Hi everyone !
I'm doing an IoT project (mostly a test for me) using an arduino Yun, but for now i have another problem.
I found that RGBW ring (from a halo ring) and i want to use it in my project but i can't find how to use is. There's no built in microcontroler just 6 pin : +; -; D; -M (?); Y; (see pictures below)
For now i want to try this LED Ring with a classic arduino uno. On the original Halo (where this ring comes from) the system is able to control color of each "pixel" (five LEDs in a row) maybe independently ? or turn them off and control the lighting of all white LEDs at the same time (and Warm white LEDs)
If you have any indication to help me i'll appreciate that !
Thank you for reading me
It's not something I have seen before. I think you will be lucky if anyone on the forum has either.
My guess would be you have an outer ring of ws2812 LEDs which connect to the +, - & D. The inner ring of white and warm white may connect to the M (which is actually a W, I suspect), Y and maybe also -.
Do some probing around with your multimeter on resistance/continuity setting. Figure out where each of the 6 connectors go to on the nearby LEDs.
If I'm correct, the ws2812 LEDs will be easy to drive using the NeoPixel or FastLED libraries. You will need a substantial 5V power supply to power them. The Uno could only provide power for 5~10 of these LEDs, and there are a lot more than that!
The White and Yellow/warm white LEDs will need MOSFET drivers, possibly H-bridge drivers. Hard to say what voltage will be needed, but one clue is that there is a current limiting resistor for every 12 or 13 LEDs, and they will have a forward voltage of around 3~3.5V, so it could be as high as 50V.
If you can find some data sheet or specifications for the halo light, that will be invaluable to you.
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No H-bridge since there's no need to reverse the voltage on this. A simple low-side MOSFET switch will be inadequate since there are apparently no current limiter resistors on the ring itself, so current control needs to be done separately. Use a suitable constant current supply. The common approach is to use a buck-mode LED driver; there are hundreds of types to be found, some with an internal MOSFET switch, some using an external one. A few have found their way onto convenient/hobby-friendly modules like the PicoBuck and FemtoBuck boards.
The main question concerning the white arrays is how they're connected; it's likely a combination of series and parallel connection, and how this is done exactly will determine the forward drop and current requirements.
Keep also in mind that white LEDs can differ a bit; the size shown can be single elements (forward drop ~3.5V or so), but I've also encountered twin-LEDs in a package (~7V drop). Test with a bench power supply set to 20mA and measure voltage drop to determine what's going on.
Hi, @elgoogK0
Welcome to the forum.
Can you please post a link to specs/data of the ring?
Thanks.. Tom.. 
@rsmls You know for sure that the white and warm white LEDs are not connected back-to-back? I'm not sure they are, I'm just saying it's a possibility.
Do you know what these are for?
Theoretically possible, practically extremely improbable.
I saw that one but thought it was only one on the entire ring and it was near the data input for the addressable LEDs, so assumed it was associated with that. I didn't observe the value. Given that it's 2r7, it sure does look like a current limiting resistor and the Vf of the white LED arrays will be close to the intended supply voltage and in that case, simply applying a suitable voltage (and using e.g. a low-side MOSFET switch) would be perfectly fine. My bad, thanks for pointing this out! No PicoBuck etc. needed!
Supply voltage will be a plausible one; probably 12V or so. Count LEDs (white and warm-white separately) and series resistors; divide the number of LEDs by the number of series resistors (divided by two), which will give the number of series-connected LEDs. Measure Vf of an LED (I'm almost sure it'll be standard 3.5V-ish) and you can work out the intended supply voltage.
I have come across, on this forum, led strips containing a mix of white and warm white LEDs but having only 2 connectors. An h-bridge was necessary to drive those. But I agree it's pretty rare and unlikely.
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I think there would need to be far more resistors than there are for such a low voltage.
You may be right. 14 resistors = 7 strings of white LEDs per color.
I guesstimate around 7 LEDs per color, which would make 24V a more likely supply voltage.
Hi again !
Thanks you all for your replies. So i tried to test the connectors with a multimeter as said by PaulRB. I soldered wires onto the ring for more test with the arduino.
Here's the installation :
It's a simple 5V supply wired to + and - of the ring, the others are wired to the arduino. I tried to use fastpixel and neopixel libraries but it doesn't seems to work, nothing happend. So i searched more info about it, i could'nt fin th reference on internet :
But i found the original product where it comes from :
I don't have much time for now so sorry for the late replies and thank you again ! i'll try to find more info
How did you connect it? I expect you only need to connect 3 things to the ring to get the RGB to work:
- and - to the +5V and GND output of your PSU
D to a data pin on your Arduino
GND output of the PSU connected to GND on the Arduino.
Btw, since the white LEDs are most likely intended to run on a 24V power supply, there's a possibility of a complication here. There are two pads on opposite sides of the + sign on the strip and it's possible that one is for the 5V of the addressable RGB LEDs and the other for the 24V of the white LED arrays. Maybe you ended up connecting the +5V to the wrong pad?
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