View Full Version : Progress on DMX/RDM dimmer

08-28-2007, 01:08 PM
Well I jumped my first technical hurdle last night with my dimmer. I have a single dimmer output working via DMX, with no jitter (that was an issue for a few days).

My goal was to not reinvent the wheel, so after months of planning I decided to use David F's hardware design. I really like how he has protected the outputs and it’s a fairly modular design. I'm trying to keep the board layout and design as close to the original as possible. The idea is the hardware remains the same not matter whose firmware you use. If you liked his version you could burn the pic with his firmware and add any additional hardware. If you liked my version you would just burn my firmware and add additional hardware.

At this point the major difference with my design is I want to have dipswitches for starting address. Over time I hope to be able to set the starting address via RDM which would make dipswitches optional.

In short my goal is to have a functional prototype for Halloween, wish me luck. ;)

09-21-2007, 06:38 PM
Progress is slow mainly due to the fact that I can't get DMX and the 40us timer interrupts to play well together without rewriting everything in assembly (same issue JEC had with is project). In short it doesn't look like I will have it ready for Halloween. :(

However another forum member and I were chatting today about the Parallax Propeller which I recently purchased for a work project. Our discussion got me thinking about moving my project to the prop. I'm going to look deeper into this. The nice thing about the prop is there are no special tools required and anyone can update and/or improve the code by downloading the free IDE and compiler. BTW For those into assembly the prop does assembly also.

11-13-2007, 11:28 AM
I bought a Propeller development kit just for this project. Everything is on the breadboard and so far things are looking good. DMX first then dimming... :lol:

12-17-2007, 08:40 PM
...I can't get DMX and the 40us timer interrupts to play well together

I'd recommend that you poll your UART for DMX512 data rather than using interrupts. Then with only one source of interrupts the latency issue causing jitter goes away...

12-17-2007, 09:44 PM
Hmmm hadn't thought about it that way. I may have to dust that off and see if I can get it going again. Your timing is good I came up with a new lighting effect that only requires 3 channels and just wanted to run DMX to it. The propeller was going to be over kill so this might get me going again.

Thanks alot.