Hmm can someone explain how the MO GPOs work, and could they be seperated/built onto another device? Can LCDC control the gpos independantly? or does it need the serial controller on the lcd? basically shooting for a serial controlled GPObus
Apologies to Henry if I'm giving away any trade secrets, but this is all stuff that seems apparent to me, I don't have any inside track to MO engineering department... The MO product is a parallel LCD with a daughterboard. On the daughterboard is a PIC (microcontroller). In fact, if you look, there ain't a whole lot else. A voltage regulator (on some models) and a RS-232 chip like a MAX232, and a crystal. So the serial->parallel conversion is done in software running on this PIC. That's the secret sauce. All their commands and whatever, that's implemented in software (not field upgradeable though). The main job is the serial conversion though. And that's not a hell of a lot of work really. So there are these other input and output lines available on the PIC. And the bright boys at MO said "hey, we can use these and implement some nice features for the customers." And thus there is a keypad and a set of GPOs. They're just leftover i/o lines on the PIC. So turning on a GPO amounts to telling the PIC, "set line n high." But they give you a command sequence that's consistent with their overall scheme. And LCDC issues these commands to do its job. So you don't need the display, you just need a PIC. And some kind of interface to the PIC that allows you to manipulate the output lines. This is assuming you just need a few TTL outputs. If you need lots, you can tack a multiplexer onto the output lines and get more. But a PIC gives you a small handful of them. Here's the deal. If you are gonna use a PIC, then make it drive a display too! If all you need is some switching, there are really simplistic circuits that do that. The PIC supports 2-way comms with your host peecee (with the MAX232 or like chip in place), so it's really handy, but it can do a lot more than just toggle output lines. There's insane amounts of info out about these things. I'm not really a PIC person myself, so I only konw about them in theory (not yet in practice). But take a look at Mr. Baybus at veys.com to get a sense of how much the little critters can do. HTH
