firmware_update

Firmware Update over The Air

This application demonstrates an example use case of object 5 - Firmware Update. It utilizes the pico_fota_bootloader to encrypt and decrypt the FOTA image, check the SHA256 of the FOTA image, and swap the flash partitions after downloading the appropriate binary file from Coiote IoT DM.

Flashing the bootloader and the application

Available compilation option

pico_fota_bootloader provides AES ECB image decryption. To set a custom encryption password, use -DPFB_AES_KEY=<value> option when invoking the cmake command, otherwise the default password will be used. Please refer to pico_fota_bootloader README for more information.

NOTE: While rebuilding the application, once set, the PFB_AES_KEY CMake option should not be changed, otherwise the Raspberry Pi Pico W won't be able to decrypt downloaded image properly.

Flashing the board

After compiling the application, you should have output similar to:

build
└── firmware_update
    ├── CMakeFiles
    ├── cmake_install.cmake
    ├── Makefile
    ├── firmware_update.bin
    ├── firmware_update.dis
    ├── firmware_update.elf
    ├── firmware_update.elf.map
    ├── firmware_update_fota_image.bin
    ├── firmware_update_fota_image_encrypted.bin
    ├── firmware_update.hex
    ├── firmware_update.uf2
    ├── Makefile
    └── pico_fota_bootloader
        ├── CMakeFiles
        ├── cmake_install.cmake
        ├── libpico_fota_bootloader_lib.a
        ├── Makefile
        ├── pico_fota_bootloader.bin
        ├── pico_fota_bootloader.dis
        ├── pico_fota_bootloader.elf
        ├── pico_fota_bootloader.elf.map
        ├── pico_fota_bootloader.hex
        └── pico_fota_bootloader.uf2

To flash the application, set Raspberry Pi Pico W to the BOOTSEL state (by powering it up with the BOOTSEL button pressed) and copy the build/firmware_update/pico_fota_bootloader/pico_fota_bootloader.uf2 file into it. Right now the Raspberry Pi Pico W is flashed with the bootloader but does not have proper application in the application FLASH memory slot yet. Then, set Raspberry Pi Pico W to the BOOTSEL state again and copy the build/firmware_update/firmware_update.uf2 file. The board should reboot and start the firmware_update application.

NOTE: you can also look at the serial output logs to monitor the application state.

Performing Firmware Update

To perform a Firmware Update Over the Air, the build/firmware_update/firmware_update_fota_image_encrypted.bin file should be sent to or downloaded by the Raspberry Pi Pico W. To do so, open your Device Page in Coiote DM Platform and go to the Firmware update tab. Then click the Update firmware button and then select Basic Firmware Update. Upload firmware_update_fota_image_encrypted.bin file to Coiote DM, click Next button twice and then Schedule Update. After doing so, a Firmware Update process will begin. Check the serial output logs - the INFO [fw_update] [/anjay-pico-client/firmware_update/firmware_update.c]: Downloaded X bytes logs should appear. For more detailed information, see AVSystem Devzone.

After downloading the file, Raspberry Pi Pico W will reboot and the bootloader will execute the application from the downloaded .bin file. After connecting to the Wi-Fi, the INFO [fw_update] [/anjay-pico-client/firmware_update/firmware_update.c]: Running on a new firmware log will appear.

Note that while rebuilding the application, the linker scripts' contents should not be changed or should be changed carefully to maintain the memory layout backward compatibility.