Do you mean to use the pull down resistor in case of power loss to the controller? (so that the LED’s don’t go to full power?) From what I’ve read, if you remove power to the arduino, the PWM output is already held low, and the lights will not come on. It would be a great safeguard if the physical connection is lost though, and very easy to add to the LDD boards.

Chris

Yes, in case if the physical connection is lost (all it takes is one loose connection). For the sake of engineering rigor and user experience, when dealing with logic or PWM values you should always use pull-up/-down resistors so that devices default to a desired state when they're unplugged. It's kinda silly for the lights to turn on 100% if you need to unplug your controller to do something, right? Imagine the amount of online bitching we'd hear if Radions did that:razz:

If the Arduino does lose power, the PWM pin should also go to ground because the -ve/ground of the Arduino is connected to the -ve of the driver, but there is also the possibility of the PWM pin of the Arduino just floating. The pull down resistors are an added safeguard in that situation as well.

Just never really thought of it like that since I planned to house controller/LDD’s within the LED pendant, so accidental disconnection shouldn’t be an issue. It is a good idea though, and something I will add.

Man it will be nice to get everything in, and get started on this project. I think I’ve changed my plans a couple of dozen times already.

Tell me about it. I almost just want to get my build done so I can get it it of my head! Hopefully all my parts will be here by next weekend so I can finish it off.

lol.... I have most everything from "plan 1, 2, & 3", too bad I din't stick with any of those. Did you find anyone on RC for a spare LDD board? I picked up an extra one when I got mine, so if you're stuck, shoot me a pm.

Chris

Ya, I'm on version "G' or "H" or something, I've lost count. When I get everything I ordered I bet I won't use some stuff and need more of others.
I thought you could order these boards straight from ITead Studio but I couldn't find them on there.
Have you decided on what you wanted to do with those drivers, ScubaSteve?

Chatouille has an extra board that I'm gong to grab from him. I'm going to add 10K resistor between the PWM inputs and ground for added safety.

I'm going to put an order through Mouser tomorrow once I make sure that I've thought of everything.

You have to purchase the PCB prototying service from Itead then send them the gerbers.

If you order the phoenix terminals, make sure you get the right part #, or check the foot print out before buying them. (ask me how I know :sad: )

Well, I got a wack load of stuff yesterday

http://i1177.photobucket.com/albums/...psee98e789.jpg

http://i1177.photobucket.com/albums/...ps6caff948.jpg

http://i1177.photobucket.com/albums/...ps05d75c0a.jpg

My main Arduino board, 3 temp sensors, a couple different adjustable resistors, screw terminals (the wrong ones, as it turns out), larger wiring terminals I'm going to use these to link my 3 fixtures, and some transistors.

Pretty soon I'm not gonna have much excuse not to start building this :D