pstorage wait problem.

[cl]

Hi.

I'm trying to make NRF52 write 6 bytes of data into flash and read in the DFU Bootloader.

For that purpose I choose to use "pstorage" library instead of other flash related library.

I referenced the code in this thread.

The first problem I noticed is my code is not working correctly in the debug mode.

If I run this code in the debug mode with Keil, main() function is called infinitely and it's unable to control.

The code is executed until it reaches first while loop in the code.

  while(pstorage_wait_flag == 1); 

But at this point the program goes back to starting point of main loop and repeating it.

I don't know what's wrong with it.

The second problem is also weird.

When I executed the code in the normal mode(not debug), the code doesn't loop the main and executed as I expected until it reaches the first while loop.

  while(pstorage_wait_flag == 1); 

At this point, this loop condition is not cleared even if pstorage_wait_flag is cleared to 0 in the pstorage_cb_handler.

I checked pstorage_cb_handler() function is called normally but nrf52 stuck in that while loop.

But, if I add debug printf code in the while loop, it works as I expected.

Like this

while(pstorage_wait_flag == 1); 
{
    SEGGER_RTT_printf(0, "while %d\r\n", pstorage_wait_flag); // problem occurs.
};

But If I remove the SEGGER_RTT_printf() function, then it stuck again.

I don't know what I'm missing in my code.

I use nRF52 (QFAAB0) with SDK 11 and s132.

Thanks for reading. Any advice will be appreciated.

Below is my code.

--- handler() --- 
static void pstorage_cb_handler(pstorage_handle_t  * handle,
	uint8_t              op_code,
	uint32_t             result,
	uint8_t            * p_data,
	uint32_t             data_len)
{
  if(handle->block_id == pstorage_wait_handle) { 
    pstorage_wait_flag = 0; 
    SEGGER_RTT_printf(0, "handler %d\r\n", pstorage_wait_flag);
    nrf_gpio_pin_toggle(LED_2);
  }  //If we are waiting for this callback, clear the wait flag.
}

--- main() ---
  ble_stack_init();
  err_code = pstorage_init();
  APP_ERROR_CHECK(err_code);

  pstorage_handle_t  handle;
  pstorage_handle_t	 block_0_handle;
  pstorage_module_param_t param;
  uint8_t  source_data_0[6] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06};
  uint8_t  dest_data_0[6];
  uint32_t  queue_count = 0;

  param.block_size  = 16;                   //Select block size for 16 bytes.
  param.block_count = 1;                   //Select 1 blocks.
  param.cb          = pstorage_cb_handler;   //Set the pstorage callback handler

  err_code = pstorage_register(&param, &handle);
  APP_ERROR_CHECK(err_code);

  //get handle to access.
  err_code = pstorage_block_identifier_get(&handle, 0, &block_0_handle);
  APP_ERROR_CHECK(err_code);

  SEGGER_RTT_printf(0, "Clear Wait %d\r\n", pstorage_wait_flag);
  err_code = pstorage_clear(&block_0_handle, 16);
  APP_ERROR_CHECK(err_code);
  pstorage_wait_handle = block_0_handle.block_id;            //Specify which pstorage handle to wait for
  pstorage_wait_flag = 1;                                    //Set the wait flag. Cleared in the example_cb_handler
 
  while(pstorage_wait_flag == 1); 
  /*
  {
    SEGGER_RTT_printf(0, "while %d\r\n", pstorage_wait_flag); // problem occurs.
  };
  */
  SEGGER_RTT_printf(0, "Store Wait %d\r\n", pstorage_wait_flag);
  err_code = pstorage_store(&block_0_handle, source_data_0, 16, 0);
  APP_ERROR_CHECK(err_code);
  pstorage_wait_handle = block_0_handle.block_id;            //Specify which pstorage handle to wait for
  pstorage_wait_flag = 1;                                    //Set the wait flag. Cleared in the example_cb_handler

  while(pstorage_wait_flag == 1);
  /*
  {
    SEGGER_RTT_printf(0, "while %d\r\n", pstorage_wait_flag); // problem occurs.
  };
  */
  err_code = pstorage_load(dest_data_0, &block_0_handle, 16, 0);
  APP_ERROR_CHECK(err_code);

  for(;;){
  }

----fix.

I found the second problem was caused by compiler optimization.

I remove the optimization option O3 and it works.

It seems like compiler removed the loop condition..

But still unsure what's wrong with the first problem.

[tesc]

Regarding the second problem: The reason why this did not work is because when you look at the code locally, it seems like the variable is never changed within the while loop. By declaring it volatile you tell the compiler that the variable has to be read from and written to memory every time (as opposed to being held in a register and/or being optimized away):

static volatile bool pstorage_wait_flag = 0;

[cl]

Thanks Terje, you're right. I solved it by removing optimization option in the Makefile but adding volatile will be better as you suggested. But, still have no clue about resetting issue during debugginig. I thought I could find this problem in the debug mode.

[tesc]

The error description (that the code reaches the first iteration of the loop, then resets) confuses me a little. I do not see why a loop such as that one should cause a reset.

• Did you define the DEBUG preprocessor define? This would change the behaviour slightly, and make sure the application hangs rather than resets in certain cases.
• To find out exactly where it fails, did you single step or put breakpoints? The SoftDevice will most likely fail when you stop executing the code, which would lead to a hardfault.
• For some hints for further debugging, see My device is freezing and restarting.
• See also An introduction to error handling in nRF5 projects, especially the sections SoftDevice Faults and HardFaults.