increase the timeout to 5 minutes

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
change bootload_delay to uint16_t

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
fix formatting

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
update checksum when saving a new value

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
fix formatting

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
add master boot record support

When booting, the bootloader should only wait for
a new image when either no image has been flashed yet or
the user explicitly wishes to update the image. Another reason
would be when a previous flash failed (image corruped, image doesn't
reach the main loop).

Apart from that, the bootloader should immidiately start the application.

The user can now invoke the extended delay by the already established
ECMD command "bootloader".

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
added longer identifier to struct

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
fixed wrong format (%s) of mbr.identifier

mbr.identifier is not always \0-terminated and therefore
needs to be printed char by char

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
fixed indentation

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
leave the last four bytes untouched for flash count

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
reduce sram footprint by using seperate structures

the rather long identifier only needs to be written
and checked by the mbr module and will not be used
during normal operation.

By keeping the identifier seperated and not in sram we
can save 3 bytes.

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
disable mbr debug output by default

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
Merge pull request #183 from mguentner/mbr-li

Master Boot Record Support