Roger that! Thanks Leo.Richard

Any chance we can get a progress update?Richard

Progress report - Scott is working hard to finish his PPT design code name "Photon". ;) He's mostly done generating the PCBs but we've been discussing the power supply situation since it's going to have to drive lots of AMPs when you add up all those LEDs and 7 seg displays.Looks like it'll use a standard PC PS.I also have a USB 256 output module ready to go, but unless you can solder fine pitch surface mount components, I have no idea what I'm going to do with it. I know I can't solder that stuff myself so that's where I stand with mine...:-zhelp-Leo

Hi Leo! Been away from the simpits a while but saw your new Plasma interface. Pretty cool. ;-) I see from your new signature that USB is starting to get to you. Hang in there! Peter http://bfu.avsim.net/sigpics/PeterR.gifBFU Forums ModeratorRenegade/Seawolf Design Group (RSDG)[table border=2 cellpadding=0 cellspacing=1][tr][td][table border=0 cellpadding=8 cellspacing=0][tr][td bgcolor=#6f0000]http://bfu.avsim.net/sigpics/logo75t.gif[/td][td align="center" bgcolor=#FFFFF6]Bush Flying Unlimited"At home in the wild"Looking for adventure? Come join us! * [link:bfu.avsim.net|Web Site] * [link:www.cafepress.com/bfu,bfu2,bfu3,bfu4|BFU Store] * [link:bfu.avsim.net/join.htm]Join!][/td][/tr][/table][/td][/tr][/table

Hi Richard,Well, as Leo noted, just working out power supply issues. Theoretically this unit could control 14 or maybe more MAX 7219 modules - but that's 784+ led segments at 25 ma each = 20 amps! I've decided upon a 20 amp ATX PC 5v power supply that will serve the main board and each output board (thank Leo for the suggestion ). Input boards will get juice from the main board.I've built working prototypes and just need to tweak the schematic to account for the power supply decision before I send out for PCBs of the prototypes."Photon" will interface with the PC parallel port using a DB25 connector (like a zip drive cable). The main board will take up to 4 Input boards @ 128 switches each and 7 output boards (though 14 or even more are theoretically possible) each capable of 8 7-segment digits or 56 individual leds.I still need to finish the software DLL for the interface and hope to have both dotnet and vb6 versions available.Price has not yet been determined though I'll probably have a "starter value package" with the main unit, power supply, an input board and an output board.More info will be available on my website in the next week or so:http://www.flightsimsolutions.comThanks for your interest. Also, don't forget to keep your eyes on Leo's site for updates on a USB-based output device.Thanks for your interest!Scott>Any chance we can get a progress update?>>Richard

> I see from your new signature that USB is starting to get to you.Hehe....damned vandals spray painted my sig! :-lol Aaagh! Don't get me started on USB.Anyway Peter, good to see you back.-Leo

I've found plenty of sites telling me how to wire a 44780 LCD display to a Parallel port, but does anyone know if one can run more than one such LCD screen from a single parallel port ?Richard

Thanks for the update. Will keep watching.Richard

Thanks for the update. Will keep watching.Richard

>I've found plenty of sites telling me how to wire a 44780 LCD>display to a Parallel port, but does anyone know if one can>run more than one such LCD screen from a single parallel port?>>RichardYou can use more than one display by hooking it up with demultiplexers. On a 44780, you have eight data and the CE and RS lines to worry about. To select the display, you'll need one or more output pins on the parallel port. I haven't tried this, but it appears that the standard PC port with DB25 connector has two output pins that you might be able to use as a channel selector: Auto Feed (pin 14) and Init Printer (pin 16). So, you could theoretically have four displays on one parallel port.The 74139 has two 1-of-4 demuxes on it so five of them would cover the eight data lines and two control lines that you need to switch.Peter http://bfu.avsim.net/sigpics/PeterR.gifBFU Forums ModeratorRenegade/Seawolf Design Group (RSDG)

Four displays...... Well. I could have com1 active and stby on one 16 char display by showing "123.45 123.45", same for com2, nav1 and nav2, so I gues a basic radio stack could be done that way. $3 each for the four displays - any idea what a demux chip like a 74139 goes for?Richard

Jameco has the 74LS139] for $0.36 each if you buy less than 10. If you have a local electronics store, you might check there first.Peter http://bfu.avsim.net/sigpics/PeterR.gifBFU Forums ModeratorRenegade/Seawolf Design Group (RSDG)[/font

Richard,It's actually simpler than what I originally thought (kinda rusty on my hardware designing). Since each display has to be enabled in order to activate the data on the lines, you don't have to demux everything.Take a look at this FSBus project (taken from the other thread on this topic):http://mikkila.wabbits.org/fsbus/lcd/All eight data lines and the RS line (parallel port pin 16) can be common to all displays. Then, you only need to demux one pin on the parallel port (e.g. parallel port pin 1: Strobe) for the enable signal. Two other pins (e.g. parallel port pins 14 and 17) can then be used as the demux selector.Note that with this design, parallel port pin 14, which was used for R/W on the FSBus project, is used for the demux input instead. As a result, you can either ground the R/W line to always have it in write mode or put a switch on it to manually switch it between read and write modes.Also note that the output of the 74x139 demux is active low so you'll need inverters (a 74x04 has six) to make each output active high for the LCD enable input.Peter http://bfu.avsim.net/sigpics/PeterR.gifBFU Forums ModeratorRenegade/Seawolf Design Group (RSDG)

OK, maybe I'm just showing my ignorance of the Parallel port itself here, but if the RS and data lines can be common, and each display needs only a stand-alone Enable signal, why couldn't 14, 15, 16 and 17 each be the Enable signal for four different displays ?I can't think of why I'd want to read from it, so just grounding out the R/W should cover that.Richard

Because pin 15 is an input line, not output, Pin 16 is already in use for the RS line (to indicate command or character data on the data lines). So, that only leaves 14 and 17 free when you ground R/W. Thus, 14 and 17 go to the demux inputs.Here's a table of the parallel port pins and their function. That'll make it clearer:http://www.indiacam.net/pinout/#6APeter http://bfu.avsim.net/sigpics/PeterR.gifBFU Forums ModeratorRenegade/Seawolf Design Group (RSDG)