View Full Version : YANP (yet another project)
08-03-2008, 11:30 PM
Here is a little something that I've been working on, again for home automation (although it uses DMX512 pinout and possibly signalling . It's a 2.5" x 4.2" board to function as an isolated, bi-directional splitter (if that's the right word). On side of the board interfaces to the USB port of a PC, the other side transmits 4 identical byte streams (in tx mode), or receives data from one channel when in rx mode. The DMX side of the board will get its power from a wall-wart, the USB side from the host PC. It's cheaper to do it this way than to use a DC-DC converter.
It is intended to fit a QS-50 enclosure from Polycase, although I suspect that getting the mechanical aspects correct will take some work.
08-04-2008, 11:14 PM
Very cool Phil, what are you plans for this one?
08-05-2008, 12:39 AM
It was based on using parts that I had on hand (enclosure, PIC, and UL245 modules), and I was going to buy a few boards. AFAIK this area is pretty well covered over on RJ's site, but I put this out just in case it tickled someone's fancy, and I'd then order a few extra boards.
Now I'm thinking about a slightly different idea, shown in the attached GIF. This is a little 1.625" x 2.25" bi-directional opto-isolator board that will fit in a Polycase LP11 enclosure. It will be a bit more expensive to field (more PCBs, more 6N137 opto-isolators, and it uses a DC-DC converter module), but more modular and hence flexible. The USB module and the PIC could be point-to-point wired using a Radio Shack prototype board, since I won't need very many of them.
BTW, both of these designs use one wire pair for data in both directions, which I think runs counter to the DMX spec. For DMX purposes, both of these designs should be considered to be unidirectional.
08-05-2008, 05:19 PM
Here is a slightly updated version of the last board. I've added a connector so that several of these boards can be used in parallel with only one set of opto-isolators.
I'm going to sit on these boards for a day or two, and then order some barebones copies (no silkscreen, no soldermask). They are a fairly esoteric item, so I'm not sure if anyone else is interested, but I might run a coop later if interest warrants (a full board, with soldermask and silkscreen).
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