always required, you can pick and choose what other modules you wish to add to
your user project.
+DMBS is also used in the LUFA Project which provides a
+[detailed documentation](http://www.fourwalledcubicle.com/files/LUFA/Doc/151115/html/_page__build_system.html)
+of DMBS.
+
Here's an example user makefile:
MCU = atmega128