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List:       flightgear-devel
Subject:    Re: [Flightgear-devel] KX165 - serially feeding data to increment a
From:       Gene Buckle <geneb () deltasoft ! com>
Date:       2011-03-31 21:44:30
Message-ID: alpine.LFD.2.00.1103311439380.25177 () grumble ! deltasoft ! com
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On Thu, 31 Mar 2011, Roberto Inzerillo wrote:

> Hallo everybody, I purchased a few rotary encoder and a bunch of 
> 7segment displays to build a physical replacement of the Bendix KX165. 
> I'm using Arduino which feeds data to FGFS on a serial connection. I'd 
> like to update "instrumentation/comm[0]/frequencies/standby-mhz" 
> property using the rotary encoder, I wonder what's the best strategy.
>
> My current setup lets me read the rotary encoder rotation (it's a signed 
> int value that measures it's direction and the amount of rotation; e.g. 
> +3 equals three steps CW, -1 is 1 step CCW and 0 means it's not 
> rotating) and send it to fgsf at 30Hz. This encoder is meant to be the 
> KX165 physical equivalent of the frequency selector knob.
>
I would only send the data if it's changed.  No sense in running the pump 
unless there's something to send.

> I can send those values to FGFS but that's useless as it is now; I 
> should make FGFS increment the "standby-mhz" property accordingly; 
> problem is that using the generic protocol to feed those data I can't 
> use the same approach as in kx165-1.xml where the "property-adjust" 
> (with a proper <step> value) command has been used.
>
You might want to trigger an up/down event via Nasal that will do what you 
need.

I did something similar to this with the hardware interface software I 
built a few years ago.

Here's the Lua end of it:

-----------------------------------------------------------
-- Cockpit Interface Master - Copyright 2008 by Gene Buckle
-- Controls COM1 frequency selection
-----------------------------------------------------------

-- Get the currently selected frequency from the simulator.
Com1Freq = CIM:GetStringValue("COM1_FRQ")
if Com1Freq == "" then
    CIM:SetValue(0, "Com1Freq was blank for this cycle.")
    return
end
-- Choose the correct frequency "step" based upon what the current
-- simulator needs.
if SimType == "FlightGear" then
    kHz_offset = .0250
    Mhz_Offset = 1.0
elseif SimType == "MSFS" then
    kHz_offset = 2
    Mhz_Offset = 100
else
    CIM:SetValue(0, "Invalid SimType - >" .. SimType .. "<-")
    return
end

-- The next four if..then blocks control how the step up/step down
-- buttons work for gross (Mhz) and fine (kHz) tuning of the COM
-- radio.
-- The routines are written to eliminate "keybounce" by ensuring that
-- the user has released the button before the script terminates.

-- The "CIM:SetValue(0,...)" calls are an easy way to see how the code is 
operating
-- if there is a problem with the simulator.

if CIM:GetInput("KHZ_DOWN") == true then
    repeat
      -- do nothing
    until CIM:GetInput("KHZ_DOWN") == false
    Com1Freq = Com1Freq - kHz_offset
    CIM:SetStringValue("COM1_FRQ", Com1Freq)
    CIM:SetValue(0, "KHZ_DOWN ->" .. Com1Freq .. "<-")
    return
end

if CIM:GetInput("KHZ_UP") == true then
    repeat
      -- do nothing
    until CIM:GetInput("KHZ_UP") == false
    Com1Freq = Com1Freq + kHz_offset
    CIM:SetStringValue("COM1_FRQ", Com1Freq)
    CIM:SetValue(0, "KHZ_UP - " .. Com1Freq)

    return
end

if CIM:GetInput("MHZ_UP") == true then
    repeat
      -- do nothing
    until CIM:GetInput("MHZ_UP") == false
    Com1Freq = Com1Freq + Mhz_Offset
    CIM:SetStringValue("COM1_FRQ", Com1Freq)
    CIM:SetValue(0, "MHZ_UP - " .. Com1Freq)
    return
end

if CIM:GetInput("MHZ_DOWN") == true then
    repeat
      -- do nothing
    until CIM:GetInput("MHZ_DOWN") == false
    Com1Freq = Com1Freq - Mhz_Offset
    CIM:SetStringValue("COM1_FRQ", Com1Freq)
    CIM:SetValue(0, "MHZ_DOWN - " .. Com1Freq)
    return
end

------------------------------------------

If I can find the files for the FG end of things I'll post them.

g.

-- 
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