Hi Tom... Tom Metro wrote: > stuart wrote: >> ...I know they're not common, but I paid something less than $20 >> US for a Vacuum Florescent Display... > > Not common? VFDs were quite commonly used as point-of-sale (POS) > displays, along side cash registers. I picked up one on eBay a few years > ago for about that price. Nicely packaged, with power supply and serial > interface. Most are made by IEE. > > I though that's what the external display options in mvpmc were designed > for.
Yea, well, I haven't touched the VFD driver in a long time. It has some bugs. The best MVPMC / MClient supported display is the IEE 2 X 40 because it mirrors the real squeezebox. The IEE 2 x 16 needed some scrolling support. But for the most part, both work w/MClient. It's when you venture into other parts of MVPMC that support is spotty. However, at that point, you probably have the MVPMC connected to a TV or monitor. > Back in the early '90's I had a similar surplus VFD made by Cherry > Semiconductor without the nice packaging that I stuck in a box in my > living room and controlled it from a computer a few rooms away via serial. Hum, you would then probably be interested in how the VFD driver actually works. Stick w/me. The VFD driver is forked off as many parts of MVPMC are when the MVPMC application starts up. To communicate with the driver, the main portion of the MVPMC application opens a port and sends data to be displayed to the VFD driver. At the conclusion of the communication, the port is closed. So, I would say, 90% of the time the VFD driver is available to anyone who wants to open the port through the MVPMC's ethernet port. Now there's nothing fancy going on if the port is busy. That is, if you open the port to the VFD driver and the main MVPMC process can not connect, the display is not updated w/any new MVPMC information. That all being said, it not very hard to write a program to send messages over the ethernet to be displayed on the VFD. So, let's say you have an old modem in your computer that can pick off caller-id. You could write a program to pop the message onto your MVPMC's VFD. Or, you could scrape weather web pages for storm notifications. Or, scrape stock pages for bid / ask prices. Or, monitor motion detection hardware (ala X10 / http://heyu.tanj.com/). Or, monitor motion detection video cameras (ala http://www.zoneminder.com/). You get the idea. >> ...which came w/a Atmel uP. The guy that designed it (Dale Wheat I think) >> for BGMicro actually had the foresight to populate the board with the >> programming interface connector. So, there's most of the HW that I need >> in a small package for not much money. > > There you go. You just need to add some IR hardware to it, and figure > out how to write the software for the Atmel MCU. But buying one of those > "smart" serial controllers might be worth the expense, when you consider > the effort required to write the software. Where's the fun it that :-)! >> The IBM PowerPC is of a BGA type mount (Ball Grid Array). ... >> In short I think you will have trouble accessing extra, if >> any, pins. > > There's always the pins used for the serial port, if you end up not > using it. Keep in mind the serial port is the console port. That is, during boot up and afterwards, this is how the outside world sees what going on and communicates with the MVPMC. Even after the flurry of boot up messages is over, most IR transmitters require the program to have direct control over the serial port pins. Regardless of MVPMC achievements, many of these low level drivers remain a mystery. But if we stuck a uP on the serial port, it could filter and direct the flow of data to the VFD (eliminating all that boot up stuff), to the VFD power switch (we can shut down the VFD when not in use), to the IR emitter (we could generate the 40K on the new uP as well as load it up w/the transmit pattern) and (for those of us with older Sony equipment) to multiple S-Link ports (which is nothing more then the Sony IR code w/o the 40KHz modulation over a wire. for an example see: http://www.nirvis.com/slink-e.htm). >> Plus, I don't think I have see any documentation w.r.t. pin >> functions... > > Unless it is a custom part, that info should be obtainable from IBM. Yea, well, I haven't looked for this kind of stuff for over a year, but let us know what you find ;-). > How did the serial port come to be discovered? It was kind-of obvious w/ the empty target, empty charge pump caps and other wiring already on the board. >>>> Adding a 40KHz oscillator would reduce the IBM PowerPC processor load >>>> to only modulating the IR LED. But this would complicate the >>>> hardware modification. >>> I'd take a look at how this was accomplished on other projects that >>> integrate IR with computers. The LIRC community probably has tons on >>> info on this. >> Regardless, it does off load the uP and can probably be done using one >> chip (the common and cheap 7400 NAND schmidt trigger gates come to mind). > > Agreed. But the point was that the LIRC community would likely have > dealt with this issue already and be able to advise whether you can get > away with doing the modulation in software, or if it is necessary to use > hardware. That community would probably have plenty of info on the other > IR related questions you raised as well. > > -Tom I thought I read somewhere that people had worked out an intermediate protocol that allowed you to send patterns and timing to a uP which would turn around and add that final physical layer to the message. It would be trivial to work it out again, but that was what I had in mind should we go with adding a uP to the serial port. Should you go and write any new code, like something on the PC to communicate with the VFD or on a PIC or Atmel uP to handle the serial port communication, I am sure Jon can set up another GIT repository to handle source so that everyone can contribute. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. 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