Configure Bluetooth: Peripheral UART application, bootloader and etc.

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Hiihtaja — Fri, 27 Jan 2023 13:14:53 GMT

Hi !

But it is not visible any delay like flash whole network image from SRAM to flash,

Can flashing be done block by block ? Or due SHA calculations, it is loaded to SRAM as first step.

Just to understand at what point image verification done in case of app and network images in case of recovery flashing.

Image can be flashed but not boot or if it not pass verification , it is not even flashing.

Regards,

Eugene

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Sigurd Hellesvik — Fri, 27 Jan 2023 11:33:49 GMT

From partition_manager_report:

  ram_flash (0x40000 - 256kB): 
+------------------------------------------+
| 0x0: mcuboot_primary_1 (0x40000 - 256kB) |
| 0x40000: ram_flash (0x0 - 0B)            |
+------------------------------------------+
  sram_primary (0x80000 - 512kB): 
+-----------------------------------------------+
| 0x20000000: pcd_sram (0x2000 - 8kB)           |
| 0x20002000: sram_primary (0x6e000 - 440kB)    |
| 0x20070000: rpmsg_nrf53_sram (0x10000 - 64kB) |
+-----------------------------------------------+

As you see, mcuboot_primary_1 is inside ram_flash.

I think that the image is written to mcuboot_primary_1, and then PCD is used to transfer the image to the network core via pcd_sram.

Regards,
Sigurd Hellesvik

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Hiihtaja — Fri, 27 Jan 2023 09:45:49 GMT

Hi !

Can it be some RAM partition ?

I can see these lines in generated .config

CONFIG_NRF53_RECOVERY_NETWORK_CORE=y
CONFIG_NRF53_MCUBOOT_PRIMARY_1_RAM_FLASH=y
CONFIG_NRF53_RAM_FLASH_SIZE=0x40000

And writing to it translated to network flash ?

Regards,

Eugene

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Sigurd Hellesvik — Fri, 27 Jan 2023 08:49:26 GMT

[quote user="Hiihtaja"]Yes, I have tried in serial recovery as well. What is partition 3 ? It is SRAM ?[/quote]

I think the numbering here is a bit bugged.
So I am not sure which one number 3 is.

My guess is that it is mcuboot_primary_1.

[quote user="Hiihtaja"]

In case of SMP server in application, I think I need flash memory extra space for app and network.

Is this so ?

[/quote]

I assume you mean external flash?

You do not have to have external flash for this to work.

Since you need a secondary slot, the application only have half flash available, so you may want to have external flash for that reason.

Regards,
Sigurd Hellesvik

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Hiihtaja — Fri, 27 Jan 2023 08:16:11 GMT

Hi !

Yes, I have tried in serial recovery as well. What is partition 3 ? It is SRAM ?

In case of SMP server in application, I think I need flash memory extra space for app and network.

Is this so ?

Regards,

Eugene

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Sigurd Hellesvik — Fri, 27 Jan 2023 08:04:26 GMT

[quote user="Hiihtaja"]CONFIG_MCUMGR=y
CONFIG_MCUMGR_SMP_UART=y
CONFIG_MCUMGR_CMD_IMG_MGMT=y[/quote]

The sample is configured for Serial Recovery, so the above configuration is not needed.

To enter Serial Recovery mode, hold Button 1 when resetting.
LED1 should now light up, signaling that the board is in Serial Recovery mode.

Now you can use mcumgr commands.

If you want to use an SMP Server in the Application instead, try my Non Simultaneous update of nRF5340 sample instead.

Regards,
Sigurd Hellesvik

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Hiihtaja — Fri, 27 Jan 2023 08:00:33 GMT

Hi !

I should enable in prj.conf few lines in your sample

CONFIG_MCUMGR=y
CONFIG_MCUMGR_SMP_UART=y
CONFIG_MCUMGR_CMD_IMG_MGMT=y

$ mcumgr -c acm1 image upload build/zephyr/net_core_app_update.bin -n 3
181.71 KiB / 181.71 KiB [===============================================================================================================] 100.00% 1.80 KiB/s 1m41s
Done

App image is also uploaded to some space

$ mcumgr -c acm1 image upload build/zephyr/app_update.bin
58.02 KiB / 58.02 KiB [=====================================================================================================================] 100.00% 956 B/s 1m2s
Done

But actual update is not happens.

Partition info

But how images are updated on fly ?

Looks like network and app core is up and running with normal images and need to be

updated by MCUMGR

Regards,

Eugene

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Sigurd Hellesvik — Thu, 26 Jan 2023 14:12:00 GMT

Hi,

[quote user="Hiihtaja"]

Looks like I should inform mcuboot or/and b0n that image in that slot and force update somehow.

How I can do it ? Does reboot is mandatory ?

[/quote]

For SMP Server in the application, you need to tag the new image with either "test" or "confirm".

For Serial Recovery, you upload it directly. Here is a quick sample I made to test this:

devzone.nordicsemi.com/.../mcuboot_5F00_netcore_5F00_serial_5F00_recovery.zip

To upload to the netcore, use

mcumgr  -c acm1 image upload build/zephyr/net_core_app_update.bin  -n 3

Then wait for ca 2 minutes before restarting the device.

Regards,
Sigurd Hellesvik

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Hiihtaja — Wed, 25 Jan 2023 13:38:21 GMT

Hi Sigurd Hellesvik !

Can we look more close this picture:

https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/main/bootloader_samples/nrf5340#non-simultaneous-update

I'm able to upload network update to second app slot in internal memory by

$ mcumgr -c acm2 image upload -e build/zephyr/net_core_app_update.bin -n 3

when upload complete, MCUboot show traces

Turned on network core

But nothing is not happens after that and after reboot.

Partition info looks correct:

$ west build -t partition_manager_report

-- west build: running target partition_manager_report

[...build/cpunet/partitions_CPUNET.yml

flash_primary (0x100000 - 1024kB):

+--------------------------------------------------+

| 0x0: mcuboot (0x18000 - 96kB) |

+---0x18000: mcuboot_primary (0x74000 - 464kB)-----+

| 0x18000: mcuboot_pad (0x200 - 512B) |

+---0x18200: mcuboot_primary_app (0x73e00 - 463kB)-+

| 0x18200: app (0x73e00 - 463kB) |

+--------------------------------------------------+

| 0x8c000: mcuboot_secondary (0x74000 - 464kB) |

+--------------------------------------------------+

otp (0x2fc - 764B):

+------------------------------+

| 0xff8100: otp (0x2fc - 764B) |

+------------------------------+

ram_flash (0x40000 - 256kB):

+------------------------------------------+

| 0x0: mcuboot_primary_1 (0x40000 - 256kB) |

| 0x40000: ram_flash (0x0 - 0B) |

+------------------------------------------+

sram_primary (0x80000 - 512kB):

+--------------------------------------------+

| 0x20000000: pcd_sram (0x2000 - 8kB) |

| 0x20002000: sram_primary (0x7e000 - 504kB) |

+--------------------------------------------+

CPUNET flash_primary (0x40000 - 256kB):

+--------------------------------------------+

+---0x1000000: b0n_container (0x8800 - 34kB)-+

| 0x1000000: b0n (0x8580 - 33kB) |

| 0x1008580: provision (0x280 - 640B) |

+---0x1008800: app (0x37800 - 222kB)---------+

| 0x1008800: cpunet (0x37800 - 222kB) |

+--------------------------------------------+

CPUNET sram_primary (0x10000 - 64kB):

+-------------------------------------------+

| 0x21000000: sram_primary (0x10000 - 64kB) |

+-------------------------------------------+

Looks like I should inform mcuboot or/and b0n that image in that slot and force update somehow.

How I can do it ? Does reboot is mandatory ?

Regards

Eugene

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Sigurd Hellesvik — Tue, 24 Jan 2023 12:45:52 GMT

Hi,

[quote user="Hiihtaja"]CONFIG_NRF53_RECOVERY_NETWORK_CORE[/quote]

I have not seen this one before!

But it looks like you should be able to use Serial Recovery to update the netcore using this option.
Then you will not need hooks I think.

I see that there are overlays in The Bluetooth Peripheral UART sample.

Try this to see if it works.

Regards,
Sigurd Hellesvik

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Hiihtaja — Mon, 23 Jan 2023 13:52:32 GMT

Hi Sigurd Hellesvik !

If I understood mRF Connect SDK v2.1.0 release note, flag

CONFIG_NRF53_RECOVERY_NETWORK_CORE specially designed for support direct update of network core. Like MCUBoot should load complete network image to shared SRAM and after that network core will update own flash. This is simplest scheme of firmware update and may be it is implemented like this. Need to be investigated.

Or how I should understand "So if you use serial recovery, I think the easiest fix is to change the hook or add a new custom hook." ? It is implemented and need some error fix or it is expected to work in other way ?

Regards,

Eugene

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Sigurd Hellesvik — Mon, 23 Jan 2023 10:35:36 GMT

[quote user="Hiihtaja"]1. App and Netcore flash memory can be split to 2 banks and firmware updates via reboot.[/quote]

App flash: 1 bank (Primary slot)
External flash: 1 bank (Secondary slot)
Net flash: 1 bank (Netcore flash)

The App flash is split into 2 banks. (Primary slot and Secondary slot)
The Netcore flash only has 1 bank. (Netcore flash)

SMP Server support: Yes
Serial Recovery support: require a custom hook or fixing of existing hook

[quote user="Hiihtaja"]2. Similar to 1st case but second copy can be stored in external flash memory.[/quote]

SMP Server support: Yes

App flash: 1 bank (Primary slot)
External flash: 1 bank (Secondary slot)
Net flash: 1 bank (Netcore flash)

Serial Recovery support: A(No) or B(Yes)

A: require a custom hook or fixing of existing hook:

App flash: 1 bank (Primary slot)
External flash: 1 bank (Secondary slot)
Net flash: 1 bank (Netcore flash)

B: Works as in the Machine Learning sample, but with 1 extra partition

App flash: 1 bank (Primary slot)
External flash: 2 banks (Secondary slot and Secondary Slot 1)
Net flash: 1 bank (Netcore flash)

[quote user="Hiihtaja"]3. Serial recovery for app core ( direct flashing ) and 2 nd copy of network core image can be located in app flash memory OR external flash memory.[/quote]

I am unsure what you mean here, but is this not covered by either 1 or 2?

[quote user="Hiihtaja"]

4. Serial recovery for network core is not possible, entire network image should e stored somewhere as first step and updated over reboot.

It is not possible to flash network core image on fly e.g by some portions via shared memory.

But it might be implemented by using hook mechanism .

Is this so ?

[/quote]

The Appcore can not write to netcore flash.

But you can try to use the PCD library from the application to update the netcore.
That would not be a hook.

The current design is the folliwng:
Save netcore update to APPCORE flash.
On MCUboot start, MCUboot will run a hook.
This hook checks if there is a netcore update in Secondary slot.
If netcore update found, use PCD to update netcore.

So if you use serial recovery, I think the easiest fix is to change the hook or add a new custom hook.

Regards,
Sigurd Hellesvik

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Hiihtaja — Mon, 23 Jan 2023 09:12:13 GMT

Hi Sigurd Hellesvik !

Looks like a lot of variants of FW updates and what is currently known state ?

1. App and Netcore flash memory can be split to 2 banks and firmware updates via reboot.

2. Similar to 1st case but second copy can be stored in external flash memory.

3. Serial recovery for app core ( direct flashing ) and 2 nd copy of network core image can be located in app flash memory OR external flash memory.

So this method might work or might not

4. Serial recovery for network core is not possible, entire network image should e stored somewhere as first step and updated over reboot.

It is not possible to flash network core image on fly e.g by some portions via shared memory.

But it might be implemented by using hook mechanism .

Is this so ?

Just to understand what schemes are work for sure, what can exists and can be configured and what can be implemented by hook mechanism.

Regards,

Eugene

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Sigurd Hellesvik — Fri, 20 Jan 2023 15:01:55 GMT

[quote user="Sigurd Hellesvik"]PCD is enabled in MCUboot.
So it will update the network core after upload the image, before a reboot.
Because of this, I recommend that you wait 1-2 minutes after the upload is done before resetting the device.
Then the new netcore image should run on the net-core on the next reboot.[/quote]

PCD is enabled for MCUboot for both serial recovery and normal operations.
First, a new update for NET core is uploaded to the secondary slot.
Then on a reboot, MCUboot will check this slot. If the secondary slot has an image for the NET core, MCUboot will perform the swap operation

[quote user="Hiihtaja"]

8. It might be so that sample is close to your picture

https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/main/bootloader_samples/nrf5340#non-simultaneous-update

But this moment is not so clear : "When updating the network core, the new image will be saved to the secondary slot. On a reboot, the image will be swapped with the network core over the shared SRAM:"

[/quote]

After some testing, it seems like this figure works for SMP Server + MCUboot but not for Serial Recovery.
It seems that serial recovery only permits one slot by default.
If we are able to configure serial recovery to use two slots here, we could upload a new netcore image to the secondary slot, and the update should be applied.

Another alternative could be to implement a MCUboot hook to handle this.

[quote user="Hiihtaja"]

External memory is not defined anywhere, extra partitions as well.

Does this configuration is close to your picture https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/main/bootloader_samples/nrf5340#non-simultaneous-update

Or this is something else ?

[/quote]

For my external flash sample, it is not like this figure, because the external flash sample parts the flash into three slots.
Use "Memory Report" in VS Code or "west build -t partition_manager_report" to see the slots.

[quote user="Hiihtaja"]

How can looks configuration when :

- Serial recovery method is required for both cores. e.g. direct update without usage of extra flash slots and external serial memory.

- To avoid external memory usage, the case when application and network core images can be updated separately is also accepted ( but no idea if external memory is really needed in case of serial recovery and multiimage.zip).

- SMP server is located in MCUBoot only ( no need in application ) e.g update is triggered by GPIO line.

Triggering works as expected and any GPIO line can be configured and I hope SMP server is not included by default in APP.

[/quote]

For the external flash example, if you run "mcumgr -acm0 image list", you can see the serial recovery bootloader list 2 slots.
I suggest that you try to figure out how the serial recovery enables the second slot in this sample.
Then you should be able to configure the example with internal flash to also have a second slot in the same way.
If you now upload a netcore image to this seconds slot, it should swap.

Alternativley you could add an MCUboot hook and make the primary slot also being checked for netcore updates.
I think the current hook ishttps://github.com/nrfconnect/sdk-nrf/blob/main/modules/mcuboot/hooks/nrf53_hooks.c.

Regards,
Sigurd Hellesvik

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Sigurd Hellesvik — Wed, 18 Jan 2023 11:44:39 GMT

Hi Eugene,

[quote user="Hiihtaja"] 1. It looks as most advanced configuration when App and network core is huge and updated via proxy storage ( external memory only or some partitions in app memory ?)[/quote]

When using the nRF5340 with bootloaders for both cores, you need three slots: primary, secondary and secondary_1.
Splitting the flash memory into three will decrease available space. Therefore, the machine learning sample uses external flash for the secondary partitions.

[quote user="Hiihtaja"]2. I have tried to enable any debug uart traces from both bootloaders but no any luck. Even all flags like UART log are set.[/quote]

This is because the serial recovery use the uart.
I recommend using UART if you need logs from the bootloader:
See an example at https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/blob/2ab21b02484dd41216454a33d7db8b4cd5c1952d/bootloader_samples/serial_recovery/mcuboot_serial_recovery_cdc_acm_wait/child_image/mcuboot.conf .

[quote user="Hiihtaja"]3. What mean -n flag for mcumgr ? It is not visible in help of utility ?[/quote]

Also see https://docs.zephyrproject.org/3.2.0/services/device_mgmt/mcumgr.html.

and my own explanation from https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/main/bootloader_samples/smp/mcuboot_smp#extra-steps-for-the-nrf5340:

The -n numbers are set as follows:

slot 0 - image 0 primary
slot 1 - image 0 secondary
slot 2 - image 1 primary ("Virtual" slot)
slot 3 - image 1 secondary

[quote user="Hiihtaja"]4. How networkapplication hci_rpmg defined as child project ? Definition is not visible in project files. Looks as some trick.[/quote]

From Working with nRF5340 DK, you can see that if CONFIG_BT=y, the build system will add hci_rpmsg to the system.
Try to add a print to the sample, and see your net core print it on the net-core VCOM.

[quote user="Hiihtaja"] 5. MCUBoot is visible as child image but n0b bootloader not. Does it appears somehow automatically ?[/quote]

It is because n0b is a child image of hci_rpmsg.
You can see it at build/hci_rpmsg/b0n.

[quote user="Hiihtaja"]

Should they be updated directly or via hiddent reboot ?

Or how whole flow works in your sample ?

[/quote]

PCD is enabled in MCUboot.
So it will update the network core after upload the image, before a reboot.
Because of this, I recommend that you wait 1-2 minutes after the upload is done before resetting the device.
Then the new netcore image should run on the net-core on the next reboot.
EDIT: I am unsure of this, and will have to research it a bit more as well.

I will have to look into the last questions, and come back to answer them by end of friday.

Regards,
Sigurd Hellesvik

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Hiihtaja — Wed, 18 Jan 2023 10:36:33 GMT

Hi Sigurd Hellesvik !

Thank you !

I'm using Ubuntu 20.04 and latest v2.2.0 SDK for my questions and examples.

Few overall questions about example mcuboot_serial_recovery_cdc_acm_nrf5340_external_flash_both_cores.zip

I have build iit from command line

west build --pristine --board nrf5340dk_nrf5340_cpuapp -- -DDTC_OVERLAY_FILE="app.overlay"

1. It looks as most advanced configuration when App and network core is huge and updated via proxy storage ( external memory only or some partitions in app memory ?)

2. I have tried to enable any debug uart traces from both bootloaders but no any luck. Even all flags like UART log are set.

3. What mean -n flag for mcumgr ? It is not visible in help of utility ?

4. How networkapplication hci_rpmg defined as child project ? Definition is not visible in project files. Looks as some trick.

5. MCUBoot is visible as child image but n0b bootloader not. Does it appears somehow automatically ?

6. Network core image is updated without problem:

mcumgr -c acm2 image upload build/zephyr/net_core_app_update.bin -n 3
181.71 KiB / 181.71 KiB [=========================================================================================================================] 100.00% 1.33 KiB/s 2m16s
Done

But app and composite always freeze at the end.

mcumgr -c acm2 image upload build/zephyr/app_update.bin -n 3
46.77 KiB / 46.91 KiB [====================================================================================================================================] 99.71% 477 B/s

mcumgr -c acm2 image upload build/zephyr/dfu_application.zip -n 3
230.07 KiB / 230.18 KiB [===================================================================================================================================] 99.95% 22 B/s

Should they be updated directly or via hiddent reboot ?

Or how whole flow works in your sample ?

7. I have study sample in more details and by using your example , have changed MCUboot partition size and move it to USB serial port.

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.2.0/nrf/samples/bluetooth/peripheral_uart/README.html#peripheral-uart

App and net cores can be updated one by one.

8. It might be so that sample is close to your picture

https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/main/bootloader_samples/nrf5340#non-simultaneous-update

I look for MCUBoot configuration what updating of both cores are not required usage any spare memory on internal flash memory and external one.

peripheral uart bootloader configuration ( important parts) looks like this

CONFIG_FLASH=y

# MCUBoot serial
CONFIG_MCUBOOT_SERIAL=y
CONFIG_MCUBOOT_SERIAL_DIRECT_IMAGE_UPLOAD=y

# The following configurations are required to support serial recovery of the
# network image
CONFIG_PCD_APP=y

CONFIG_FLASH_SIMULATOR=y
CONFIG_FLASH_SIMULATOR_DOUBLE_WRITES=y
CONFIG_FLASH_SIMULATOR_STATS=n

CONFIG_BOOT_IMAGE_ACCESS_HOOKS=y
CONFIG_NRF53_RECOVERY_NETWORK_CORE=y

CONFIG_MCUBOOT_INDICATION_LED=y

# Extra
CONFIG_BOOT_SERIAL_CDC_ACM=y
CONFIG_SIZE_OPTIMIZATIONS=y
CONFIG_UART_CONSOLE=y
CONFIG_LOG=y

CONFIG_UPDATEABLE_IMAGE_NUMBER=1

External memory is not defined anywhere, extra partitions as well.

Does this configuration is close to your picture https://github.com/hellesvik-nordic/samples_for_nrf_connect_sdk/tree/main/bootloader_samples/nrf5340#non-simultaneous-update

Or this is something else ?

How can looks configuration when :

- Serial recovery method is required for both cores. e.g. direct update without usage of extra flash slots and external serial memory.

- SMP server is located in MCUBoot only ( no need in application ) e.g update is triggered by GPIO line.

Triggering works as expected and any GPIO line can be configured and I hope SMP server is not included by default in APP.

Regards,

Eugene

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Sigurd Hellesvik — Tue, 17 Jan 2023 13:57:12 GMT

Hi,

Instead of answering your questions one by one, I created an example to do the following:

Serial Recovery over CDC_ACM
For both cores of the nRF5340
nRF Connect SDK v2.2.0

devzone.nordicsemi.com/.../mcuboot_5F00_serial_5F00_recovery_5F00_cdc_5F00_acm_5F00_nrf5340_5F00_external_5F00_flash_5F00_both_5F00_cores.zip

The configurations for this sample is based on nRF Machine Learning sample.
The base is from my unofficial Serial Recovery sample.

You upload an update to the network core using:

mcumgr  -c acm0 image upload build/zephyr/net_core_app_update.bin -n 3

PS: You might have to shorten the projects name before building if you use windows.

I hope this can help you.

Let me know which of your questions are still relevant after looking at this sample.

Regards,
Sigurd Hellesvik

RE: Configure Bluetooth: Peripheral UART application, bootloader and etc.

Hiihtaja — Tue, 17 Jan 2023 11:53:22 GMT

Hi !

Just correction for my question.

1. No success with usage of USB_CDC_ACM in actual application e.g lines

west build --build-dir ./build . --pristine --board nrf5340dk_nrf5340_cpuapp -- -DBOARD_ROOT=. -DDTC_OVERLAY_FILE="usb.overlay" -DCONF_FILE="prj_cdc.conf"

I'm able to build image with MCUboot by using command line:

$ west build --build-dir ./build . --pristine --board nrf5340dk_nrf5340_cpuapp -- -DBOARD_ROOT=. -DDTC_OVERLAY_FILE="app.overlay" -DCONF_FILE="prj.conf" -DOVERLAY_CONFIG="nrf5340dk_app_sr_net.conf" -Dmcuboot_OVERLAY_CONFIG="$(pwd)/nrf5340dk_mcuboot_sr_net.conf"

I have got set of images

[293/303] Generating ../../zephyr/app_update.bin
sign the payload
[294/303] Generating ../../zephyr/net_core_app_update.bin
sign the payload
[296/303] Generating ../../zephyr/net_core_app_signed.hex
sign the payload
[297/303] Generating ../../zephyr/net_core_app_test_update.hex
sign the payload
[299/303] Generating ../../zephyr/app_test_update.hex
sign the payload
[300/303] Generating ../../zephyr/app_signed.hex
sign the payload
[303/303] Generating zephyr/merged_domains.hex

where app_update.bin and net_core_app_update.bin can be used by mcumgr for update firmware.

But really it is not so clear where are separate images for mcuboot and b0n updates what can be used for initial flashing of a board.

Looks like composite images only.

Due lack of traces difficalt to conclude how nrf5340dk_mcuboot_sr_net.conf really works. Does external memory in use or not.

How serial recovery work in this case ?

Regards,

Eugene