Director & GPS howto

Director & GPS HOWTO

DRIVERS
Windows: you might need to install one
Mac OS X: you need to install the one that came with the device or with the USB to serial converter.
On OS X any serial device needs a driver from the device manufacturer, because there no generic driver.

INSTALL THE SERIAL XTRA
Director can process GPS input by way of the serial Xtra. The Xtra extends Director's functionality.It can be used to access all kinds of micro controllers
You can download the free trial version at http://www.physicalbits.com (you need the full version for making executables/projectors but if you just want to mess around then the free version is enough)
Like all Xtras, this one needs to go to your Xtras folder.

WORKING WITH THE SERIAL XTRA
1. Testing if the serial Xtra works:enter the lingo "showxlib" command into Directors message window. It should now show up like this:

2. Setting up the movie.
Make a new Director movie.

Doubleclick Frame 5 in the script row

In order to make the script run continously in a loop we need to tell it to stay looping on this frame.

on exitFrame me
go to the frame
end

Then we need to make the script do something. In this case, it will call a handler called "doStuff" that is contained in a seperate script. Here we are just making a reference to that script that will then call that script.

3. More setting up....
Go to the "Window" menu and click on "script" in the window that opens, enter the following lines:

-----------------------------------
-----------------------------------
on startmovie

serialinit

end
--------------------------------------
-- When the movie is being stopped this handler calls the "serialclose"
-- handler that will then close the serial connection
--------------------------------------
on stopmovie

serialclose

end
--------------------------------------
-- This is the "do stuff routine"...
--------------------------------------
on dostuff

readserial

end
--------------------------------------
-- This initializes the serial port when the movie starts
--------------------------------------
on serialinit

end
-----------------------------------------
-- These are the things that are automatically done when the movie is stopped
-----------------------------------------
on serialclose

-- call from stopmovie!
set gSerialPort to 0
closexlib
put "Closed"

end
--------------------------------------
--This is where the serial port is read our main working area...
--------------------------------------
on readserial

--- in theory you should do this but i'm not sure if it can drop data
flushinputbuffer (gSerialPort)

exit

end
--------------------------------------
--------------------------------------

So the main scripframework is now set. We now want to query the serial port for data... this is how we do it:

Fist we must define a global variable. This global variable is put at the very beginning of the script.
This means that it is accessible for all other handlers in the script and not just from within a handler.
So we put:

global gSerialPort

Then we modify the serialinit part of the script as follows:

--------------------------------------
-- This initializes the serial port when the movie starts
--------------------------------------
on serialinit

  put new(xtra "serialXtra", "/dev/cu.usbserial0") into gserialPort
  setProtocol(gSerialPort, 9600, "n", 8, 1)

  result=gSerialPort.OpenPort("/dev/cu.usbserial0")

  if result <> "Ok" then
        put "ERROR: GPS not connected -- " & result
  else
        put "GPS connected."
end if

end
-----------------------------------------

If using Windows put:

-----------------------------------
on serialinit

  if the platform contains "Macintosh" then
        openxlib "SerialXtra"
  else
        openxlib "SerialXtra.x32"
  end if

  put new( xtra "SerialXtra", ("modem") ) into gSerialPort
  put gSerialPort

  -- you may need to do this to force the port to match your device... but has worked without before...
  SetProtocol (gSerialPort, 9600, "n", 8, 0)

end

4. This was just the serial Xtra initialization. Now we actually try to get the output from the serial Xtra

on readserial

  rawinput = ReadString (gSerialPort)
  put rawinput

  flushinputbuffer (gSerialPort)

exit

end

5.This generates data---- but the data is somewhat messed up because the serial port is queried too often. So we want to query it only once a second. Director handles time in "ticks".

The command "the ticks" stands for the current time. So if you are assigning "the ticks" to a variable, it's like looking on your watch-

so we add a global variable to gSerialPort

global gSerialPort, gSerialCheck

Under "on startmovie" we say that gSerialCheck is "a quick glance on the watch".

on startmovie

-- ticks says what time it is
gSerialCheck=the ticks

serialinit

end

In the dostuff handler we need to write, that we want "readserial" called up every second. So if the time is 60 ticks (one second) than the previous time we looked at the watch, the serial port gets read.
After that we need to change the gSerialCheck variable to include the current time, so that a second later the script will call "readserial again".

on dostuff
  if the ticks > gSerialCheck+60 then

    readserial
    gSerialCheck = the ticks

  end if
end

To pick apart the input we use the character commands in director so "on readserial" then looks like this:

--------------------------------------
--------------------------------------
on readserial

  rawinput = ReadString (gSerialPort)

  start = offset ("_", rawinput)

  if start = 0 then
    input = rawinput

    put "satellite found..."

    -- figure out Latitude and Longitude
    start2=offset("G",input)
    delete input.char[start2..input.length]

  -- delete all characters after the "@"-sign including the "@"-sign as well as delete all character     preceding the "N"-sign
    start3 = offset ("N",input)
    start4 = offset ("@", input)
    delete input.char[start4..start3]

    --divide the 0000W000 string to get the minutes
    lat = input
    longi = input

    start5 = offset ("W", input)
    delete lat.char[start5..lat.length]
    delete longi.char[1..start5]

    put lat &" "& longi

-- Optional: the formula for calculating decimals out of degrees/minutes/seconds
-- Decimal Degrees = Degrees + minutes/60 + seconds/3600

    set the height of sprite 1 to 100
    set the width of sprite 1 to 200

    set the height of sprite 2 to 100
    set the width of sprite 2 to 200

  else

    delete rawinput.char[start..rawinput.length]
    put rawinput
    put "satellite not found.offset ==" & start

  end if

  flushinputbuffer (gSerialPort)
exit

end
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