bootloader project in nCS

[Ubaid_M]

Hi,

1. Is bootloader file and firmware file, different for projects build on nCS..?
    Or a single executable build file consists both bootloader & firmware..?

2. Can you suggest a sample program to build a bootloader project..?

Thanks,

[Edvin]

Hello,

In NCS, the bootloader is enabled through configurations, mostly. 

I suggest that you check out the documentation of FOTA upgrades:

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.9.1/nrf/ug_nrf52.html#fota-upgrades

And there is also a written guide on how to add DFU to your project, that I can recommend:

https://devzone.nordicsemi.com/guides/nrf-connect-sdk-guides/b/software/posts/ncs-dfu

If you struggle with the implementation, I suggest that you follow the guide first, and add DFU to the smp_svr sample from NCS, so that you know that everything around (uploading via nRF Connect for iOS/Android/mcumgr) is working as it should, before you start looking into potential issues in your custom application.

BR,

Edvin

[Ubaid_M]

Hello Edvin,

Edvin said:

And there is also a written guide on how to add DFU to your project,

Towards DFU, i see that we make the following configuration to the project:

# Ensure an MCUboot-compatible binary is generated.
CONFIG_BOOTLOADER_MCUBOOT=y

So,
1. By enabling MCUBOOT what happens..?
2. Where is the bootloader image file in the device memory..?
3. Is the boot loader image file different than firmware image file or bootloader code is integrated into the firmware image file..?

Thanks,

[Edvin]

Please see this link on how to generate new key pairs.

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/tfm/docs/technical_references/design_docs/tfm_secure_boot.html#second-stage-bootloader-in-tf-m

There is also a Kconfig definition

CONFIG_BOOT_SIGNATURE_KEY_FILE (described as "config BOOT_SIGNATURE_KEY_FILE" in NCS\nrf\modules\mcuboot\Kconfig) where you can set the absolute path of the key file that you have generated.

Best regards,

Edvin

[Ubaid_M]

Hello Edvin,

Edvin said:

CONFIG_BOOT_SIGNATURE_KEY_FILE

Thank you for the suggestion, it helps.

Further, I understand the usual way mcuboot works with SLOT-0, SLOT-1 & SCRATCH memory locations towards swapping of images for firmware update.

I want to customize a few things here,

1. I want to map SLOT-1 & SCRATCH memory locations to external serial flash locations.

2. I want to provide mcuboot SPI interface APIs to interact with external flash.

So, for the above 2 requirements, kindly suggest how and where I can tweak & build the mcuboot source code.

If any sample is available wherein mcuboot source code is modified, it would be great.

Thanks,

Ubaid

[Edvin]

Ubaid_M said:

1. I want to map SLOT-1 & SCRATCH memory locations to external serial flash locations.

2. I want to provide mcuboot SPI interface APIs to interact with external flash.

What chip are you using? I believe it is possible to offload this to an external QSPI flash chip by using CONFIG_NORDIC_QSPI_NOR=y. Without knowing the details, perhaps you can look into what this does, and try to implement something similar using SPI. 

The MCUBOOT bootloader project is located in ncs <vX.Y.Z>\bootloader\mcuboot.

BR,
Edvin

[Ubaid_M]

Hello Edvin,

Edvin said:

The MCUBOOT bootloader project is located in ncs <vX.Y.Z>\bootloader\mcuboot.

1. So i can tweak in the and make changes to mcuboot source code from here right..?

Another query i had was with copying of mcuboot,

Edvin said:

So in this case you can see that the bootloader is located at address 0x0

2. WHO does this copying of mcuboot onto device memory location 0x00..?

Thanking you,

Ubaid

[Ubaid_M]

Hello Edvin,

Edvin said:

The MCUBOOT bootloader project is located in ncs <vX.Y.Z>\bootloader\mcuboot.

Where can i find the mcuboot source code..?

Edvin said:

What chip are you using?

I am using nrf52833dk_nrf52833 board with an external flash IS25LQ040B.
The interface is SPI single line & not QSPI.

That is, i need to change mcuboot source code to provide, SPI access to it, so that  mcuboot can copy new firmware file from external flash to internal flash.

Thanks,

[Edvin]

Hello,

Please see the v1.9.1\bootloader\mcuboot\boot\zephyr (that is the project folder, containing the main.c for the bootloader. You can see that if you follow the guide from one of the links, it should print something like 

I: Starting bootloader

I: Primary image: magic=bad, swap_type=0x0, copy_done=0x2, image_ok=0x2

I: Secondary image: magic=unset, swap_type=0x1, copy_done=0x3, image_ok=0x3

I: Boot source: none

I: Swap type: none

I: Bootloader chainload address offset: 0xc000

I: Jumping to the first image slot
*** Booting Zephyr OS build v2.7.99-ncs1  ***

The first and last line is coming from that main.c file.

BR,
Edvin

[Ubaid_M]

Thank you Edvin,

Edvin said:

the bootloader is located at address 0x0

Can you please suggest who copies bootloader code from hex file onto memory location 0x000..?

And also what is the size overhead added by enabling MCU_BOOT on the firmware file..?

Can i compile mcboot separately..?

Thanks,

Ubaid

[Ubaid_M]

Hello Edvin,

Edvin said:

bootloader is located at address 0x0

1. Can you please suggest who copies bootloader code from hex file onto memory location 0x000 on the target board..?

2. what is the size overhead added by enabling MCU_BOOT on the firmware file, by enabling and disabling CONFIG_MCUBOOT I found that 17kb size difference of .bin file was the difference, is this fine..?

3. Can I compile mcboot separately..?

4. Can you please refer me to a link wherein I can find sample programs on mcuboot..?

Thanks,

Ubaid

[Edvin]

Ubaid_M said:

Can you please suggest who copies bootloader code from hex file onto memory location 0x000 on the target board..?

You need to program the bootloader using a programmer.

Ubaid_M said:

what is the size overhead added by enabling MCU_BOOT on the firmware file, by enabling and disabling CONFIG_MCUBOOT I found that 17kb size difference of .bin file was the difference, is this fine..?

It says when you compile your project. Both the compiler will give some output on each child image (the mcuboot is a child image) and you can see it in the partitions.yml file in your build folder.

Ubaid_M said:

Can I compile mcboot separately..?

Yes, but no need to do that. For all practical reasons, you would want to do it with your application.

Ubaid_M said:

4. Can you please refer me to a link wherein I can find sample programs on mcuboot..?

Please follow the instructions from FOTA upgrades for the 52 series in our documentation, which points to the smp_svr as an example, or you can check this guide, which is a step by step blog post. 

BR,

Edvin

[Ubaid_M]

Hello Edvin,

I will try to keep my problem definition brief, my device is a nrf528333dk interfaced with a 512kb serial flash memory.
I have a requirement to update the firmware for my device via BLE. which I can work with the dfu app.
Now the memory breakdown of my device is as:

The DFU app will download the updated firmware file via BLE interface into SLOT-1 which is in my external memory. After successful download, the DFU app will initiate a soft reboot which gives the control over to mcuboot.

mcuboot is now supposed to overwrite SLOT-0 with contents of SLOT-1.

1. Please point me or help me with an example mcuboot project with copies from external memory to internal memory as in my requirement above, I need to get an idea on where mcuboot source code needs to be tweaked and how..?! Along with the details on how dts file would look for this.

Edvin said:

You need to program the bootloader using a programmer

Post this, comes my second challenge.

If say the signed key of firmware is compromised or i will need to update the key on new firmware. Here I can built firmware on new key and DFU will copy the new firmware via BLE on SLOT-1.

2. But what about mcuboot..? How will I update mcuboot in this case..? as the firmware update is happening wirelessly and programmer cannot help here..?

3. Crazy idea, if we know where exactly in mcuboot memory the firmware signing key is stored.! can we use DFU app to access the memory and update only the key..? How to know the key address if this is possible..?


Appreciate your help.
Thanks.