Re: [Opengc-devel] Linux Hardware

[John W. <ca...@mm...>]

Hi Manuel,

> > 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 suspect if you surveyed the users you would find most are not deeply
involved in software, but rather the hardware aspects of building something
tangible so windows and windows-related hardware provide a nice comfort
zone.

> 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.
>
Right, you need to get to the kernel and leave the application alone.

> 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.
>
Running is kernel space is both risky and very effective. In my case, the
driver works with the hardware and never bothers the application (FG and
OpenGC) which simple poll the driver. Displays, LEDs, switch states are all
updated based on hardware interrupts and the application never sees or hears
about it.

> Costwise, I estimate my currently "in-progress" circuit schematic would
> cost around $50-70 in components, depending on the prices of your
> suppliers.
>
There are some sites that provide circuit design, PCB layout software and
prices vary also as well with quantities purchased. Looks like my component
costs for the MCP are around $30 to $35 but then I've kept the interface
simple by using the parallel port so after you buy a PCI board ($40) it
turns out to be a wash... And the start-up costs for the PCB range from $50
to $80 for the first unit. Then throw in some sockets, connectors, and
you're over the century mark.The panel, produced by AGT, is excellent and
with all the lights and switches goes for $325. This can be an expensive
hobby...
>
> I'm glad I'm not alone doing things like that under linux.
>
I don't think there are a lot of us ;-)

> If you are interested, I can send you a png of the circuit I'm working
> on right now.
>
I would appreciate that; Don't have a schematic of the my circuit, just a
bunch of notes and scribbles which I need to turn into a finshed product
with a circuit design tool to do a PCB layup. There are some boards at
www.phdigit.com that you might take a look at, only drawback ( I think ) is
software is for windows. Still researching it.

BTW, if your not familiar with Rubini's book on linux device drivers,
recommend it highly. Google on device drivers or go to the O'Reilly website.
Text and source are online and GPL'd

Thank you for your comments

Regards
John W.