NMEA extraction AppleScript need help

zapwizard · 02-24-2006, 03:51 AM

I am trying to improve my GPS to Google Earth script.
One way is to get rid of the GPSNavX program, and get the NMEA data off the serial port in the first place.

I am just learning apple script and I have gotten far enough to see the actual data in the return window.

Code:

New Code below

But I am having problems processing that data in order to extract the $GPRMC data. I may be going about this all wrong.

SerialPortX is needed to interface AppleScript and the Serial Port.
http://osaxen.com/files/serialportx1.0.html

Bugbyte · 02-24-2006, 05:34 PM

Question: if you build this into an application, does the user need to install the SerialPortX scripting addition, or will it be embedded in the executable?

zapwizard · 02-24-2006, 06:16 PM

I have no idea

I did fix my problem above

Here is the new code though:

Code:

New code below

zapwizard · 02-24-2006, 07:58 PM

Ok so I now have integrate a some-what working script with my other GPS to Google Earth script.

But my GPS seems to spit out a LOT of crap data before spiting out the GPS data.

The script runs once or twice in a row, but then craps out returning the giberish.
Anyone want to try it out and see if it does the same on your GPS puck?

Code:

--WRITTEN by ZAPWIZARD
--Requires GPSNavX and XML RPC

--Find current Serial Ports
property thePorts : {} --Attached Serial Ports

--List the Serial Ports & select one from list
set thePorts to serialport list
set dev to choose from list thePorts

--UnComment this, and insert your serial port name to diable the prompt menu.
--set dev to "/dev/cu.usbserial"

--Set your Time Zone Offset here
set TimeZoneOffset to -6

--Set Default Course direction
set Old_Course to 0

repeat
	--Get data no more then twice a second
	delay 0.5
	
	--Open Serial Port
	set portRef to serialport open dev bps rate 4800 data bits 8 parity 0 stop bits 1 handshake 0
	
	
	--Check if available
	if portRef is equal to -1 then
		--Close port if program quit in error
		serialport close portRef
		serialport close 10
		serialport close "/dev/cu.usbserial"
		--Try again
		set portRef to serialport open dev bps rate 4800 data bits 8 parity 0 stop bits 1 handshake 0
		
		--Display Dialog if still cannot open port.
		if portRef is equal to -1 then
			display dialog "Could not open port "
		end if
	end if
	--Que enough GPS data to capture valid data
	repeat until (serialport bytes available of portRef) > 370
	end repeat
	--Read Buffered Data	
	set Buffer to serialport read portRef as text
	--return Buffer --Uncomment to Debug your Buffer
	--Split raw data into data After $GPMRC
	set AppleScript's text item delimiters to "$GPRMC"
	set x to text items of Buffer as list
	set y to second text item of x as string
	--Extract data before "$GPGGA"
	set AppleScript's text item delimiters to "$GPGGA"
	set z to first text item of y as string
	--Split up data
	set AppleScript's text item delimiters to ","
	set GPS to text items of z as list
	set GPS_TIME to second item of GPS
	set GPS_Status to third item of GPS
	set GPS_Latitude to fourth item of GPS
	set GPS_NS to fifth item of GPS
	set GPS_LOngitude to sixth item of GPS
	set GPS_EW to seventh item of GPS
	set GPS_Speed to eighth item of GPS
	set GPS_Course to ninth item of GPS
	set AppleScript's text item delimiters to ""
	
	
	
	--If Moving store course in Old_Course
	if GPS_Speed > 1 then
		set Old_Course to GPS_Course
	end if
	--Close Serialport
	serialport close portRef
	
	
	
	--Is GPS fix valid?
	if GPS_Status = "V" then
		display dialog "Lost GPS, Click OK to try again"
	end if
	
	--Convert GPS_Latitude into Decimal
	set dd to characters 1 thru 2 of GPS_Latitude as string
	set mm to characters 3 thru 9 of GPS_Latitude as string
	set mmD to mm / 60
	set GPS_Latitude to dd + mmD
	if GPS_NS is equal to "S" then
		set GPS_Latitude to "-" & GPS_Latitude as string
	end if
	
	--Convert GPS_Longitude into Decimal
	set ddd to characters 1 thru 3 of GPS_LOngitude as string
	set mm to characters 4 thru 10 of GPS_LOngitude as string
	set mmD to mm / 60
	set GPS_LOngitude to ddd + mmD
	if GPS_EW is equal to "W" then
		set GPS_LOngitude to "-" & GPS_LOngitude as string
	end if
	
	--Convert Knots to MPH
	set GPS_Speed to GPS_Speed * 1.15077945
	
	--Convert Time to 12hr time
	set hh to characters 1 thru 2 of GPS_TIME as string
	set mm to characters 3 thru 4 of GPS_TIME as string
	set ss to characters 5 thru 10 of GPS_TIME as string
	set ss to round ss
	
	--Setup time formats
	if hh > 12 then
		set PM to "PM"
		
	else
		set PM to "AM"
	end if
	set hhh to hh - 12 + TimeZoneOffset
	
	set GPS_Time12 to hhh & ":" & mm & ":" & ss & " " & PM as string
	set GPS_Time24 to hh & ":" & mm & ":" & ss as string
	
	--Camera range above ground linked to speed
	set GPS_Range to 300 + (100 * GPS_Speed)
	
	--Camera tilt angle linked to current speed
	set GPS_Tilt to GPS_Speed * (50 / 100)
	
	--Don't change angle data unless moving
	if GPS_Speed > 1 then
		set GPS_Course2 to GPS_Course
		
	else
		set GPS_Course2 to Old_Course
	end if
	
	--Generate KML File
	set XMLFile to {class:XML element, XML tag:"kml", XML attributes:{xmlns:"http://earth.google.com/kml/2.0"}, XML contents:{{class:XML element, XML tag:"Placemark", XML contents:{{class:XML element, XML tag:"Name"}, {class:XML element, XML tag:"LookAt", XML contents:{{class:XML element, XML tag:"longitude", XML contents:GPS_LOngitude}, {class:XML element, XML tag:"latitude", XML contents:GPS_Latitude}, {class:XML element, XML tag:"range", XML contents:GPS_Range}, {class:XML element, XML tag:"tilt", XML contents:GPS_Tilt}, {class:XML element, XML tag:"heading", XML contents:GPS_Course2}}}, {class:XML element, XML tag:"Style", XML contents:{{class:XML element, XML tag:"IconStyle", XML contents:{class:XML element, XML tag:"Icon", XML contents:{{class:XML element, XML tag:"href", XML contents:"root://icons/palette-4.png"}, {class:XML element, XML tag:"x", XML contents:"32"}, {class:XML element, XML tag:"y", XML contents:"128"}, {class:XML element, XML tag:"w", XML contents:"32"}, {class:XML element, XML tag:"h", XML contents:"32"}}}}}}, {class:XML element, XML tag:"Point", XML contents:{{class:XML element, XML tag:"coordinates", XML contents:GPS_LOngitude & "," & GPS_Latitude & "," & 0}}}}}}}
	
	generate XML XMLFile saving as file "Macintosh HD:Users:Shared:GPS-XML.kml"
	
end repeat
--If you get error "Cannot open port" then the script crashed.
--Try Runnning this code in a seperate script: 
--serialport close 10
--serialport close "/dev/cu.usbserial"

Bugbyte · 02-24-2006, 08:47 PM

I ran it and got the following:

1. Couldn't compile the XML stuff but figured I'm missing a scripting addition for that. I commented it out.

2. It ran, and I got the following:

"xÜxÃÊ0a…GPGSA,A,1,,,,,,,,,,,,,50.0,50.0,50.0 *05

$GPGSV,1,1,01,25,00,000,00*4F

$GPRMC,000820.969,V,0000.0000,N,00000.0000,E,0.000 000,,101102,,*05

$GPVTG,,T,,M,0.000000,N,0.000000,K*4E

$GPGGA,000821.969,0000.0000,N,00000.0000,E,0,00,50 .0,0.0,M,0.0,M,0.0,0000*7B

$GPGLL,0000.0000,N,00000.0000,E,000821.969,V*2E

$GPGSA,A,1,,,,,,,,,,,,,50.0,50.0,50.0*05

$GPGSV,1,1,01,25,00,"

zapwizard · 02-24-2006, 10:57 PM

I got it to work.

I see you also have some giberish at the beginning, I wonder if that is something the GPS units do, or something SerialPortX does.

But, basiclly when it pulls the serial port buffer the data there is randomly located.
So what I have it do is first split the data up by "$GPMRC
" as a list.
This means that the first chunk of data is always $GPMRC, which has all the info we need to work.
I think split that bit of data by "$GPGGA" which on my GPS is sent as the next line after $GPMRC, but in your case it looks like it is $GPVTG, so you would have to change that to match.

But the solution to the script not running more then a frew times is to let the buffer fill to 100% (1020 bytes in the case of my GPS) then read the buffer (effectivly clearing it) then reading about half of it again (512bytes)
Worked for me, ran for 15 minutes on a test drive.

Of course there is lots more to do.

The new code to fix the repeating bug is:

Code:


--Let buffer fill up (1020 bytes in my case, set to a high number and watch your script log to see your max number)
repeat until (serialport bytes available of portRef) >= 1020
end repeat
--CLear buffer
set Junk to serialport read portRef as text
--Que enough GPS data to capture valid data
	repeat until (serialport bytes available of portRef) > 512
	end repeat
	--Read Buffered Data	
	set Buffer to serialport read portRef as text
--Split up data

Bugbyte · 02-25-2006, 01:03 PM

It's working for me now, although I don't get reception in the house, so I get the "GPS Lost" message. Here's the output:

$GPGSA,A,1,,,,,,,,,,,,,50.0,50.0,50.0*05

$GPGSV,1,1,01,19,00,000,00*40

$GPRMC,003739.862,V,0000.0000,N,00000.0000,E,0.000 000,,101102,,*0B

$GPVTG,,T,,M,0.000000,N,0.000000,K*4E

$GPGGA,003740.862,0000.0000,N,00000.0000,E,0,00,50 .0,0.0,M,0.0,M,0.0,0000*7A

$GPGLL,0000.0000,N,00000.0000,E,003740.862,V*2F

$GPGSA,A,1,,,,,,,,,,,,,50.0,50.0,50.0*05

$GPGSV,1,1,01,19,00,000,00*40

$GPRMC,003740.862,V,0000.0000,N,00000.0000,E,0.000 000,,101102,,*05

$GPVTG,,T,,M,0.000000,N,0.000000,K*4E

If you don't mind, I'm modularizing the script just a little bit. You don't have to use it, but I just wanted to play around with it a little bit to see if I understand how it works.

zapwizard · 02-25-2006, 01:36 PM

Ya, you will get GPS lost if there is a "V" in the GPRMC line, it stands to inValid.

There are lots of comments on what each part does, and it's all linear so it shouldn't be to hard to pick around.

Bugbyte · 02-25-2006, 07:01 PM

I've messed around with it a little bit. It works fine on my system now, although I haven't tested it to see if I can get a lock from the GPS. It ought to work.

It turns out that you don't need to constantly close the serial port. I also made use of the Record function in Applescript to put all of the GPS info into a list. The main changes were to make most of the program into handlers and move them out of the main repeat loop.

This was fun and now I'm psyched to work with the serial port. I've got all kinds of stuff I want to do with it.

Here's the code:

(*WRITTEN by ZAPWIZARD
Requires GPSNavX available from here: http://osaxen.com/files/serialportx1.0.html
and XML RPC*)

global dev --the serial port device
global TimeZoneOffset
--UnComment this, and insert your serial port name to diable the prompt menu.
--set dev to "/dev/cu.usbserial"

set TimeZoneOffset to -6 --Set your Time Zone Offset here
set dev to FindPorts() --Find out what ports are available
set portRef to OpenSerial() --Open the port select by the user

repeat
--Get data no more then twice a second
delay 0.5

set GPSBufferData to FillBuffer(portRef)
set GPSinfo to ParseData(GPSBufferData)

--Close Serialport
--serialport close portRef --is this necessary?

--Is GPS fix valid?
(*if Status of GPSinfo = "V" then
display dialog "Lost GPS, Click OK to try again"
end if*)
GEGenerate(GPSinfo)
end repeat

----------------------------------------------------------------------------
---------- This handler lists all the available ports ----------------------
----------------------------------------------------------------------------

on FindPorts()

--List the Serial Ports & select one from list
set thePorts to serialport list
set dev to choose from list thePorts

end FindPorts

----------------------------------------------------------------------------
------ This handler opens the serial port ----------------------------------
----------------------------------------------------------------------------
on OpenSerial()
--Open Serial Port
set SerialPortReference to serialport open dev bps rate 4800 data bits 8 parity 0 stop bits 1 handshake 0

--Check if available
if SerialPortReference is equal to -1 then
--Close port if program quit in error
serialport close SerialPortReference
serialport close 10
serialport close "/dev/cu.usbserial"
--Try again
set SerialPortReference to serialport open dev bps rate 4800 data bits 8 parity 0 stop bits 1 handshake 0

--Display Dialog if still cannot open port.
if SerialPortReference is equal to -1 then
log "Failed to open serial port"
return false
end if
end if
log "Serial port opened"
return SerialPortReference
end OpenSerial

----------------------------------------------------------------------------
-----This handler fills the buffer from the serial port ---------------
----------------------------------------------------------------------------

on FillBuffer(myPortRef)
--Let buffer fill up (1020 bytes in my case, set to a high number and watch your script log to see your max number)
repeat until (serialport bytes available of myPortRef) ? 1020
end repeat
--CLear buffer
set Junk to serialport read myPortRef as text
--Que enough GPS data to capture valid data
repeat until (serialport bytes available of myPortRef) > 512
end repeat
--Read Buffered Data
set Buffer to serialport read myPortRef as text
return Buffer
end FillBuffer

----------------------------------------------------------------------------
-----This handler receives a buffer with the GPSData inside it and ---------------
-----splits it into the right bits of information by putting it into -------------
-----a record, then returning that record -------------
----------------------------------------------------------------------------

on ParseData(GPSBufferData)
--Split up data
--Look at the buffer data and find where it begins with $GPMRC
set AppleScript's text item delimiters to "$GPRMC"
set x to text items of GPSBufferData as list --This put the data that begins with $GPRMC into a list
set y to second text item of x as string --This sets a string variable that contains only the data itself

--Look at the Y data and find where it contains "$GPGGA"
set AppleScript's text item delimiters to "$GPGGA"
set z to first text item of y as string
--Split up data
set AppleScript's text item delimiters to ","
set GPS to text items of z as list --Here's where the good stuff like position, speed, course, etc. are stored in a list

set AppleScript's text item delimiters to ""
set GPSdata to {GPStime:second item of GPS, Status:third item of GPS, Latitude:fourth item of GPS, NS:fifth item of GPS, Longitude:sixth item of GPS, EW:seventh item of GPS, Speed:eighth item of GPS, Course:ninth item of GPS, OldCourse:0}
return GPSdata
end ParseData

----------------------------------------------------------------------------
-----This handler receives a record with the GPS info in it. ---------------
-----It uses this record to generate a KML file for Google Earth -------------
-----tracking -------------
----------------------------------------------------------------------------

on GEGenerate(geGPSinfo)
--Convert GPS_Latitude into Decimal
set dd to characters 1 thru 2 of Latitude of geGPSinfo as string
set mm to characters 3 thru 9 of Latitude of geGPSinfo as string
set mmD to mm / 60
set Latitude to dd + mmD
if NS of geGPSinfo is equal to "S" then
set Latitude of geGPSinfo to "-" & Latitude of geGPSinfo as string
end if

--Convert GPS_Longitude into Decimal
set ddd to characters 1 thru 3 of Longitude of geGPSinfo as string
set mm to characters 4 thru 10 of Longitude of geGPSinfo as string
set mmD to mm / 60
set Longitude of geGPSinfo to ddd + mmD
if EW of geGPSinfo is equal to "W" then
set Longitude of geGPSinfo to "-" & Longitude of geGPSinfo as string
end if

--Convert Knots to MPH
set Speed of geGPSinfo to (Speed of geGPSinfo) * 1.15077945

--Convert Time to 12hr time

set hh to characters 1 thru 2 of GPStime of geGPSinfo as string
set mm to characters 3 thru 4 of GPStime of geGPSinfo as string
set ss to characters 5 thru 10 of GPStime of geGPSinfo as string
set ss to round ss

--Setup time formats
if hh > 12 then
set PM to "PM"

else
set PM to "AM"
end if
set hhh to hh - 12 + TimeZoneOffset

set GPS_Time12 to hhh & ":" & mm & ":" & ss & " " & PM as string
set GPS_Time24 to hh & ":" & mm & ":" & ss as string

--Camera range above ground linked to speed
set GPS_Range to 300 + (100 * (Speed of geGPSinfo))

--Camera tilt angle linked to current speed
set GPS_Tilt to (Speed of geGPSinfo) * (50 / 100)

--Don't change angle data unless moving
if Speed of geGPSinfo > 1 then
set GPS_Course2 to Course of geGPSinfo

else
set GPS_Course2 to OldCourse of geGPSinfo
end if

--Generate KML File
set XMLFile to {class:XML element, XML tag:"kml", XML attributes:{xmlns:"http://earth.google.com/kml/2.0"}, XML contents:{{class:XML element, XML tag:"Placemark", XML contents:{{class:XML element, XML tag:"Name"}, {class:XML element, XML tag:"LookAt", XML contents:{{class:XML element, XML tag:"longitude", XML contents:GPS_LOngitude}, {class:XML element, XML tag:"latitude", XML contents:GPS_Latitude}, {class:XML element, XML tag:"range", XML contents:GPS_Range}, {class:XML element, XML tag:"tilt", XML contents:GPS_Tilt}, {class:XML element, XML tag:"heading", XML contents:GPS_Course2}}}, {class:XML element, XML tag:"Style", XML contents:{{class:XML element, XML tag:"IconStyle", XML contents:{class:XML element, XML tag:"Icon", XML contents:{{class:XML element, XML tag:"href", XML contents:"root://icons/palette-4.png"}, {class:XML element, XML tag:"x", XML contents:"32"}, {class:XML element, XML tag:"y", XML contents:"128"}, {class:XML element, XML tag:"w", XML contents:"32"}, {class:XML element, XML tag:"h", XML contents:"32"}}}}}}, {class:XML element, XML tag:"Point", XML contents:{{class:XML element, XML tag:"coordinates", XML contents:GPS_LOngitude & "," & GPS_Latitude & "," & 0}}}}}}}

--generate XML XMLFile saving as file "Macintosh HD:Users:Shared:GPS-XML.kml"
end GEGenerate

--If you get error "Cannot open port" then the script crashed.
--Try Runnning this code in a seperate script:
--serialport close 10
--serialport close "/dev/cu.usbserial"

zapwizard · 02-25-2006, 10:24 PM

Thanks for the edits.
I have fixed some bugs in yours (typos mostly)
I added a MPH readout as a seperate placemark.
I also split out the XML code, finally found the dang carriage return button.

The code is located here (too long to post)
http://www.zapwizard.com/GPS.scpt

Sharkbite86 · 05-02-2006, 05:00 PM

wow im pretty darn lost in all this.... i have been looking over other theads about using google earth as a gps tracker on a mac but i cant get it to work. I think mostly because i cant get my handheld gps to sync with my mac at all... I have this usb adapter from an old palm handheld that i have and i am currently using it to interface my garmin etrex legend to my mac. The only trouble is my mac cant see it at all. you guys know of any software that might will recognize it? Otherwise I guess i will just have to caugh up ~$200 for a gps receiver

...

Not sure exactly what i need to get this to work though (your applescript software) i keep getting this error:

MINI4cathy · 05-02-2006, 05:32 PM

Did you install the driver software for the USB interface? If it doesn't have a driver, then the interface isn't working. Also, what's the event SPA_ISPA reference in your code? It looks like AS isn't getting to the point of talking to the serial driver.

Sharkbite86 · 05-02-2006, 05:36 PM

the drivers are os 9 only...

Bugbyte · 05-02-2006, 07:56 PM

Note the first line in the script:
(*WRITTEN by ZAPWIZARD
Requires GPSNavX available from here: http://osaxen.com/files/serialportx1.0.html
and XML RPC*)

You need to install the serialportx1.0.html and also the XML RPC scripting additions before this script will work. They are easy and free, but required.

If you did that, then you are getting a driver error. But it looks like in trying to execute the command to get a list of the serial ports -which depends on the serialportX scripting addition to do this on Applescript's behalf, it is getting an error. That points to the scripting addition not being installed.

One way to test your GPS is to download GPS Utility. You can set your serial port and watch the data come in from the GPS. If that's working, then you know your GPS is working.

Also, GPS receivers aren't $200. You can get one of the BU-303's for under $100, I'm sure.

Sharkbite86 · 05-02-2006, 08:09 PM

got a link to gps utility? when i googled it all i got was something for windows...

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