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By: xDGx (offline) on Monday, January 11 2010 @ 09:56 AM PST (Read 7492 times)  
xDGx

I have a question and - maybe - a suggestion for future builds of the board.
Using/modifying the peggy to use OPENDMX USB (with arduino) would make it easier for beginners to use the board without programming. I'm not really a PRO on the subject, but after reading about DMX lately, I thought that maybe it would make life easier for peggy users, because there's a DMX shield for arduino available and working... or maybe I'm just wrong ?
Thanks


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By: Windell (offline) on Monday, January 11 2010 @ 11:49 AM PST  
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The Arduino OpenDMX USB scheme that I can see uses the FTDI chip on the Arduino (or in the USB-TTL cable that we use, perhaps) as one half of a DMX interface-- the other half is an RS485 chip. This is a way of building a bridge between your computer and a DMX network-- the "Arduino" part of the board (the AVR) isn't even needed for this to work. That's a far cry from an AVR-based DMX solution, which is what I think you're asking about.

If you wanted to add RS485 (aka DMX) to a Peggy 2, that involves the same modification otherwise needed to add the serial port, plus an RS485 chip [EDITED-- see post below]. That's reasonably straightforward form a design point of view, but I'm not entirely sure what could be done with it then. I suppose that you could use another Arduino (or a standard USB-DMX controller) as the RS-485 controller, and then hook it to multiple Peggy boards. The I2C that we already support as a standard option gives a similar function-- control of multiple Peggy boards -- without extra hardware, though.

Now, you say "maybe it would make life easier for peggy users"-- Why is that? I haven't heard much about DMX, nor do I know who is using it or why. Is there something that I should know?


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By: xDGx (offline) on Tuesday, January 12 2010 @ 06:03 PM PST  
xDGx

Thanks for the reply, I'll try I2C on my board ! Windell thanks for the info, I got a little confused with all of this.

The thing about DMX is the available software - some open source afaik - as there are DMX software useful for LED matrix (that means *no programming* afaik for preprogrammed effects that come with them, not to mention the controls on the apps themselves, I'm supposing all LED matrixes can use DMX). Not that I'm sure they'd work with the Peggy, again, I'm new to all of this !

"maybe it would make life easier for peggy users" Why is that? -- I assume not all Peggy owners know how to code, and, - IF - a Peggy owner does not want to learn how to code some kind of effect, for instance, one could make a DMX shield (this is an example only, not even sure if it works!) and use one of the apps already available (again, I'm not sure it works, didn't do any kind of testing, I'm just assuming all I read is correct AND it could be tweaked to work with the Peggy boards!)

I haven't heard much about DMX, nor do I know who is using it or why. Is there something that I should know? I wrote my post yesterday after coming back from a fashion show that I went, and had a chance to chat with one of the guys backstage: the guy was controlling a HUGE LED panel (not my intention here, only 1 peggy is enough, well, why not 2 or 3 ? hehe ) with a laptop and a DMX controller (probably an expensive lightboard). My point is that guy was using an app on that laptop and I am sure he's no programmer, just like me. Turns out that most guys running those panels around here are using some kind of DMX device (Lighting control console) to control it, that's why I got all curious about the devices and stumbled upon the protocol.

WHY they use it ?
Maybe because of this (from wikipedia) "...The most common protocol used in the entertainment industry today is DMX-512.."
http://en.wikipedia.org/wiki/DMX512-A

That's all I know, lots of reading, nothing done or working tho. Comments/additions (if possible!)/etc appreciated !


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By: Windell (offline) on Tuesday, January 12 2010 @ 07:01 PM PST  
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Well... that certainly is food for thought. Thank you for the pointers; we'll have to take some time to consider this all.


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By: karlgg (offline) on Sunday, January 17 2010 @ 10:10 PM PST  
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To clarify a bit, "DMX" isn't a way to program without programming, it's an interface (basically the stage-lighting equivalent to MIDI). (wikipedia entry) It sounds to me like he wants to use a "stage lighting sequencer" (or whatever they call them, I've never seen one) to define the sequence on the Peggy. However, that sort of thing is meant to drive the devices over a link, which would require connecting the Peggy and running the sequencer every time you wanted to use the display.

I suppose you could have the Peggy listen to the sequence and remember it, but it would probably be easier to have some sort of "compiler" that turns the DMX sequence into code or a .HEX file to burn into the AVR. Both of those seem like a pain to me, and probably unnecessary.

Some sort of Peggy-specific display editor that lets you draw frames and save to code wouldn't be too hard to do, if somebody hasn't already done it. Just display a Peggy-sized grid on the screen, and let the user click the boxes to light LEDs... Basically a low-res paint program, with pages for multiple images.

I've done similar stuff way back in the day (DOS, and before that, TI-99/4A sprite editors) so I know somebody younger and/or more enthusiastic could do one for the Peggy without much fuss.


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By: xDGx (offline) on Monday, January 18 2010 @ 04:36 AM PST  
xDGx

Hm... so maybe DMX is not the best way to control Peggy's... I'm not conformed..yet(?) Cry

DMX came to my mind because it would work similarly to the I2C that's already done and working (read-display-forget - no need to remember the sequence in any way). The main diference is that I2C still requires some kind of code (peggymirror.pde for example), while DMX would only need an app like FreeStyler DMX. I've downloaded FreeStyler DMX (it's free) and will take a closer look. I'm not really experienced with any of this so if you guys are interested, I encourage you to download and take a look so we can come to a conclusion; if it's not viable, I'll live with it, and try something else. I'm willing to test it, too (build a shield for arduino etc) but I'd probably need some help. Cool

Exclaimation The main question is still if there's a way to change animations on the fly and make "live animation/presentation" using Peggy. I didn't try it with Quartz Composer because I don't have a Mac (yet). Maybe I'm looking for the answer to the question on DMX because I'm not done messing with I2C (is QT and I2C able to control the Peggy on the fly, without code?) . Btw, will nodekit for windows work the same way as QC ?

Some sort of Peggy-specific display editor that lets you draw frames and save to code wouldn't be too hard to do, if somebody hasn't already done it. Just display a Peggy-sized grid on the screen, and let the user click the boxes to light LEDs... Basically a low-res paint program, with pages for multiple images.

That's PeggyDraw, I'm eagerly waiting for a new version. I like it's premise: program an image or animation onto Peggy - without ever touching code. I hope it's out soon.

I'd like to thank all of you for the (fast) answers and support! Big Grin


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By: Windell (offline) on Monday, January 18 2010 @ 10:11 AM PST  
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The main diference is that I2C still requires some kind of code (peggymirror.pde for example), while DMX would only need an app like FreeStyler DMX. I've downloaded FreeStyler DMX (it's free) and will take a closer look.



DMX is a *software* protocol that is used over an RS-485 interface.

Both RS-485 and I2C are examples of hardware serial interfaces. The AVR hardware natively supports I2C. The AVR also has a native serial port either called an "SCI" (Serial Communications Interface) or "UART" (universal asynchronous receiver/transmitter) as well as a 3-wire serial port "SPI" (Serial Peripheral Interface). Most (if not all) microcontollers do not have an on-board RS-485 interface, but instead require external circuitry (for example, an RS-485 interface chip) to communicate over RS-485. Because of this, it's possible to get RS-485<->Serial, RS-485<->SCI, or RS-485<->SPI converter chip. There are lots of ways to do it.

Regardless of which hardware protocol that you use to get data to and from the Peggy, the Peggy needs to know what to do with that data, and so any of them will still require appropriate code running on the Peggy side of the problem. If DMX solves one end of that, it becomes the problem to write a program for the Peggy that can receive the code. It's certainly possible to use an I2C<->RS485 interface to make the hardware connection to a stock Peggy without other modifications, but there's some software to deal with after that. (I'm just realizing this now; earlier I said that the Serial hack was required.)

That's PeggyDraw, I'm eagerly waiting for a new version. I like it's premise: program an image or animation onto Peggy - without ever touching code. I hope it's out soon.



Er... Yeah. I was working on that new version but got distracted by the Bulbdial clock and haven't gotten back to it yet.
(You've seen the teaser shot: http://www.flickr.com/photos/oskay/4031984864/)


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