Issue discovering services using discovery module

[gdutk001]

Good afternoon, 

  I have been having issues discovering any service within a peer device which i have recently paired with. I am using Nordic SDK 15.2 and softdevice 6.1 on a nrf52840 development board. I am currently using the BLE_Central_multilink example and have modified it to pair with another device. The application pairs successfully however when attempting to discover the services the database discovery module returns BLE_DB_DISCOVERY_SRV_NOT_FOUND.  I have attempted to add the service i want to discover before starting the database discovery process like this: 

ret_code_t err_code = ble_db_discovery_init(db_disc_handler);
APP_ERROR_CHECK(err_code);

ble_uuid_t BATTERY_SERVICE;
BATTERY_SERVICE.uuid = 0x108A;
BATTERY_SERVICE.type = 2;

uint32_t error_code = ble_db_discovery_evt_register(&BATTERY_SERVICE);
APP_ERROR_CHECK(error_code);

 The above code however does not work. I have noticed that when i try to discover the services of another ble application in the SDK the database discovery module returns BLE_DB_DISCOVERY_COMPLETE however i cannot replicate this with my peer device for some reason. I am using SEGGER studio on a windows machine. Any help would be very much appreciated. 

thanks, 

Gian

[awneil]

How to properly post source code:

[gdutk001]

thank you, i edited the post, do you have any input on how to possibly solve this issue? 

thanks 

[tesc]

Hi,

It is not clear to me what service UUID you are searching for. The line "BATTERY_SERVICE.type = 2;" could do anything, as the type field is an index into the SoftDevice's table of vendor specific base UUIDs. If you have a look at the ble_app_multilink_central example, you will see an example of a service being initialized and the UUID for the service registered with the database discovery module, in the function ble_lbs_c_init() in ble_lbs_c.c. You will find that the base UUID is registered with the SoftDevice using sd_ble_uuid_vs_add(), and then the UUID type returend is used when registering the UUID with the database discovery module.

Hopefully the above will lead you in the right direction.

Regards,
Terje

[gdutk001]

I apologize for the for the lack of clarity. I do not know the base UUID for the peer device which i am paired with, however i do have access to some one of its services which i would like to discover using the ble_db_discovery_start() function. Shortly after connecting(pairing) i call the ble_db_discovery_start() function which returns the error BLE_DB_DISCOVERY_SRV_NOT_FOUND within its handler. I believe i made a mistake earlier and that the previous code should be the following: 

ret_code_t err_code = ble_db_discovery_init(db_disc_handler);
APP_ERROR_CHECK(err_code);

ble_uuid_t BATTERY_SERVICE;
BATTERY_SERVICE.uuid = 0x108A;
BATTERY_SERVICE.type = 1; // since its a 16 bit UUID

uint32_t error_code = ble_db_discovery_evt_register(&BATTERY_SERVICE);
APP_ERROR_CHECK(error_code);

 Do i still need to add the SIG UUID using sd_ble_uuid_vs_add() even though i do not have the base UUID of the peer device?  Is there a way for me to locate the base UUID of the peer device and add it to the ble stack table with sd_ble_uuid_vs_add() ?  Even with the edited code it still returns the same error. Any help would be very much appreciated, thank you.

[tesc]

Hi,

If it is a 16 bit UUID then it must either be one of the GATT Services specified by the Bluetooth SIG, or any of the 16 Bit UUIDs For Members. 0x108A is neither.

You can use nRF Connect for Desktop or nRF Connect for Mobile to connect to the device and investigate what services it offers (and see the UUIDs of those services.)

Regards,
Terje