BLE DFU via PC nrfutil is really slow

[chewlm86]

Hi,

I have downloaded the latest SDK12 for nRF52.

And i tried out the new "BLE Secure DFU Bootloader" example.

But i found that doing the BLE DFU with nrfutil on windows take 1 minute for the pre-generated package "dfu_test_app_hrm_s132.zip" to complete uploading.

Then tried it on the nRF Toolbox on Android, it only 20 seconds to complete.

Why does PC take 3 times longer to complete the upload?

Best Regards,

Chew

[bjorn-spockeli]

The actual time it takes to complete a DFU will depend on the connection interval. I think that Android v6.0.0 allows for a connection intervals down to 11.25ms, and the bootloader has preferred connection parameters between 15 and 30ms. I am not sure what the minimum and maximum connection parameters are set to in the connectivity firmware, but it most likely closer to 30ms.

[chewlm86]

I see. Is there a way to change these setting on the connectivity firmware?

[bjorn-spockeli]

You can try to set the minimum and maximum connection interval defines in nrf_ble_dfu.c in the bootloader to the same value, i.e.

#define MIN_CONN_INTERVAL                    (uint16_t)(MSEC_TO_UNITS(15, UNIT_1_25_MS))            
#define MAX_CONN_INTERVAL_MS                  15                                                    
#define MAX_CONN_INTERVAL                    (uint16_t)(MSEC_TO_UNITS(MAX_CONN_INTERVAL_MS, UNIT_1_25_MS))

This should force the central on the connectivity chip to set the connection interval to 15ms and not somewhere between 15 and 30ms.