[simpits-tech] Switchs, Rotary and pot
Frank Riedel
simpits-tech@simpits.org
Mon, 19 Aug 2002 22:07:17 +0200
Hi All !
Can anybody tell me what module to buy to the EPIC
so all of F16 button, lamps, rotary etc,. will be funcktional ?????
All the best
Frank
----- Original Message -----
From: "Mark Doran" <msdoran@attbi.com>
To: <simpits-tech@simpits.org>
Sent: Tuesday, August 06, 2002 8:20 AM
Subject: RE: [simpits-tech] Switchs, Rotary and pot
> I've been thinking about this some lately too as I plow through the epic
> (sic) task of EPL programming for a complete set of F-16 panels. Left
> side console and half the center console all done now, but I digress.
>
> Encoders seem to get used (from a human factors-ish sort of view) where
> you have knobs that turn without an end stop and where the knob fitted
> doesn't need to line up with any particular markings on the panel that
> it's mounted on. Losing any one click 'cos you go by too fast isn't a
> problem because you can always click on one more time in the same
> direction to adjust...same for overshooting if you were really going
> fast just go back a click or two...
>
> For encoders, there's no real problem in syncing a physical mark on the
> knob, like a stripe say, with an orientation versus the panel the knob
> is on. But if you need to sync in orientation or you need end stops on
> travel of the knob in either direction, well then you definitely want a
> rotary switch, not an encoder.
>
> FWIW, I wonder about using pots in places where the real jet has
> encoders (like HSI heading and course controls for example). How do you
> get around the fact that a pot has an end stop?? Ralph's default
> keystroke to analog axis mapping technique gives you only 32 steps in
> both up and down directions...not enough resolution steps if you are
> doing compass headings, say. Yes, you can hand code something to read
> the pots absolute value to get more resolution in each of the 32 "slots"
> but that's a lot of code, I think you are still limited to ~256 steps of
> resolution, and you still don't really have the right "feel" equivalent
> given that an encoder just doesn't bump into an end stop.
>
> Plus of course, there are already near enough more things that need
> analog axes than you have to play with in the first place with a single
> EPIC: 2 for stick, 5 for TQS, 1 for rudder, 1 for HUD brightness, 2 for
> radio volumes, 2 for threat and sidewinder volume...that's 13 out of 16
> possible max right there just for the controls I actually use a lot when
> flying. You certainly won't be using pots to replace all the rotary
> knobs anyway ;-) [Mmm, presuming you use EPIC for flight control axes
> that is.]
>
> Back to encoders though...
>
> Electrically after all the complex circuitry is boiled down what you get
> is on of two switch make pulses that mean either "clockwise" (CW) one or
> "counter clockwise" (CCW) one. A bit over simplified perhaps but
> looking at this as a programmer that's what I see.
>
> Now, I can't see why if you have a rotary mechanical switch that has no
> end stop CW or CCW why you can't do a "software encoder" in EPL and save
> lots of painful circuitry and wiring...not to mention cash.
>
> How about this:
>
> A three pole rotary switch with no end stops. Wire each pole for a
> separate EPIC mod/row/bit number for this example with bits in
> "increasing" order clockwise:
>
> --BEGIN EPL EXCERPT
>
> // I haven't actually compiled and tried this but it's similar to the
> code I
> // have put together for positional rotary knobs that is working.
> // this uses the newer "device" and function call syntax but translating
> // back to EPICenter pre-v47 should also work well enough for this.
>
> byte vLastPos = 0;
>
> device(dFakeEncoder)
> {
> connector(FirstExpansionModule);
> button(0, 0, bBit0);
> button(0, 1, bBit1);
> button(0, 2, bBit2);
> };
>
> void dFakeEncoder.bBit0.On(void)
> {
> if(vLastPos == 2) {
> call(pulse_cw_keystroke);
> } else if (vLastPos == 1) {
> call(pulse_ccw_keystroke);
> } // else we're confused so don't send key presses :-)
> vLastPos = 0;
> }
>
> void dFakeEncoder.bBit1.On(void)
> {
> if(vLastPos == 0) {
> call(pulse_cw_keystroke);
> } else if (vLastPos == 2) {
> call(pulse_ccw_keystroke);
> } // else we're confused so don't send key presses :-)
> vLastPos = 1;
> }
>
> void dFakeEncoder.bBit2.On(void)
> {
> if(vLastPos == 1) {
> call(pulse_cw_keystroke);
> } else if (vLastPos == 0) {
> call(pulse_ccw_keystroke);
> } // else we're confused so don't send key presses :-)
> vLastPos = 2;
> }
>
> --END EPL EXCERPT
>
> Ok, so the switch has only three positions but if you put a round knob
> on it with no markings, who's to know?? It'll feel like an encoder
> (ish). In my testing with EPL code for rotary knobs that do have
> positional line up requirements, EPL execution is plenty fast enough to
> keep up with you even if you spin the knob pretty fast as you would with
> an actual encoder.
>
> The EPIC encoder module is quite spendy. If this works it might save a
> little that way. Of course we may end up using some encoders in our
> project since Falcon4 uses so many switches now the hardware may be on a
> "switch count diet" to fit onto a single EPIC and encoders do seem to
> use 1/3 less EPIC MRB namespace up when coding :-)
>
> Cheers,
>
> Mark.
>
>
> > -----Original Message-----
> > From: simpits-tech-admin@simpits.org [mailto:simpits-tech-
> > admin@simpits.org] On Behalf Of Marv De Beque
> > Sent: Monday, August 05, 2002 3:32 PM
> > To: simpits-tech@simpits.org
> > Subject: Re: [simpits-tech] Switchs, Rotary and pot
> >
> > That is an open question.
> >
> > The answer is, it depends.
> >
> > However, you have not qualified the exact application, so it is hard
> to
> > give
> > you a good answer.
> >
> > However, since I am constructing a F-16 cockpit, I can tell you what I
> > plan
> > to use. I will use a potentiometer for almost all of my applications
> > where
> > there is a knob. Except....
> >
> > ... the caveat is there are many knobs that use a rotary switch and I
> will
> > use a rotary switch where it is required. I think you know what a
> rotary
> > switch is, but if not, it is a mechanical switch that rotates to
> preset
> > positions.
> >
> > There are not too many places where an encoder will be applicable in
> my
> > sim.
> > I may possibly use them for the ICP panel that sticks in the pilots
> face.
> > There are 4 thumb wheels that control contrast, brightness, and other
> > functions on the HUD. An encoder may be physically easier to mount
> than a
> > pot in those instances.
> >
> > Encoders require more expensive circuitry to operate than a pot.
> General
> > rule of thumb is that there should be a good reason for using an
> encoder
> > where normally a pot will not do.
> >
> > I would recommend a pot.
> >
> > That being said, from the scope of the questions you are asking, I
> wonder
> > where you are at in your project and what your project goals are? I
> ask
> > because I get a sense that you might be putting the cart before the
> horse.
> >
> > What is your goal and what is your plan to get there?
> >
> > I am sure that you can get all the help you need right here, but it is
> > good
> > to get the basics first, outline your goals, and then we can help you
> > execute your plan (or at least help you get a plan together).
> >
> > Marv
> > --
> >
> >
> > > From: "Frank Riedel" <frank@rezultat.dk>
> > > Reply-To: simpits-tech@simpits.org
> > > Date: Tue, 6 Aug 2002 00:09:33 +0200
> > > To: <simpits-tech@simpits.org>
> > > Subject: Re: [simpits-tech] Switchs, Rotary and pot
> > >
> > > Great exampels ;o)
> > > GOT IT ;o)
> > > BUT - can i use POT instead of ENCODERS in my pit ???
> > >
> > > Frank
> > >
> > > ----- Original Message -----
> > > From: "Marv De Beque" <mdebeque@woh.rr.com>
> > > To: <simpits-tech@simpits.org>
> > > Sent: Monday, August 05, 2002 11:57 PM
> > > Subject: Re: [simpits-tech] Switchs, Rotary and pot
> > >
> > >
> > >> No.
> > >>
> > >> A pot (short for potentiometer) is a device that rotates over a
> given
> > >> portion of a circle. This is usually about 270 degrees, but there
> are
> > >> multi-turn pots that rotate 5, 10, or 20 turns from lock to lock.
> > >>
> > >> A pot is nothing more than a resistor that can be changed from zero
> > >> (usually) to its maximum value. 100,000 Ohms is typical for
> simulator
> > > use.
> > >>
> > >> A pot, theoretically, has an infinite adjustment between its two
> > extreme
> > >> values (i.e., 0 to 100,000 Ohms). So, like a faucet (in good
> working
> > >> order), you can adjust the flow to any value in between.
> > >>
> > >> A rotary encoder is different. It is a device that rotates like a
> pot,
> > > but
> > >> instead of acting like a variable resistor, it sends out a set of
> > pulses
> > > as
> > >> the knob turns. It is sort of like putting playing cards on the
> forks
> > of
> > > a
> > >> bicycle and turning the wheel. As each spoke passes, an audible
> click
> > is
> > >> heard (a pulse). You can count the pulses and then determine how
> far
> > the
> > >> wheel has rotated. You need two two playing cards slightly offset
> in
> > an
> > >> angular fashion to tell which direction the wheel is rotating. By
> > looking
> > >> at which card clicks first you can tell direction of spin.
> > >>
> > >> The thing about encoders is that they have a "granularity". Unlike
> a
> > pot
> > >> which is infinite, there are finite steps to an encoder. There may
> be
> > any
> > >> number of steps you can get from a few to several hundred steps per
> > >> revolution. You can resolve the rotation only down to the step,
> but
> > you
> > > can
> > >> not tell how much an encoder rotates between step steps (i.e., a
> half
> > > step).
> > >>
> > >> Most encoders do not remember their positions when power to the
> system
> > is
> > >> turned off. So, the system must somehow save the last known
> position
> > if
> > > it
> > >> is to pick up where it left off at power down. A pot has the same
> > >> resistance whether the system has power or not.
> > >>
> > >> A pot almost always has a mechanical stop. Resistance can only go
> so
> > far.
> > >> An encoder does not necessarily have a mechanical stop and can be
> > rotated
> > >> continuously without stopping.
> > >>
> > >> An example of an encoder is a computer mouse (at least the old
> ones).
> > > Some
> > >> new car stereos have them too.
> > >>
> > >> Two different animals that can be used in similar ways and each has
> its
> > >> advantages.
> > >>
> > >> Sorry for the long message, but I am short on time.
> > >>
> > >> Marv
> > >> --
> > >>
> > >>
> > >>> From: "Frank Riedel" <frank@rezultat.dk>
> > >>> Reply-To: simpits-tech@simpits.org
> > >>> Date: Mon, 5 Aug 2002 23:35:45 +0200
> > >>> To: <simpits-tech@simpits.org>
> > >>> Subject: Re: [simpits-tech] Switchs, Rotary and pot
> > >>>
> > >>> Thanks alot for the explanation ;o)
> > >>>
> > >>> I found the F16 panels at simpits.org...
> > >>>
> > >>> Did i get it right - rotary encoders = potentiometers ??
> > >>>
> > >>> Thanks
> > >>> Frank !
> > >>>
> > >>> ----- Original Message -----
> > >>> From: "Andreas Fransson" <andreas.fransson@post.utfors.se>
> > >>> To: <simpits-tech@simpits.org>
> > >>> Sent: Monday, August 05, 2002 9:09 PM
> > >>> Subject: Re: [simpits-tech] Switchs, Rotary and pot
> > >>>
> > >>>
> > >>>> Frank,
> > >>>>
> > >>>> 3-way switches are (usually) on-off-on. With or without automatic
> > > return
> > >>> to
> > >>>> center position (not sure what the english expression for this
> would
> > > be).
> > >>>>
> > >>>> Rotaries, if you mean rotary switches and not rotary encoders,
> may or
> > > may
> > >>>> not have limits. A couple I have here for example do not. They go
> all
> > > the
> > >>>> way around. What they do is just rotate a common ground around a
> > number
> > > of
> > >>>> connections. Like a "normal" switch but with many more positions.
> > Mine
> > >>> have
> > >>>> 12 I think. You could say that they are "all-on" in the sense
> that
> > one
> > >>> lead
> > >>>> is always active. Encoders are a different breed altogether. They
> are
> > >>>> commonly used to sense motion (rotation) rather than indicate
> switch
> > >>>> positions.
> > >>>>
> > >>>> "Pots", or potentiometers, are basically variable resistors. I
> you
> > use
> > > one
> > >>>> with EPIC, or as a replacement for a joystick pot, it is 100 ohm
> > linear
> > >>> pots
> > >>>> you want.
> > >>>>
> > >>>> If you use the EPIC, the kind of switches you use are almost
> > > unimportant.
> > >>>> EPL (the EPIC programming language) is very flexible. It's not at
> all
> > > like
> > >>>> the standard joystick momentary on/off pushbuttons.
> > >>>>
> > >>>> What aircraft (or whatever) panels are you looking for?
> > >>>>
> > >>>> Andreas
> > >>>> http://valhallainc.d2g.com
> > >>>>
> > >>>>
> > >>>> From: "Frank Riedel" <frank@rezultat.dk>
> > >>>>> Hi All !
> > >>>>>
> > >>>>> 3 way switchs - is that off-on-off or ????
> > >>>>> Rotary - is that 360 dg. or ???
> > >>>>> 2 way switchs - is that on-on or ???
> > >>>>> Pot - is that a normal potmeter 100 ohm or ???
> > >>>>> Is EPIC control all those switchs nomatter if it is on-of or
> on-on
> > ???
> > >>>>>
> > >>>>> Do anyone of you guys have a link to a page where i can read
> about
> > it
> > >>> ???
> > >>>>>
> > >>>>> and do anyone have a set of drawings of panels without knobs on
> ????
> > >>>>>
> > >>>>> thanks for all your help... i'm on the road for my first real
> pit
> > ;o)
> > >>>>>
> > >>>>> Frank
> > >>>>
> > >>>>
> > >>>>
> > >>>> _______________________________________________
> > >>>> Simpits-tech mailing list
> > >>>> Simpits-tech@simpits.org
> > >>>> http://www.simpits.org/mailman/listinfo/simpits-tech
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> > above
> > >>> page. Thanks!
> > >>>
> > >>>
> > >>> _______________________________________________
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> > >>> Thanks!
> > >>
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