TinyUF2 flash unlocker for STM32F411 (easily adaptable to other STM32F4xx)

This small program is meant to unlock the first 2 (=32kb) flash sectors that are occupied by the TinyUF2 bootloader, if they have been locked by it. After the unlock procedure it jumps to the built-in DFU bootloader of the STM32F4 MCUs. This is useful for e.g. self-updating the TinyUF2 bootloader or replacing it with something else.

Usage

1. Put your TinyUF2 bootloader into DFU mode, this is usually done by double tapping reset.
2. Warning this will overwrite your currently flashed program copy tinyuf2-unlocker-stm32f411.uf2 image into mass storage device that pops up.
3. The mass storage device will disappear and a new STM32 DFU device appear.
4. Flash a new version of TinyUF2 or another image via dfu-util or similar.

Pre-built

Download the tinyuf2-unlocker-stm32f411.uf2 UF2 image from the releases section.

Building from Source

1. Install Rust via https://rustup.rs/
2. Add ARM-Thumbv7 toolchain rustup target add thumbv7em-none-eabi
3. Install Cargo binutils https://github.com/rust-embedded/cargo-binutils
4. Compile the binary to a Hex file cargo objcopy --release -- -O ihex tinyuf2-unlocker-stm32f411.hex
5. Get the uf2conv converter from https://github.com/microsoft/uf2/tree/master/utils
6. Convert the Hex file to a valid UF2 image uf2conv.py tinyuf2-unlocker-stm32f411.hex --family STM32F4 --output tinyuf2-unlocker-stm32f411.uf2