Evaluating LwM2M Advanced Firmware Update for external MCU

This page describes how to evaluate FOTA to external MCU using LwM2M with Advanced Firmware Update object on the nRF9160 DK.

Connecting nRF9160 SiP to nRF52840 SoC 

On the nRF9160 DK, you can configure the hardware interface between the nRF9160 SiP and nRF52840 SoC to use serial connection. In this sample, the nRF9160 SiP uses UART2 and nRF52840 SoC uses UART1. The reset line is needed for activating MCUboot recovery mode.

/*
   | nRF9160     |                            |    nRF52840    |
   | UART 2      |                            | UART1          |
   | RTS   P0.17 | -- nRF interface line 0 -- | P0.17  CTS     |
   |       P0.18 | -- nRF interface line 1 -- | P0.20          |
   |       P0.19 | -- nRF interface line 2 -- | P0.15          |
   | RX    P0.21 | -- nRF interface line 3 -- | P0.22  TX      |
   | CTS   P0.22 | -- nRF interface line 4 -- | P1.04  RTS     |
   | TX    P0.23 | -- nRF interface line 5 -- | P1.02  RX      |
   |       COEX0 | -- nRF interface line 6 -- | P1.13          |
   |       COEX1 | -- nRF interface line 7 -- | P1.11          |
   |       COEX2 | -- nRF interface line 8 -- | P1.15          |
   |       P0.24 | -- nRF interface line 9 -- | P0.18 (nRESET) | (in v0.14.0 or later)
*/

SMP and MCUmgr protocols are used to communicate over UART.

The nRF9160 SiP is configured as an MCUmgr client and nRF52840 SoC as a server.

External MCU FOTA options 

By default, the Advanced Firmware Update object supports two instances. To support an external DFU SMP target, the extra instance is defined for SMP FOTA as follows:

Instance ID	Owner	DFU types
0	Application	DFU_TARGET_IMAGE_TYPE_MCUBOOT
1	Modem	DFU_TARGET_IMAGE_TYPE_MODEM_DELTA, DFU_TARGET_IMAGE_TYPE_FULL_MODEM
2	SMP	DFU_TARGET_SMP

The sample supports firmware update from the nRF9160 to nRF52840. External FOTA SMP adds a new instance to the Advanced FOTA object and registers that to the device management server.

Some additional overlay files need to be included in the sample configuration for evaluating LwM2M Advanced Firmware Update for external MCU. For the purpose of evaluating, the Cellular: SMP Server sample is used. It is a reference implementation that uses MCUboot recovery mode or serial SMP server mode to allow image update.

Verifying image update 

The following steps use generic MCUmgr client mode and Coiote without bootstrap.

Set up the /scripts/fota.py script by using the same username and password that you used for AVSystem’s Coiote Device Management server:
```
# Setup phase
export COIOTE_PASSWD='my-password'
export COIOTE_USER='my-username'
```

Build the Cellular: SMP Server sample and flash it to the nRF9160 DK after making sure that the PROG/DEBUG switch is set to nRF52.

cd samples/cellular/smp_svr/
west build --pristine -b nrf9160dk/nrf52840 -- -DEXTRA_CONF_FILE="overlay-serial.conf" -DEXTRA_DTC_OVERLAY_FILE="nrf9160dk_nrf52840_mcumgr_srv.overlay"
west flash --erase

Open the prj.conf file.
Change CONFIG_MCUBOOT_IMGTOOL_SIGN_VERSION to 1.1.0.

Rebuild the sample and copy the binary file to the lwm2m_client folder:

west build
cp build/zephyr/app_update.bin ../lwm2m_client/app_update52.bin
cd ..

Open a terminal connection for the nRF52840 SoC (VCOM1), in Linux /dev/ttyACM1, and call the mcuboot command on the shell.

uart:~$ mcuboot
swap type: none
confirmed: 1

primary area (2):
   version: 1.0.0+0
   image size: 70136
   magic: unset
   swap type: none
   copy done: unset
   image ok: unset

failed to read secondary area (5) header: -5
uart:~$

Register your nRF9160 DK with the Coiote Device management server.

Build and flash the Cellular: LwM2M Client sample after making sure the PROG/DEBUG switch is set to nRF91.

cd lwm2m_client/
west build  --pristine -b nrf9160dk/nrf9160/ns --  -DEXTRA_CONF_FILE="overlay-adv-firmware.conf;overlay-fota_helper.conf;overlay-avsystem.conf;overlay-lwm2m-1.1.conf;overlay-mcumgr_client.conf" -DEXTRA_DTC_OVERLAY_FILE="nrf9160dk_mcumgr_client_uart2.overlay"
west flash --erase

Wait for the device registration to complete.

Use the /scripts/fota.py script to update the nRF52840 SoC firmware.

./scripts/fota.py -id urn:imei:351358811331351 update 2 file app_update52.bin

Replace the urn:imei:... with your device IMEI from the above. This value is printed on the development kit.

Following is an example output of the command:

[INFO] fota.py - Client identity: urn:imei:351358811331351
[INFO] fota.py - Binary app_update52.bin, Size 70799 (bytes)
[INFO] coiote.py - Creating fota resource for binary app_update52.bin with id lwm2m_client_fota_instance_2
[INFO] fota.py - Init setup for instance 2 firmware Update resource:lwm2m_client_fota_instance_2
[INFO] fota.py - Start Firmware Update
[INFO] fota.py - Delete Observation Multicomponent Firmware Update
[WARNING] coiote.py - Coiote: Path 'Multicomponent Firmware Update' was not observed
[INFO] fota.py - Write Fota Download url to Multicomponent Firmware Update.2.Package URI
[INFO] coiote.py - Device is Queuemode Coiote have to wait next Registration Update
[INFO] fota.py - Download Url Write done
[INFO] fota.py - Enable Observation Multicomponent Firmware Update
[INFO] fota.py - Downloading instance: 2
[INFO] fota.py - Download ready instance: 2
[INFO] coiote.py - Device is Queuemode Coiote have to wait next Registration Update
[INFO] fota.py - Firmware Update Successfully instance: 2
[INFO] fota.py - From: to
[INFO] fota.py - Firmware update process finished
[INFO] fota.py - Delete Observation Multicomponent Firmware Update

Call the mcuboot shell command on the terminal to validate the updated image version on the nRF52840 SoC:

*** Booting Zephyr OS build v3.3.99-ncs1-2938-gc7094146b5b4 ***
I: Starting bootloader
I: Primary image: magic=good, swap_type=0x2, copy_done=0x1, image_ok=0x1
I: Secondary image: magic=good, swap_type=0x2, copy_done=0x3, image_ok=0x3
I: Boot source: none
I: Swap type: test
I: Starting swap using move algorithm.
I: Bootloader chainload address offset: 0xc000
�: Jumping to the first image slot

<inf> board_control: vcom0_pins_routing is ENABLED
<inf> board_control: vcom2_pins_routing is ENABLED
<inf> board_control: led1_pin_routing is ENABLED
<inf> board_control: led2_pin_routing is ENABLED
<inf> board_control: led3_pin_routing is ENABLED
<inf> board_control: led4_pin_routing is ENABLED
<inf> board_control: switch1_pin_routing is ENABLED
<inf> board_control: switch2_pin_routing is ENABLED
<inf> board_control: button1_pin_routing is ENABLED
<inf> board_control: button2_pin_routing is ENABLED
<inf> board_control: nrf_interface_pins_0_2_routing is disabled
<inf> board_control: nrf_interface_pins_3_5_routing is disabled
<inf> board_control: nrf_interface_pins_6_8_routing is disabled
<inf> board_control: nrf_interface_pin_9_routing is ENABLED
<inf> board_control: io_expander_pins_routing is disabled
<inf> board_control: external_flash_pins_routing is ENABLED
<inf> board_control: Board configured.
*** Booting Zephyr OS build v3.3.99-ncs1-2938-gc7094146b5b4 ***
<inf> app_smp_svr: Booting image: build time: Sep  4 2023 10:38:09
<inf> app_smp_svr: Image Version 1.1.0-0
<inf> app_smp_svr: Image is not confirmed OK
<inf> app_smp_svr: Marked image as OK
uart:~$ mcuboot
swap type: none
confirmed: 1

primary area (2):
  version: 1.1.0+0
  image size: 70136
  magic: good
  swap type: test
  copy done: set
  image ok: set

secondary area (5):
  version: 1.0.0+0
  image size: 70136
  magic: unset
  swap type: none
  copy done: unset
  image ok: unset
uart:~$

You can see that MCUboot swaps the running image to version 1.1.0 and the previous image is on the secondary slot.

Evaluating LwM2M Advanced Firmware Update for external MCU

Connecting nRF9160 SiP to nRF52840 SoC

External MCU FOTA options

Verifying image update

Connecting nRF9160 SiP to nRF52840 SoC 

External MCU FOTA options 

Verifying image update 