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Return Value different to content of Variable ?

 
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Baerle1983



Joined: 21 May 2013
Posts: 1

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Return Value different to content of Variable ?
PostPosted: Sat May 25, 2013 12:38 pm     Reply with quote
Hello Everyone,

i have a function to read from the SPI:
Code:
char *edip_read(void)
{   char result[10];
   int i=0;
   edip_SendC(0x00);
   do
   {
   output_bit(edip_ss,0);
   result[i] = spi_read2(0);
   output_bit(edip_ss,1);
   i++;
   }while(!input(Pin_B0));
   
   #ifdef debug
   printf("EDIP_Read:%s",result);
   #endif
   return result;

}


which is called from my isr with:
Code:

   Printf("Int Result:%s",edip_read());


The written results from the 2 printf´s differ in the first 2 Characters, the 3rd to 9th are equal.

Can anyone tell me what i´m doing wrong ?
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Sat May 25, 2013 1:14 pm     Reply with quote
Read this thread about returning a pointer to a local variable:
http://www.ccsinfo.com/forum/viewtopic.php?t=38421
asmboy



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

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PostPosted: Sat May 25, 2013 2:54 pm     Reply with quote
Quote:

which is called from my isr with:
Code:

Printf("Int Result:%s",edip_read());


it is i very risky and not good practice to do serial IO
from inside an ISR

instead use flags to semaphore "data ready"
and do the printf from main() or one of its child functions.
hmmpic



Joined: 09 Mar 2010
Posts: 314
Location: Denmark

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PostPosted: Sun May 26, 2013 6:24 am     Reply with quote
Define the return array as static in your function.
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