Target Platforms

ferrite-sdk supports ARM Cortex-M3, M4, and M4F processors. Each target needs a linker script fragment to reserve retained RAM at a target-specific address.

Supported targets

Target	Rust target triple	Pre-built linker fragment
nRF52840	thumbv7em-none-eabihf	linker/nrf52840-retained.x
RP2040	thumbv6m-none-eabi	linker/rp2040-retained.x
STM32F4	thumbv7em-none-eabihf	linker/stm32f4-retained.x

Porting to a new target

To use ferrite-sdk on an unsupported Cortex-M microcontroller:

1. Identify the SRAM layout. Find the start and end addresses of the main SRAM region in the datasheet.
2. Reserve 256 bytes at the end of SRAM for the retained block. Adjust your MEMORY block so the main RAM region ends 256 bytes earlier.
3. Create a linker fragment with a RETAINED region and the .uninit.ferrite section (see the existing fragments for the pattern).
4. Read the reset-cause register for your MCU and map it to a RebootReason variant.
5. Verify retained RAM survives soft resets. Flash a test firmware that writes a magic value to retained RAM, triggers a software reset, and checks whether the value persists.

What varies per target

Aspect	Target-specific
Retained RAM address	Yes -- depends on SRAM layout
Reset-cause register	Yes -- different peripheral address and bit layout
RAM regions for fault handler	Yes -- pass your SRAM range(s) to SdkConfig.ram_regions
Probe tool	Usually probe-rs, but some targets need vendor tools
Linker script format	Mostly identical, just different addresses

Everything else (SDK init, metrics, transport, upload) is the same across all targets.