Bootjack

What is Bootjack?

Bootjack is a bootloader and configuration framework for AVR microprocessors. It is designed to function much like the BIOS on your PC. It uses the avr109 protocol to communicate over serial (RS-232) with a host-based bootload client (e.g. AVRDUDE). Bootjack is written entirely in C, which makes it very easy to read and modify. Despite the fact that its written in C, Bootjack can fit into as little as 1KB of flash.

Bootloader?

The bootloader is a self-modifying program that allows the processor to flash itself. Instead of using an ISP, JTAG, or HVPP programmer to flash the device, the image can be transfered over a serial connection. This is especially useful if you don't have a hardware programmer readily available.

Configuration framework?

Bootjack's configuration framework makes it easy to create command-line interfaces. Menus are the core of the interface and can be easily defined with the 'menu' structure. A simple example is provided for reference. When run, the example menu looks like the following:

How do I build this?

Note: Bootjack currently requires avr-gcc 4.7.1 or greater to build. Support for avr-gcc 4.7.0 and earlier is coming soon.

The following packages are needed to build:

• make
• avr-gcc >= 4.7.1
• avr-libc >= 1.8

Once these have been installed, run make from Bootjack's root directory. This will build the default project and create build/bootjack.elf and build/bootjack.hex. When changing target architectures or build options, its easiest to copy and rename config/default.mk and then modify the first line of the main Makefile (CONFIG = default) to point to the new config. For example, copy config/default.mk to config/myproject.mk and change CONFIG = default to CONFIG = myproject.