2

using the uvision IDE for STM32 development, I want to have some timer variables not initialized at startup. I have tried:

volatile unsigned int system_time __attribute__((section(".noinit")));

and

__attribute__((zero_init)) volatile int system_timer;

but nothing seems to work. Following the hints from elswhere, I have additionally checked NoInit at options/target/IRAM1. Still, the variables are set to zero after reset.

Can anybody help?

TRPV4
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2 Answers2

4

You need to follow these steps. declare your variable as follows:

volatile unsigned int system_time __attribute__((section(".noinit"),zero_init));

Then you have to use a scatter file to declare the execution section with the NOINIT attribute and use it with the linker. example scatter file:

LR_IROM1 0x08000000 0x00080000  {    ; load region size_region
   ER_IROM1 0x08000000 0x00080000  {  ; load address = execution address
      *.o (RESET, +First)
      *(InRoot$$Sections)
      .ANY (+RO)
   }
   RW_IRAM1 0x20000000 UNINIT 0x00000100  { ;no init section
      *(.noinit)
   }
   RW_IRAM2 0x20000100 0x0000FFF0  {                ;all other rw data
      .ANY(+RW +ZI)
   }
}
Ray
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3

You have to check the address of that variable from .MAP file and use the The at keyword

allows you to specify the address for uninitialized variables in your C source files. The

following example demonstrates how to locate several different variable types using the at keyword.for example......

struct link  {
  struct link idata *next;
  char        code  *test;
};

struct link idata list _at_ 0x40;     /* list at idata 0x40 */
char xdata text[256]   _at_ 0xE000;   /* array at xdata 0xE000 */
int xdata i1           _at_ 0x8000;   /* int at xdata 0x8000 */
char far ftext[256]    _at_ 0x02E000; /* array at xdata 0x03E000 */

void main ( void ) {
  link.next = (void *) 0;
  i1        = 0x1234;
  text [0]  = 'a';
  ftext[0]  = 'f';
}

I hope it helps for solving your problem.

anand prakash
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