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

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

Component Identification:

The components marked with dashed lines are only of significance on vehicles with Comand (Code 352a).

Function requirements:
^ Circuit 15 ON

General information
For a time measurement (clock) a periodic process with a cycle duration of high accuracy is required. (e.g. earth's rotation, pendulum oscillation.)
Likewise, an electronic clock requires an electric clock signal with high frequency accuracy. This clock signal is usually derived from the very constant, mechanical vibrations of an oscillator crystal. A quartz (1) with a very high frequency (several MHz) is normally used. This frequency is then scaled down to the required frequency of 1 Hz using an electronic frequency scaler (2). Every second the display (3) receives an electrical pulse for switching on the display.

Displaying the time in vehicles without COMAND
The electronic clock (A70) works according to the aforementioned principle. In addition electronics are still required for adjusting the clock.
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 pushbuttons are read in by the steering column tube module (N80) and passed to the instrument cluster (A1) via the interior compartment CAN. (For further information see Operating Instructions)

The liquid crystal display (LCD) of the electronic clock (A70) is located in the front center instrument panel PTS warning indicator (A44/4). This is connected to the instrument cluster via a serial interface (LIN-bus; LIN=Local Interconnect Network)A1

The instrument cluster (A1) also gives the current time as a message on the CAN-interior.

Display time on vehicles with COMAND (code 352a)

In vehicles with COMAND, the instrument cluster (A1) adopts the time from the COMAND operating, display and controller unit (A40/3). The time is therefore set there.
Every minute time information is placed on the CAN interior as a message from the COMAND operating, display and controller unit (A40/3).
If A1) the equipment variant COMAND (code 352a) is coded in the instrument cluster, it takes over this time information.

If GPS signals are received from the GPS antenna (A2/23), then it is possible to switch over automatically from summer time to standard time. Adjustments for different time zones are also automatic. This is possible as COMAND has local information through GPS.

If no time information is being received from COMAND, the instrument cluster accesses its own internal clock. The is no provision for manual adjustment of this internal timekeeper.