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EX_SISR.C modification

 
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art



Joined: 21 May 2015
Posts: 159

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EX_SISR.C modification
PostPosted: Fri May 18, 2018 2:04 am     Reply with quote

Hai,

I've modified "EX_SISR.C" file follow to my design.
I'm trying to get a "GOOD" reply when it receive "OK" signal, other than "OK" signal, it will be ignored.
My code below can be compiled, but it will not reply "GOOD" when I send "OK" signal. I need help to fix this problem.

Thanks in advance.


Code:

#include <18F452.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#include <string.h>
#include <input.c>
#include <stdio.h>
#include <stdlib.h>

#define BUFFER_SIZE 32
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;
   if(next_in==next_out)
     next_in=t;           // Buffer full !!
}

#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 main() {

   enable_interrupts(int_rda); 
   enable_interrupts(global);
   
   printf("\r\n\Running...\r\n");


   do {
      delay_ms(10000);
      printf("\r\nBuffered data => ");

      while(bkbhit=="OK")

          printf("\r\nGOOD");         
     
   } while (TRUE);
}
Mike Walne



Joined: 19 Feb 2004
Posts: 1745
Location: Boston Spa UK

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PostPosted: Fri May 18, 2018 2:27 am     Reply with quote

What is/are the value(s) that your 'bkbhit' can have?
Have you looked at it? (Either by using a watch window or printing it)

Mike
art



Joined: 21 May 2015
Posts: 159

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PostPosted: Fri May 18, 2018 2:58 am     Reply with quote

it seems that the 'bkbhit' can receive any character or numbers
RF_Developer



Joined: 07 Feb 2011
Posts: 839

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PostPosted: Fri May 18, 2018 3:26 am     Reply with quote

art wrote:
it seems that the 'bkbhit' can receive any character or numbers


No. bkbhit() returns just true (not zero) or false (zero). It tells you whether there are any characters in the buffer. it does not tell you what the character(s) are. So you call bkbhit() to tell you if its worthwhile reading stuff from the buffer.
temtronic



Joined: 01 Jul 2010
Posts: 6251
Location: Greensville,Ontario

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PostPosted: Fri May 18, 2018 5:00 am     Reply with quote

also..
whenever you're using the HW UARTs of PICs, you need to add 'ERRORS' to #use RS232(...options...). This adds a small chunk of code that will prevent the UART from 'freezing' or 'locking' up should you not read the UART buffer faster than the data comes in.

If you check the code library or do a search for 'ex_sisr.c' in this forum, you'll find a lot of 'hits' about using it . Several deal with your question.

Jay
Ttelmah



Joined: 11 Mar 2010
Posts: 13536

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PostPosted: Fri May 18, 2018 10:48 pm     Reply with quote

Also, if bkbhit _did_ return the data, you can't compare 'strings' in C with ==.
There is a lot of basic learning needed here... Sad
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