Here you find the sources of the bootloader for printers based on the BEETHEFIRST 3D printer. The bootloader has a GPL license so you can use it and edit it. It is a mashup between many original parts and you can find the respective acknowledges in the sources.
Please find the stable releases here: https://github.com/beeverycreative/beethefirst-bootloader/tree/develop/releases
You may flash the bootloader using the BootloaderUpdaer tool.
If you are interested in following and/or participating on development, feel free to contact us to: jpinto@beeverycreative.com
The ARM toolchain used is Sourcery G++ Lite 2010q1-188 for ARM EABI.
On the bootloader sources folder you should execute make all to build the bootloader. The built bootloader will be placed inside FLASH_RUN folder. You may after write the bootloader using the BootloaderUpdaer tool or by using an In-System Programming tool such as LPC21ISP.