Questions of DFU over BLE example

[PingISTL]

Dear all

I following the example here , over the air one, and get it basically working, thanks for the tutorial.

Now I have a few questions:

1. It looks like it always keep 2 images at Slot 0 and slot 1, one active at a time, after I Uploaded successfully, It running with new updated image, however when I go to BASIC menu on the the Device Manger Mobile app, and hit SEND RESET COMMAND , it back to previous image, I wonder why and is there a reliable way  to choose which slot it runs?

2.  I am thinking of use it for production, and I got a warning message like below:

CMake Warning at D:\WORK\ncs\v1.9.1\nrf\modules\mcuboot\CMakeLists.txt:262 (message):

---------------------------------------------------------
--- WARNING: Using default MCUBoot key, it should not ---
--- be used for production. ---
---------------------------------------------------------

I wonder what more procedures are needed to make it suitable for production use. 

3. Also the option for CONFIG_MCUMGR_SMP_BT_AUTHEN, if I choose y for it, what is the rest of procedure ? do I still choose app_update.bin for upgrade?

Regard

Thank you!

Ping

[PingISTL]

Hello, Vidar

Thanks for reply.

1. I tried and it works with confirm only. Also read a bit more on image uploading procedure and know a bit more now.

2. I am stuck in generating new key pair, it seems like I need to install the image tool first according to the link , I opened cmd window and tried following and got a error message below. Sorry, I am not familiar with python, and need more help here to install the tool. I am a windows user.

Could you help further please?

Ping

[PingISTL]

Hi, Vidar

Thanks for point out, imgtool is installed although I don't know where it is, but I generated a key file and put it into the keys folder created according to your instruction.

Now what is the next step please? I am not fully understand the final step you mentioned and the link, could you specify a bit more please?

Regards!

Ping

[Vidar Berg]

Hi Ping,

Assuming you have made the child image folder as I outlined in my initial reply, the next step would be to build the project. You can check the build log to confirm that your key is being used.

Regards,

Vidar

[PingISTL]

Hi, Vidar

I did follow your steps and build successfully, I have not seen any warning message about the default keys are being used, does it mean I am using my own generated key now?

is there any other way to know this after build?

Ping

[Vidar Berg]

Hi Ping,

The build log will state which key file is used. You can always try do DFU with the default key again to verify that the update gets rejected to be absolutely sure.

Regards,

Vidar

[PingISTL]

Hi, Vidar

Thank you for your help - I tried to do a clean build and it shows which key file is used only with a clean build. BTW - I have to do a clean build by remove the build and add again as I don't see the pristine option in VS code ACTIONS window now since a upgrade.

Then I factory programmed the image.hex into the board, and also tried to load a update file with default key. It updated successfully, but it doesn't run and log says "E: Image in the secondary slot is not valid!"

I suppose this is expected. It works if I upload a new build file with same key file.

So the procedure for future production is like what I just did? and keep the key file safe? If anyone uploaded another file, it won't work.

Regards!

Ping

[Vidar Berg]

Hi,

In vs code you now have to press this button to do a pristine build:

PingISTL said:

So the procedure for future production is like what I just did? and keep the key file safe? If anyone uploaded another file, it won't work.

Yes, correct. If others get access to the private key, they will be able to create and distribute FW updates for your device.

[PingISTL]

Thank you, Vidar

You solved my another puzzle.

I have a few more questions about the Device Management mobile app, shall I carry on asking here or start a new ticket? You already done a great job in this ticket.

Thanks!

Ping

[Vidar Berg]

Hi Ping,

I'm glad you found my answers helpful. I would prefer if you could create a new ticket for questions not directly related to the original topic as it better fits the Q&A style of this forum. Long threads are generally hard to follow for others who may be looking for the same answers.

Regards,

Vidar