Noob E1.31 protocol question

[David_AVD]

Traditionally, DMX512 was used to send up to 512 channels to dimmer packs in stage lighting applications. Each channel value (0..255) simply corresponded to the required intensity (0..100%) for the light(s) assigned to that channel. When other devices (such as moving heads) started using DMX512, the values were used for pan/tilt position and for gobo (pattern) selection, etc.

The point is that DMX512 is just a group of 8 bit values in a frame. The values can vary each frame (for dimming / flashing, etc) but don't have any inherent meaning by themselves. It's up to the sender (lighting console or sequencing software) and the receiver (dimmer, pixel controller, moving head) to use that data in some predefined way.

Feel free to ask more. That's how we all learn.

[firstone]

Thanks. I've had an understanding of the concept but not the concrete details. I was finally able to play with sequencing programs and figure out all the little details. One little issues is that the software, such as, Lightshow Pro, organizes R,G,B channels into a single RGB logical channel. But GE G-35 lights that I use also have a separate dimming value. Of course, I can just have 4 separate channels - R,G,B and level. But then I loose nice logical RGB organization. Either way, I have a very clear picture of DMX protocol (and E1.31 wrapper) in action.

[jpelzer]

Thanks. I've had an understanding of the concept but not the concrete details. I was finally able to play with sequencing programs and figure out all the little details. One little issues is that the software, such as, Lightshow Pro, organizes R,G,B channels into a single RGB logical channel. But GE G-35 lights that I use also have a separate dimming value. Of course, I can just have 4 separate channels - R,G,B and level. But then I loose nice logical RGB organization. Either way, I have a very clear picture of DMX protocol (and E1.31 wrapper) in action.

I'm looking to do exactly the same with my Arduino. Are you planning to open-source your code, and if so, do you mind sharing it in its current form?

[firstone]

I have git projects set up. I just didn't include E1.31 code because it's so painfully slow, beyond unusable. But I should still have the code. I'll include it into the project and post the link.

[jpelzer]

I have git projects set up. I just didn't include E1.31 code because it's so painfully slow, beyond unusable. But I should still have the code. I'll include it into the project and post the link.

Yeah, I saw some of your posts in a different thread. That's a shame. I'd still like to take a look at the code, so yes, if you can find it, please do post. Cheers!

[mschell]

Don't confuse the "pixel" protocol with the control protocol. For example, the E68x controller line uses E1.31, which is DMX over Ethernet. DMX just has values for each channel, and takes 3 channels to control pixels, using R, G and B values. Somewhere in the E68x controller, those RGB values get mapped to the GE protocol, that also indicates brightness on a 4th channel, I guess, from your description.

The source code for the E680 is posted in a thread elsewhere in this section of the forum.

[erm213]

Don't confuse the "pixel" protocol with the control protocol. For example, the E68x controller line uses E1.31, which is DMX over Ethernet. DMX just has values for each channel, and takes 3 channels to control pixels, using R, G and B values. Somewhere in the E68x controller, those RGB values get mapped to the GE protocol, that also indicates brightness on a 4th channel, I guess, from your description.

The source code for the E680 is posted in a thread elsewhere in this section of the forum.

I think the 680 just sets the max brightness all of the time on the GE's. You use the color values to mix the color. I could be wrong here.

Erik

[firstone]

Ok, I've added E1.31 translation code to my project. The only thing that you might add is layers' length validation.

The project is here: GECERemote

This is how you would use it (just an example, won't necessarily compile):

#include "E131.h"

E131 packet;

void loop() {

  if (Udp.available()) {

    int len = Udp.readPacket(buf, BUF_SIZE);

    if (packet.validate(buf)) {
      for (int i = 0; i < packet.getLength(); i += 3) {
        uint8_t red = static_cast<uint8_t>(buf[E131::DATA_OFFSET + i]);
        uint8_t green = static_cast<uint8_t>(buf[E131::DATA_OFFSET + i + 1]);
        uint8_t blue = static_cast<uint8_t>(buf[E131::DATA_OFFSET + i + 2]);
      }

    }

  }

}