The Pixels Have Arrived!

The schematic for this board over in the coop thread shows the base resistors R1-R3 as being 100 Ohms. Assuming that this is not just a documentation error, I think that they should be increased in value to around 1K Ohm, or more.

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Phil
 
P. Short said:
The schematic for this board over in the coop thread shows the base resistors R1-R3 as being 100 Ohms. Assuming that this is not just a documentation error, I think that they should be increased in value to around 1K Ohm, or more.

--

Phil
Click to expand...

Thanks for catching that. Yes, they are 1K resistors and I've update the PDF file in the co-op area to reflect it.
 
Its de ju vue all over again.:shock:

I think I was in the same position with renard last year at this time.

So I just need to verify a few things before I dive blindly headlong into this project.

1a Each pixel is one DMX device.
1b DMX is limited to 32 devices per string(a DMX standard)
1c A DMX splitter would allow an additional 32 devices.
2 One pixel will use 3 channels.
3a You need a DMX USB Pro from Enttec
3b Will the Open DMX USB work?
3C Will anybody write a serial communication adapter THIS YEAR?
4a I will need a 5 pin male XLR to create a custom cable that will combine the DMX signal and 6amps @ 12v into a cat5 cable.
4b I will need a 100ohm 1/2watt resistor to terminate the last pixel.
5a Vixen now supports both the Enttec Open and Pro adapters.
5b The RGBLED Addin already has some color blending capabilities Just no way to see it one you have created it.
5c Worst case scenario could I just select a DMX output plugin and set the values for the RGB channels and hope for the best(thats going to take a lot of imagination or a good color blending program)

I already know I am going to get them. Now I am just trying to talk myself into it.

JOel
 

1a Each pixel is one DMX device.

Yes.

1b DMX is limited to 32 devices per string(a DMX standard)

The limitation has more to do with the type of RS-485 receiver chip used and how it 'loads' the line. I've seen chips which allow up to 256 devices on one chain, but in this case, stick to 32.

1c A DMX splitter would allow an additional 32 devices.

Yes.

2 One pixel will use 3 channels.

Yes.

3a You need a DMX USB Pro from Enttec

Probably not.

But that's what I have. I specifically didn't buy the Open design because it relied on the computer to generate each frame of DMX. My computer was busy doing other things and I didn't want to bog it down. The Pro design can accept a frame of data and repeat it forever, until a new packet comes down the USB bus.

The Open system rolls over and dies if it's not continually updated by the PC.

I've never tested the Pro with Vixen, but I'm told there's a plug-in being worked one.

I also build custom pattern generator circuit boards based on PIC microcontrollers. If anyone's interested, I can post some source code.

3b Will the Open DMX USB work?

Yes. So long as the output conforms to the DMX timing specs, *any* DMX source can be used. Hooray for international standards!

3C Will anybody write a serial communication adapter THIS YEAR?

Maybe. I probably won't have time. Fortunately, each pixel contains a programming header, which I've already tested successfully.

You provide +12V and ground to the RJ-45 jack and clock, data, ground and Vpp to the programming header. I use the MeLabs serial programmer (melabs.com) but anything should work. The target chip is a 16F688.

Also, I connected the RS-485 transeiver to the PIC's on-board USART. So by changing the receive registers in software, nearly any standard baud rate could be used.

4a I will need a 5 pin male XLR to create a custom cable that will combine the DMX signal and 6amps @ 12v into a cat5 cable.

Yes. The pinout you need is posted on the most recent 'group buy' thread in the co-op forum.

4b I will need a 100ohm 1/2watt resistor to terminate the last pixel.

Yes. The signal gets wonky if it's not terminated properly. For a good time, take a look at the signal with a 'scope.

5a Vixen now supports both the Enttec Open and Pro adapters.

?? Don't know.

5b The RGBLED Addin already has some color blending capabilities Just no way to see it one you have created it.

?? Don't know.

Here's one other thing. I chose these particular LEDs because of their high light output for individual colors. This means that if you want white, you won't find it at [255 255 255]. You'll need to experiment a bit. White is still there, but it's not going to be exactly what the color picker says.

5c Worst case scenario could I just select a DMX output plugin and set the values for the RGB channels and hope for the best(thats going to take a lot of imagination or a good color blending program)

Yes. It's not the fastest way to do things, but you'll still have complete control over the output.

I already know I am going to get them. Now I am just trying to talk myself into it.

Decisions like this are *always* emotional; the justification by logic comes much later. *grin*

John
 
3a You need a DMX USB Pro from Enttec

In response to the Open relying on the PC, I've had my Open for two years (built it myself). I've used it for theatrical shows, Halloween displays, and DMX development. I have never had an issue. You would need a pretty slow PC doing a lot of processing before you would see issues with the Open. While the Pro is great the Open will work fine in this application, at $35 (if you build it yourself) you can’t beat the price.

3b Will the Open DMX USB work?

Should work fine. DMX is DMX, doesn’t matter what the source is.

4b I will need a 100ohm 1/2watt resistor to terminate the last pixel.

I would suggest a 110-120 ohm resistor.

5a Vixen now supports both the Enttec Open and Pro adapters.

As of Beta2, Vixen only supports the Open. There is a plug-in that is being tested for the Pro but has yet to be released. Stay tuned…
 
Thanks your your answers John and Ben.
That clears up a few things for me.

Ben:
You haven't read the release notes for Vixen 2.0.3.0

Added support for Enttec's DMX USB Pro module. [Thanks to RJ for his time and efforts in testing this!]

Its in there.

Found the DMX Open at siris-e for a little less than Ebay.
http://www.sirs-e.com/st/dmx-usb-c-27.html
They also offer $6.60 priority mail shipping.

Joel
 
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