I decided the Maximite is too slow to do both the EFI and the EFIS job
    so I intend to use two Maximites and one aux card for the sensors
    and injector transistors. The two Max's can share sensor data.

    The EFI is time critical so that is demanding
    of program execution time. The EFIS Maximite has all the time
    in the world as all it has to do is up date the VGA display every half
    second.


    Here is the BASIC source code for a simple EFIS program that update
    the VGA  every half second. This is just a clock but I hope you get the idea.

    Mode 1 ' sets the screen rez

    SetTick 500, doit 'set the interrupt to every half second AKA 500 msec

    twiddle: ' The EFIS work would be done in here.
    Print " "; 'the half second hardware interrupt  occurs in here
    GoTo twiddle

    doit: 'upon half second hardware interrupt
    CLS                   'clear the VGA screen
    Locate 30, 30 'Put the clock at column 30 row 30 on the VGA
    Print Time$   'Print the battery backed up real time clock on the VGA
    IReturn  'interrupt routine done. go back to twiddle


    Pretty simple.

    The easiest hard ware package to build  is just a 4 inch length of six by six aluminium extrusion
    with 3/16 wall that can be drilled and taped for end covers.

    Over kill on volume but lots of room for expansion.

    Paul Lamar



As you make progress I expect you will find that the only way to ensure the efi works correctly will be to use an RTOS real time operating system like other modern time critical systems use. An RTOS schedules each event and makes sure everything happens on time. Your current system waits for a signal to calculate rpm , map etc. If one signal isn't there because of component failure, rmi or anything else the system fails and you stop flying.

Kevin Alderman
President Aviation and Avionics Services Inc.


I think it is cheaper in terms of programming time  and easier to use multiple processors.
In fact I am thinking of adding a third Maximite and run my moving map software on that.
I'll have a selector switch to see which processor gets the VGA display. This is the way they
do it in airliners. I have plenty of room in the box.

There can be horns for things like low oil pressure. You switch off the moving map
and switch to the EFIS to assess the problem. Each Maximite will have 64 gig of storage
on an SD card so a comprehensive history will be available. BTW that  is tens times
the size of the FAA Airport data base.

Robin got mad at me when I wrote this back in 1990. I had a booth at OSH and was totally
ignored other than by the FAA dropping by and telling me not to sell it as people
could use it to land in IFR conditions at non IFR airports with out talking to a controller. :)
Of course it would behove you to monitor the radio to make sure nobody else was landing
on the same runway :)

Paul Lamar


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