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Author Topic: Need advice of Digital Individually Addressable vs Analog RGB LED Strips.  (Read 988 times)
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So I am embarking on my first real arduino project, which is to line the perimeter of my room's ceiling with a 15 meter long LED strip and be able to control it with both audio input or via remote control.

I started looking into LED strips and found that the RGB analog ones are much cheaper than the digitally addressable ones. Clearly this is because the digitally addressable ones require much more sophisticated chips. I really want to use the digitally addressable ones because it would allow me to make cool patterns instead of just choosing color, but I still have many questions regarding both of them.

First off the analog ones, If  i end up buying these i will want to control brightness and color in two ways, first with an IR remote ( i will need to learn about IR arduino protocol) as well as sound input (i hear a lot of talk bout the MSGEQ7 chip but i have no idea how it is used to control color/brightness. I have looked online but the resources i have found do not go into much detail about the chips involved.

Secondly if i did end up buying the digitally addressable ones i will still want to controlo color and brightness with both a remote and sound input, but i will also want to be able to to switch into modes. Such as a visualizer mode where it picks up sound and "pushes" the LEDs across the strip according to the sound, or a rainbow chase mode where it circles through the colors except all offset a little. I assume this is just a little more coding to do and won't be much more complex than setting up IR control for the analog ones.

The difference though, is that the analog ones only have 4 input (one for each color and then ground) but the digital ones have  data in, clock in, power, and ground. Clearly if i chose to do analog it will require a lot more chips in order to control brightness and color as i will need to vary the voltage going into each of the three color controls (I am assuming). Is there somewhere i can go for a very detailed look at these analog RGB strips? Just to show you what I might be buying, this is what I was looking at.. This one comes with its own IR remote and controller, as well as a power supply. My goal is to instead use the arduino as the remote reciever/controller.

If i chose to buy the digitally addressable ones then I still need to learn how to make the arduino receive the IR remote control data, but instead i will be trying to figure out how to control the color, brightness of the digitally addressable ones, which i feel is much easier. If i am not mistaken (and please correct me if i am wrong) the digitally addressable ones can have color and brightness set via just the digital signal sent to it? I will need to learn the protocol for sending digital signals to each individual LED, is there a resource I can go to learn more about this in depth? I know a lot of libraries have been written for controlling individually addressable LEDs, but which one should i use/learn? These are currently the ones i am looking at, but I can't help but wonder if there is any cheaper ones? 15 meters is a lot and I don't want to be breaking the bank just to get individually addressable LEDs on my walls!

Lastly i am curious about powering such a long strip of LEDs. I read on adafruit that to avoid "brown out" you need to power the LEDs every meter, does that imply i need a separate power supply each meter? Or is there  a way to wire it such that you apply "fresh" power from the power supply each meter?

Thanks for all the information!

Oh two last questions! Since this is my first real arduino project and i intend to keep it forever, where do i go to learn about burning the design to a "permanent" chip? Or do i have to keep my arduino attached to the LED strip forever if i want to keep these forever?

Secondly, What is a good material to diffuse the LED light so i get an even spread instead of just a bunch of dots of light? I need it to be easy to cut and apply to walls and it needs to house the LEDS.
« Last Edit: December 04, 2013, 08:50:39 pm by Silman » Logged

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i hear a lot of talk bout the MSGEQ7 chip but i have no idea how it is used to control color/brightness.

The MSGEQ7 doesn't control color/brightness, it analyses sound data and gives you the results. YOU are the one who writes the software function to map the output of the MSGEQ7 to the LEDs.

Secondly if i did end up buying the digitally addressable ones i will still want to controlo color and brightness with both a remote and sound input, but i will also want to be able to to switch into modes. Such as a visualizer mode where it picks up sound and "pushes" the LEDs across the strip according to the sound, or a rainbow chase mode where it circles through the colors except all offset a little. I assume this is just a little more coding to do and won't be much more complex than setting up IR control for the analog ones.

That's more software. Once the hardware is set up you can really do whatever you like (and change it as many times as you want...)

The difference though, is that the analog ones only have 4 input (one for each color and then ground) but the digital ones have  data in, clock in, power, and ground. Clearly if i chose to do analog it will require a lot more chips in order to control brightness and color as i will need to vary the voltage going into each of the three color controls (I am assuming).

You need three MOSFETs.

If i chose to buy the digitally addressable ones then I still need to learn how to make the arduino receive the IR remote control data, but instead i will be trying to figure out how to control the color, brightness of the digitally addressable ones, which i feel is much easier. If i am not mistaken (and please correct me if i am wrong) the digitally addressable ones can have color and brightness set via just the digital signal sent to it? I will need to learn the protocol for sending digital signals to each individual LED, is there a resource I can go to learn more about this in depth?

It's just RGB color, 8 bits of each for each LED.

These are currently the ones i am looking at, but I can't help but wonder if there is any cheaper ones? 15 meters is a lot and I don't want to be breaking the bank just to get individually addressable LEDs on my walls!

Do you need 60 LEDs/m? Strips with 30 LEDs are much cheaper.

Lastly i am curious about powering such a long strip of LEDs. I read on adafruit that to avoid "brown out" you need to power the LEDs every meter, does that imply i need a separate power supply each meter? Or is there  a way to wire it such that you apply "fresh" power from the power supply each meter?

Yes, 15m at 60 RGB LEDs/m is 2700 LEDs so you need a LOT of amps.

For 15m of those strips you'll need a 60 amp power supply (seriously!).

You only need one power supply. You can run a really thick power cable alongside the strip and put in little 'jumper' wires from that across to the LED strip. Every meter sounds a bit much to me on a long strip (don't believe everything you read in forums), every two meters should be fine.

Oh two last questions! Since this is my first real arduino project and i intend to keep it forever, where do i go to learn about burning the design to a "permanent" chip? Or do i have to keep my arduino attached to the LED strip forever if i want to keep these forever?

Secondly, What is a good material to diffuse the LED light so i get an even spread instead of just a bunch of dots of light? I need it to be easy to cut and apply to walls and it needs to house the LEDS.

An Arduino Uno with wires poked into the header strips isn't ideal for permanent installations. For that I use Arduino Pro Minis - much cheaper/smaller and you can solder wires directly to the board.

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i hear a lot of talk bout the MSGEQ7 chip but i have no idea how it is used to control color/brightness.

The MSGEQ7 doesn't control color/brightness, it analyses sound data and gives you the results. YOU are the one who writes the software function to map the output of the MSGEQ7 to the LEDs.

Where can i read about how to map it to color and brightness? Has someone posted an explanation about how they do it? Sometimes i get discouraged from starting a project because i feel like i wont be able to figure out how something was programmed/assembled...

Secondly if i did end up buying the digitally addressable ones i will still want to controlo color and brightness with both a remote and sound input, but i will also want to be able to to switch into modes. Such as a visualizer mode where it picks up sound and "pushes" the LEDs across the strip according to the sound, or a rainbow chase mode where it circles through the colors except all offset a little. I assume this is just a little more coding to do and won't be much more complex than setting up IR control for the analog ones.

That's more software. Once the hardware is set up you can really do whatever you like (and change it as many times as you want...)
Is there a place i can go to read about programming these LED strips? Are the WS28112Bs always programmed the same way? How many bits of input do i need to specify the location and color of a specific LED? I hear there are libraries for this but how do they work? I really just want to read documentation on it so i can get some bearing on what to do.

The difference though, is that the analog ones only have 4 input (one for each color and then ground) but the digital ones have  data in, clock in, power, and ground. Clearly if i chose to do analog it will require a lot more chips in order to control brightness and color as i will need to vary the voltage going into each of the three color controls (I am assuming).

You need three MOSFETs.
Is there an article i can read to explain how MOSFETs do this? I keep hearing about pulse width modulation but i have no idea what it really is or how to do it...

If i chose to buy the digitally addressable ones then I still need to learn how to make the arduino receive the IR remote control data, but instead i will be trying to figure out how to control the color, brightness of the digitally addressable ones, which i feel is much easier. If i am not mistaken (and please correct me if i am wrong) the digitally addressable ones can have color and brightness set via just the digital signal sent to it? I will need to learn the protocol for sending digital signals to each individual LED, is there a resource I can go to learn more about this in depth?

It's just RGB color, 8 bits of each for each LED.

Does that mean i cannot control brightness? Only color? I am a little confused...

These are currently the ones i am looking at, but I can't help but wonder if there is any cheaper ones? 15 meters is a lot and I don't want to be breaking the bank just to get individually addressable LEDs on my walls!

Do you need 60 LEDs/m? Strips with 30 LEDs are much cheaper.

From the looks of videos of the 30LED/meter i feel as though they are not powerful enough to give a smooth consistent look, even if they are diffused through a thing frosted plastic (which i plan to do). Maybe I am mistaken though, are these LEDs very powerful?

Lastly i am curious about powering such a long strip of LEDs. I read on adafruit that to avoid "brown out" you need to power the LEDs every meter, does that imply i need a separate power supply each meter? Or is there  a way to wire it such that you apply "fresh" power from the power supply each meter?

Yes, 15m at 60 RGB LEDs/m is 2700 LEDs so you need a LOT of amps.

For 15m of those strips you'll need a 60 amp power supply (seriously!).

You only need one power supply. You can run a really thick power cable alongside the strip and put in little 'jumper' wires from that across to the LED strip. Every meter sounds a bit much to me on a long strip (don't believe everything you read in forums), every two meters should be fine.
How do you calculate how much amperage the power supply must be? I am a beginner in electronics and want to learn how you did this.

I am a little confused about how to set that up though. I am under the impression that if i hook up the 12volt source to 2 meters down from the start, then it will be pinned at 12 volts so there will be no voltage differential between the beginning of the strip and the place where i hooked it up... I must not fully understand how these LEDs work.

Oh two last questions! Since this is my first real arduino project and i intend to keep it forever, where do i go to learn about burning the design to a "permanent" chip? Or do i have to keep my arduino attached to the LED strip forever if i want to keep these forever?

Secondly, What is a good material to diffuse the LED light so i get an even spread instead of just a bunch of dots of light? I need it to be easy to cut and apply to walls and it needs to house the LEDS.

An Arduino Uno with wires poked into the header strips isn't ideal for permanent installations. For that I use Arduino Pro Minis - much cheaper/smaller and you can solder wires directly to the board.

Do i have to buy an arduino pro Mini for each project i build and want to keep? Isn't there a way to burn the program onto a processor without buying a mini each time? Also what kind of memeory will i need to run 15 meters of LEDs?
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keep hearing about pulse width modulation but i have no idea what it really is or how to do it...
See:-
http://www.thebox.myzen.co.uk/Tutorial/PWM.html

Quote
Do i have to buy an arduino pro Mini for each project i build and want to keep? Isn't there a way to burn the program onto a processor without buying a mini each time?
No you want a "Stand alone Arduino" - Google it.

Quote
Does that mean i cannot control brightness? Only color? I am a little confused...
The only way to control the colour is to control the brightness of the individual LEDs, so if you can control the colour you can control the brightness.

Quote
Where can i read about how to map it to color and brightness
There are many ways of doing this. The simplest is to take the amplitude value in each frequency band and use that number to set the brightness of one colour of an LED. But it can get very much more involved. Look up colour models
http://en.wikipedia.org/wiki/Color_model
Remember it can be easier than this.

Quote
Is there a place i can go to read about programming these LED strips?
Normally the web site you buy them from, failing that the Lady Ada and SparkFun websites have tutorials.

Quote
i feel as though they are not powerful enough to give a smooth consistent look,
Not sure what you mean. For better diffusion distance the LEDs some way off the diffuser and have a pre diffuser in between.

Quote
Is there an article i can read to explain how MOSFETs do this?
http://bildr.org/2012/03/rfp30n06le-arduino/
Google is your friend.
Quote
How do you calculate how much amperage the power supply must be
You take the current for one LED and multiply it up by the number of LEDs you have.

Quote
I am a little confused about how to set that up though.
The strip has 4 connections. Voltage +, Voltage -, Data signal, Clock signal. Wire up the + and - to your 12V supply. Connect the - of your supply to the Arduino ground and the clock and data signals to the output pins of the Arduino, which output pins depend on the software.

Quote
Also what kind of memeory will i need to run 15 meters of LEDs?
Work it out, for one LED you need three bytes of memory, so multiply the number of LEDs by three to get the total memory size to define one pattern. Multiply that by the number of patterns, and then get an SD card to hold it in.
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I am a little confused about how to set that up though. I am under the impression that if i hook up the 12volt source to 2 meters down from the start, then it will be pinned at 12 volts so there will be no voltage differential between the beginning of the strip and the place where i hooked it up... I must not fully understand how these LEDs work.

In theory, yes it would be 12V all the way. However, wire has a current rating based on its diameter. It has to move electrons. If you move too many, the resistance of the wire becomes an issue, as well as the fact that you'll start a fire. So, if you need to carry lots of current, you need a thick wire, also called a bar of copper. Let's say, 20mA x 900 LEDS is 18A. That's a very thick wire/metal rod.

Note: I originally said 1700 leds for 34A. I have corrected it for 900 Leds for 18A, but the point is the same.
« Last Edit: December 06, 2013, 04:05:17 am by arduinodlb » Logged

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I am a little confused about how to set that up though.
The strip has 4 connections. Voltage +, Voltage -, Data signal, Clock signal. Wire up the + and - to your 12V supply. Connect the - of your supply to the Arduino ground and the clock and data signals to the output pins of the Arduino, which output pins depend on the software.
I know how the connections work, but if i have to connect the the Voltage + terminal of the LED strip every few meters doesnt that ruin the voltage differential through the line making there be zero voltage drop across the LEDs from the beginning to the next place where i hook up the 12 V+?

Quote
Also what kind of memeory will i need to run 15 meters of LEDs?
Work it out, for one LED you need three bytes of memory, so multiply the number of LEDs by three to get the total memory size to define one pattern. Multiply that by the number of patterns, and then get an SD card to hold it in.
[/quote]
I never though of using an SD card to hold the patterns! Can you hook up an SD card to an arduino to use an more memory? And how would it hook up to a standalone arduino or arduino mini pro? Do i need to solder the SD card to the board?

I am a little confused about how to set that up though. I am under the impression that if i hook up the 12volt source to 2 meters down from the start, then it will be pinned at 12 volts so there will be no voltage differential between the beginning of the strip and the place where i hooked it up... I must not fully understand how these LEDs work.

In theory, yes it would be 12V all the way. However, wire has a current rating based on its diameter. It has to move electrons. If you move too many, the resistance of the wire becomes an issue, as well as the fact that you'll start a fire. So, if you need to carry lots of current, you need a thick wire, also called a bar of copper. Let's say, 20mA x 1700 LEDS is 34A. That's a very thick wire/metal rod.

Where are you getting 1700 LEDs from? 60 per meter for 15 meters is only 900 LEDs. Also i am curious, does this mean i cannot do this project without having a hulking piece of copper lining my ceiling also? I feel like it should be that hard to power 900 LEDs, certainly requires some power, but not huge pieces of metal.
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doesnt that ruin the voltage differential through the line making there be zero voltage drop across the LEDs from the beginning to the next place where i hook up the 12 V+?
That is exactly what you want it to do. You want there to be no voltage difference between one +12V and the next. The voltage differance that drives the strip is between 12V and ground.

The normal way of powering these strips is to have a 2A power supply every so often on the 12V line.
Make no mistake so any LEDs is not a simple or trivial project. You are a beginner so you don't know what is easy and what is not.

You can get an SD card shield or solder one on. Again google it.

Even 900 LEDs is 18 amps, that is a lot of current and at 12V is over 200W, that is a lot of light to spread over a ceiling, get your sun glasses out.  smiley-cool
« Last Edit: December 06, 2013, 03:39:16 am by Grumpy_Mike » Logged

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I know how the connections work, but if i have to connect the the Voltage + terminal of the LED strip every few meters doesnt that ruin the voltage differential through the line making there be zero voltage drop across the LEDs from the beginning to the next place where i hook up the 12 V+?

The point is the very opposite.  You do not want a voltage "differential" along the supply lines.  The copper foil tracks on the LED strips have a comparatively high resistance.  If one amp is flowing every tenth of an ohm introduces a 0.1V drop, and the resistance of that foil over a two meter length  will be a few tenths of an ohm.  You need a much more sturdy wire, at least the gauge of that in an average power cord, paralleling the LED strip and connecting into the Vcc and ground, each two metres.  Note that this will feed current in both directions, forward into the next two meter section and back into the second metre of the previous section.  Fed in this fashion, there will be a small drop in the total voltage available halfway between the two ends, but if my rough analysis is correct, significantly less than half the drop that would exist at that point if power was not being fed back from the other end of the given two metre section.

I never though of using an SD card to hold the patterns! Can you hook up an SD card to an arduino to use an more memory? And how would it hook up to a standalone arduino or arduino mini pro? Do i need to solder the SD card to the board?

You use a socket.  There are shields available for the UNO/ Mega format for this purpose, but I believe you could simply wire a socket to the necessary ports and power.  There are no necessary interface components (apart from a bypass capacitor) AFAIK, but I believe the SD cards use 3.3V.

Where are you getting 1700 LEDs from? 60 per meter for 15 meters is only 900 LEDs. Also i am curious, does this mean i cannot do this project without having a hulking piece of copper lining my ceiling also? I feel like it should be that hard to power 900 LEDs, certainly requires some power, but not huge pieces of metal.

Eighteen amps is not insignificant.  For starters, you need to use cable at least as heavy as you use for your 1800W electric radiator, but you generally do not care about losing a volt or two at 110V.  At 5V, you really do care about how many volts (or fractions thereof) you lose.
« Last Edit: December 06, 2013, 02:31:03 pm by Paul__B » Logged

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doesnt that ruin the voltage differential through the line making there be zero voltage drop across the LEDs from the beginning to the next place where i hook up the 12 V+?
That is exactly what you want it to do. You want there to be no voltage difference between one +12V and the next. The voltage differance that drives the strip is between 12V and ground.

Oh so are these LEDs powered by 12volt drops? meaning each individual LED needs 12volts to operate? That would make sense as to why you need it near 12 volts at all points. I was just confused because i though that the electricity didnt hit ground until it went through the very last LED.

The normal way of powering these strips is to have a 2A power supply every so often on the 12V line.
Make no mistake so any LEDs is not a simple or trivial project. You are a beginner so you don't know what is easy and what is not.
If i am not mistaken (given what i know about basic electronics), if i take a 2A power supply at 12V, and i connect it to multiple points along the length of the 15meter LED strip, then the current will not be 2A at each point where i connect it

You can get an SD card shield or solder one on. Again google it.

Will do, thanks!

Even 900 LEDs is 18 amps, that is a lot of current and at 12V is over 200W, that is a lot of light to spread over a ceiling, get your sun glasses out.  smiley-cool

Uh oh... Now you are scaring me. What kind of power supply am i going to need to run this thing? Is this too much for a beginner? Could someone link me to an example power supply one might buy to power this thing?

I know how the connections work, but if i have to connect the the Voltage + terminal of the LED strip every few meters doesnt that ruin the voltage differential through the line making there be zero voltage drop across the LEDs from the beginning to the next place where i hook up the 12 V+?

The point is the very opposite.  You do not want a voltage "differential" along the supply lines.  The copper foil tracks on the LED strips have a comparatively high resistance.  If one amp is flowing every tenth of an ohm introduces a 0.1V drop, and the resistance of that foil over a two meter length  will be a few tenths of an ohm.  You need a much more sturdy wire, at least the gauge of that in an average power cord, paralleling the LED strip and connecting into the Vcc and ground, each two metres.  Note that this will feed current in both directions, forward into the next two meter section and back into the second metre of the previous section.  Fed in this fashion, there will be a small drop in the total voltage available halfway between the two ends, but if my rough analysis is correct, significantly less than half the drop that would exist at that point if power was not being fed back from the other end of the given two metre section.

Ah, I didnt realize that these LEDs operated at 12Volts, that makes sense then that each one needs to drop 5volts to ground. I was under the impression that the 12volts dropped to zero across the entire length of the strip (not hitting ground until the last LED drop. So you are saying that each LED needs 12volts, at some amperage, and in order to supply the correct amperage to each LED i need to hoot it up every 2 meters or so? Please correct me if i am still mistaken.

I never though of using an SD card to hold the patterns! Can you hook up an SD card to an arduino to use an more memory? And how would it hook up to a standalone arduino or arduino mini pro? Do i need to solder the SD card to the board?

You use a socket.  Three are shields available for the UNO/ Mega format for this purpose, but I believe you could simply wire a socket to the necessary ports and power.  There are no necessary interface components (apart from a bypass capacitor) AFAIK, but I believe the SD cards use 3.3V.

Okay i will look into that more, I assume there is also some library for writing and reading from the SD card? Or is the arduino smart enough to know to use that extra memory?

Where are you getting 1700 LEDs from? 60 per meter for 15 meters is only 900 LEDs. Also i am curious, does this mean i cannot do this project without having a hulking piece of copper lining my ceiling also? I feel like it should be that hard to power 900 LEDs, certainly requires some power, but not huge pieces of metal.

Eighteen amps is not insignificant.  For starters, you need to use cable at least as heavy as you use for your 1800W electric radiator, but you generally do not care about losing a volt or two at 110V.  At 5V, you really do care about how many volts (or fractions thereof) you lose.

Jesus, that sounds a lot scarier to me than i though this project was going to be. I am a little worried about something going wrong now because i dont really know how i am supposed to connect the power supply to the strip. What does a power supply like that look like? And how do i go about safely attaching it to the LED strips? I have never used any wires larger than 20 gauge. What kind of wire will i need to hook this up?

This is turning out to be a larger beast than i thought it would be.

Also just to note, I have found a seller on alibaba that is supplying individually addressable WS2812B LED strips that run at 5 volts. Is this better or worse? It is 60LEDs per meter and they are rated at 14.4Watts/meter and have an Epistar SMD 5050RGB LED. Is this good for what i want to do? Or is there something fishy about it?

EDIT: I just checked around and apparently the individually addressable LEDs typically run at 5volts, instead of 12volts like the non-addressable ones. Why is that? Is there a reason that the individually addressable ones run on 5VDC instead of the non-addressable ones that run 12VDC? And how does running at 5VDC change the way i need to connect the power supply?
« Last Edit: December 06, 2013, 02:11:57 pm by Silman » Logged

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I am a little confused about how to set that up though. I am under the impression that if i hook up the 12volt source to 2 meters down from the start, then it will be pinned at 12 volts so there will be no voltage differential between the beginning of the strip and the place where i hooked it up... I must not fully understand how these LEDs work.

It appears that you were the one who initially referred to twelve volts, and others have simply echoed that presumption.

The WS2812B LED strips do indeed run at 5 volts because they have only one LED element per individually-addressable driver chip; the strips that are not individually-addressable are wired in sets of three series LEDs and require (about) 12V which is actually somewhat more efficient since you are only wasting about 2.1 out of twelve volts (presuming 3.3V per LED) instead of 1.7 out of 5V.

But the loss of voltage in the lines is then all the more significant at 5V than it would be at 12V.

You can provide power in various ways; you can have multiple power supplies as Mike implies, or one "gruntier" supply with (fairly) heavy cables radiating to the various supply points.  I doubt you would want power packs studding your ceiling either (though 2A ones are quite small compared to the 20A ones), but the power lines are  a serious consideration when you are using significant power at low voltage.

This is what a 5V, 20A power supply looks like:

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I don't know where the "12V" thing came from, but those strips are 5V.

The best thing to do is GET STARTED. Get hold of 1M of LEDs, a little 5V power supply and go to work.

PS: Learn to use google - all the information is out there.
« Last Edit: December 07, 2013, 05:44:46 am by fungus » Logged

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