The MAC address changes after OTA

[Daliwan]

Dear Sir:

    We observed that everytime we use OTA to update the firmware of the nRF52, the 6Byte address will change, just minus 1 compared with before, such as

   FC:AE:3F:03:A1:15 changes to FC:AE:3F:03:A1:14

   We observed that this happens only at the first time, is this true?

   Thank you.

[bjorn-spockeli]

HI Daliwan, 

this is the intended behaviour of the bootloader if the bond sharing feature is not used, i.e. NRF_DFU_BLE_REQUIRES_BONDS is set to 0 in the sdk_config.h file. 

The address is incremented in the bootloader to avoid issues with smartphones that cache the GATT attribute table and/or does not support the Service Changed Characteristic. Otherwise, when the bootloader re-initializes the SoftDevice after the application resets and repopulates the GATT table, the smartphone will still think that its communicating with the application as the address is identical and use the wrong handles when writing/reading characteristics/descriptors. 

Best regards

Bjørn