scheduler and struct

[samo]

Hi,

I would like to save some data from characteristic into the Flash. Due to this fact I decided that I will use scheduler. When the value of actual characteristic is changed the writing event handler triggers the following event handler

static void name_write_handler(ble_infs_t *p_infs,  ble_srv_utf8_str_t name)
{		
	
	app_sched_event_put(&name, sizeof(name),scheduler_name_flash_handler);
	
	
}

which is defined in one of my service. Then the scheduler is called by scheduler_name_flash_handler function which is defined as

void scheduler_name_flash_handler(void *p_event_data, ble_srv_utf8_str_t name)
{
}

Maybe it is worth mentioning that ble_srv_utf8_str_t is structure by the following body

typedef struct
{
    uint16_t  length;                                   /**< String length. */
    uint8_t * p_str;                                    /**< String data. */
} ble_srv_utf8_str_t;

I do not know why i get warning incompatible pointer type. I will be really grateful for any help.

Best regards

Samo

[Bill Siever]

It doesn't look like your event handler matches the app_sched_event_handler_t required by app_sched_event_put. It should probably look like:

void scheduler_name_flash_handler(void *p_event_data, uint16_t size) {
   // Note the signature is void function(void *, uint16_t)
   // Assuming the data really points to a "ble_srv_utf8_str_t", just type cast it.
   ble_srv_utf8_str_t *p_srv_utf8_str = (ble_srv_utf8_str_t *)p_event_data;
    ...
}

You may need to typecast the parameter being passed too, like:

    app_sched_event_put((void *)&name, sizeof(name),scheduler_name_flash_handler);

[samo]

Now everythink work fine, you have right:) Thanks for help, Bill.

[samo]

At this point, I have still one short question. How I can check if void *p_event_data is really ble_srv_utf8_str_t type. I would like to apply different types in p_evet_data and if statment before that is required. What is the best solution for my problem.

Thanks for help

[Bill Siever]

There are at least two major approaches. A) If all your events have different lengths, you could decide based on the length. (I consider this a poor design, but it would work). B) It would be better to use struct that contains a type-tag and a union of all the possible message types (i.e., a tagged union). In this approach all messages would take the same space in the event queue even if not all of it was used. Here's a stackoverflow article that has a response (by Tom Anderson) showing the C syntax for such a union and explaining a bit about it: http://stackoverflow.com/questions/4194506/how-to-know-that-which-variable-from-union-is-used

[samo]

Thank one more time, Bill.