RE: Enabling/Using nus characteristics in the DFU Service.

Hieu — Fri, 21 Oct 2022 13:13:11 GMT

Hi Inam,

You most likely can. I am assuming you are using the nRF5 SDK? I will give some hints below assuming nRF5 SDK v17.1.0.

I would start by creating a custom replacement of the DFU BLE service files. Modifying the SDK file also works, but I personally recommend against that since it modifies the environment for all projects using the SDK.

Assuming you only use the TX/RX characteristics in the application you are probably fine with only replacing ble_dfu.c. You probably will need to make sure your Android app is still happy when it doesn't find the characteristics once the device goes into bootloader though.

If you also need it during bootloader operation, assuming you are based on the secure_bootloader example, you will also need to replace nrf_dfu_ble.c. It feels like there might be some risk regarding processing, since flashing will take most of the CPU time.

Regarding what to do in the replacement, you can start by looking at where characteristic_add() is called in ble_nus.c. From there you should trace back how the characteristics are built up.

Hope those serves as a decent starting point for you. Let me know if you need any further help.

Best regards,

Hieu