[simpits-tech] Controlling synchros

[Cris Harrison]

Simon Bennett wrote:

>>     Man, you've bitten off quite a big piece here. :) 
>> Powering/controlling real
>> instruments is not known as one of the easiest things in sim 
>> building. Good
>> luck on it, though. Have you decided on how you're going to control your
>> stepper motor (or whatever other device you decide to use to drive your
>> torque transmitter)?
>
>
> I like a challenge.
>
> The stepper motors will be controlled by a PIC microcontroller, which 
> communicates with the FS2004 via the serial port.
>
>>     Since you're going to be driving instruments, I assume you're 
>> digging into
>> the programming aspect of things..what sim are you using? Depending 
>> on the
>> sim, you may be able to go a step further and set certain sim 
>> variables based
>> on switch state (this is a lot more straightforward when using joystick
>> buttons as opposed to keystroke events, however). This would mean if 
>> a switch
>> is in the "on" state, the respective sim function would always be 
>> "on" as
>> well. You wouldn't have to sync up the sim's internal functions to 
>> switch
>> positions every time you run it.
>
>
> Unfortunately this is probably the only way I can really do this with 
> just a keyboard port connection. I intend to create my own 
> microcontroller-controlled keyboard interface which will handle all of 
> this, but that will have to wait. The ex-keyboard controller is only a 
> temporary solution.
>
>
> I'm using FS2004, for sure, and possibly LOMAC or Falcon 4, 
> eventually. I plan on having the sim hardware being totally 
> independent of the software. All of the gauges, switches, lights, etc. 
> are to be managed by a second PC. This box will run FreeBSD as an 
> operating system since I hate windows and the windows API with a 
> passion. It also frees up resources on the main sim computer, since 
> all it has to do is swap a few bytes back and forth across the LAN. 
> The second PC communicates with the cockpit electronics over the 
> serial port. The cockpit electronics tell the 2nd computer when a 
> switch has been pressed. The 2nd computer then decides what action to 
> take and communicates with the main sim computer either directly over 
> the LAN, or if that isn't possible, by telling the homemade keyboard 
> interface to send a command in the form of a keypress.
>
> All of the cockpit electronics will be PIC microcontroller based. I'll 
> probably use mainly 16F88 chips, since they are cheap, packed with 
> neat features, and pin-compatible with the ubiquitous PIC16F84. I'll 
> have to design my own data bus and break everything down into systems 
> and sub-systems to keep everything moving in the right direction.
>
> If I opt for MFDs or a working HUD, I have a couple 386 laptops that 
> would be more than able to drive the displays.
>
> When this system gets built depends on the amount of time I have. I 
> have a lot of parts I have to order from digikey. I have already begun 
> writing the software. All of the PC stuff will be written in C++, the 
> PIC code in assembly.

Simon,
You should look at what I am doing with my NEXT GEN flight simulator.. 
my method is cheaper & eazyer & faster..
first code (not machine code but what things do when you do things rates 
etc.) what you want to sim to do. Second put it into software to test 
it... using a test platform. Stanardize on a communication protocols so 
boxes can talk together, then and only when you like what you see build 
hardware but it should be modular.. so that it can be used over again 
like building blocks... get it?

> For the individual console panels, I originally thought each one was 
> going to have to have its own microcontroller, but now I'm not so 
> sure. I was worried that a single microcontroller wouldn't have enough 
> I/O pins to handle even a single panel full of switches or lights, but 
> it didn't take me long to think of a way around that. For a panel with 
> a lot of switches, like an audio panel, I can just put each set of 8 
> switches behind a latch or a buffer or something, and have a counter 
> to turn them on and off, cycling between them. If I use 8 I/O pins on 
> the PIC for switches, and 4 to select the set of switches, I could 
> have up to 128 switches running off of a single microcontroller. My 
> original idea was to have a line encoder like a 74HC148 to send a 
> binary signal to the PIC when a switch was triggered, but this 
> wouldn't let me tell whether the switch was on or off at any given time.
>
> For output to LEDs or the like, for, say, an annunciator panel, I 
> could just use the same approach only have a few latches to keep track 
> of whether the light should be on or off. Hmm.
>
>
> So this is what I get for not having any money for an EPIC card. Well, 
> it's more fun to do it yourself, anyway.
>
> Sorry for the rantyness.
>
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