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31 lines
1.6 KiB
Markdown
31 lines
1.6 KiB
Markdown
# embassy-boot-nrf
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An [Embassy](https://embassy.dev) project.
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An adaptation of `embassy-boot` for nRF.
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## Features
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- Load applications with or without the softdevice.
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- Configure bootloader partitions based on linker script.
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- Using watchdog timer to detect application failure.
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## Working with a SoftDevice
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When a SoftDevice is present, it handles starting the bootloader and the application as needed.
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The SoftDevice architecture supports the bootloader via a configurable base address, referred to as `BOOTLOADERADDR`, in the application flash region. This address can be specified either:
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1. At the `MBR_BOOTLOADER_ADDR` location in flash memory (defined in `nrf_mbr.h`), or
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2. In the `UICR.NRFFW[0]` register.
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The `UICR.NRFFW[0]` register is used only if `MBR_BOOTLOADER_ADDR` has its default value of `0xFFFFFFFF`. This bootloader relies on the latter approach.
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In the `memory.x` linker script, there is a section `.uicr_bootloader_start_address` (origin `0x10001014`, length `0x4`) that stores the `BOOTLOADERADDR` value.
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Ensure that `__bootloader_start` is set to the origin address of the bootloader partition.
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When a bootloader is present, the SoftDevice forwards interrupts to it and executes the bootloader reset handler, defined in the bootloader's vector table at `BOOTLOADERADDR`.
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Once the bootloader loads the application, the SoftDevice initiates the Application Reset Handler, defined in the application’s vector table at APP_CODE_BASE hardcoded in the SoftDevice.
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The active partition's origin **must** match the `APP_CODE_BASE` value hardcoded within the SoftDevice. This value can be found in the release notes for each SoftDevice version.
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