Citrus is a bare metal lightweight operation system designed for the Cortex®-A series. Every thing will be completely bare metal - no libraries - literally.

Coming soon

Download and burn the disk image file and insert into the board. This will load the bootloader which will load the kernel. To enter debug mode, connect a jumper to PC20 and make the kernel using make install.

Some packages is required in order to build the operating system. I recomend using Ubuntu, either native or in WSL. The build-essentials package is used for running make, and the gcc-arm-none-eabi is the compiler toolchain used for building and debugging the operating system.

> sudo apt update
> sudo apt install build-essential
> sudo apt install gcc-arm-none-eabi

Then you must install the second stage bootloader; c-boot, which will load the operating system into main memory.

> git clone https://github.com/strawberryhacker/c-boot
> cd c-boot
> make

This will generate a binary called boot.bin in the build/ folder. Place this file in the root directory of a FAT formatted SD card and plug it into the board. The next step is to download and build the kernel.

> git clone https://github.com/strawberryhacker/citrus
> cd citrus
> make install

This will load the kernel image to main memory over serial and start it. Support for loading the kernel from an SD card will be added to c-boot later.