Unable to read the 128 bit uuid with base uuid

Question

Hello Team 
 I need to scan the peripheral dongle's 128 bit UUID service and its characteristics,my code is based on heart rate collector of pc-ble-driver,before scanning I am registering the uuid with the softdevice as per the suggestions from your forum posts as below, its adding and registering but the problem is its displaying the uuid as all 0's as 0x0000000000000000 ,I am also attaching the screenshots 
 
 ble_uuid_t dfu_uuid; 
 uint8_t uuid_type = BLE_UUID_TYPE_VENDOR_BEGIN; 
 
 /*Base UUIDs for DFU service characteristics*/ 
 ble_uuid128_t dfu_base_uuid = 
 {{ 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX , 0xXX } 
 }; 
 
 dfu_uuid . type = BLE_UUID_TYPE_VENDOR_BEGIN; 
 dfu_uuid . uuid = BLE_UUID_VALO_SERVICE; 
 
 err_code = sd_ble_uuid_vs_add (m_adapter,&dfu_base_uuid, &uuid_type); 
 if (err_code != NRF_SUCCESS) 
 { 
 printf ( "custom uuid failed 
 " ); 
 fflush (stdout); 
 } 
 else 
 { 
 printf ( "custom uuid added 
 " ); 
 fflush (stdout); 
 } 
 err_code = ble_db_discovery_evt_register (&dfu_uuid); 
 if (err_code != NRF_SUCCESS) 
 { 
 printf ( "ble_db_discovery_evt_register failed 
 " ); 
 fflush (stdout); 
 } 
 else 
 { 
 printf ( "ble_db_discovery_evt_register added 
 " ); 
 fflush (stdout); 
 } 
 // Initiate procedure to find the primary BLE_UUID_MY_SERVICE. 
 err_code = sd_ble_gattc_primary_services_discover (m_adapter, 
 m_connection_handle, 0x0E , 
 &dfu_uuid); 
 if (err_code != NRF_SUCCESS) 
 { 
 printf ( "Failed to initiate or continue a GATT Primary Service Discovery procedure 
 " ); 
 fflush (stdout); 
 } 
 else 
 { 
 printf ( "Initiated or continue a GATT Primary Service Discovery procedure 
 " ); 
 fflush (stdout); 
 } 
 
 output:

Einar Thorsrud · Accepted Answer

Hi, 
 Beulah Preethi Vallur said: Could you please correct my code ,you mean not to update the dfu_uuid.type with the assigned ID(BLE_UUID_TYPE_VENDOR_BEGIN)? Could you please elaborate your answer so I can understand 
 You pass a pointer to one variable (uuid_type) to the call to sd_ble_uuid_vs_add(), and this variable is populated with the ID for this UUID base type by the sd_ble_uuid_vs_add() function (so it is an output ). But you do not use this variable further or the data from it, you just use dfu_uuid.type. And since this is not set to the value of uuid_type that may not be correct. This may not be the issue though since it will be BLE_UUID_TYPE_VENDOR_BEGIN if this is the first to be added. Can you print both and double-check their values? Then you should fix the issue, by passing &dfu_uuid.type instead of &uuid_type to sd_ble_uuid_vs_add() 
 Beulah Preethi Vallur said: If I try to not update the dfu_uuid.type then I "failed to ailed to initiate or continue a GATT Primary Service Discovery" 
 I see. This suggests that BLE_UUID_TYPE_VENDOR_BEGIN was correct (by luck since this was the first base UUID to be added), so that is likely not the issue. 
 Beulah Preethi Vallur said: Please check the below code 
 With the current changes, the type (dfu_uuid.type) is random (whatever happens to be in memory), since you still pass &uuid_type but don't set dfu_uuid.type. So this will not work. Also, I strongly recomend that you don't just log that there was an error, you should also log the error code for all functions that don't return NRF_SUCCESS to make the logging a lot more useful. 
 Can you try to either revert back your code, or do as I suggested, and then post the complete code in a readable way so that I can look at it properly? Either by inserting the files using Insert -> Insert image/video/file or using Insert -> Insert Code.

Beulah Preethi Vallur · Answer

I need to scan the 128 bit uuid which I added and registered with the soft device and its connecting to my peripheral device based on device name and displaying the correct address but the service id is showing as all 0's,please advise

Unable to read the 128 bit uuid with base uuid

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