Control high power RGBW leds individually with an arduino? - Page 1
Forum section: electronics / beginners

author: sebrassino
author_rank: Newbie
timestamp: January 09, 2017, 05:56:26 pm
content: Hello everyone,My first post here. So its also a short introduction. Im Sebastiaan (31years) and Im from the Netherlands. As a kid I was always inspired by electronics but I had put it aside for a long time. Im having an idea already for a long time and decided to put it into work. So hours of googling and searching the web has gone already. Many ideas, sketches and schemes have past already.The problem Im having is ofcourse lack of knowledge. By googling a few months ago I came across Dave's channel. So started to watch a vid, and another, and another. Well, alot of things I learned. Made me understanding the problems I had and have to overcome. But step by step im learning more and more.What I want is to control high powered RGBW leds indivualy.Because coding is quite new to me(I do understand it). I thought its wise to start with arduino. Mainly because there is such a big community behind it where many examples are shown and described. An arduino can dim with quite simple constant current circuit and a pwm signal a single RGBW led. Or more if you put the leds in series and have the right driver for it. To control more individual led's you need another arduino wich makes the project expensive and it wouldnt make any sense to be honest.Then I came agross the WS2812B Led. I believe the ws2811. Wich has an ic inside and makes it really easier with an arduino to adress multiple RGB leds. There are loads of examples of arrays/matrixes of that on youtube. Probably known by you but it was new for me. Im quite at that moment Im going to order a few of these to start at least experimenting with the code. and arduino itself.The led I want to power is the Cree mce rgbw led. Wich needs 700mAh of constant current. Or basicly any high powered led can be filled in.I have searched alot for the answer to my question, but cant find it. I probably dont know how to search for it.I search something simular to the ws2811. Something that listens to the serial data line and generates a pwm signal wich can be feeded into the pwm dimmer circuit.Where should I look? Or what should I look for? Im quite stuck at this at the moment. Thats why I post it.Thanks alot already!Sebas

author: tooki
author_rank: Super Contributor
timestamp: January 10, 2017, 01:00:15 am
content: Hi Sebastian,I'm also rediscovering electronics in my 30s.You can control many LEDs with a single Arduino. Each PWM pin can run a single LED, though if you want to run many more than that, the Arduino's PWM speed becomes an issue. The WS2812B's are easy to control but can be expensive. Another alternative you might not know about (I've just looked at the specs so far, haven't used them myself yet) are the various LED driver chips from TI (probably others make competing products). They handle dozens of LEDs per chip, and much like the WS2812B, the Arduino just tells it what to do, and the chip makes it happen. Might be worth a look, depending on what your application is.(I was looking into this for a project I'm envisioning, a DIY alarm clock with RGB LED matrix display, but at higher resolution than most. Maybe using Chinese video wall tiles, which now exist with pixel pitch as small as 1.2mm.)Good luck!

author: Mr.B
author_rank: Unknown
timestamp: January 10, 2017, 01:16:01 am
content: Quote from: tooki on January 10, 2017, 01:00:15 amDo you have a known source for these?Ali or eBay, wherever.Searching eBay for *video wall tiles* only gives me buckets of Wall Tiles (ceramic).Thanks.

author: Audioguru
author_rank: Super Contributor
timestamp: January 10, 2017, 02:11:01 am
content: You do not want to look for "video wall tiles". Instead you need to look for "LED driver IC". Never mind buying the fakes or second rated Chinese junk from Ali or ebay, instead buy name-brand parts locally.

author: LukeW
author_rank: Frequent Contributor
timestamp: January 10, 2017, 05:54:42 am
content: You can generate logic-level PWM from your Arduino, for each LED channel, and then buy or build appropriate constant-current drive electronics for running the high-power LEDs which can be controlled from logic-level PWM.

author: tooki
author_rank: Super Contributor
timestamp: January 10, 2017, 11:00:12 am
content: Quote from: Mr.B on January 10, 2017, 01:16:01 amLook for "Pnled module", wherenis the pixel pitch.This company has a wide array of these things, but their aliexpress pricing is clearly placeholders:https://www.aliexpress.com/store/product/Leeman-P1-6-P1-8-P1-9-P2-P2-5-P3-P3-9-P4-P4-8/1239156_32357980878.html?spm=2114.12010608.0.0.nxulrYWhat I haven't been able to find out in any way is info on how to drive these things. I obviously haven't yet discovered the right google incantation to find that info. (I was actually planning to make a post asking about this. Somebody here must know, since it was on this very forum that I was made aware of the existence of these panels, by someone pointing out how affordable they are.)

author: Psi
author_rank: Super Contributor
timestamp: January 10, 2017, 11:33:48 am
content: the LED wall tiles i'm using are 32x32 pixel RGB and cost ~$22 each from aliexpress, an amazing price.Not sure if this is true of all types but for my ones driving them is not trivial.If you want to go down the arduino route there is arduino code available to drive them but only if you buy the right one.Also control options are limited with arduino. The 8bit mcu running at 16mhz can only really do 3bit colour. maybe a bit more if you really push things.The tiles are intended to be driven by FPGA and so require you to do the colour mixing and row scanning yourself in software.I had to pull out the STM32F4 and do some funky DMA tricks to get 16bit color out of a 64x256 led array that im making

author: BrianHG
author_rank: Super Contributor
timestamp: January 10, 2017, 11:40:36 am
content: Quote from: Mr.B on January 10, 2017, 01:16:01 amYou should be searching for: *rgb led display modules*or:https://www.aliexpress.com/wholesale?initiative_id=QRW_20170110034646&site=glo&g=y&SearchText=rgb+led+display+modules&needQuery=n&page=1

author: Psi
author_rank: Super Contributor
timestamp: January 10, 2017, 11:44:06 am
content: I think this is the same ones i have.Looks a little different on the back but specs are the samehttps://www.aliexpress.com/item/Waterproof-SMD2727-LED-Outdoor-P5-LED-Panel-160MM-160MM-MBI-IC5020-1-8-Scan-7500Nit-High/32699838147.html

author: sebrassino
author_rank: Newbie
timestamp: January 10, 2017, 02:40:47 pm
content: Quote from: tooki on January 10, 2017, 01:00:15 amQuote from: LukeW on January 10, 2017, 05:54:42 amThanks! Yeah electronics is something I couldnt let go haha. Debugging something is just something amazing!I will take a look to the arduino, ive read somewhere the mega variant has more pwm channels (yes 14). For now, that might do the trick. I might control 3 RGBW leds with indeed its constant current circuit. But have to look into that. In the end I would like to control 10+ RGBW high power leds. Well, I would like it to be modular, so more or less leds can be fitted in. (like the ws2812b neopixels idea) So I need a different solution to control them. Maybe there the TI chips would become handy. Will google that aswell.I dont want to make a led matrix or tile/panel. It could be possible to make one though. (imagine a 5x5 10watt per pixel matrix)I also came across the "pixie" wich is basicly that what Im searching for. Yet its not rgbw. And its only limited to a 3watt led. So a very specific design.https://learn.adafruit.com/pixie-3-watt-smart-chainable-led-pixels/overviewWich is basicly like a shift register signal? Am I right? It takes its data and passes it on? Im very interested to learn more about it.What im looking for in an ideal situation is an ic that listens to the serial data. And generates 4 channels of logic level pwm, wich is then feeded into a pwm dimmer circuit for the led. Or just 1 pwm channel but then youll need 4 per rgbw led wich creates signal loss issues probably. If someone rings a bell that says, this is what you need! Let me knowThis will create a high variety in the leds you can drive. Basicly every single one. From a low power led to the 100watts. There are so much different led drivers. That almost everything is possible.I will dive into the ti drivers you mentioned tooki. And I will order an arduino mega. To discover and experiment with that in general.Thanks for the repsonses.

author: BrianHG
author_rank: Super Contributor
timestamp: January 10, 2017, 05:52:47 pm
content: I once created a little PIC project using the PIC12F1571 which took in a ttl RS-232 command and fed 8 to 16 (or more is possible) RGB WS2812 leds on a chain.It was to alleviate the strict PWM refresh requirements allowing for easy 2-4 character commands. Were not talking video refresh speeds if you were attempting graphics, but it's cheap and you can chain a few PICs on 1 serial port with addressing if you want to do something more complex than pre-programmed colored flashing, strobing, chasing patterns, text or still graphics. You would have to write your own PIC software to do the same.

author: sebrassino
author_rank: Newbie
timestamp: January 10, 2017, 11:45:45 pm
content: Quote from: BrianHG on January 10, 2017, 05:52:47 pmMmmm. Thanks, I think I kinda found/learned something on this. It is also what Pixie project uses. But I need to understand it.https://learn.adafruit.com/pixie-3-watt-smart-chainable-led-pixels/designwich also uses the pic:http://www.microchip.com/wwwproducts/en/PIC12F1571wich basicly creates a pwm channel. Wich, can be feeded into a led driver circuit wich in that project is happening. (correct me please if im wrong) Yes that can work. I assume that there are more Pics that have 4 or more pwm channels.

author: BrianHG
author_rank: Super Contributor
timestamp: January 11, 2017, 08:48:04 am
content: The PIC12F1572 is an 8 pin pic & 65cents, without any other part except a decoupling cap, in my project, it fed a WS2812 compatible bus from 1 pin and received RS232 in it's RS232 input. The remaining IOs were used to configure and ID. I performed my setup like this since the 1 PIC is fast enough to feet a string of 64 RGB Led through the 1 wire WS2812 format at around 30 refreshes a second. 8 of these PICs with connected to 8 strings gave me a 64x8 pixel RGB display. The all were fed the same serial input, it was the spare IOs which I configured an ID for each pic. It was the serial commands which addresses which column 1 through 8.Ok, now, If you want a high powered manual PWM a R & G & B led, there are larger pics with multiple PWMs where you can use 1 channel for each color, but, this would be suited for RGB flood lighting or lamps where you can store and ID for each pic is you want multiple lamps in an environment with custom ID control for each one from a single RS232 source. This would also be good for wireless RS232 control.

author: sebrassino
author_rank: Newbie
timestamp: January 12, 2017, 04:14:34 pm
content: I like the idea of making this. As much as I want it the more I am googling this the more I realise this is way out of my capabilities right now. Besides. I think this is somehow kinda already made.I was searching to control more pwm channels. And I think I found it.https://www.adafruit.com/product/815