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newbe programing help

 
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newbe programing help
PostPosted: Fri Apr 11, 2008 1:52 pm     Reply with quote
Hi all,

Here a little explanation of what I want. I have a 16F877A board with a LCD display and a RS232 port. I receive continuously some info from the RS232 port, and I want to display only one info from the RS232 stream.

Here is the RS232 stream :


    
    ADCO 050622013932 8
    OPTARIF HC.. <
    ISOUSC 45 ?
    HCHC 000000000 F
    HCHP 000000001 T
    PTEC HP..
    IINST 000 W
    IMAX 000 ?
    PAPP 00000 !
    HHPHC A ,
    MOTDETAT 000000 B


This is repeated all the time.

The line I am interested of is "HCHC 000000000 F" and especially the value "000000000" which will change of course.

I wrote a basic program, but I am not very firendly with string manipulation. Anyway here is my code for the moment :

Code:

#include <16F877.H>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=1200, parity=E, bits=7, xmit=PIN_C6, rcv=PIN_C7, ERRORS)

#include "lcd.h"
#include <string.h>

#define BUFFER_SIZE 20
BYTE buffer[BUFFER_SIZE];
BYTE next_in = 0;
BYTE next_out = 0;

#int_rda
void serial_isr() {
   int t;

   buffer[next_in]=getc();
   t=next_in;
   next_in=(next_in+1) % BUFFER_SIZE;
   // Buffer full !!
   if(next_in==next_out) next_in=t; 
}

#define bkbhit (next_in!=next_out)

BYTE bgetc()
{
   BYTE c;
   while(!bkbhit) ;
   c=buffer[next_out];
   next_out=(next_out+1) % BUFFER_SIZE;
   return(c);
}

void my_get_string(char* s, unsigned int8 max)
{
  unsigned int8 len;
  char c;
  --max;
  len=0;
  do
  {
    c = bgetc() & 0x7F;   // 7 bits so force data7 to 0
    //lcd_putc(c);
    //putc(c);
    if(len<=max)
      s[len++]=c;
    else
      c=0x0D;
  } while(c!=0x0D);
  s[len]=0;
}

//===================================
void main()
{
  char input_str[BUFFER_SIZE];
  lcd_init();
  lcd_putc("\fReady...\n");
  SET_TRIS_A(0x00);
  enable_interrupts(int_rda);
  enable_interrupts(global);

  while(1)
  {
   my_get_string(input_str, BUFFER_SIZE-1);
  lcd_putc("\f");
  lcd_writestring(input_str);
   output_bit(PIN_A0, !input(PIN_A0));
  }
}


Of course this code was one of an example I modified.

Can you please have a look at this and let me know/help to do what I want ?

Thank you for your help.

Br,
Denis
Dimmu



Joined: 01 Jul 2007
Posts: 37

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PostPosted: Fri Apr 11, 2008 2:43 pm     Reply with quote
Hi,

Here is a simple example of code that should help you. Be careful that this code is not error proof.
I tested it with a 18F97J60.

You have to initialise the function with a call to
"Rs232Init();"

The your mainloop function must call as often as possible the function
"SerialTask();"


Under interrupt :
The bytes are stored into a buffer. In case of overflow, the complete buffer is lost ( due to the WRITE pointer that reached the READ pointer. no protection here )

Main function :
If the char '\n' is found, the last line of data received is treated at once. The function "HandleCommand" reads the first word of the line and compares it with a given keyword ( here : HCHC ). If found, the rest of the line is interpreted.


Best regards,
Dimmu

Code:
#define RS232_BUFFER_SIZE  64
#define RS232_IDX_MASK     RS232_BUFFER_SIZE - 1

#include "ctype.h"
#include "string.h"
#include "stdlib.h"

struct _RS232_BUFFER_T {
   char           DATA[RS232_BUFFER_SIZE];
   unsigned int8  READ_IDX;
   unsigned int8  WRITE_IDX;
} RS232_BUFFER;



// interrupt driven data reception
// each byte is written into the buffer
// the buffer must be read BEFORE overflow !
#int_rda
void Rs232ReceiveByte ( ) {
   RS232_BUFFER.DATA[RS232_BUFFER.WRITE_IDX++] = getc();
   RS232_BUFFER.WRITE_IDX &= RS232_IDX_MASK;
}

// same as a kbhit function
int1 Rs232DataAvailable ( void ) {
   return (RS232_BUFFER.READ_IDX != RS232_BUFFER.WRITE_IDX);
}

// reads one byte from the buffer
char Rs232GetData ( void ) {
   char c;

   c = RS232_BUFFER.DATA[RS232_BUFFER.READ_IDX++];
   RS232_BUFFER.READ_IDX &= RS232_IDX_MASK;
   return c;
}

// initialisation function
// this function enables the interrupts !!
void Rs232Init ( void ) {
   // Set the wsrite IDX to 1 and clear the input buffer
   RS232_BUFFER.WRITE_IDX = 1;
   RS232_BUFFER.DATA[0]   = 0;

   // enable interrupts
   enable_interrupts ( INT_RDA );
   enable_interrupts ( GLOBAL );

   // A delay is added to clear any pending data
   // this can be removed if necessary
   delay_ms ( 100 );

   // Now clear the input buffer
   RS232_BUFFER.WRITE_IDX = 0;
   RS232_BUFFER.READ_IDX  = 0;

}


// reads a string value from the current position ( only alphanum values )
// no provision is taken to ensure that the input string
// is big enough to content the input data
// However the returned string shall never be greater than the input buffer
void GetString ( char * STR ) {
   int1  LOOP     = TRUE;
   char  c;

   while ( LOOP ) {
      if ( Rs232DataAvailable() ) {
         c = Rs232GetData();
         putc ( c );
         if ( isalnum ( c ) )
            *STR++ = c;
         else
            LOOP = FALSE;
      }
   }
   *STR = 0;
}

// skips the blank chars from a given string and returns the
// number of shar skipped
// only the blank chars are removed, not the TABS, ...
int8 SkipBlank ( char * DATA ) {
   int8 IDX = 0;
   while ( DATA[IDX] == ' ' ) {
      IDX++;
   }
   return IDX;
}

// copy the next token from string SOURCE into sting DEST
// the token is delimited by the trailing blanks
// the heading blanks are skipped
int8 CopyToken ( char * DEST, char * SOURCE ) {
   int8 IDX = 0;
   char c;

   IDX      = SkipBlank ( SOURCE );
   SOURCE  += IDX;

   while ( TRUE ) {
      c = *SOURCE++;
      if ( ( c == ' ' ) || ( c == 0 ) )
         break;

      *DEST++ = c;
      IDX++;
   }
   *DEST = 0;

   return IDX;
}


// reads the input string and handles the data
void HandleCommand ( char * DATA ) {
   char     CMD[32];
   char     VALID_CMD[5];
   int8     DATA_IDX          = 0;
   int32    VALUE;

   // copy first token of data into CMD
   // and save the current size of the token
   DATA_IDX += CopyToken ( CMD, DATA );

   strcpy ( VALID_CMD, "HCHC" );
   if ( strcmp ( VALID_CMD, CMD ) == 0 ) {
     
      // increase DATA in order to point to the next element from the string
      DATA += DATA_IDX;
      printf ( "HCHC found ==> " );
     
      // read the element ( must be the desired value )
      DATA_IDX += CopyToken ( CMD, DATA );
      printf ( "string value = %s", CMD );
     
      // convert the string into an int32 value
      VALUE = atoi32( CMD );
      printf ( " ==> numeric value = %lu \n", VALUE );
   }
}

void SerialTask ( void ) {
   static char DATA[32];
   static char IDX = 0;
   char c;

   while ( Rs232DataAvailable() ) {
      c = Rs232GetData();
      putc ( c );
      // BackSpace
      if ( c == 8 ) {
         if ( IDX != 0 )
            IDX--;
      }
      else if ( c == '\n' ) {
         DATA[IDX] = 0;
         HandleCommand( DATA );
         IDX = 0;
         DATA[0] = 0;
         // Send ACK
         putc ( 0x07 );
      }
      else if ( c == '\r' ) {
         // nothing to do !
      }
      else {
         if ( IDX < 32 ) {
            DATA[IDX++] = c;
         }
      }
   }
}
tyhon
Guest
Re: newbe programing help
PostPosted: Sat Apr 12, 2008 7:28 am     Reply with quote
[quote="Anonymous"]Hi all,

Here a little explanation of what I want. I have a 16F877A board with a LCD display and a RS232 port. I receive continuously some info from the RS232 port, and I want to display only one info from the RS232 stream.

Here is the RS232 stream
you can post circuit ?
tyhon
Guest
PostPosted: Sat Apr 12, 2008 7:30 am     Reply with quote
you can post circuit on forum?
Guest
PostPosted: Thu Apr 17, 2008 9:13 am     Reply with quote
Hi, Yes I can post the schématics, but what part do you need?

I still not had time to test the code, but hope to have time next week.
I keep you posted.

Br
Denis
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