DMX vs WS2801

[Pixeltech]

Im new user in forum and i want to make also my own christmass tree , i read many subjects in forum but i didnt understand some contents, if we talk about dmx512 i usually think that i can use PIC16F628A or Atmel or AVR and can make dmx512 data receive code and can set address in code for dmx start , but what about WS2801 ? what kind of IC is it ? and how to program or set address ?

i want to start to make rgb pixels from this site http://www.response-box.com/rgblights/2007half.shtml , i want to use pic and schema like whata this site has and i will use almost 2250 module to create my tree , what is difference between normal dmx512 with pic and ws2801 ? what you prefer me ?

[Pixeltech]

Howlong distance i must use for between 2 IC ws2801 , i want to make pixels but i need 50cm distance between 2 pxl , what you can prefer to me for this ? WS2801 or Normal Dmx512 with PIC ?

[DynamoBen]

W2801 is an RGB LED dimming IC made in China, and DMX is a communications protocol to control lighting equipment. Its difficult to answer your question when you are comparing two unrelated concepts.

With that said DMX can travel over 1000 feet.

[DynamoBen]

I have merged these threads into one since they both appear to be related to DMX vs RGB LED dimming (WS2801)

[Pixeltech]

Thank you very much DynamoBen , i will make Tree Project and i have 17 Tree and every Tree will have 70 pxl module , for this reason i just wanted to count low price if i can make it with WS2801 but i think it is not good choice maybe because if i make with usually dmx protocol and use PIC and i can make long distance between pixels , because i will need to connect from tree to second tree also i want to make animation for all tree from 1 controller

[Entropy]

It's still not entirely clear what you're asking. The WS2801 is a custom dimmer ASIC used for RGB nodes. It is EXTREMELY difficult to obtain bare WS2801 ICs in the United States, preassembled products like the various pixel strands are a bit easier to find.

If you want each node to have native DMX control, your cost per node will be very high - the RS485 receivers required for DMX are alone more expensive than many fully assembled nodes based on the WS2801.

Note that in nearly all cases, people using WS2801 strands are not driving the WS2801s directly from their show controller - their show controller outputs DMX or E1.31 (DMX over Ethernet) data, and their show hardware includes one or more DMX/E1.31-to-WS2801 protocol bridges.

Some examples:
RPM is working on an Atmel AVR-based DMX-to-WS2801 bridge for smaller installations
jstjohnz and DynamoBen are working on E1.31-to-WS2801 bridges for larger installations, both based on a Wiznet Ethernet module and a Parallax Propeller.

[P. Short]

Also, bear in mind that the size of your display seems to exceed the size of one DMX512 universe. If I read you correctly, you are looking for 17*70 (or 1190) pixels, each of which would use 3 DMX channels, for a grand total of 3570 DMX channels. The maximum size of one DMX universe is 512 channels, so you seem to be looking for 7 DMX512 universes or so.

This would seem to be a larger installation...

[mrpackethead]

W2801 is an RGB LED dimming IC made in China

The chinese would say that, but the taiwanese would say it was made in taiwan. And the difference between mainland chinese manufactred IC's and Taiawanese manufactured often is like chalk and cheese.

[Pixeltech]

yes you are right i will use 3750 channel and i know 1 dmx can control max 512 channel , for this reason i will also need some interface to control my system with 7 * 512 channel dmx output. i found 1 schema on old site and it is here on my picture , for me project cost is not important i will make good one , for me important project without any problem and for this reason i couldn decide yet between WS2801 and Dmx512 , i know protocol is different , i only want to know how long distance i can make between 2 pxl if i use WS2801 ? because on my project everypxl has 50cm distance , here my project picture what i want to make

http://img828.imageshack.us/i/dmxtree.jpg/

[P. Short]

The datasheet that I found on the web shows that all of the input control signals are buffered and retimed to generate the output signals. This leads me to think that the WS2801 should be good for 50cm inter-chip distances without any problem. Of course, this is an educated assessment based only on the datasheet and not on experience with the actual component.

[Pixeltech]

Thank you P.Short , i looked also datasheet now and i think WS2801 will be not good choice because , this IC work with in and out data and if 1 of WS2801 will have problem from the string , then other ws2801 modules will not work , but dmx is another if 1 dmx module will have problem , only that module will not work but other modules will work , because i have 17 Tree and from first tree to last tree i have 350 meter distance and i want to make 1 controller for all tree , and i want to control all tree in 1 animation , it will not be same animaton every tree , it must connect all Tree same like line :) i know it is big and difficult maybe but i want to make it , and what you think about this module what i found on old Christmast old site , i will make 1190 Pxl Module from this schema http://www.response-box.com/rgblights/2007point.shtml and i will set dmx address in asm code and put hex to Pic16F688 , when all tree ready every tree will have 70 Pxl rgb module , and i know 1 Dmx cable line can control max 32 module , and i need to make 2 line for 70 pxl or i must use dmx data splitter for every tree , but i will need some control interface with 17 out and need special program for controll all tree same like display 70 * 17 PXL :) i will share all projects detail here when i solve it , what kind of controller and dmx data splitter i can use for this project ? or you think it is good idea to make same like this ?

[kychristmas]

I'm confused. (no comments!) Are we not talking Apples and Oranges here? Are there Pixel designs that are purely DMX vs 2802 or the other IC designs we have seen? I have only been watching from a very high-level, but I thought all the Pixel Controller designs were basically converting DMX to whatever protocol was required by the IC/Program used on the PIXELS, NO?

Again, I'm not too up on the DMX stuff, so be gentle.

[n8huntsman]

Ky, you are correct and no offense to anyone, but it's not you who is confused. There is no way for the 2801 pixels to communicate amongst each other with DMX. They use SPI protocol to communicate amongst each other. This is where people are getting confused. How you get to SPI, whatever bridge you choose, is up to you. Most people are using DMX but nothing precludes one from using Renard or any other protocol if there were a controller available.

[P. Short]

A few years ago JEC created some designs in which each individual pixel receives DMX512 data. These are described (and probably still available) on his site (www.response-box.com). Apparently pixeltech has been looking at those pages on John's site, and is thinking about using a similar design. However, I think that pixeltech will find those designs several times more expensive than using a WS2801 approach. A single DMX line (without repeaters) can only drive 32 of the el-cheapo RS485 chips, and the better RS485 chips were quite a bit more expensive the last time that I looked.

[Pixeltech]

Thank you answers my friends but still nobody understood what i ask :( and i know what is dmx512 , what is WS2801 and about protocols also , i know all what you tell me , my quesiton is another my quesiton is , what is better for my project ? Ws2801 or PIC with rs485 IC ? because i have 17 Tree and every tree has long distance between other tree , and every pxl has 50cm distance from another pxl , i will have cable 50cm long between 2 pxl , if i use WS2801 and if i make 70 pxl and without data repeater every pxl will have 50cm pitch distance , doers it work ? i will repeat +5V at every 15 or 20 Ws2801 but data will go almost 35-40 meter long cable ? 1 string will be 40 meter and string will have 70 WS2801 Module ? what is better ? WS2801 or PIC with dmx receive code inside ?

[n8huntsman]

The data will be fine at 50 cm because each 2801 will regenerate the data before passing it to the next pixel. What is your distance between trees?

[fasteddy]

The WS2801 will regenerate the signal between each IC, this should give you approx 2 to 4 metres distance between each 2801 IC. So the length of the string is not the issue as a 40 metre string with 70 pixels with 50cm between each one is within the design specs as the signal between each 2801 IC will be regenerated. The issue will be voltage drop so you would have to inject power into the line at several points which you are aware of.
Now for controlling these 2801 IC, what is the distance between each tree? you may have to either use a dedicated 2801 controller for each tree if the trees are more than a few metres apart or else use 1 2801 controller with multiple outputs and place some dummy 2801 IC pixels in between the controller and trees so the signal can be regenerated which will allow you to get the distance you want.

[Matt_Edwards]

I think FE has the best solution for you. DMX based Pixels will be considerable more expensive than 2801 base pixels.
The 2801 pixels strings in the tree with a dedicated DMX /2801 bridge at the base of each tree. Running DMX between the trees will give you more flexibility for display design, layout and movement.

[n8huntsman]

If the distance isnt too far, you could place the controller in the middle of two trees and untilize 140 of the possible 170 pixel nodes on one universe. Something like a TP3244 I think would work well for that.... or maybe RPM's design; http://doityourselfchristmas.com/forums/showthread.php?15286-DMX-to-WS2801-Pixel-Bridge/page4

[Pixeltech]

Thank you friends , My Distance is 4meter between every Trees and from first tree to last 17th tree i have almost 70 meter and distance from control hause to first tree is 10 meter , i will repeat voltage at every 5 meter, for me problem was data distance between 2 WS2801 and i see 50cm will not be problem and i can make 1 string with 70PXL , i dont want to use seperate controller for every tree becacuse i want to make 1 controller for all tree and want to make animation for all tree in same time , and in this case i will need controller with 17 * 70pxl output ( 70pxl is 210ch and maybe better to use 2 trees for 1 out output and i will need 9 out interface )

[n8huntsman]

Are you making your own controller?

[Pixeltech]

No , i will only make dmx data receive card , i will buy controller ready and also i will need some card with 17 output for my all trees

[Matt_Edwards]

Actually you probably want to reconsider having 17 DMX outputs. 8 universes will be fine, with 2 trees per universe.
The Ethergate (http://www.j1sys.com/ecg-dmxren8/)from Joshua 1 Systems is an option to look at.

[RPM]

Actually you probably want to reconsider having 17 DMX outputs. 8 universes will be fine, with 2 trees per universe.
The Ethergate (http://www.j1sys.com/ecg-dmxren8/)from Joshua 1 Systems is an option to look at.

AFAIK, the Ethergate is just a transport system for DMX signals, so he will still need to translate it to a signal his pixels can use.

[Matt_Edwards]

totally agree with you their. the outputs of the Ethergate would drive your DMX/2801 bridge, fitted in each tree.

[fasteddy]

Here is something that is being developed, its a pixel IC that talks DMX, the MY9941 and the MY9942. I suspect though it wont be cheap but may be an alternative for what your looking for.
Take a look here
http://forums.auschristmaslighting.com/index.php/topic,883.0.html

[Pixeltech]

Dear Friends , i decided to use PIC16F88 + SN75176 RS485 IC for dmx receive card and i will make code with assembly and i will set dmx start addres in code by hand before hex , i know it will be 10 times more expencive string for me when we compare WS2801 because only PIC is almost 1.50$ but WS2801 is only 0.15$ but i think it will be more quality system and without any problem because i will also not have distance problem with dmx cable 4 - 5 meter is nothing for dmx , and second advantage is i didnt think about this problem before and couldnt ask it before im sorry that take your times , i will have long strings and 70pxl and 70pcs WS2801 IC on 1 string , WS2801 is working with IN - OUT data system, it means for example i have 70pxl on 1 string cable , if second or third PXL's WS2801 broken or have problem on my string , after this ws2801 all pxl will be lost and they will not work because broken ws2801 will not generate data for them , but when i make dmx with pic or avr , i will not have such problem , if some pxl broken only that pxl will not work and all pxls will work

[Entropy]

The chinese would say that, but the taiwanese would say it was made in taiwan. And the difference between mainland chinese manufactred IC's and Taiawanese manufactured often is like chalk and cheese.

Oh, I thought that the WS chips were mainland-sourced, not Taiwanese. Thanks for the correction!

[Entropy]

After reading further - Since your display can be evenly divided into multiple subunits, I would suggest something along these lines:
One DMX-to-WS2801 bridge per tree, each driving a strand of WS2801s
Some sort of multichannel DMX controller - perhaps one of the E1.31-to-whatever bridges

As someone who has tried to create their own pixel nodes before, I can tell you - you REALLY want self-addressing nodes at this scale! Also in terms of "quality" - do you have injection molding equipment and such? Have you given thought to how you will encapsulate/package your nodes? One of the big advantage of the WS2801s, in addition to price, is the fact that the strands are prepackaged to some level of weathersealing.

Also, I don't know if anyone has actually tried yet, but it should be possible to extend the distance between two WS2801 pixels (such as for a tree-to-tree cable run) by taking the clock/data signals out of one chip, converting them to differential with a pair of SN75176s, running differential signals over a Cat5, then converting back to single-ended signaling at the next tree.

[P. Short]

Another factor - other than cost - to think about with using 75176-style chips is the number of loads that you can put on a single line, and the power that the 75176 chips require. With the oldest (and probably cheapest) 75176-style parts (such as the SN65176B from TI) one transmitter should only drive 32 receivers, and each part is spec'd to use up to 35 mA of current. The SN65LBC176 from TI allows you to place more than 32 receivers on one line, and they draw a lot less power. The LBC parts, on the other hand, are more than twice as expensive in quantities of 100.

[Pixeltech]

and it means for my project PIC + SN75176 is better than WS2801 because of distance , and quality , and problems because if one of ws2801 will have problem it will not generate signal for next one and all pxl will not work , but dmx line is not so , and 32device is not problem i can use 1 dmx data splitter for every tree

[jflin]

You can refer to MY9941 and MY9942, designed by MY-semi company in Taiwan.
These two chips integrate all components of DMX512 system, like regulator, RS485, DMX decoder and constant current LED driver.
Maybe, these solutions are great choices for your projects. Any questions can ask me.

1. Serial DMX512 system : MY9941, cascade, auto-addressing DMX512 LED driver, pixel-to-pixel 300M by RJ45 and ethernet cable
video link : http://www.youtube.com/watch?v=FbOaI4xqn9g

2. Parallel DMX512 system : MY9942, addressable DMX512 LED driver
video link : http://www.youtube.com/watch?v=zOHUceuDaEw&feature=related

[Pixeltech]

Yes it is also good IC but what about prices for this IC models ? do you have any idea and i still didnt understand what is auto address , if not any dip sw how possible to address auto ? we need to write it in chip or we must send address also with data ?

[Entropy]

and it means for my project PIC + SN75176 is better than WS2801 because of distance , and quality , and problems because if one of ws2801 will have problem it will not generate signal for next one and all pxl will not work , but dmx line is not so , and 32device is not problem i can use 1 dmx data splitter for every tree

I think you need to look at the complete picture here - How are you packaging your DMX pixels? If you don't package them well, the failure rate is going to be MUCH higher than for prepackaged weatherproof WS2801-based pixels. And what makes you think there is going to be a reliability problem with WS2801s? So far, to my knowledge, the only failures people have had were due to failures of the weatherproofing.

I think you need to calculate - what's the failure rate of prepackaged WS2801s, and how high does it have to be before it makes sense to replace individual failed homegrown pixels (I'd estimate with a native DMX-per-pixel approach you will be lucky to get your cost per node below $2-3 USD prepackaged) as opposed to just outright replacing an entire strand. (Since you can probably purchase at least 3-4 WS2801 strands at around 60 cents/node for weatherproofed preassembled for what it will cost you to build one homegrown strand, not factoring in the cost of your time.)

You now see why my own attempt at a homegrown pixel strand technology got abandoned. For more details on my project see http://doityourselfchristmas.com/forums/showthread.php?10157-I2C-addressable-RGB-LED-Project

[Pixeltech]

i will use epoxy for cover it and sure i will not have any problem from water , sure i can buy ready string with pxls and can be more cheap for me but my each module will have 6 5050smd RGB led , it will be big pxla and also i will use npn transistor also to drive to them , it will be kit little big and because of this problem i must make my own pxl myself and cant use ready module , if i use WS2801 its cost will be almost 2.50$ and if i use PIC its cost will be almost 3.80$ , i can use WS2801 and i can make dmx to ws2801 bridge to convert dmx data to ws2801 and it will be easy for me , if i use pic i know i will need to spend long time to make dmx start address for every pic while make program , or i will write it from IC protocol to pic start address but for me before make hex , i can set dmx start address in pic and make hex and make program , for my project WS2801 and PIC suit both of them work good , i want to make pic only because of my long distance problem between trees and i dont want to have data problem lost or something and i decided to make same module from john here on his site http://response-box.com/rgb/2008/12/point-source-pixel-first-run/ and i will use PIC16F88 , now i decided to use it and i will share all here as a DIY after fiinish project , now we settled about dmx receive module with 3ch , and for me now important computer software and interfaces for every dmx512 channel because i have 70pxl on every tree and i have 17 tree it makes 1190pxl and it is 1190 * 3ch = 3570 dmx channel i have , 1 dmx out line can control only 512 channel and i will need 7 x dmx512 output from computer , what kind of interface i can use for 7 x 512 dmx out ? and software ? is there any DIY share on forum i searched but couldnt found it

[jflin]

You don't need to send any address data to MY9941 chips.
The addressing technique of MY9941 is to "mark" the loaded slots by "Mark time between slots" following the start code.
Therefore, each MY9941 regard loaded data as preceding slots.

[Pixeltech]

Thank you and what about this
i decided to make same module from john here on his site http://response-box.com/rgb/2008/12/...xel-first-run/ and i will use PIC16F88 , now i decided to use it and i will share all here as a DIY after fiinish project , now we settled about dmx receive module with 3ch , and for me now important computer software and interfaces for every dmx512 channel because i have 70pxl on every tree and i have 17 tree it makes 1190pxl and it is 1190 * 3ch = 3570 dmx channel i have , 1 dmx out line can control only 512 channel and i will need 7 x dmx512 output from computer , what kind of interface i can use for 7 x 512 dmx out ? and software ? is there any DIY share on forum i searched but couldnt found it

[Entropy]

Hey Pixeltech, got your PM, but I'll respond here since I'd prefer if others can see the discussion and because my PM box is nearly full:

My I2C nodes described above don't have autoaddress. Addressing is one of the issues I never found an elegant solution for, which is one of the reasons I stopped the project. (I'm not sure if there was any way to get a workable solution without moving to a chip with more pins - although the Atmel ATTiny48 is only slightly more expensive than the Tiny25, and has more pins PLUS proper hardware I2C support so likely would solve both of my problems.) The only reason to move forward with this project would be the fact that my nodes apply a gamma curve to the received 8-bit values for a better dimming range. So sometime you might see me resume this using Tiny48s. I have too much else in mind though - anyway the source code is there. :)

My DMX-to-PCA9635 bridges didn't yet have DMX address programming support - it's still on my TODO list for when I get around to it. The typical method for DMX start address programming that a lot of people use is to have one of the pins on the microcontroller set as a "program" pin - when the pin is grounded, the microcontroller reads DMX addresses 0 and 1 and uses these values to construct its "normal operation" start address.

DMX-to-WS2801 - Possible with the same hardware as my PCA9635 bridge, but as I haven't yet gotten around to ordering a batch of pixels from Ray Wu to work with and hence develop the firmware. Still need to do this... However, RPM just recently released a design that is basically identical to the hardware configuration I use, except his firmware is written in assembler and not C.

E1.31-to-WS2801 - Designs from jstjohnz and DynamoBen exist. DynamoBen's PropController may also be able to do E1.31-to-DMX

Since you're looking into doing multiple RGB emitters per pixel, the WS2801 does lose a lot of its cost advantages. Most people are focusing on single-emitter-per-pixel solutions using the 2801, using strands like this one http://www.aliexpress.com/fm-store/701799/209889132-320389559/12mm-8mm-led-pixel-RGB-led-channel-lettet-waterproof-WS2801IC-256-level-gray-scale-DC5V-input.html, and here, the 2801 is a clear cost-per-node and sanity winner if you only have one LED per pixel.

[P. Short]

Nobody asked me, but here is one method that I would strongly consider using to implement such a project (RGB, DMX, PIC-based):

I would use a PIC12F1822, which is an eight-pin part with a built-in USART. It is less expensive than the PIC16F688 or PIC16F628, and has a smaller footprint.

Then, to make the project much easier to manage, I would use the extra pins on the part and the internal EEPROM to implement an addressing scheme. One way to use these extra pins would be to connect one of them to a jumper/switch to invoke a programming mode, and use vixen or a utility program to send the address to one pixel (PIC) at a time when the strings are first manufactured. An alternative way would be implement a daisy chain solely for the purposes of programming the pixel addresses, which are then stored in EEPROM, without using any switch. The normal brightness control would be handled through the usual DMX mechanisms (all of the pixels on a single bus). The reason that I make these suggestions is that I think that using a 9-bit DIP switch (or jumpers) will not be very reliable (especially if the pixels are encased in epoxy), and that having a separate program for each pixel will be quite cumbersome.

[Pixeltech]

Thank you for answers , my pixels will be in epoxy and i my pxls with pic16F628A , you can see here pictures i shared , i have 1190 pxl , and i dont have any problem on coding or receive dmx data or give address to my pxls , i can give address before programming in source code to pic flash too , it is no problem , my problem is i need 512 ch x 7 output interface to control my project , i have 1190pxl and it is 3570dmx channel , ready softwares and interfaces are very expencive for such project and i want to make it my self and want to use vixen , but what kind of interface i need with 7 x 512 output ?

http://img27.imageshack.us/i/imag0244h.jpg/

http://img138.imageshack.us/i/imag0252k.jpg/

[mlkren]

http://img138.imageshack.us/img138/1180/imag0252k.jpg

http://img27.imageshack.us/img27/9013/imag0244h.jpg
Fixed image links.

[Pixeltech]

http://img138.imageshack.us/i/imag0252k.jpg/

http://img27.imageshack.us/i/imag0244h.jpg/

[dmoore]

Thank you for answers , my pixels will be in epoxy and i my pxls with pic16F628A , you can see here pictures i shared , i have 1190 pxl , and i dont have any problem on coding or receive dmx data or give address to my pxls , i can give address before programming in source code to pic flash too , it is no problem , my problem is i need 512 ch x 7 output interface to control my project , i have 1190pxl and it is 3570dmx channel , ready softwares and interfaces are very expencive for such project and i want to make it my self and want to use vixen , but what kind of interface i need with 7 x 512 output ?

How much did each one of those 3ch controllers cost to make (board, pic, dip, etc)?

[Pixeltech]

1 Pxl With LED Cost 3.80$ , Which controller board i must make for 1190 pxl to control with vixen

[n8huntsman]

No board needed for vixen. Vixen can output DMX directly. All you need is 7 DMX universes out of your computer. You can use dongles, e1.31, ecg-dmx ren8, ... etc.

[fasteddy]

Which controller board i must make for 1190 pxl to control with vixen

I would tend to think if you need 7 DMX universes then the best value would be going with the ECG-DMX/REN8 it will give you 8 DMX universes (4096 channels) so you end up having a spare universe to do other things with.
Take a look here
http://www.j1sys.com/ecg-dmxren8/

[Pixeltech]

Thank you For Answers Friends you helped me very much in my project , i will read about ECG-DMX/REN8 card and e1.31 card , im new in this kind of projects and ready systems are very expencive to buy , i need to understand first what is difference between this two DIY cards ECG-DMX/REN8 and e1.31 , but i can use both of them with vixen ? and e1.31 also can give me 8 output with 512dmx ch ?

[mschell]

E1.31 is DMX over TCP/IP using Ethernet.

An ECG is a E1.31 to DMX gateway box. These have an Ethernet port and multiple output ports. The ECG-DR4 is a already built board with 4 DMX universe outputs. The ECG-DMXRen8 is a DIY board with up to 8 outputs, each feeding a separate full 512 channel DMX universe.

There are other E1.31 (or sACN) -> DMX gateway boxes and kits, some of which have been designed by members here on DIYC.

FastEddy posted the link to the j1sys website, who is the creator of the ECG series.

[Pixeltech]

i will try to make ECG-DMXRen8 and will use it with vixen program

[Pixeltech]

my rgb modules are ready , all finished and i will try it soon but i need optosplitter between ECG-DMXRen8 and my rgb pxls for dmx data , i will use it for every 32pxl because i used 16F628A pic for dmx data receive and it is 250k baud rate and with 20mhz external osc , i have 2 schema for splitter and which one i can use ? whic one is better for me ?
1.

http://img822.imageshack.us/i/datasplitter.png/

2.
http://img843.imageshack.us/i/pcdimmerdmx512splittern.png/

[DynamoBen]

my rgb modules are ready , all finished and i will try it soon but i need optosplitter between ECG-DMXRen8 and my rgb pxls for dmx data , i will use it for every 32pxl because i used 16F628A pic for dmx data receive and it is 250k baud rate and with 20mhz external osc , i have 2 schema for splitter and which one i can use ? whic one is better for me ?
1.

http://img822.imageshack.us/i/datasplitter.png/

2.
http://img843.imageshack.us/i/pcdimmerdmx512splittern.png/

The only problem with a splitter like this is because each output is not galvonically isolated the whole splitter could be damaged.

[Pixeltech]

What kind of splitter i can use ? i made my rgb module with PIC mcu + sn75176A and i will ned splitter for every 32devices , what you can offer to me ? which kind of splitter i must use ?

[DynamoBen]

What kind of splitter i can use ? i made my rgb module with PIC mcu + sn75176A and i will ned splitter for every 32devices , what you can offer to me ? which kind of splitter i must use ?

The splitter you designed will function for its intended use. However that design is susceptible to damage. Typically each output of the splitter would have its own isolated power supply and have optically isolated data lines. Using a design like ensures that if receive a voltage spike or short on one output it doesn't effect the other outputs.

This is strictly a design choice, both will function, I'm just pointing out the risks.

[P. Short]

Whether or not galvanic isolation is helpful also depends on how power is distributed. If he is using a separate power supply for each 32-node sub-string (where each power supply has internal isolation), then using opto-isolators on each splitter would result in a more robust display. On the other hand, if he is using one large supply to handle more than 32 nodes at a time, galvanic isolation in the splitters might not add much to the robustness.

[P. Short]

Pixeltech,

How are you providing power for the pixels?

[Pixeltech]

Pixeltech,
How are you providing power for the pixels?

i will use meanwell power supply (i think it is the best for such projects ) http://img847.imageshack.us/i/supply.jpg/

I Have 17 trees , and every tree has 70rgb pxl , i will repeat power at every 5meter and i use 2 power supplay for 1 tree 35+35 and each splitter will have seperate power supply but no problem i can use only 1 also for all , i tested all treess one by one with 70pxl and i used open dmx ennttec usb interface and freestyler dmx program , it is also free program and enntec also free designed usb interface but freestyler and ennttec open dmx can control only 512 channel , i have 17 trees , and i will also need dmx data splitter too and interface with 7x512 output i will use vixen if i can use, please can you give me advice on this stuation what to do ? which kind of data sptlitter i need to use for my project ?

[Pixeltech]

project install done :) i changed system little i didnt make light for 17 Tree , i made 1 big tree and 16 line group between lights on all street , i control system now with same address and with 1 usb interface 512ch and software is freestyler but im going to do ECG-DMX/REN8 with 8 x512ch and it will be enough for me to control all my system but my dmx512 decoder modules has 16F628A and i made coding for 20mhx external osc and 250k baud rate , ECG-DMX/REN8 can control it ? i will not have any problem ?

project picture here : http://img96.imageshack.us/i/snc00163.jpg/

i will send also video when all done exactly

[dmoore]

Pixeltech -

If you don't mind me asking - where do you live?

[Pixeltech]

Pixeltech -

If you don't mind me asking - where do you live?
i live in Turkey

[timon]

I was on Ray's site and found this:

http://www.aliexpress.com/fm-store/701799/209915969-440556828/Mini-protocol-Decoder-DMX-to-WS2801-512-dmx-address-decoded.html

Looks to me as something worth looking into. The ability to power 2801 strings from 8 to 12VDC is a positive thing. The unit is small, can be attached close to the strings and can be powered using the RJ45 connection.

Has anyone had a chance to check these out?

[jstjohnz]

I think that might be mis-labeled, it looks to me like it has individual RGB outputs, not an output for driving pixels.


I was on Ray's site and found this:

http://www.aliexpress.com/fm-store/701799/209915969-440556828/Mini-protocol-Decoder-DMX-to-WS2801-512-dmx-address-decoded.html

Looks to me as something worth looking into. The ability to power 2801 strings from 8 to 12VDC is a positive thing. The unit is small, can be attached close to the strings and can be powered using the RJ45 connection.

Has anyone had a chance to check these out?

[David_AVD]

That box doesn't provide power for the strings. You'd still need a 5V source for the WS2801.

[dannito]

...The transmit the data over long distance by cascading, the WS2801 integrates push-pull output stage with strong driving capability which enables the data and clock can be transmitted up to 6 meters at 2MHz clock frequency. To prevent the reflection, it is necessary to connect a 50Ω resistor at the data input or output port for impedance match...