the +24V line disconnected in the middle. Powering one strip from the beginning and the other from the end at least means that I can run the power lines to one central point.
Before I power anything up though, I’m hoping to confirm what @Daniel_Garcia had mentioned above. That the power line coming from the Teensy/OctoWS2811, will work to provide data at 5V despite the leds being powered at 24V (and that there shouldn’t be any damage to the leds strips in trying to do so or if there is anything else I should add to circuit if there is risk of that).
The only connections to your leds from the Teensy should be data (which is at 5v) and ground - you shouldn’t be running power from the Teensy to the leds.
Thanks @Daniel_Garcia . I’m on the same page there. I wasn’t anticipating running power from the Teensy to the strips. Just not clear on how the power coming into the Teensy affects the output on the data line. As I have it now, I’ve got a 5V supply into the Teensy. Data + Clock wires out from the OctoWS2811 via Cat6 and connecting to the WS2811 leds strips, which will be powered separately with 24V.
Reading up on the WS2811 data sheet and going through some other forums posts about 24V strips has just had me unclear if there was anything else needed. A resistor or mosfet connecting the data line? Also, I’m curious… have you had experience using any 24V led strips with a Teensy? Same goes for anyone else reading this? Appreciate the help!
A MOSFET is sometimes used to control the individual R,G,B on NON-addressable 12V RGB strips (the “dumb” strips with a +12V,R,G,B connection) since the micro controller can’t safely switch the higher voltage/amperage through it’s pins.
Thanks for clarifying that point @marmil . I didn’t spend too much of my time researching exploring that option, so wasn’t sure if it was applicable in this context.
Can you offer any insights on if I should be worried of doing any damage to the LED strips with the set up I’ve outlined above? I’m working towards powering them up tomorrow and that’s my main concern. Any additional thoughts or considerations there would be appreciated!
One note: Since you will be powering the strips and controller with different power supplies, good practice recommends to always power the strips up first and then the controller, and do the reverse when shutting down, power off the controller, then the strips. This is to avoid the strip from trying to use the data line as a source of power.
If you later power the controller off one of your 24V power supplies using with voltage regulator to step the voltage down to 5V for the controller then you can turn it all on/off together at the same time. (But note that if you’re using a Teensy and powering with external power and not via the USB cable you’ll need to cut the power trace on the bottom of the Teensy board to seperate VIN from VUSB. See info card that came with your Teensy or ask on the PJRC forum if you need more info.)
Btw, how long is your CAT6 data line going to be? Also, you mentioned data + clock previously, but your strips only have a data connection (no clock) correct?
These notes are really helpful! I’d already caught some of that from reading the NeoPixel best practices as the strips I’m using are very similar to them, just 24V instead. They do have data and clock wires.
I had done some reading about options for powering the Teensy, but the part that was helpful to hear from you was the external power being the difference in allowing me to turn it all on/off together. The installation will be running all day and powered off at night. I’m looking to automate that so a very useful consideration!
The CAT6 line will be either close to 2 meters or close to 5. Depends if I’m able to elevate the box that will be holding the Teensy/power supplies, etc.
One more note about those Adafruit best practices. I was planning to take their recommendation to add a capacitor (1000µF, 25V) across power and ground as well as a resistor (510 Ohm) between the data signal from the CAT6 and the data input wire in the led strip. That recommendation make sense to you? and given that I’m working with the 24V strips do those values for the components make seem suitable too?
Since your strips are 24V (not the more commonly used 5V) you will want a cap with a higher voltage rating! Get 1000uf 50V capacitors and put one at the start of each strips.
Some people use the resistor on the data line and others don’t and seem to get along just fine. My understanding is you only need 100 ohm resistor when using CAT5/CAT6. And here’s the suggested wiring for that. (Basically don’t put the data and clock on the same twisted pair, and ground the other wire in the pair.)
Glad I asked! Thanks for the wiring diagram too. I did confirm the 100 ohm resistors are built in to the OctoWS2811. Hopefully that’s the last of my questions for now and my next post will be sharing results!
Hey again @marmil . I ran into something else before getting to powering things up so I’m holding off a little longer till I give that a go. It was pointed out to me that if the strips have a data AND clock wire, that they likely aren’t WS2811 but more likely WS2801. I tried cutting a piece out of the weather proof casing it’s in. Was hoping that would provide some clarity for me, but it hasn’t. The strips were clearly listed as WS2811 and my conversations with the supplier had confirmed this but now I’m second guessing that. Is it possible that fourth wire is data ground? I’m attaching a pic of the piece I cut out and will post another with some additional details from the spec sheet. Are you able to tell what I’m working with?
This is why I was trying to clarify why you said Data + Clock the other day. I did see this on the FastLED wiki:
“UCS1903 - similar to tm1809/ws2811. Not sure why this exists, honestly. Very very slow protocol, closer to 400kbps.”
I would wire up that piece you cut out and just try to light it up. When specifying the chipset you’re using on the FastLED.addLeds line in the setup part of your sketch, if you specify the wrong type of chipset it won’t hurt anything, it just won’t light up correctly or won’t light up at all. If it doesn’t light properly try another chipset. Experiment and hopefully something will work!
I would first try hooking your Data line to that solder pad near the “D11” (the one near the GND pad). My guess is that label should actually be DI1 (a capital i for In, not a 1). You’ll note on the other end of that section it’s a DO1 and 2 (for Data Out). Let us know what you find out.
Hey @marmil , good catch on those labels. Looks like you’re right. With the last LED of the six looking a little different and having the 4 connections instead of 3 like the others, the strip likely has a P943 setup. I’m waiting to hear back form the supplier on this, which should hopefully be in the next day or two as I’ve got another question I’m trying to clarify from too (noted below).
Your posts have helped me made progress. Here’s where I’m at so far…
Connected an Arduino Uno to a single cut length (6 LEDs).
Set up a basic circuit with a capacitor (1000µF, 50V) bridging power/ground and a resistor (510ohm) connected to data on the strip (DI1).
Set the chipset as UCS1903 in the FastLED example Cylon.
Powered everything on in the sequence: power, ground, data.
It worked!
Changed the chipset to WS2811 and powered everything up again.
It worked!
Note, for both instances above… connecting power lit all LEDs blue until the data signal was connected and the colors began to cycle.
At that point I tried moving everything from the Arduino to the Teensy setup, including the larger LED strip. This is where I’ve gotten stuck. I’ve attached a photo of how I wired everything together. One point to note, is I can’t tell which cable from the LED strip is connected to DI1 without damaging its casing. I’m hoping the supplier will clarify that. So when I tried connecting this setup, I tried connecting data to both the green and blue wires from the LED strip. Here are the other steps I took.
Connected the wiring as detailed in the attached photo (not shown in the photo, the LED strip with 1788 LEDs).
The entire strip (all 1788 LEDs) turned blue for maybe a half second then all turned off.
Tried changing the data wire coming from the strip and tried again. Same result.
All that said… notice anything in my setup that needs changing? or have any advice on what my next steps should be?
Appreciate the help.
Thanks!
Jeff missing/deleted image from Google+
Also to note… that green data wire in the picture actually isn’t attached to anything, just looks like it’s connected to power. When I tried testing each data line from the LED strip, I left the other floating.
Not to sure. Perhaps try with short section of LEDs first. Also, I would avoid powering the 1,788 LEDs through the bread board. You could move the capacitor to the terminal block.
Stick with the simple cylon sketch of that was already working before changing sketches.
