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sareehy
Joined: 03 May 2016
Posts: 20
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| problem in getting a set of characters from string?! |
 Posted: Tue May 03, 2016 4:22 pm |
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Hi ,
I need to set date & time of the real time clock connected to PIC.
I want to use a GSM in my project to control some devices also to set the real time clock with the correct time and date via sms 
The first thing I did was write a program to get the time & date from the received sms.
The received string of the new message has the following form:
+CMT: "+00962780055097","+962788990088","16/04/30,18:42:37+08",20
CLOCK=16/05/03,19:50:00
I need to get the characters after '=' character which are represent the date and time to be set
But i faced a problem to get those characters. When I tried to print the string where i store the characters in i got garbage characters or some of characters before the '=' character.. OR NO CHARACTERS APPEARS ON THE TERMINAL ^_^
I am using
- compiler V5.056
- GSM type SM5100B
| Code: |
#include <16F877a.h>
#include <string.h>
#include <stdlib.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600,xmit=PIN_C6, rcv=PIN_C7,STREAM=GSM,ERRORS)
#define buffer_size 96
#define NULL '\0'
#DEFINE CMTI 0
#DEFINE CLOCK 1
UNSIGNED char RECSTRING[buffer_size];
unsigned int8 CT=0;
UNSIGNED CHAR *STRINGS[]={"+CMT\0","CLOCK\0"};
CHAR *CLL;
void CLEAR_BUFFER()
{
memset(RECSTRING,NULL,buffer_size); // Set all elements to NULL
CT=0; // Reset index
}
#int_rda
void serial_isr() {
RECSTRING[CT]=Fgetc(GSM);
CT++;
if(CT==buffer_size){CT=0;}
}
int1 SEARCH_STRING(int8 index){
if(strstr(RECSTRING,STRINGS[index])!=NULL) return (1);
else return (0);
}
void main() {
CLEAR_BUFFER();
enable_interrupts(int_rda);
enable_interrupts(global);
Fprintf(GSM,"AT\r");
DELAY_MS(5000);
CLEAR_BUFFER();
Fprintf(GSM,"AT+CMGF=1\r");
DELAY_MS(3000);
CLEAR_BUFFER();
Fprintf(GSM,"%s","AT+CNMI=3,3,0,0\r");
DELAY_MS(3000);
CLEAR_BUFFER();
while(1){
WHILE(!SEARCH_STRING(CMTI));
if(SEARCH_STRING(CLOCK)){
CLL=strrchr(RECSTRING,'='); Fprintf(GSM,"%s",CLL);
CLEAR_BUFFER();}
}
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue May 03, 2016 5:56 pm |
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1. You don't have any code in your #int_rda routine that looks at the
incoming bytes for an end-of-message marker. So how does your main()
code know when you have a complete string available to process ?
2. The next thing is, you're using string functions, but you don't put a
string terminator byte of 0x00 at the end of the received string. Without
that marker, string functions (like strstr, etc.) don't know when to quit.
However, this may not be a problem because you zero the receive buffer
and reset the index to 0 prior to a string coming in. But this is a band-aid.
It would be better if you explicitly put a 0x00 at the end of the string
after it's received.
3. Your string extraction problem itself is a pure code problem.
That means it can be totally inspected and solved with a test program
in MPLAB simulator. I used MPLAB vs. 8.92 simulator to do this.
A. I took your program and stripped out all the data acquisition code that
I just don't need. I substituted your sample string as hard-coded data
in the receive buffer. I wasn't sure about the 20 before the CLOCK.
Did you really mean a space ? Is there a space in there after the 20 ?
But it doesn't really matter for this test.
B. Next I put in marker messages (printf's) that tell me where I'm at
in the program.
Before the next step, I put in a printf() statement to display the hard-
coded received string in MPLAB simulator, just to make sure that I
did it correctly, with the escape sequences on the double-quotes, etc.
After looking at the displayed string, I comment out the first printf.
C. Then I compile and run the test program and I get this and it's working
just fine:
| Quote: |
Next search string for CMD1:
Next search string for CLOCK:
=16/05/03,19:50:00
Done |
This means the problem is going to be items 1 or 2 above, or something else.
Test program.
| Code: | #include <16F877a.h>
#include <string.h>
#include <stdlib.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, STREAM=GSM, ERRORS)
#define buffer_size 96
//#define NULL '\0'
#DEFINE CMTI 0
#DEFINE CLOCK 1
UNSIGNED char RECSTRING[buffer_size] = "+CMT: \"+00962780055097\",\"+962788990088\",\"16/04/30,18:42:37+08\",20 CLOCK=16/05/03,19:50:00";
UNSIGNED CHAR *STRINGS[]={"+CMT\0","CLOCK\0"};
CHAR *CLL;
//====================================
int1 SEARCH_STRING(int8 index)
{
if(strstr(RECSTRING, STRINGS[index]) != NULL)
return (1);
else
return (0);
}
//======================================
void main()
{
//printf(recstring);
printf("Next search string for CMD1:\r");
WHILE(!SEARCH_STRING(CMTI));
printf("Next search string for CLOCK:\r");
if(SEARCH_STRING(CLOCK))
{
CLL = strrchr(RECSTRING,'=');
Fprintf(GSM,"%s",CLL);
}
printf("\rDone\r");
while(TRUE);
}
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temtronic
Joined: 01 Jul 2010
Posts: 9125
Location: Greensville,Ontario
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| Posted: Wed May 04, 2016 5:34 am |
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OK, FIRST you MUST step back and get the HARDWARE correct !
You have a 5 volt PIC and a 3 volt GSM module, at least according to the Googling that found the SM5100B as a Sparkfun product.
Even proper code will not run right on incorrect hardware.
You also stand a good chance of destroying the GSM according to the datasheet when you force 5 volts to it!!
Always read and understand the 'electrical specification' chapter of the PIC and peripherals BEFORE wiring up and applying power.
With 99% of all 'peripherals' or 'modules' these days they are 3 volt devices, so choose a PIC with the 'L', like xxxLFyyyyy OR a PIC that does work at 3 volts like the 18F46K22.
Jay |
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