OpenSK Bootloader

This bootloader supports upgradability for OpenSK. Its functionality is to

• check images on A/B partitions,
• boot the most recent valid partition.

How to use

The bootloader is built and deployed by OpenSK's deploy.py. If your board defines a metadata address, it is detected as an upgradable board and this bootloader is flashed to memory address 0.

How to debug

The bootloader prints debug message over RTT when compiled in debug mode. Using nrfjprog for flashing and inspecting memory is recommended for debugging.

RUSTFLAGS="-C link-arg=-Wl,-Tlink.x -C link-arg=-nostartfiles" \
    cargo build --target thumbv7em-none-eabi
llvm-objcopy -O ihex target/thumbv7em-none-eabi/debug/bootloader \
    target/thumbv7em-none-eabi/debug/bootloader.hex
nrfjprog --program target/thumbv7em-none-eabi/debug/bootloader.hex \
    --sectorerase -f nrf52 --reset

To read the debug messages, open two terminals for:

JLinkRTTLogger -device NRF52840_XXAA -if swd -speed 1000 -RTTchannel 0
JLinkRTTClient

The first command also logs the output to a file. The second shows all output in real time.