UI layout
=========

There are two buttons for UI operation, SELECT and BACK. Outside of the menu,
these simply cycle between the available modes. The current mode is announced
(morse code) after a short delay.

Holding down SELECT puts you in menu mode. The POWER LED will now flash to
indicate this. To navigate, press the SELECT and BACK buttons momentarily to
move up and down in the menu. Again, after a pause the item will be read out.
Holding SELECT or BACK either chooses the option, or backs out.

Pressing PTT while in a menu exits the entire menu tree without saving
changes to flash storage.

The menu structure looks like this:

    -> Root menu:
        |---> "MODE": Boot-up Operating mode
        |       |---> "ANA":    Analogue mode
        |       |---> "1600":   FreeDV 1600
        |       '---> "TONE":   Test tone
        |
        |---> "TOT": Time-out timer
        |       |---> "TIME":   Total time-out period (0 == disabled)
        |       |               0-10 minutes in 5 second steps
        |       '---> "WARN":   Warning beep period (0 == disabled)
        |                       0-${TIME} seconds in 5 second steps
        |
        '---> "UI": User interface options
                |---> "FREQ":   Morse frequency
                |               50-2000 Hz in 50Hz steps
                |---> "WPM":    Morse send speed (PARIS standard)
                |               5-60 WPM in 5 WPM steps
                '---> "VOL":    Menu volume
                                1-15 units.

Settings are saved when you hold down BACK to leave the root menu.

Factory Reset
=============

To perform a factory reset, hold down BACK whilst powering the device on. A
loud beep should be heard and the SYNC LED should flash. Release, and the
device should boot up with factory defaults.
