LXR V2 bootloader (STM32F765VG)
Lives in flash sector 0 (0x08000000–0x08007FFF, 32 KB).
- Normal boot: jumps to the application at 0x08008000, provided a valid application is there (its initial stack pointer is 0x20080000).
- Update: with the encoder button held at power-up, it reads an update image from the SD card
(
LXR*.img), checks its header and checksum, programs it to 0x08008000 and resets.
Update images are produced by the application build (LXR_V2_V<version>.img).
Building
To program blank devices, the firmware build can merge the bootloader with the firmware into one
full-flash image (LXR_V2_V<version>_full.hex) and a flash_full target. Give it either the
LXR_V2_STM32F765_Bootloader.hex built here (-DLXR_BOOTLOADER_HEX=...) or this source folder
(-DLXR_BOOTLOADER_DIR=...); see the firmware README.
Building the bootloader on its own needs the same tools as the firmware (CMake ≥ 3.21, Ninja, arm-none-eabi-gcc):
cmake --preset release
cmake --build --preset release
cmake --build --preset release --target flash_bootloader # program the bootloader only (OpenOCD + ST-Link)
flash_bootloader warns and asks you to type yes before it erases the bootloader on the device
(set LXR_CONFIRM_BOOTLOADER_OVERWRITE=yes to skip the question in scripts). If programming is
interrupted, the device can no longer update itself from the SD card and has to be recovered with
the debug probe.
| Preset | Flags | Output |
|---|---|---|
release | -Os | LXR_V2_STM32F765_Bootloader.{elf,hex,bin,map} |
debug | -Og -g3, DEBUG defined | LXR_V2_STM32F765_Bootloader.* |
The toolchain file and the CMake modules and tools are in the cmake/ folder.
Cleaning the build
Remove the compiled files but keep the settings:
cmake --build --preset release --target clean
To start completely from scratch, also forgetting the settings, delete the build/ folder
(rm -rf build, or Remove-Item -Recurse -Force build in PowerShell) and run cmake --preset release
again. Do this after switching to a different compiler. See "Cleaning the build" in the firmware README
for details.
Licence
Copyright (C) 2012-2026 Erica Synths. Licensed under the GNU General Public License version 3 with the additional permission and terms in NOTICE.md. The names "Erica Synths" and "LXR" and the LXR hardware are the property of Erica Synths and are not covered by this licence; see NOTICE.md.