Re: [Opengc-devel] Linux Hardware

[Manuel B. <li...@va...>]

Hi John,

On Thu, Sep 18, 2003 at 10:50:24AM -0700, John Wojnaroski wrote:
> Hi,
> 
> Over the course of the last year I've been trying to find simulation hardware (MCP,EFIS,EICAS,etc) that works with Linux and would support open source programs like FlightGear and OpenGC. All I could find was Windows stuff ( EPIC, FSUIPC, etc). And there did not seem to be a lot of interest in developing stuff for open source software under Linux.

Sadly, this is true. Maybe Flightgear will change this in the future.
In the home cockpit building community, Linux and flightgear don't seem
to be very well known and used. 

I think that flightgear is especially suited for that since its open
source so you can get information in and out easily and dont have to
rely on peek'ing and poke'ing the memory of the running simulator
program.

> Well, I never followed the herd and was not about to move over to Windows or FSxxxx.

That would be a step back, wouldn't it :-)

> So I sat down and designed an interface board for the MCP and EFIS as starters. Turns out, the board is somewhat generic in that it takes rotary enconder data and key scan circuits and along with the Linux driver stuffs the data into a small file that the application can read/write. Using the board goes like this:
> 
> The board has a standard parallel port interface (I wanted to use IEEE1284 EPP but opted for the most common, simplest for the moment). It will run either on your printer port or any additional parallel port board (ISA or PCI) you care to install or I've got a custom ISA board with three programmable ports I used for development and testing.

I've done something very similar. I'm using the serial port, however.
The whole thing is based on microchips PIC line of microcontrollers.
(Like someone else pointed out in this thread, these are very good for
our purposes)

Right now I'm tying things together to build a board that can take up to
1024 inputs (switches/rotaries/..), 35 analog input channels, 
and 64 digital 8 bit channel outputs for things like 7segment displays,
steppers, Digital to analog,...

I've written a joystick kernel driver for linux for a earlier 16 channel
analog to digital system. And its Flightgear tested :-)

I've made Panels myself for a 747-400 MCP and EFIS. 

I thing all other things except the analog inputs will not be driven by
a kernel driver, but rather by a user mode program that can connect to
flightgear. That way, I can specify mappings eg. for the switches
without having to unload/reload the kernel module over and over.

> So if you were running a MCP panel the data would be airspeed, mach, heading, vvi, and altitude. Plus the state of the pushbutton switches on the panel which would go to the FMC for the appropriate action and control of the system autopilot(s) and such. Or you could configure it as a NAV/RADIO panel and process the data as frequencies. Or whatever..... 
> 
> The board and driver run in kernel space and use an interrupt to process changes in the state of the connected panel
> 
> I'm still testing the board but getting close to a decision on moving from a breadboard to a PCB layout. Best guesstimate on cost is between $100 and $200. ( I have no idea on what the manufacturing costs beyond the production of the bare PCB look like, as always very dependent on size of the lot and quantity discounts for parts and amortization of start-up costs,etc,etc)

Costwise, I estimate my currently "in-progress" circuit schematic would
cost around $50-70 in components, depending on the prices of your
suppliers.

> Trying to gauge the interest in such an item and welcome any feedback, questions, etc.
> 
> For a look at some of the hardware panels I plan to use check out http://www.a-g-t.com

I'm glad I'm not alone doing things like that under linux.

Some older circuits and pics of my MCP/EFIS panels can be found at my
home cockpit site: http://cockpit.varxec.de/ 

If you are interested, I can send you a png of the circuit I'm working
on right now.

Oh, and - of course - everything is released under the GPL, including
the PIC assembly language firmware programs.


Regards, 
Manuel