nRF52 SDK14.2 "ble_app_buttonless_dfu" example: What is the value written to the characteristic when entering the bootloader using nRF Connect application (Android).

[Rishi]

I am trying the buttonless DFU example from SDK14.2.0. I am not following the testing procedure mentioned at infocentre for SDK14.2. 

Followed test procedure:

1. Erase device.

2. Upload softdevice v5.0.0

3. Upload bootloader_secure_ble bootloader.

4. Compile ble_app_buttonless_dfu example and generate a ZIP package.

5. Device advertising as DfuTarg. Connect and upload generated ZIP package using nRF Connect (Android).

6. Connect to Nordic_Buttonless.

7. Select: Secure DFU Service.

8. Enable Notification and click on Write Characteristic icon.

9. Prompt: "Enter Bootloader mode?"

10. Select: Yes

11. Device exits application, enters bootloader mode and advertises as DfuTarg.

The above procedure works absolutely fine.

Problem arises when I change the vendor specific UUID. 

On doing so, all the steps from 1 to 8, mentioned above work fine, however, I do not get a prompt from step 9. This is expected as the nRF Connect application does not recognise the new UUID and service.

I have to manually enter the value to enable bootloader.

In SDK12.2.0, this value used to be 0x01, however this value does not work for this version of SDK. 

I have tried both 0x01 and 0xB1, but to no vain.

Can you please recreate this test and/or suggest me the exact value to be entered to enter bootloader mode 

[Bjørn Kvaale]

Hi Rishi,

Quick question: are you using an nrf52 Dev Kit?

Just finished testing on my nrf 52 DK with a 52832 chip. I went through the exact same procedure as you did and got it working with both the nordic base uuid & a vendor specific UUID using SDK 14.2!

To get the vendor specific UUID, I used this online generator to generate the UUID. Then, I went into ble_dfu.h in the buttonless dfu app & wrote this code underneath the #define BLE_NORDIC_VENDOR_BASE_UUID.

/**@brief Test vendor-specific base UUID, 3fd64673-9a82-49c5-adaa-349a9faadece from
 https://www.uuidgenerator.net/
 */
#define BLE_VENDOR_SPECIFIC_BASE_UUID               \
{{                                                  \
    0xCE, 0xDE, 0xAA, 0x9F, 0x9A, 0x34, 0xAA, 0xAD, \
    0xC5, 0x49, 0x82, 0x9A, 0x73, 0x46, 0xD6, 0x3F  \
}}

Then, in ble_dfu.c, I added a line under: ble_uuid128_t   nordic_base_uuid = BLE_NORDIC_VENDOR_BASE_UUID;

where I defined the vendor_base_uuid:

ble_uuid128_t   vendor_base_uuid = BLE_VENDOR_SPECIFIC_BASE_UUID; // added by BK

Lastly, I changed the code err_code = sd_ble_uuid_vs_add(&nordic_base_uuid, &m_dfu.uuid_type); 

to:

err_code = sd_ble_uuid_vs_add(&vendor_base_uuid, &m_dfu.uuid_type);

I used the regular bootloader with private & public keys & followed the Nordic secure dfu blog post to get that set up. Should work with the debug bootloader too, but I have not tested this.

I then followed your steps 1-7 & on step 8 I press the button with the up & down arrows next to the unknown characteristic. A cross mark should appear on the button. This characteristic should have the same base UUID that you generated with the online calculator above. Then, I pressed the write button (the one with the upwards arrow) & wrote 0x01 to the characteristic & pressed send. 

You should then notice that the DK enters bootloader mode because LEDs 1 & 3 start lighting up. I tested this using nrf connect for mobile on both Android & iPhone & both methods worked out of the box.

Hope that helps! Kind Regards,

Bjørn Kvaale

[Rishi]

Hey Bjorn,

I am using nRF52832 (PCA10040) board.

I repeated your test procedure and it worked out fine.

The issue persists if I define these parameters in separate include and source files. As I do not wish to make changes to the SDK files, I defined a new function to initialise the buttonless service. However, this is where things don't work out.

Also, I call dfu_buttonless_init(&dfus_init) in the services_init() function. So this is consistent.

Please check the function included below and try performing a similar test. I would like to ensure if I am missing out on something or there are some other dependencies which are causing this issue on having a new file.

Thanks,

Rishi

/**@brief Function to initialize buttonless bootloader service.
 */
uint32_t dfu_buttonless_init(const ble_dfu_buttonless_init_t * p_dfu_init)
{
    uint32_t        err_code;
    ble_uuid_t      service_uuid;
    ble_uuid128_t   vendor_base_uuid = BLE_UUID_OUR_BASE_UUID;

    VERIFY_PARAM_NOT_NULL(p_dfu_init);

    // Initialize the service structure.
    m_dfu.conn_handle                  = BLE_CONN_HANDLE_INVALID;
    m_dfu.evt_handler                  = p_dfu_init->evt_handler;
    m_dfu.is_waiting_for_reset         = false;
    m_dfu.is_ctrlpt_indication_enabled = false;

    err_code = ble_dfu_buttonless_backend_init(&m_dfu);
    VERIFY_SUCCESS(err_code);
    
    BLE_UUID_BLE_ASSIGN(service_uuid, BLE_UUID_OUR_SERVICE_UUID);

    // Add the DFU service declaration.
    err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY,
                                        &service_uuid,
                                        &(m_dfu.service_handle));

    VERIFY_SUCCESS(err_code);

    // Add vendor specific base UUID to use with the Buttonless DFU characteristic.
    // err_code = sd_ble_uuid_vs_add(&nordic_base_uuid, &m_dfu.uuid_type);
    err_code = sd_ble_uuid_vs_add(&vendor_base_uuid, &m_dfu.uuid_type);
    VERIFY_SUCCESS(err_code);

    // Add the Buttonless DFU Characteristic (with bonds/without bonds).
    err_code = ble_dfu_buttonless_char_add(&m_dfu);
    VERIFY_SUCCESS(err_code);

    return NRF_SUCCESS;
}

[Bjørn Kvaale]

Hi Rishi,

Did you remember to comment out the SDK version of ble_dfu_buttonless_init() in the ble_dfu.c & the header file? Regarding the struct ble_dfu_buttonless_init_t in the ble_dfu.h header file, I guess it might be better to leave it in the old header file & only write your new code in your new files (.c. & .h) to see the code separation between the SDK & what you have customized. See this link for good practice regarding making changes to the SDK code. Then, I would remember to search in your copy of the buttonless DFU SDK example & include the new header file in all of the places that the old ble_dfu_buttonless_init() function got called. Remember to include ble_dfu.h in your new header file. If you are only making this change & adding your custom vendor specific base UUID like I mentioned, this should be pretty straightforward. Hope that helps & good luck!

Kind Regards,

Bjørn Kvaale