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ocean-server compass

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ronnarone.r

Joined: 23 Dec 2008
Posts: 12

ocean-server compass

Posted: Thu Jun 03, 2010 10:29 pm

Code:

#include <18F8722.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdlibm.h>
#include <string.h>
#include <math.h>
#fuses HS,NOPROTECT,NOLVP,NOBROWNOUT
#use delay(clock = 10000000)
#use rs232(baud =38400,xmit=pin_C6,rcv=pin_C7,PARITY=N,bits =8,RESTART_WDT,stream=Ocs,errors) //ocean_server
#use rs232(baud =9600,xmit=pin_G1,rcv=pin_G2,PARITY=N,bits =8,RESTART_WDT,stream=GPS,errors) //LEA-4S
#use rs232(baud =38400,xmit=pin_E0,rcv=pin_E1,PARITY=N,bits =8,stream=HOSTPC,errors)//Computer

#define N 1
#define S -1
#define E 1
#define W -1
#define f 1/297

#define lat_1 13.50 //Decimal Degree
#define lon_1 100.30 //Decimal Degree

char NmeaSentence[100];
char Fixsentence[]="GPRMC";
char k ; // Character in NMEA
char NMEA ;
int i=0;
/*...........................................*/
double lat1 ;
double lon1 ;
/*...........................................*/
char latitude_longitude_LEA_4S[26];
char lat_dd_LEA_4S[3];
char lat_mm_LEA_4S[10];
char lon_dd_LEA_4S[4];
char lon_mm_LEA_4S[10];
double lat_d_LEA_4S ;
double lat_m_LEA_4S ;
double lon_d_LEA_4S;
double lon_m_LEA_4S;
double lat_2;
double lon_2;
double lat2 ; //Rad
double lon2 ; //Rad

/**************************************************************/
int16 f_4 ; //T. Vincenty " Inverse Formula " Alfa_1
double U_1 ;
double U_2 ;
/********************************************************/
char compass_raw[7];
char buffer_ocs[80];
int16 compass;
int select;
signed int16 Azimuth;

void readMessage_Ocs(void);
void calulation(void);

void readMessage_Ocs()
{
fgets(buffer_ocs,Ocs);

for(select=3; buffer_ocs[select] != 'P'; select++)
{
compass_raw[select-3] = buffer_ocs[select];
fprintf(HOSTPC,"%c",compass_raw[select-3]);
bit_clear(buffer_ocs[80],31);
bit_set(buffer_ocs[80],31);

}
fprintf(HOSTPC,"\n\r");

compass = atol(compass_raw);
fprintf(HOSTPC,"compass=%lu\n\r",compass);
}

void calulation()
{

lat1 = (lat_1)*(pi/180)*(N);
lon1 = (lon_1)*(pi/180)*(E);

do
{
while ( fgetc(GPS) != '$' );
for (k=0;k<6;k++)
NmeaSentence[k]=fgetc(GPS);
}
while (strncmp(NmeaSentence,Fixsentence,5)!=0);
k = 0 ;
NMEA = 0 ;

while (NmeaSentence[k] !='*' && k<79 )
{
NMEA = fgetc(GPS);
NmeaSentence[k++] = NMEA ;
}

for ( i= 12; i<= 37;i++ ) //1239.60366,N,10057.25350,E
{
latitude_longitude_LEA_4S[i-12]= NmeaSentence[i];
fprintf(HOSTPC,"%c" ,latitude_longitude_LEA_4S[i-12] );
}
fprintf(HOSTPC,"\n\r");

for ( i= 0 ; i<2;i++ )
{
lat_dd_LEA_4S[i]= NmeaSentence[i+12];
}
lat_d_LEA_4S = atof(lat_dd_LEA_4S);
fprintf(HOSTPC,"lat_d_LEA_4S=%f \n\r",lat_d_LEA_4S );

for ( i= 0 ; i<6;i++ )
{
lat_mm_LEA_4S[i]= NmeaSentence[i+14];
}
lat_m_LEA_4S = atof(lat_mm_LEA_4S)/60;
fprintf(HOSTPC,"lat_m_LEA_4S =%f \n\r" ,lat_m_LEA_4S );

lat_2 = (lat_d_LEA_4S + lat_m_LEA_4S)*N; //Decimal Degree
fprintf(HOSTPC,"lat_2 =%3.7f \n\r" ,lat_2 );

fprintf(HOSTPC,"lon_dd_LEA_4S[i]=" );
for ( i= 0 ; i<3;i++ )
{
lon_dd_LEA_4S[i]= NmeaSentence[i+25];
fprintf(HOSTPC,"%c" ,lon_dd_LEA_4S[i] );
}
fprintf(HOSTPC," \n\r");

lon_d_LEA_4S = atof(lon_dd_LEA_4S);
fprintf(HOSTPC,"lon_d_LEA_4S =%f \n\r" ,lon_d_LEA_4S );

for ( i= 0 ; i<6;i++ )
{
lon_mm_LEA_4S[i]= NmeaSentence[i+28];
}
lon_m_LEA_4S = atof(lon_mm_LEA_4S)/60;
fprintf(HOSTPC,"lon_m_LEA_4S =%f \n\r" ,lon_m_LEA_4S );

lon_2 = (lon_d_LEA_4S + lon_m_LEA_4S)*E ; //Decimal Degree
fprintf(HOSTPC,"lon_2=%3.7f \n\r" ,lon_2 );
}

void main ()
{
while(true)
{
readMessage_Ocs();
calulation();
}
}

Output for compass has error. But when I run only compass function, it works and I can not change baud rate. I want to know why ? Thank you.

ckielstra

Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands

Posted: Fri Jun 04, 2010 5:08 am

Code:

bit_clear(buffer_ocs[80],31);
bit_set(buffer_ocs[80],31);

I don't know what you want to do here, but whatever it is it is a bug.
buffer_ocs has a length of 80, meaning the last item in the buffer is buffer_ocs[79]. Also, it is an 8-bit array so when setting bit 31 of buffer_ocs[80] you are actually writing to bit 8 of buffer_ocs[83].
You are writing outside the array, corrupting other variables in RAM with unpredictable results.

Code:

for ( i= 0 ; i<6;i++ )
{
lat_mm_LEA_4S[i]= NmeaSentence[i+14];
}
lat_m_LEA_4S = atof(lat_mm_LEA_4S)/60;

You have this construction several times in your code. atof() expects a string as input, i.e. a null terminated string of characters. This zero terminator is missing causing unpredictable output for atof().

Code:

fgets(buffer_ocs,Ocs);

for(select=3; buffer_ocs[select] != 'P'; select++)

This will fail in two situations:
1) When the string is shorter than 3 characters
2) When the string does not contain a 'P' character

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