How BLE scan is done in the DFU (OTA) example?

[TigerD]

Hi,

For nRF52840 BLE, in the DFU (OTA) example (buttonless OTA):

../nRF5_SDK_15.3.0_59ac345/examples/ble_peripheral/ble_app_buttonless_dfu

How scanning is done? Or where and which function initializes scan parameters?  Something similar to 

nrf_ble_scan_init_t init_scan;
m_scan.scan_params.window = m_iCommandScanWindow_MS; //MIN_SCAN_WINDOW;
m_scan.scan_params.interval = SCAN_INTERVAL;
m_scan.scan_params.timeout = 0;
m_scan.scan_params.scan_phys = 0 ;

err_code = nrf_ble_scan_init(&m_scan, &init_scan, scan_evt_handler);

Is there any way that I can modify the scanning interval and scanning timeout?

Thank You,

David Zhou

[Vidar Berg]

Hi David,

Could you try to explain a bit more about why you are adding a scanner to this project? Is it to connect to other peripheral devices? The 'ble_app_buttonless_dfu' is a peripheral only example so it doesn't do scanning by default.

Regards,

Vidar

[TigerD]

Vidar,

It is under peripheral category or folder. I may miss something. If no scanning at all, how does it receive a new version of firmware data through Over-the-Air? And how does it know when to start firmware update when this example is buttonless DFU?

What I am looking for is to optimize and reduce the power consumption. Even no scanning, the advertising interval is about 150ms, and I don't know where is the interval is set, and how to change it.

Thank you,

David 

[TigerD]

Vidar,

Correct myself, the advertising interval is set through:

  Init.config.ble_adv_fast_interval   = APP_ADV_INTERVAL.

That I can change.

Thanks,

David

[Vidar Berg]

Scanning is usually done by the DFU controller/master to find connectable advertising packets from the DFU target. You can adjust the APP_ADV_INTERVAL define to change the advertisement interval as you said. You may use our online power profiler (https://devzone.nordicsemi.com/nordic/power/) to estimate what impact it will have on power consumption.

Regards,

Vidar

[TigerD]

Vidar,

Thank you for your input.

I have profiler and currently it measured at >500uA during advertising. It is too high for us. Could you please be more specific on the DFU controller/master? Is it in the SoftDevice or BLE library.  i guess if it is in the library, I would be able to make changes?

Best Regards,

David

[Vidar Berg]

Hi David,

The DFU controller is the one that transfers the FW image to your DFU target device. It's usually a smartphone or PC.

Please make sure you have disabled UART logging (NRF_LOG_BACKEND_UART_ENABLED=0) as that may explain the high base current.

Best regards,

Vidar