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about scanf retarget in Cortexm3 of SmartFuson of Actel

fisher

Hi,

I have one question about Cortexm3 from smartfusion device from actel. Could you pls help me?
I add follwing codes into retarget.c and then add retarget.c into source code group and find :
printf function works.however scanf function doesn't. anybody knows why?

int fputc(int ch, FILE *f) {
return ((int)ITM_SendChar(ch));
}

int fgetc(FILE *f) {
int i=0;
i=ITM_ReceiveChar();
if((-1)!=i)
        return ((int)ITM_SendChar((uint32_t)i));
else
        return (0);
}

  printf("hello world\n\r"); // when executed, string displayed in debug(printf)window
  scanf("%s",str);                // when executed, hard fault occurs

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  • 0

    Hello Fisher Cheng,

    µVision provides for a CM3/CM4 debug support via ITM (Instrumented Trace Macrocell).
    In a debug session the Debug (printf) Viewer window is used to display the debug data.

    Direction: Microcontroller -> µVision:
    * Characters received via ITM communication channel 0 are written in a printf style to Debug (printf) Viewer window.

    Direction: µVision -> Microcontroller:
    * variable ITM_RxBuffer is used for data transfer.
    * Check if ITM_RxBuffer variable is available (only performed once).
    * Read character from Debug (printf) Viewer window.
    * If ITM_RxBuffer empty write character to ITM_RxBuffer.

    Note: Current solution does not use a buffer mechanism for transmitting the characters.

    For my tests (only simulation) I used following code in retarget.c

    #include <stdio.h>
#include <rt_misc.h>
#include "a2fxxxm3.h"

#pragma import(__use_no_semihosting_swi)

volatile int ITM_RxBuffer = ITM_RXBUFFER_EMPTY;       /* used for Debug Input */

struct __FILE { int handle; };
FILE __stdout;
FILE __stdin;


int fputc(int ch, FILE *f) {
  return (ITM_SendChar(ch));
}

int fgetc(FILE *f) {                /* blocking */
  while (ITM_CheckChar() != 1);
  return (ITM_ReceiveChar());
}

int ferror(FILE *f) {
  /* Your implementation of ferror */
  return EOF;
}

void _ttywrch(int ch) {
  ITM_SendChar(ch);
}

void _sys_exit(int return_code) {
label:  goto label;  /* endless loop */
}

    Do not use MicroLib if you are using scanf(..)

    Best Regards,
    Martin Günther

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  • 0

    Hello Fisher Cheng,

    µVision provides for a CM3/CM4 debug support via ITM (Instrumented Trace Macrocell).
    In a debug session the Debug (printf) Viewer window is used to display the debug data.

    Direction: Microcontroller -> µVision:
    * Characters received via ITM communication channel 0 are written in a printf style to Debug (printf) Viewer window.

    Direction: µVision -> Microcontroller:
    * variable ITM_RxBuffer is used for data transfer.
    * Check if ITM_RxBuffer variable is available (only performed once).
    * Read character from Debug (printf) Viewer window.
    * If ITM_RxBuffer empty write character to ITM_RxBuffer.

    Note: Current solution does not use a buffer mechanism for transmitting the characters.

    For my tests (only simulation) I used following code in retarget.c

    #include <stdio.h>
#include <rt_misc.h>
#include "a2fxxxm3.h"

#pragma import(__use_no_semihosting_swi)

volatile int ITM_RxBuffer = ITM_RXBUFFER_EMPTY;       /* used for Debug Input */

struct __FILE { int handle; };
FILE __stdout;
FILE __stdin;


int fputc(int ch, FILE *f) {
  return (ITM_SendChar(ch));
}

int fgetc(FILE *f) {                /* blocking */
  while (ITM_CheckChar() != 1);
  return (ITM_ReceiveChar());
}

int ferror(FILE *f) {
  /* Your implementation of ferror */
  return EOF;
}

void _ttywrch(int ch) {
  ITM_SendChar(ch);
}

void _sys_exit(int return_code) {
label:  goto label;  /* endless loop */
}

    Do not use MicroLib if you are using scanf(..)

    Best Regards,
    Martin Günther

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