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RS232 interrupts

 
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snowbell
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RS232 interrupts
PostPosted: Mon Dec 14, 2009 9:27 am     Reply with quote
Hi,

I've tried the example EX_SISR.c but it didn't seem to work properly for me. It doesn't print the characters which I entered through Hyperterminal. It only prints "Running..." and "Buffered Data =>". I tried printing an 'a' as shown in the code below, and it managed to print it only the first time I tried to do the interrupt. Anyone can help me with this? Thanks.

Code:

#if defined(__PCM__)
#include <18F2620.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=12000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)

#elif defined(__PCH__)
#include <18F2620.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=12000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)

#elif defined(__PCD__)
#include <18F2620.h>
#fuses HS, NOWDT, NOPROTECT
#use delay(clock=12000000)
#use rs232(baud=9600, UART1A)
#endif

#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);
   #if defined(__PCD__)
   enable_interrupts(intr_global);
   #else
   enable_interrupts(global);
   #endif

   printf("\r\n\Running...\r\n");

               // The program will delay for 10 seconds and then display
               // any data that came in during the 10 second delay

   do {
      delay_ms(10000);
      printf("\r\nBuffered data => ");
      while(bkbhit)
      {
        putc( bgetc() );
        putc('a');
       }
   } while (TRUE);
}
snowbell
Guest
PostPosted: Mon Dec 14, 2009 10:12 am     Reply with quote
By the way, i'm using compiler version 4.057. Thanks.
snowbell
Guest
PostPosted: Tue Dec 15, 2009 12:25 am     Reply with quote
I've also tried this very simple code of receiving a char and then displaying it on HyperTerminal. It still doesn't display, the char that I entered in HyperTerminal. It can print "Start:" and only show 'a' the first time, after that, it seems to hang. Can anyone help please. Thanks.

Code:

#include <18F2620.H>
#fuses HS, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP   
#use delay(clock=12000000)                           
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)

//=================================
void main()
{
char c;

printf("Start: ");

while(1)
  {
        c = getc();
        putc(c);
   putc('a');
  }
 
}   
bkamen



Joined: 07 Jan 2004
Posts: 1615
Location: Central Illinois, USA

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PostPosted: Wed Dec 16, 2009 1:17 am     Reply with quote
it's always a good idea to TEST to see if there is a char in the RX buffer before doing a getc().

In CCS-C that's most easily accomplished with kbhit();

Also, what kind of data are you receiving, ASCII or binary?

-Ben
_________________
Dazed and confused? I don't think so. Just "plain lost" will do. :D
LegolasMicrochip



Joined: 28 Jun 2009
Posts: 1

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PostPosted: Tue Dec 22, 2009 6:58 am     Reply with quote
It actually does not hang, in fact its waiting for the character. Until or unless it does not receive a new character it would keep waiting on the getc().
So if you would type a character through your hyperterminal then it would display 'a' again.
Also verify that your circuit is correct.
asmboy



Joined: 20 Nov 2007
Posts: 2128
Location: albany ny

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to make it clearer and faster try this hack
PostPosted: Tue Dec 22, 2009 4:43 pm     Reply with quote
Code:

// useless ->   delay_ms(10000);
      printf("\r\nBuffered data =>\r ");
do {
         while(bkbhit)
      {         putc( bgetc() );         putc('a');    }
   } while (TRUE);
}


U only see the setup print out - once and the delay does NOTHING useful anyway IF the ISR is actually working - each line with CR U send will be on a line of its own - minus all the 'a's
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