Persistent storage manager writing problem for one block

Question

Hello Everyone , 
 I want to use pstorage for my project.i get the example code from here
 devzone.nordicsemi.com/.../ 
and its working properly(i.e read and write operation). but when i modified it for my requirement as given below its not to read the data what i have write .what mistake i am doing. 
 //Get block identifiers
 pstorage_block_identifier_get(&handle, 0, &block_0_handle);
 pstorage_clear(&block_0_handle, 32); //Clear 32 bytes
 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
//Store data to block one. Wait for the last store operation to finish before reading out the data.
pstorage_store(&block_0_handle, source_data_0, 16, 0); //Write to flash, only one block is allowed for each pstorage_store command
 while(pstorage_wait_flag) {
 power_manage(); 
 } //Sleep until store operation is finished.

 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 
 pstorage_load(dest_data_0, &block_0_handle, 16, 0); //Read from flash, only one block is allowed for each pstorage_load command
 while(pstorage_wait_flag) { power_manage(); } //Sleep until store operation is finished.

 if(dest_data_0[1] == source_data_0[1])
 {
 nrf_gpio_pin_clear(LED_3);
 }
 
 while debugging in keil, if i put the breakpoint on the the pstorage_load(dest_data_0, &block_0_handle, 16, 0); line and then at if(dest_data_0[1] == source_data_0[1]) the read value is same as what is written. 
 but when i put breakpoint directly on
 
 if(dest_data_0[1] == source_data_0[1])
 the read value is 0xFF.

Why it is so.
Please let me know what mistake i am doing...

Thanks & Regards,

Bill Siever · Accepted Answer

Hi (updated post. I replaced my earlier answer with the following) 
 It looks like both the pstorage_clear and the pstorage_store are queued. You should wait for each to complete before proceeding to the next since they are working on the same block. That is, do: 
 pstorage_block_identifier_get(&handle, 0, &block_0_handle);

 pstorage_wait_handle = block_0_handle.block_id; // Specify which pstorage handle to wait for

 pstorage_wait_flag = 1; // Set the wait flag.
 pstorage_clear(&block_0_handle, 16); // Clear 16 bytes
 while(pstorage_wait_flag) power_manage(); // Wait for clear

 pstorage_wait_flag = 1; // Set the wait flag. 
 pstorage_store(&block_0_handle, source_data_0, 16, 0); // Write to flash
 while(pstorage_wait_flag) power_manage(); // Wait for store

 pstorage_load(dest_data_0, &block_0_handle, 16, 0); // Read from flash, 
 
 You should probably also change: 
 static uint8_t pstorage_wait_flag = 0;
 
 to: 
 static volatile uint8_t pstorage_wait_flag = 0;
 
 In your earlier version: 
 
 clear was queued 
 write was queued 
 you wait for a command on the block to complete. You get an acknowledgement when the CLEAR completes. 
 you do the load, which loads the cleared values. The write is still in the queue. 
 
 I believe when you used the additional breakpoint the extra delay allowed the write to complete.

Persistent storage manager writing problem for one block

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