Using ble_db_discovery to find the DFU service

[Jeremy]

I understand there isn't a code example of the DFU updater since it is expected that we will use a phone or other device running the Nordic app to deploy updates, but in my case I am trying to implement the update process from a nRF52833. I'm able to scan for and connect to a "DfuTarg" (running a generic secure_bootloader_ble project), but run into trouble when I try to discover the services and update the local discovery db.

// Init Macros
BLE_DB_DISCOVERY_DEF(m_db_disc);
NRF_BLE_GQ_DEF(m_ble_gatt_queue,
               NRF_SDH_BLE_CENTRAL_LINK_COUNT,
               NRF_BLE_GQ_QUEUE_SIZE);

// From bootloader_ble project
#define DFU_UUID_BASE  {0x50, 0xEA, 0xDA, 0x30, 0x88, 0x83, 0xB8, 0x9F, \
                        0x60, 0x4F, 0x15, 0xF3,  0x00, 0x00, 0xC9, 0x8E}
#define DFU_UUID_SERVICE 0xFE59

// Base and Service UUID
static ble_uuid128_t dfu_base_uuid = {DFU_UUID_BASE};
static ble_uuid_t dfu_uuid = 
{
  .type = BLE_UUID_TYPE_VENDOR_BEGIN,
  .uuid = DFU_UUID_SERVICE,
};

// Discovery Handler
static void db_disc_handler(ble_db_discovery_evt_t * p_evt)
{
    nrf_delay_us(1);  // Testing Breakpoint
}

// Discovery Init
static void db_discovery_init(void)
{
    ble_db_discovery_init_t db_init;

    memset(&db_init, 0, sizeof(db_init));

    db_init.evt_handler  = db_disc_handler;
    db_init.p_gatt_queue = &m_ble_gatt_queue;

    ret_code_t err_code = ble_db_discovery_init(&db_init);
    APP_ERROR_CHECK(err_code);
}

// Setup
void discovery_setup(void)
{
	db_discovery_init();

	sd_ble_uuid_vs_add(&dfu_base_uuid, &dfu_uuid.type);

	ble_db_discovery_evt_register(&dfu_uuid);
}

// Start
uint32_t discovery_start(uint16_t conn_handle)
{
  return ble_db_discovery_start(&m_db_disc, conn_handle);
}

My current thought is that my assumption that the DFU service UUID is "vendor specific" and uses the same base UUID as the characteristics is incorrect, but without an example project I'm not sure what it should be.

I start discovery by calling "discovery_start()" within my BLE_GAP_EVT_CONNECTED case in the main BLE event handler, and pass in the p_gap_evt->conn_handle. This triggers two event responses at my breakpoint in the discovery handler, neither is what I think I'm looking for.

First, a BLE_DB_DISCOVERY_SRV_NOT_FOUND response that appears to be referencing what I'm targeting, just unsuccessfully:

Second, a BLE_DB_DISCOVERY_AVAILABLE response, but from a UUID that doesn't match the DFU service running on the BLE bootloader (UUID 0x2CAC):

I tried to cut down the code to the meaningful bits relating to discovery, but if everything above looks OK or more context would help let me know. Any insight would be appreciated!

Thanks.

*edit* Added m_ble_gatt_queue macro definition that was missing before, but used in the initialization of the discovery db.

[Sigurd]

Hi,

I don't see anything wrong with the code snippet provided. But could you check the return value of sd_ble_uuid_vs_add(), and make sure that it's NRF_SUCCESS ?

[Jeremy]

I can confirm that both sd_ble_uuid_vs_add() and ble_db_discovery_evt_register() both return NRF_SUCCESS.

I can also confirm that the secure_bootloader_ble project has built correctly and I am able to complete an update using the DFU update Android phone app.

I'm not in this instance, but it sounds like sd_ble_uuid_vs_add() is set up to allow me to add multiple vendor specific UUIDs at the same time. Is there some way I need to convey which base I want a specific ble_uuid_t with .type = BLE_UUID_TYPE_VENDOR_BEGIN to be associated with?