Pushing information to a computer

[Heckler]

Here is a program called "earthbridge" that takes a serial GPS data stream and plots it on Google Earth.

http://mboffin.com/earthbridge/

I don't think it is being developed any more (no new revisions for several years)

I have used it to recieve gps coordinates over an XBEE wireless connection and plot it on google earth.
I had a PIC (12F683) connectd to the GPS module and parsing the data and then sending it to my PC via the XBEE link.

On the PC end I just had the XBEE radio connected to the PC via an FTDI USB to Serial converter.
Here is the code I was using in the PIC...

@ device  pic12F683, intrc_osc_noclkout, BOD_OFF, PWRT_OFF, wdt_off, mclr_off, protect_off

DEFINE ADC_BITS 8     ' Number of bits in ADCIN result
define ADC_CLOCK 3    'SET CLOCK SOURCE TO RC = 3
DEFINE ADC_SAMPLEUS 50

' -----[ Initialization   ]------------------------------------------------

Reset:
                      
CMCON0     = %00000111 ' Comparators off

TRISIO     =   %101100 
ADCON0     = %00001100 ' LeftJust,VDD,x,x,AN3,x,ADCdisabled
ANSEL      =  %0010000 ' -001xxxx Fosc/8, -xxx0000 all pins digital not analog
                      
IOC        =   %001000 'enable gpio.3 interrupt on change 
    'NOTE: you must also clear the CONFIG.5 fuse bit to change gpio.3 to 
    'an I/O instead of MCLR (its under the configuration link on the 
    'pickit2 programing app. This bit must be done each time before you
    'program the chip.

OPTION_REG = %10111111 'b7=pullups disabled
                       'b6=int on falling edge
                      

Xpwr var gpio.0 'Output to turn on XBee
XBrx var gpio.1 'Output serial data to XBee
XBtx var gpio.2 'Input
rst  var gpio.3 'Input
Gpwr var gpio.4 'Output to turn on GPS
GPS  var gpio.5 'Input serial data from GPS

symbol I = 254        'LCD prefix for Instruction
symbol clr = 1        'LCD CLEAR SCREEN
SYMBOL LINE2 = 192    'LCD ADDR FOR 1ST CHAR ON 2ND LINE
SYMBOL H = 2          'LCD HOME COMMAND

NMEA1 VAR BYTE[35]
NMEA2 VAR BYTE[35]
FN    var byte        ' For Next loop counter variable


'============= Main Program ==========================================
Main:
high gpwr     'turn ON GPS module
pause 5000

GPSin:
for fn = 0 to 5

     SERIN2 GPS,188,1500,tmout,[WAIT("$GPRMC,"),WAIT("A")]
     serin2 gps,188,3000,tmout,[WAIT("$GPGGA,"),STR NMEA1\35,STR NMEA2\35\"$"] 'Data IN from GPS
    
    
next


low gpwr    'Turn OFF GPS module
high xpwr   'Turn ON XBEE radio
    pause 500
    
    SEROUT2 xbtx,188,[$0D,$0A,"$GPGGA,",STR NMEA1\35,STR NMEA2\35]            'Data OUT to XBEE
    pause 500

low xpwr    'Turn OFF XBEE radio

pause 5000  

goto main

'-----------subroutines-------------------------
NoFix:
  high xpwr
  pause 500  
  serout2 xbtx,188,[13,10,"X"]  ' send X's while waiting for satelite fix
  low xpwr
  goto gpsin 

tmout:   'end up here if no data from gps within 3 seconds
  high xpwr
  pause 500
  serout2 xbtx,188,["timeout"]
  low xpwr
  GOTO MAIN

The code is a bit rough... I wasn't actually using the ADC yet the code contains setup for the ADC.
Also the CINFIG is the old style and needs to be updated for newer PBP

I can post a schematic if you want it.

The GPS/PIC/XBEE combination was powered by a single Lithium ion cell (old cell phone batt)
And was designed to track my dog around the yard so I could see where he went.

[lerameur]

HI Dwight,
Thanks for the program ,
I would not mind the schematic.
How do you know what data to put in your SEROUT statement. I looked through the earthbridge web page but did not see any technical details.
Thanks
Ken

[Heckler]

Hi Ken,

I just looked through my stack of papers and notebooks and can't locate the schematic. I will keep looking.
It actually was quite simple... I used two BS170 FET's to allow the pic to power on/off the GPS module and the XBEE radio.
If you haven't used small FET's in this manner they work great. Very easy to interface to a PIC and control ~500 ma or so.
The radio pair that I used was a XBEE09P by Digi International (note: if you go XBEE they have nonstandard pin spacing so you may need a .1 inch adapter board so it will fit a breadboard)
They make several models of the XBEE radios, so if you decide to go that way, take a look at the various models and range capabilities.
SparkFun, Adafruit, digikey, (probably Amazon) all carry them
You can see in the code where I turn on/off the GPS and the XBEE radio, one after the other.

For shorter ranges you could also probably use the cheaper serial radios sold on ebay. http://www.ebay.com/itm/2pcs-433Mhz-...item1e869e9107
Or as you were thinking, bluetooth.

Here are a couple of pics of my little project.

To answer your question I think the earthbridge was able to parse the NEMA strings coming from the gps and pull out what was needed.
It has been over a year since I built this so I am a bit rusty. If you mock up the same thing I build you could just output the serial string that I was sending to the XBEE radio instead to a local LCD or to a serial terminal on your PC to have a look at it. ( I find having on hand an LCD with Serial Backpack invaluable for quick testing and debugging serial comms)

Actually I think you could just fire up earthbridge and recieve the serial string from the 12F683 directly into the serial port defined in earthbridge.
If you take a look at the code I posted you can see in the SEROUT and SERIN statements I did a little NEMA parsing as the data came in and before I sent it out.






The only component on the bottom of the board is a single diode (for reverse battery protection) and the wiring connections.
Notice on the PCB I included a 6 pin header strip to allow me to connect my PICKIT 2 to update the code in the PIC easily.
If I locate the schematic I will post it.