Enable Secure feature in BLE application and do DFU over Secure Serial bootloader

Question

Hello, 
 
 I am using nRF52840, SDK_16.0.0, S140 SoftDevice and Segger 4.16 for flashing the image. I am using ‘ble_app_blinky’. 
 
 1) If I enable “Just works” and without bonding at BLE blinky app, still do I need to do any changes in Secure Serial Bootloader. I want to do DFU of BLE Blinky application over Secure Serial Bootloader. 
 
 2) Similarly how about any changes to be done in Secure BLE bootloader, if I want to do DFU of BLE blinky app over Secure BLE Bootlolader. 
 
 3) To my understanding NRF_DFU_BLE_REQUIRES_BONDS is required only for Button-less BLE DFU and with Bonds. Please correct me if I am wrong. 
 
 Thanks & Regards 
 Vishnu Beema

bjorn-spockeli · Accepted Answer

Hi Vishnu, 
 I sincerly apologize for the late reply. We're catching up to the backlog due to Christmas. 
 1) If I enable “Just works” and without bonding at BLE blinky app, still do I need to do any changes in Secure Serial Bootloader. I want to do DFU of BLE Blinky application over Secure Serial Bootloader. 
 If your application, the BLE Blinky app, only performs paring using "Just Works" then you do not do any changes in the Secure Bootloader. You only need to modify the Secure bootloader config if you only want the bootloader to accept firmware images from bonded peers. 
 
 2) Similarly how about any changes to be done in Secure BLE bootloader, if I want to do DFU of BLE blinky app over Secure BLE Bootlolader. 
 No, same as above. If your application, the BLE Blinky app, only performs paring using "Just Works" then you do not do any changes in the Secure Bootloader. You only need to modify the Secure bootloader config if you only want the bootloader to accept firmware images from bonded peers. 
 3) To my understanding NRF_DFU_BLE_REQUIRES_BONDS is required only for Button-less BLE DFU and with Bonds. Please correct me if I am wrong. 
 Yes, if NRF_DFU_BLE_REQUIRES_BONDS is defined in the secure bootloader project, then the bootloader will only accept firmware images from bonded peers. If you set NRF_DFU_BLE_REQUIRES_BONDS in the secure bootloader code, then you also need to set NRF_DFU_BLE_BUTTONLESS_SUPPORTS_BONDS in the application so that the bonding information stored by the application can be shared with the bootloader. 
 Best regards 
 Bjørn

Enable Secure feature in BLE application and do DFU over Secure Serial bootloader

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