CCS/MSP-EXP430FR2433: How to parse GPS string?

Yu-Hung

Expert 1130 points

Part Number: MSP-EXP430FR2433

Tool/software: Code Composer Studio

Hi,

I'm using MSP-EXP430FR2433.

This board does not have enough memory to use sscanf with float format. (like latitude)

1. how to get float value?

2. Sometimes I get $GPRMC,075643.00,A,2237.93764,N,12017.28144,E,,,110618,,,A*7C.
how to get char array in continuously delimiter?
I can't get the string "110618"

simple example:
It is work if the string is "$GPRMC,A,B,C*XX"
but not work in "$GPRMC,,B,C*XX"

#include <msp430.h>

#include <stdio.h>

int main()
{
//char buf[50]="$GPRMC,A,B,C*XX";
char buf[50]="$GPRMC,,B,C*XX";
char tmp1[10]={0},tmp2[10]={0};

sscanf(buf,"$GPRMC,%[^,],%[^,],*XX",tmp1,tmp2);

printf(tmp1);
printf(tmp2);

return 0;
}

over 7 years ago

0 George Mock over 7 years ago

TI__Guru**** 249005 points

This is a how-to-write-the-code kind of question. We rarely see such questions in this forum. Other forums, outside of TI, are probably a better choice.

That said, I can suggest some standard RTS functions that might be helpful. To split a string up, based on a delimiter like a comma, use strtok. To see if a string contains a '.', and thus is probably a floating point constant, use strchr.

To completely parse a float constant string, without using sscanf, requires a lot of code. It would probably be smaller than sscanf. But the size difference may not be enough to matter.

Thanks and regards,

-George

0 Yu-Hung over 7 years ago in reply to George Mock

Expert 1130 points

Dear George,

Thank you for your response.

strtok has the same problem.

Simple example is shown below.

I will try to find programming forums. :)

Thanks.

#include <stdio.h>
#include <string.h>

int main()
{

char gps[]="$GPRMC,,,075643.00,A,2237.93764,,,A*7C";
char *token;

token = strtok(gps, ",");
printf( "1. %s\n", token );
token = strtok(NULL, ",");
printf( "2. %s\n", token );
token = strtok(NULL, ",");
printf( "3. %s\n", token );
token = strtok(NULL, ",");
printf( "4. %s\n", token );

return 0;
}

0 George Mock over 7 years ago in reply to Yu-Hung

TI__Guru**** 249005 points

Consider the possibility that printf is not working. Please see the article Tips for using printf.

Thanks and regards,

-George

Code Composer Studio™︎

Code Composer Studio forum

CCS/MSP-EXP430FR2433: How to parse GPS string?