GF54.30-P-3024T Display Time, Function

GF54.30-P-3024T Display Time, Function

Component Identification:

The components indicated by broken lines are only relevant for vehicles with COMAND operating and display system (code 352) and navigation module for COMAND (code 527).

General information
Time measurement (clock) requires a periodic process with a cycle duration of high accuracy (e.g. earth rotation, pendulum oscillations).
Likewise, an electronic clock requires an electric clock signal with high frequency accuracy. This clock signal is derived from the very constant, mechanical oscillations of a quartz crystal. These oscillations/frequency is then scaled down to the required frequency of 1 Hz using an electronic frequency divider with control electronics (2).

In this way, the liquid crystal display (LCD) (3) receives one electrical pulse every second to change the display.

Displaying time on vehicles without COMAND
The electronic clock (A1p6) works according to the aforementioned principle.

The clock is adjusted via the "Settings" menu using the keys on the multifunction steering wheel:
^ Scroll forward/back button (S110s1)
^ System select button (S110s3)
^ Pushbutton + and -, specific function setting and volume control (S111s1)

The signals from these buttons are read in by the steering column module (N80) and passed on to the instrument cluster (A1) via the interior CAN.

The instrument cluster (A1) also outputs the current time as a message over the interior CAN.

Displaying time via COMAND operating and display system (Code 352) with navigation module for COMAND (code 527)
In vehicles with this equipment, the instrument cluster (A1) adopts the time from the COMAND operating, display and control unit (A40/3). The menus for adjusting the time are therefore unnecessary.
The time information is transmitted by the COMAND operating, display and control unit (A40/3) over the interior compartment CAN as a message.

If the equipment code for COMAND is set in the instrument cluster (A1), it uses this time information.
If the GPS antenna (A2/49) is receiving GPS signals, these can be used to switch between summer and winter time automatically.

If it fails to receive time information from COMAND, the instrument cluster (A1) accesses its own internal clock (timer). The is no provision for manual adjustment of this internal timekeeper.