Beginner Questions - Pixels

[Kane]

Hi

Given I'm pretty new to this world, I've been reading up as much as I can.  I think I understand the basics, but thought I might post a bit of a summary of how I think these pixel controllers work, with a few queries, and this will not only help me, but any new visitors that find themselves here.

When talking about pixels, you're effectively talking about being able to individually control each LED (or pixel) in a collection.   And with the introduction of RGB LEDs, you can not only turn each LED on or off, you can control the colour of each LED.

With the LEDs, from what I can see, there are different types of RGB LEDs available, depending on the protocol that they speak (primarily either 6803 or 2801)   Each LED has a little chip in it, as well as 8 wires, 4 for incoming (2 for power, 2 for data?), and 4 for outgoing, allowing them to be daisy chained (the output from one is connected to the input of the next)       

Next is a controller - which is where Phil's TP3212 and TP3244 come in.    You connect power (12v or 5v depending on what your LEDs need), DMX 485 IN (coming from either a DMX Dongle or an ECG-DR4), and also the four wires that go to the first LED.

You can now use either Vixen or LSP to drive the LEDs however you like.


Now, I just had a couple queries:


How does the addressing work?   My best guess is that each LED knows it's position in the daisy chain, and responds based on that.   Therefore, if you hookup 50 RGB LEDs to a controller with starting address of 1, the first LED uses channels 1-3, the second 4-6 and so on?

What is the difference between the 6803 and 2801 protocols - is one better and/or more expensive than the other?    From what I've read there has been a few flickering issues with 2801?

[dmoore]

How does the addressing work?   My best guess is that each LED knows it's position in the daisy chain, and responds based on that.   Therefore, if you hookup 50 RGB LEDs to a controller with starting address of 1, the first LED uses channels 1-3, the second 4-6 and so on?

Yes - they get their address from the location in the string.  Watch video 1 for details:  http://holidaycoro.com/RGB

What is the difference between the 6803 and 2801 protocols - is one better and/or more expensive than the other?    From what I've read there has been a few flickering issues with 2801?

Watch video 3:  http://holidaycoro.com/RGB - you can also find lots of the technical details here:  http://holidaycoro.com/RGB/RGB-Basics.pdf

I think there was some flickering early on with the French guy's (RIRI?) but I wasn't aware that it affected others - anyone?  Do you have some weblinks?

[mrpackethead]

I'll try to explain this simply but accurately..   None of the strings actually have any concept about where they are located in a string.  Technically, every pixel actually "thinks" its first in the string.  An example will make this simple for you to understand.

Lets say we have a string of 5 pixels;  the controller will send out data on the wire than looks like this;

A B C D E

The first pixel in the chain looks at that and says, " i'm pixel 1 ", and uses the first data in the string.. In this case A.   It then does its other job, it resends that data, but without the "A" data..  So, it retransmits the data like this;

B C D E

The seond pixels in the chain ( although it does'nt know its second says " im pixels 1, and uses the first data in the string, which is now B.      It then does it other, resending the data but dropping the "B" data.. so it send outs

C D E.

The system repeats it self until the last pixel who will only receive one bit of data... and it will have nothing to send out.

[mrpackethead]

What is the difference between the 6803 and 2801 protocols - is one better and/or more expensive than the other?    From what I've read there has been a few flickering issues with 2801?

 At a protocol level theres quote a few differences, but if you want to see all that then you best to look at the datasheets.. Are you more interested in the difference beytween the chipsets, or just the protocols?

Also, its quite easy to get a 2801 to flicker, you simply remove the recommended capacitor from the pixel ( typically a 100nF ) and it doesnt work very well. mind you many IC's suffer this fault..   Well constructed i've not suffered flickering, and i've used lot of these 2801's..

[Kane]

 At a protocol level theres quote a few differences, but if you want to see all that then you best to look at the datasheets.. Are you more interested in the difference beytween the chipsets, or just the protocols?

Also, its quite easy to get a 2801 to flicker, you simply remove the recommended capacitor from the pixel ( typically a 100nF ) and it doesnt work very well. mind you many IC's suffer this fault..   Well constructed i've not suffered flickering, and i've used lot of these 2801's..

I'm just more interested at a consumer level - if I was going to buy a couple hundred LEDs, then is there any reason to choose one protocol over the other (especially given the controllers support both - if you were using a different controller than only supported one protocol, then your decision would be made for you!)

[Kane]

I'll try to explain this simply but accurately..   None of the strings actually have any concept about where they are located in a string.  Technically, every pixel actually "thinks" its first in the string.  An example will make this simple for you to understand.

Lets say we have a string of 5 pixels;  the controller will send out data on the wire than looks like this;

A B C D E

The first pixel in the chain looks at that and says, " i'm pixel 1 ", and uses the first data in the string.. In this case A.   It then does its other job, it resends that data, but without the "A" data..  So, it retransmits the data like this;
....

Thanks, yes, that does make 100% sense.   I would have thought that it would be something like that, otherwise there would be way too much logic for a little IC to work out (therefore increasing complexity and therefore cost)

[mrpackethead]

i'd recommend the 2801's over the 6803's because of the colour resolutuion..   6803's are 5 bit, 2801's are 8 bit,  Simply it means better colour control when you start making them, and  if you are ramping up and down, the 2801's will look smoother...  Having used 100'000's of 2801's, i've been able to access their reliablity and provided that you operate them within spec and the pixel is well designed around it, its a good solid performer.

A much more tricky decision is actually which manufacturer you'll buy. Many use 2801's but some are rubbish, and some are great.   

[Kane]

i'd recommend the 2801's over the 6803's because of the colour resolutuion..   6803's are 5 bit, 2801's are 8 bit,  Simply it means better colour control when you start making them, and  if you are ramping up and down, the 2801's will look smoother...  Having used 100'000's of 2801's, i've been able to access their reliablity and provided that you operate them within spec and the pixel is well designed around it, its a good solid performer.

A much more tricky decision is actually which manufacturer you'll buy. Many use 2801's but some are rubbish, and some are great.

So if I was going to get 200-300 to play around with, should I get them from Ray Wu, or should I be looking elsewhere?

Also, are there ay TP3244 controllers available? (or likely to be available in the next few months?)   

[ɟɐsʇǝppʎ]

i'd recommend the 2801's over the 6803's because of the colour resolutuion..   6803's are 5 bit, 2801's are 8 bit,  Simply it means better colour control when you start making them, and  if you are ramping up and down, the 2801's will look smoother...  Having used 100'000's of 2801's, i've been able to access their reliablity and provided that you operate them within spec and the pixel is well designed around it, its a good solid performer.

A much more tricky decision is actually which manufacturer you'll buy. Many use 2801's but some are rubbish, and some are great.

So if I was going to get 200-300 to play around with, should I get them from Ray Wu, or should I be looking elsewhere?

Also, are there ay TP3244 controllers available? (or likely to be available in the next few months?)   

Now that decision is based on price and the quality you want. You could buy commercial brand with great warranty and support or you could take the DIY path which requires a bit more work and knowledge.

These look to be good value for the DIYer as they appear to try and address the water ingress issue.
http://www.aliexpress.com/fm-store/701799/209889132-404056686/12mm-WS2801-pixel-module-IP68-DC5V-input-full-color.html
As far as the pixels from Ray, I havent really heard any bad reports on the WS2801 pixel strings. I used 200 last season and didnt have any issue at all.

The TP3244 should look to be available around the end of March

[TheBanker]

How are these 5050's working out so far?  How are they compared to the regular pixel led?

http://www.aliexpress.com/fm-store/701799/209889132-342765392/5050-RGB-pixel-led-module-2801IC-256level-scale-DC5V-input-0-3W.html

[Kane]

How are these 5050's working out so far?  How are they compared to the regular pixel led?

http://www.aliexpress.com/fm-store/701799/209889132-342765392/5050-RGB-pixel-led-module-2801IC-256level-scale-DC5V-input-0-3W.html

That one hasn't got a mention of level of weatherproofness (new word?) - would the 5050 ones be brighter than others?

[Tabor]

The 5050 provide a "sharper" type of colour. Not sure about comparable brightness, but would expect them to be brighter.
The 5050 type would be better for a video matrix of sorts.

The sample i got did require an extra level of "waterproofness" from the user.

[Kane]

Yes - they get their address from the location in the string.  Watch video 1 for details:  http://holidaycoro.com/RGB

Only just had a chance to look over the videos - great information in there David - much appreciated.

[Shanta]

The two pixel options linked from Ray Wu's store each say 5V input, but am wondering if that means the pixel uses 5V even if supplied 12V (which means there is more power downstream to combat voltage drop? Just queueing off of David's video series, which I may have misunderstood. TIA

[ɟɐsʇǝppʎ]

The two pixel options linked from Ray Wu's store each say 5V input, but am wondering if that means the pixel uses 5V even if supplied 12V (which means there is more power downstream to combat voltage drop? Just queueing off of David's video series, which I may have misunderstood. TIA

The standard design for pixel strings is to run at 5VDC, there are variations that will run at 12vdc but its not the normal design as it is an inefficient design with energy wasted dropping the voltage down from 12vdc  to run a single LED thats why you see the majority of RGB string designs running at 5vdc.

With strips and modules these run at 12vdc as they use 3 leds instead of 1 per pixel and as such do not need to drop the voltage so much to run


But do not put a 12vdc power supply to a 5vdc rated string or it will damage it