RE: BLE device services are not detected on iOS nRF Connect app

glowinac — Thu, 10 Jan 2019 08:16:33 GMT

I just found the solution from here and here.

Seems like that the the iOS device negotiates with the MTU size when establishing the connection, and the GATT module is different since I migrated the code from S132 to S332 softdevice. In older version softdevices, the "BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST" event is handled in nrf_ble_gatt.c. But In the newer version(in my case it's s332 5.0.0) it uses different way.

So I added #include "nrf_ble_gatt.h" in main.c and deal with the BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST event manually in ble_evt_handler, and the connection works fine now.

case BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST:
    	err_code=sd_ble_gatts_exchange_mtu_reply(p_ble_evt->evt.gatts_evt.conn_handle, 23);
    	APP_ERROR_CHECK(err_code);
	break;