Am 26.03.2012 um 19:44 schrieb Charles Goyard:

Hi, Jim Hickcox wrote:

...

I am working on an architectural installation with a guy and part of the goal is to control some dim lighting from Pd. Does anyone have any experience with the steps for taking the midi output and making that control some LEDs? Any recommended workflows?

Try DMX as an output and off-the-shelf LED projectors/washers. It's the most time efficient for sure.

out of curiosity: did anyone try http://www.anyma.ch/research/udmx/

m.

Thank you all for getting back to me.

Patrick: I actually tried to call Enttec today, but both of their sales people were on an airplane, and they should get back to me tomorrow I guess. But what do you need? They have a usb to dmx, right? And then you need the driver, and then just the lights? That seems pretty straightforward.

Max: That udmx looks awesome, if it's a functional thing.

Jean-Marie/Björn: Thanks for the heads up on interface-z. I'd never heard of them. Looks easy enough.

Charles: I guess I don't know how to just do a dmx output. Although, now I seem to have some options.

Again, thanks all.

-Jim

2012/3/26 Björn Eriksson miulew@gmail.com:

Found this when as suggested doing some googling on Interface-Z - on this page some test pd patches and more... http://www.interface-z.com/produits/act054_8_trans-puiss.htm and a vid: http://www.youtube.com/watch?v=JAjILa4MOu8

/Björn Eriksson

On Mon, Mar 26, 2012 at 9:35 PM, Jean-Marie Adrien jma@jeanmarie-adrien.net wrote:

...

hi if you're in a hurry, google interface-z jmadrien

Le 26 mars 2012 à 20:02, Jim Hickcox a écrit :

...

Hey there.

I am working on an architectural installation with a guy and part of the goal is to control some dim lighting from Pd. Does anyone have any experience with the steps for taking the midi output and making that control some LEDs? Any recommended workflows? I was thinking about trying to build something with an arduino, but maybe there's something more time-efficient, since I only sort of know what I am doing.

Any suggestions would be appreciated.

-Jim

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Hi,

You can make a USB to DMX interface really easily with an Arduino. Then you'll have to make a protocol that encodes the data in Pd and that is decoded on the Arduino side and then sent via DMX. It really depends on what you need. It's not that complicated once you've decided on the limits of your system. http://www.arduino.cc/playground/Learning/DMX You will need the DmxSimple library to send the DMX from the Arduino.

You can also make your own dimmers as the email below describes. I have made some with a transitor between the arduino and the strips of LEDs. You need a transistor that reacts to 5V and can handle rather large intensities. I used this one: IRFZ34N (spec sheet attached). If you need more you will need to have chips (I2C to PWM) but at the cost of faster/higher number of steps (like 16 instead of 256)... I'm thinking of a chip like this one: Max7313.

Hope this helps Cheers Pierre-Olivier

On 27/03/2012 09:04, Jim Hickcox wrote:

For the archives, I had emailed my brother in law Pete about the potential of using an arduino chip to process the midi and send the signals to the LEDs, and his response was fairly enlightening as well, so here's that in case it's helpful for the future:

The "analog" outputs of the arduino are in fact pulse width modulated (PWM) digital signals. These are easy to convert into an analog voltage with a filter but you dont have to worry about that. The best way to dim an LED is with PWM. What this means is that the LED turns on and off really fast. The brightness is a result of the ratio of ON to OFF per cycle, thats pulse width.

The arduino makes this really easy. When you assign a value to an analog output it translates that into a PWM ratio. So with a little midi translation you should easily be able to take midi data and make it into a value between 0 and 256 which you can send to a few analog outputs.

BUT

you cant drive high power LEDs directly from the arduino. A regular LED draws about 15mA. The arduino outputs can drive (I think) around 20mA each. A high power LED or LED array can draw at least a full AMP (1000mA). The solution to this is a simple transistor based LED driver. A driver is an amplifier and an isolator. It essentially takes very low current from the arduino and outputs high current to the LEDs. The kind of driver you use and the amount of current it supplies will depend on the LED array you want to drive.

On Tue, Mar 27, 2012 at 1:45 AM, Jim Hickcoxtango.mceffrie@gmail.com wrote:

...

Thank you all for getting back to me.

Patrick: I actually tried to call Enttec today, but both of their sales people were on an airplane, and they should get back to me tomorrow I guess. But what do you need? They have a usb to dmx, right? And then you need the driver, and then just the lights? That seems pretty straightforward.

Max: That udmx looks awesome, if it's a functional thing.

Jean-Marie/Björn: Thanks for the heads up on interface-z. I'd never heard of them. Looks easy enough.

Charles: I guess I don't know how to just do a dmx output. Although, now I seem to have some options.

Again, thanks all.

-Jim

2012/3/26 Björn Erikssonmiulew@gmail.com:

...

Found this when as suggested doing some googling on Interface-Z - on this page some test pd patches and more... http://www.interface-z.com/produits/act054_8_trans-puiss.htm and a vid: http://www.youtube.com/watch?v=JAjILa4MOu8

/Björn Eriksson

On Mon, Mar 26, 2012 at 9:35 PM, Jean-Marie Adrien jma@jeanmarie-adrien.net wrote:

...

hi if you're in a hurry, google interface-z jmadrien

Le 26 mars 2012 à 20:02, Jim Hickcox a écrit :

...

Hey there.

I am working on an architectural installation with a guy and part of the goal is to control some dim lighting from Pd. Does anyone have any experience with the steps for taking the midi output and making that control some LEDs? Any recommended workflows? I was thinking about trying to build something with an arduino, but maybe there's something more time-efficient, since I only sort of know what I am doing.

Any suggestions would be appreciated.

-Jim

On 2012-03-27 05:07, Bastiaan van den Berg wrote:

On Tue, Mar 27, 2012 at 09:41, Pierre-Olivier Boulant <po.boulant@free.fr mailto:po.boulant@free.fr> wrote:

Hi,

You can make a USB to DMX interface really easily with an Arduino.

FYI, USB is pretty slow for DMX stuff.

It's faster than DMX though. It's the arduino that can't read fast enough, its maximum baud rate seems to be 115200 without going into assembler. The DMXUSBPro works well for me with Pd. I set the [comport] baud rate to 250000 but I don't think it's necessary.

Martin