Add multi-board sync.

Signed-off-by: Paul Brook <paul@nowt.org>
Fix reset glitch

Signed-off-by: Paul Brook <paul@nowt.org>
Disable unused peripherals

Signed-off-by: Paul Brook <paul@nowt.org>
Process incoming data first

Signed-off-by: Paul Brook <paul@nowt.org>
Sleep mode

Signed-off-by: Paul Brook <paul@nowt.org>
Avoid sending data when idle.

Signed-off-by: Paul Brook <paul@nowt.org>