examples: Add blink example

This patch adds a simple blink example which inverts the green led
each second.

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
cc2540mini: Add putchar()

Each platform should define its own putchar() according to platform
characteristics.

Since cc2540mini porting is in early stage, we define an empty
putchar() so we are able to compile hello-world example.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
cc2540mini: Add README with general instructions

This patch adds a README file containing general instructions about
how to prepare the system to work with cc2540mini and how to build
applications targeting it.

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
cc2540mini: Add upload rule to Makefile

This patch adds "upload" rule to make easier to upload a new firmware
to cc2540mini using CC-Debugger hardware and cc-tool software.

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
Add cscope files to .gitignore

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Add cc2540mini build files to .gitignore

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
cc2540mini: Initialize clock module

Since cc2540 and cc253x shares same SFR for clock configuration, we can safely
call cc253x's implementation. We also need to call soc_init() because it
activates the global interruption flag (EA).

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
cc2540mini: Initialize process module

This patch initializes the process module and implements a simple
main loop, which process events and polls.

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
cc2540mini: Initialize etimer module

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
cc2540mini: Initialize ctimer module

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
cc2540mini: Initialize rtimer module

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
cc2540mini: Add support for platform buttons

This patch implements support for cc2540mini B3 and B4 buttons using
Contiki sensor feature.

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>
examples: Add platform buttons example

This patch adds an example which handles with both buttons present
in the platform.

Signed-off-by: Paulo Borges <paulo.borges@openbossa.org>