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nmea.c

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/*! \file nmea.c \brief NMEA protocol function library. */
//*****************************************************************************
//
// File Name    : 'nmea.c'
// Title        : NMEA protocol function library
// Author       : Pascal Stang - Copyright (C) 2002
// Created      : 2002.08.27
// Revised      : 2002.08.27
// Version      : 0.1
// Target MCU   : Atmel AVR Series
// Editor Tabs  : 4
//
// NOTE: This code is currently below version 1.0, and therefore is considered
// to be lacking in some functionality or documentation, or may not be fully
// tested.  Nonetheless, you can expect most functions to work.
//
// This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************

#ifndef WIN32
    #include <avr/io.h>
    #include <avr/signal.h>
    #include <avr/interrupt.h>
    #include <avr/progmem.h>
    #include <string.h>
#endif

#include "global.h"
#include "buffer.h"
#include "rprintf.h"
#include "uart2.h"
#include "gps.h"

#include "nmea.h"

// Program ROM constants

// Global variables
extern GpsInfoType GpsInfo;
#define BUFFERSIZE 80
u08 NmeaPacket[BUFFERSIZE];
u08 debug;

void nmeaInit(void)
{
    debug = 1;
}

u08 nmeaProcess(cBuffer* rxBuffer)
{
    u08 foundpacket = FALSE;
    u08 startFlag = FALSE;
    //u08 data;
    u08 i,j;

    // process the receive buffer
    // go through buffer looking for packets
    while(rxBuffer->datalength)
    {
        // look for a start of NMEA packet
        if(bufferGetAtIndex(rxBuffer,0) == '$')
        {
            // found start
            startFlag = TRUE;
            // done looking for start
            break;
        }
        else
            bufferGetFromFront(rxBuffer);
    }
    
    // if we detected a start, look for end of packet
    if(startFlag)
    {
        for(i=1; i<(rxBuffer->datalength)-1; i++)
        {
            // check for end of NMEA packet <CR><LF>
            if((bufferGetAtIndex(rxBuffer,i) == '\r') && (bufferGetAtIndex(rxBuffer,i+1) == '\n'))
            {
                // have a packet end
                // dump initial '$'
                bufferGetFromFront(rxBuffer);
                // copy packet to NmeaPacket
                for(j=0; j<(i-1); j++)
                    NmeaPacket[j] = bufferGetFromFront(rxBuffer);
                // dump <CR><LF> from rxBuffer
                bufferGetFromFront(rxBuffer);
                bufferGetFromFront(rxBuffer);

                if(debug)
                {
                    rprintf("Rx NMEA packet type: ");
                    rprintfStrLen(NmeaPacket, 0, 5);
                    rprintfCRLF();
                    rprintfStrLen(NmeaPacket, 6, (i-1)-6);
                    rprintfCRLF();
                }
                // found a packet
                // done with this processing session
                foundpacket = TRUE;
                break;
            }
        }
    }

    if(foundpacket)
    {
        // check message type and process appropriately
        if(strncmp(NmeaPacket, "GPGGA", 5))
            nmeaProcessGPGGA(NmeaPacket);
        else if(strncmp(NmeaPacket, "GPVTG", 5))
            nmeaProcessGPVTG(NmeaPacket);
    }
    return foundpacket;
}

void nmeaProcessGPGGA(u08* packet)
{
    PORTC = ~(1<<0);
    
}

void nmeaProcessGPVTG(u08* packet)
{
    PORTC = ~(1<<1);
}

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