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Why does #use rs232 ENABLE=PIN not work with puts or printf

 
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nurquhar



Joined: 05 Aug 2006
Posts: 149
Location: Redditch, UK

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Why does #use rs232 ENABLE=PIN not work with puts or printf
PostPosted: Sun Oct 08, 2006 1:08 am     Reply with quote
I have an odd problem with the way puts and printf are working when using the #use rs232 ENABLE feature. Basically I can see the output on Hyperterminal from the putc() but a string sent with puts() or printf() sends blanks. I am using SP485REN chip with B0 connected to the DE and /RE inputs.

The following prog compiled with 3.249 gives the following output.

Code:

// CPU Clock Freq
#define   FOSC   20000000
#define BAUDRT   9600

#include <16F876A.h>
#include <stdio.h>

#fuses HS,NOWDT,PUT,NOPROTECT,NOBROWNOUT,NOLVP,NOCPD,NOWRT
#use delay(clock=FOSC)
#use rs232 (baud=BAUDRT, xmit=PIN_C6, rcv=PIN_C7, PARITY=N, BITS=8, ENABLE=PIN_B0)


void main()
{
   unsigned int ch ;

   putc('O') ;
   putc('k') ;
   putc('\r') ;
   putc('\n') ;

   puts("Hello from Puts") ;

   putc('H') ;
   putc('e') ;
   putc('l') ;
   putc('l') ;
   putc('o') ;
   putc('\r') ;
   putc('\n') ;

   while(1) {
      if (kbhit()) {
         ch = getc() ;
         putc(ch) ;
         if (ch == 0x31) {
            puts("Puts a long string to test the output") ;
            putc('N') ;
            putc('o') ;
            putc(' ') ;
            putc('1') ;
            putc('\r') ;
            putc('\n') ;
         }
      }
   }
}



The output on the terminal with me typing 1,2,3

Quote:
Ok
ts
Hello
1ut
No 1
23


I thought puts()/printf used putc at the bottom level ? However it seems to be doing the enable in a different way.

Any ideas ?
nurquhar



Joined: 05 Aug 2006
Posts: 149
Location: Redditch, UK

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PostPosted: Sun Oct 08, 2006 1:29 am     Reply with quote
I made a small mod and used my own puts which works ! Whats wrong with CCS version ?


Code:
// CPU Clock Freq
#define   FOSC   20000000
#define BAUDRT   9600

#include <16F876A.h>
#include <stdio.h>

#fuses HS,NOWDT,PUT,NOPROTECT,NOBROWNOUT,NOLVP,NOCPD,NOWRT
#use delay(clock=FOSC)
#use rs232 (baud=BAUDRT, xmit=PIN_C6, rcv=PIN_C7, PARITY=N, BITS=8, ENABLE=PIN_B0)

char buf[40] ;

void myputs(char *str)
{
   for(; *str != 0 ; str++) {
      putc(*str) ;
   }
   putc('\r') ;
   putc('\n') ;
}

void main()
{
   unsigned int ch ;

   putc('O') ;
   putc('k') ;
   putc('\r') ;
   putc('\n') ;

//   puts("Hello from Puts") ;
   strcpy(buf, "Hello from Puts") ;
   myputs(buf) ;

   putc('H') ;
   putc('e') ;
   putc('l') ;
   putc('l') ;
   putc('o') ;
   putc('\r') ;
   putc('\n') ;

   while(1) {
      if (kbhit()) {
         ch = getc() ;
         putc(ch) ;
         if (ch == 0x31) {
//            puts("Puts a long string to test the output") ;
            strcpy(buf, "Puts a long string to test the output") ;
            myputs(buf) ;

            putc('N') ;
            putc('o') ;
            putc(' ') ;
            putc('1') ;
            putc('\r') ;
            putc('\n') ;
         }
      }
   }
}


Output for 1,2,3

Quote:
Ok
Hello from Puts
Hello
1Puts a long string to test the output
No 1
23

[/code]
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Sun Oct 08, 2006 2:16 pm     Reply with quote
puts() is a macro that calls printf. Here's the macro definition
from stdlib.h.
Code:
#define puts(s) {printf(s); putchar(13); putchar(10);}

Here's the stdlib.h file location: c:\program files\picc\drivers\stdio.h

So the problem is in printf.

Here's a report in April 2005 of the same problem.
http://www.ccsinfo.com/forum/viewtopic.php?t=22421

It appears that 'enable' only works with putc(). So one way to do
a work-around would be to use the re-direction feature of the CCS
printf() function, and send the output to putc. Example:

Code:

#include <16F877.h>
#fuses XT, NOWDT, NOPROTECT, PUT, BROWNOUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, Enable=PIN_B0, ERRORS)

my_putc(char c)
{
putc(c);
}

//===================================
void main()
{
printf(my_putc, "Hello World");

while(1);
}

I looked at the .LST file, and this does work.
nurquhar



Joined: 05 Aug 2006
Posts: 149
Location: Redditch, UK

View user's profile Send private message Visit poster's website

PostPosted: Mon Oct 09, 2006 12:52 am     Reply with quote
Dear PCM

Thanks for confirming what I suspected. ie its a long standing CCS bug. Re-directing through "myputc" with printf(myputc, "xxx") is certanily a good work around, however it would be much better if CCS fixed it. I am guesing the fix will consume another valuable stack level. Especialy if you only have an level 8 stack to start with !

I'll post it as bug to CCS, you never know if may get fixed by April 2007.
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