Displaying time, function - GF54.30-P-3024Q
Model 209.3 /4
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 usually derived from the extremely constant mechanical oscillations of an oscillator crystal. An oscillator crystal (1) with a very high frequency (several megahertz) is normally used. This frequency is then scaled down to the required frequency of 1 Hz using an electronic frequency scaler with control electronics (2). In this way, the liquid crystal display (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 driver can set the clock in the "Settings" menu using the buttons on the multi-function steering wheel:
- Scroll forward/back button (S110s1)
- System selection button (S110s3)
- + and, specific function setting and volume control button (S111s1)
The signals from these buttons are registered by the steering column module (N80) and relayed to the instrument cluster (A1) over the interior CAN.
The instrument cluster (A1) also outputs the current time as a message on the interior CAN.
Displaying the time using COMAND operating, display and control unit system (code 352a) with navigation module for COMAND (code 527)
In vehicles with COMAND, 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 relayed by the COMAND operating, display and control unit (A40/3) as a message on the interior CAN.
If the equipment code for COMAND is set in the instrument cluster (A1), it uses this time information.
If the antenna systems (A2/49) receive GPS signals, these signals 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.
| Instrument cluster (IC), location / task | GF54.30-P-3039Q |