A makefile to be included from a small, configuration makefile in
your arduino sketch dir. It tries to have enough sane defaults that
you ought to be able to simply include it or copy it into the dir
as Makefile. At the very least, you should probably set BOARD to the
proper value and include.

e.g.

BOARD=atmega328
include /path/to/mard.mk

Typical values to set are as follows:

BOARD
COREH
HARDWARE
ALIBS
ALIBPATH
TARGET

BOARD is the board tag for your target environment. This is how the
clock speed, mcu and f_cpu values are found, from $(HARDWARE)/boards.txt
From there, it creates a board.mk file, which is also included. board.mk
defines various variables from the definitions for that board in
boards.txt. Defaults to uno

COREH is a list of core include files used by your program, such as
wiring.h or WProgram.h. These can be listed by just name, e.g.
"HardwareSerial wiring" or with the extension "HardwareSerial.h
wiring.h". COREH has no defaults.

HARDWARE is the path to the arduino hardware directory, usually (and by
default) /usr/share/arduino/hardware/arduino

ALIBS is a list of arduino library addons to use, like LiquidCrystal or
MeetAndroid. Simply list each one you use by name. e.g.
ALIBS=MeetAndroid Wire

ALIBPATH is the path where the ALIBS are found. You can list multiple
paths, seperated by space. The first path found that works for each ALIB
will be the one used. e.g. ALIBPATH=libs /usr/share/android/libraries
Default is /usr/share/android/libraries

TARGET is the name of your program, aka the name of your directory. This
is what will ultimately be built (and possibly uploaded) It will be set
to the name of your directory by default.  The default goal will be to
build $(TARGET).$(BOARD).hex, building the executable
$(TARGET).$(BOARD).elf along the way. BOARD is included in the final
output as a clear communication of what board was built for (so you
don't have to double check board.mk to be sure)

Other things can be overridden, such as CC, CFLAGS, CXX, CXXFLAGS, etc.
CC and CXX are already set to avr-gxx versions, but may need to be set
with the full path on your system if it can't find them.