query related to NBU update

[Chan_17]

Hi NXP Team,

There is a procedure to enable Bluetooth related sdk for kw45 evk board to download NBU Image , but when we make our custom PCB using kw45 processor , so will those processors comes with NBU Image by default or there is any other document to download NBU image in raw processor? 

[luis_maravilla]

Hello

For uploading the NBU image to a KW45 device two types of keys must be written to KW45 fuse during mass production, by default, RoTKTH and SB3KDK are provided for KW45B41Z-EVK board but in a factory chip, the keys in the fuse are null.

I would recommend following the instructions on the Application note [Programming the KW45 flash for Application and Radio firmware via Serial Wire Debug during mass production]

It's important to mention that the method of burning the fuse provided in this document cannot be reversed. The keys programmed to fuses on KW45 cannot be changed anymore. Therefore, it is recommended to modify the fuse with caution.

If you want to use your board for development same as the KW45 EVK you could use the same keys values from the KW45B41Z-EVK board directly; If you want to use your board for a different end product or custom end application; I would recommend creating your own keys and generating the sb3 file using the .xip file for a new NBU image dedicated to your end product

For more information about this please refer to Application note AN14003 in chapter 4.2 and chapter 5.1 in the following link Programming the KW45 flash for Application and Radio firmware

Best Regards

Luis

[Chan_17]

You mean for now we can use EVK board keys / given .sb3 file as it is , as we are just in development phase . Also is it possible not to program fuse and only to download NBU Image in Radio core, its not clearly mentioned in the document you shared.

Please let us know possible ways.

can we use MCUxpresso secure provisioning tool for the same purpose to load NBU image in radio core using swd.

[luis_maravilla]

Hello,

I made a list for scenarios with KW45 and what they need to implement for loading the NBU image:

It's important to mention that the method of burning the fuse cannot be reversed on the board so the customer needs to evaluate what they need to do for their board. Therefore, it is recommended to modify the fuse with caution.

KW45B41Z-EVK Board:

RoTKTH and SB3KDK are provided for KW45B41Z-EVK by default. You only need to upload the NBU image as the instructions in Updating NBU for Wireless Examples — MCUXpresso SDK Documentation,.

KW45 Custom board [Functionality same as KW45B41Z-EVK]:

Keys in fuse are null by default, you will need to generate the keys as the process described in Programming the KW45 flash for Application and Radio firmware, if you want to use your board same as the KW45B41Z-EVK the keys are provided in Chapter 5.2.1 Figure 9. If the user burns the fuse using EVK default keys, the .sb3 file located in Chapter 5.1 can be used; Writing RoTKTH and SB3KDK keys to fuse is essential. Otherwise, the sb3 update would fail.

KW45 Custom board [Custom Functionality]

Keys in fuse are null by default, If you want to use your board for a different end product or custom end application; You will need to generate the custom keys and signed image as the process described in Programming the KW45 flash for Application and Radio firmware, for custom keys you must generate the .sb3 file using the .xip file to configure for the custom keys. The process is described in Chapter 5. Writing RoTKTH and SB3KDK keys to fuse is essential. Otherwise, the sb3 update would fail.

It's required to load the sb3 file before flashing any application [Like eatt] on a new KW45. After successfully upload the sb3 file and update NBU image you can flash the applications.

For updating the NBU, you may use the SPSDK command line tool or merging the CM33 image and NBU image, the merged image can be burnt to KW45 via SWD for mass production as described in Chapter 5.4 in AN14003, To load the sb3 file via SPSDK is command line[>> blhost -p COMxx receive-sb-file \kw45b41_nbu_ble_hosted_a1.sb3] with the board on ISP mode.

Best Regards

Luis

[Chan_17]

We are using KW45 board and eatt peripheral example.

If we flash eatt_ peripheral code and then flash .sb3 file is is KW45 processor works ?

as bare mcu dont have switch how to directly flash .sb3 file in the mcu and how to set key as bare mcu have null key set.

[Chan_17]

Thank you!!