Triggering event handler upon CCCD for notifications change

RE: Triggering event handler upon CCCD for notifications change

Susheel Nuguru — Tue, 20 Sep 2016 19:32:25 GMT

in that case just add one more variable in ble_nus_t

bool cccd_changed;

and on write

static void on_write(ble_nus_t * p_nus, ble_evt_t * p_ble_evt){
ble_gatts_evt_write_t * p_evt_write = &p_ble_evt->evt.gatts_evt.params.write;

if (
    (p_evt_write->handle == p_nus->rx_handles.cccd_handle)
    &&
    (p_evt_write->len == 2)
   )
{
    if (ble_srv_is_notification_enabled(p_evt_write->data))
    {
        p_nus->is_notification_enabled = true;
    }
    else
    {
        p_nus->is_notification_enabled = false;
    }
    p_nus->cccd_changed = true;
    p_nus->data_handler(p_nus, p_evt_write->data, p_evt_write->len);
}
else if (
         (p_evt_write->handle == p_nus->tx_handles.value_handle)
         &&
         (p_nus->data_handler != NULL)
        )
{
    p_nus->data_handler(p_nus, p_evt_write->data, p_evt_write->len);
}
else
{
    // Do Nothing. This event is not relevant for this service.
}}


static void nus_data_handler(ble_nus_t * p_nus, uint8_t * p_data, uint16_t length)
{
  if(p_nus->cccd_changed)
   {
     p_nus->cccd_changed = false;
     // do your processing here
   }
   
   ....
   ....
}

RE: Triggering event handler upon CCCD for notifications change

Tosa — Tue, 20 Sep 2016 19:12:49 GMT

I think I confused you by saying "main application". What I mean is that I want the event handler p_nus->data_handler() to be called with some information stating that the CCCD has changed. What is the simplest way to do this?

RE: Triggering event handler upon CCCD for notifications change

Susheel Nuguru — Tue, 20 Sep 2016 19:05:50 GMT

then it will still be executed in SWI interrupt context, not in the main context.

RE: Triggering event handler upon CCCD for notifications change

Tosa — Tue, 20 Sep 2016 15:07:45 GMT

Is it possible to call this handler p_nus->data_handler(p_nus, p_evt_write->data, p_evt_write->len); when the CCCD event occurs? The handler would need to be able to check the fields and see if it's a CCCD event. Using the scheduler seems overkill and it's not used in the example to call the event handler, right?

RE: Triggering event handler upon CCCD for notifications change

Tosa — Tue, 20 Sep 2016 15:05:22 GMT

Seems overkill to poll it when there's a stack event available that just needs to be sent back to app's handler function, no?

RE: Triggering event handler upon CCCD for notifications change

Susheel Nuguru — Tue, 20 Sep 2016 13:02:03 GMT

You can use app_scheduler to queue this event when notification is changed and pull this in main thread.

You can find documentation here for SDK scheduler

Also find some explanation about how scheduler works here

RE: Triggering event handler upon CCCD for notifications change

frogofmagic — Tue, 20 Sep 2016 05:21:11 GMT

Maybe set a timer to check p_nus->is_notification_enabled every 100ms?