[simpits-tech] Wiring of POT and EPL

Sat, 1 Mar 2003 15:59:30 -0800

All this chat about synchros is all very educational.  But I wonder if
your original question actually got answered yet, Frank.

Some info that I hope you find useful:

I suggest you scrap the idea of using a pot -- it won't work very well
for what you are trying to do.  Here's why --

In EPICenter you can map EPL functions to an analog axis directly
through the interface.  In that case you get 32 functions assignable for
each direction of rotation of the pot (i.e. 32 as you turn from max to
min and 32 more from min back to max).

If your functions mapped this way sent the heading increment/decrement
functions for right and left rotation of the pot respectively, you
wouldn't get anywhere near the required resolution.

Falcon4 models the heading knob on the HSI gauge (note: the HDG knob on
the INSTR panel doesn't appear to be active in the game) as having 72
steps for a full 360 degree rotation of the heading bug (i.e. 5 degree
increments per key press).  32 steps aren't enough to match the required
72 in the game.

Now EPIC stores the analog axis position as a byte value between 0 and
255.  You could write code to camp on the actual axis stored value and
scale down so that each time the value changes by three-ish, the
keystroke would get sent.  This is not a pretty piece of code and if you
are doing a full cockpit's worth of EPL may well tax EPIC performance
beyond reason.  Not to mention that given the lack of precision and
consistency in pots the chances of you accurately being able to adjust
the knob with your hand so the value EPIC sees changes by more than 3
but less than 6 (say) would be very, very difficult.  And also not to
mention that the end stops on the pot will mean that in some cases you'd
have to rotate the pot almost all the way to the other end of it's
travel to make very small heading changes in some cases.

That is to say using a pot for this control is doable in theory with EPL
code but there are several drawbacks that in practice just make it a bad
idea.

What you want, with due deference to the experts on synchros and all the
other "real" hardware that is used for this kind of thing in actual
jets, is a plain old encoder for this job.

EPIC supports those and the EPL code is as straightforward as it is for
switches.

Ralph's encoder module is pretty spendy:      

  http://www.flightlink.com/epic/rotary.html

$250 a pop.  It supports a bunch of encoders though -- more than you
will need for an F-16 project based on Falcon4!

There is a cheaper alternative in the shape of the offering from Blue
Side Up:

  http://www.avsim.com/bluesideup/

$169 a pop and all ready to wire in to an EMDA card for use with EPIC.

All that said, I can't vouch for either one just yet.  Now that switches
and indicator lamping are basically all done, we are just this week
starting on making the hardware for the software driven bitmap displays
we will produce for DED, RWR, PFL, HSI and the CMDS.  Encoders are the
very next on the list so we haven't got there yet but FWIW, I believe we
are planning to use one bluesideup unit which can support 8 encoders
which should be enough for a Falcon4 driven F-16 implementation.

Cheers,

Mark.

> -----Original Message-----
> From: simpits-tech-admin@simpits.org [mailto:simpits-tech-
> admin@simpits.org] On Behalf Of Frank Riedel
> Sent: Friday, February 28, 2003 5:03 PM
> To: simpits-tech@simpits.org
> Subject: Re: [simpits-tech] Wiring of POT and EPL
> 
> Stupid me... did''nt see that....Thanks !
> just what i neeeded !
> 
> Frank
> 
> ----- Original Message -----
> From: "Simpitter@btopenworld.com" <simpitter@btopenworld.com>
> To: <simpits-tech@simpits.org>
> Sent: Saturday, March 01, 2003 1:52 AM
> Subject: Re: [simpits-tech] Wiring of POT and EPL
> 
> 
> > Frank,
> >
> > Its been many months since I;ve been near my Epic kit, but if I
remember
> > correctly, pots have to be connected to the ABA module.  The 64BTN
> module
> is
> > only for connecting switches.
> >
> > Look at www.fsim.com they have the documents and diagrams on the
site.
> >
> > Darren
> >
> > ----- Original Message -----
> > From: "Frank Riedel" <frank@rezultat.dk>
> > To: <simpits-tech@simpits.org>
> > Sent: Friday, February 28, 2003 11:05 PM
> > Subject: Re: [simpits-tech] Wiring of POT and EPL
> >
> >
> > > Sorry... it's getting late, and alot of wire has been mountet :o)
> > >
> > > I have:
> > > EPIC USB
> > > 1 expansion
> > > 3 output
> > > 1 rotary
> > > in a week:
> > > 1 ABA (new model)
> > > 5 64BTN module
> > >
> > > Frank
> > >
> > >
> > > ----- Original Message -----
> > > From: "Gene Buckle" <geneb@deltasoft.com>
> > > To: <simpits-tech@simpits.org>
> > > Sent: Friday, February 28, 2003 11:18 PM
> > > Subject: Re: [simpits-tech] Wiring of POT and EPL
> > >
> > >
> > > >
> > > >
> > > > On Fri, 28 Feb 2003, Frank Riedel wrote:
> > > >
> > > > > y
> > > > >
> > > > ?!  Is than an answer or a typo? :)
> > > >
> > > > g.
> > > >
> > > >
> > > > _______________________________________________
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