MCUBOOT and bonding

[janR]

Hi,

We have some problems with Zephyr MCUBOOT when doing FOTA over BLE.

Our device has characteristics protected with LESC.

When device is bonded, the update fails in one of the last stages.
Everything seems correct while doing FOTA. The image is uploaded and swapped (and the updated image even starts up and works).
But when we do a power cycle or reset device with HW pin, the image is reverted back to the old version.

When we do the same without bonding, everything works fine.

We use Android tablet with nRF Connect installed, and PCA10056 (nRF52840) with a modified Pheripheral lbs example.
The example is modified to have FOTA and the Nordic LED Button Service characteristics protected with LESC.

NCS is 2.6.0

Currently we can come around this by remove bonding before we update, but this is not too good for a customer to do.

Is there a configuration we have missed?

Regards, Jan

[Jesse_Carpenter]

Hi, you may be overwriting the user space storage (or wherever you're storing the bonding info). If you disable that, it should work.

[Einar Thorsrud]

Hi,

I agree with the comment you allready got. Could it be that the partition layout has changed? Note that the partition layout needs to stay constant when doign DFU in the field, so you need to use static partitions to getting such problems.

[janR]

Hi,

Yes, it seems like the settings (where bond information are stored) is overwritten. I need to rebond after FOTA.

However, the memory report shows a reserved settings_storage area in the upper part of flash (0x000F8000 - 0x000FFFFF).

But is it still overwritten at DFU?

The memory report:

What I am doing to get the behaviour:

- Build the modified lbs example

- Erase flash on PCA10056

- Flash it with the modified lbs example

- Check debug output

- Connect with the lbs example and access the Button characteristics, so pairing is triggered

- Pair and bond

- Do a little modification for the lbs example and copy it the tablet

- Do FOTA DFU with nRF Connect from tablet

- Verify that the modification is installed on PCA10056 (debug output)

If I now reset the board, the firmware is reverted back to old version, or if I try to access a characteristics, pairing is triggered (then bonding must be bonding deleted)

I tried to add a pm_static.yml to the project root:

app:
  address: 0xc200
  end_address: 0x82000
  region: flash_primary
  size: 0x75e00
mcuboot:
  address: 0x0
  end_address: 0xc000
  placement:
    before:
    - mcuboot_primary
  region: flash_primary
  size: 0xc000
mcuboot_pad:
  address: 0xc000
  end_address: 0xc200
  placement:
    align:
      start: 0x1000
    before:
    - mcuboot_primary_app
  region: flash_primary
  size: 0x200
mcuboot_primary:
  address: 0xc000
  end_address: 0x82000
  orig_span: &id001
  - mcuboot_pad
  - app
  region: flash_primary
  sharers: 0x1
  size: 0x76000
  span: *id001
mcuboot_primary_app:
  address: 0xc200
  end_address: 0x82000
  orig_span: &id002
  - app
  region: flash_primary
  size: 0x75e00
  span: *id002
mcuboot_secondary:
  address: 0x82000
  end_address: 0xf8000
  placement:
    after:
    - mcuboot_primary
    align:
      start: 0x1000
    align_next: 0x1000
  region: flash_primary
  share_size:
  - mcuboot_primary
  size: 0x76000
settings_storage:
  address: 0xf8000
  end_address: 0x100000
  region: flash_primary
  size: 0x8000
sram_primary:
  address: 0x20000000
  end_address: 0x20040000
  region: sram_primary
  size: 0x40000

But that did not change anything. Memory report stays the same, bonding information is still overwritten, and firmware still reverts.

How do I prevent the overwrite of bonding information?

Regards, Jan

[janR]

I found the issue:

nRF Connect -> "Mcu Manager options" had "Erase application settings" enabled.

When I disabled this setting, bond information is not erased on DFU update anymore.

Thanks both of you for pointing me in the right direction.

Regards, Jan