BLE_NUS_C_EVT_NUS_TX_EVT event received twice when the central connect peripheral second times

[CSZ_110]

Hi,

  I'm using two  boards with nrf52832 and sdk 15.3.0.  One alter the  ble_app_mult_uart__c example as  ble center ，the othe alter the  ble_app_uart example as  ble peripheral .Two boards connect well .

  But the problem is that when the peripheral disconnect and the center connected the same peripheral second time ,I found that BLE_NUS_C_EVT_NUS_TX_EVT event received twice .That caused the center prinf the rx. data twice on PC . I haved follow this issue'suggestion ,add 

   ble_nus_c_evt.conn_handle = p_ble_evt->evt.gap_evt.conn_handle;

  before

  p_ble_nus_c->evt_handler(p_ble_nus_c, &ble_nus_c_evt);

 But it didn't work ,the problem still happen .Debug found that p_ble_nus_c->conn_handle(0xffff)  caused it , so i add the code   in the ble_nus_c_on_ble_evt() function 

   case BLE_GATTC_EVT_HVX:
      #if 1 //20210130 add this,due to printf twice
          if(p_ble_nus_c->conn_handle != BLE_CONN_HANDLE_INVALID){
             on_hvx(p_ble_nus_c, p_ble_evt);
         }
     #else
        on_hvx(p_ble_nus_c, p_ble_evt);
    #endif
    break;

The issue won't happen again. Add this code would affect the other fuction ?  I know that it can't slove the source of the problem .

Any good suggestion on this will be of great help.

Thank you very much .

[Vidar Berg]

Hi,

It sounds like you are experencing the same as described in this post: https://devzone.nordicsemi.com/f/nordic-q-a/70651/double-notifications-on-multilink-example-with-custom-service?  The solution I suggested there was to ignore the event whenever the connection handles didn't match.

[CSZ_110]

 Thank you for your reply.Yes,you're right.I add a filter in ble_nus_c_on_ble_evt().When the connection handles didn't match ,make it return.By the way,I download the latest SDK 17.02 ,I found that the issue has already solved.I revised my code in the ble_nus_c_on_ble_evt() function :

   if ( (p_ble_nus_c->conn_handle == BLE_CONN_HANDLE_INVALID)
        ||(p_ble_nus_c->conn_handle != p_ble_evt->evt.gap_evt.conn_handle)
      )
    {
       return;
    }

  instead of the original code 

  if ( (p_ble_nus_c->conn_handle != BLE_CONN_HANDLE_INVALID)
      &&(p_ble_nus_c->conn_handle != p_ble_evt->evt.gap_evt.conn_handle)
     )
   {
       return;
   }

 Thanks again for you kind help.