GF82.90-D-3001H Scanning of Switch Positions, Function
GF82.90-D-3001H Scanning Of Switch Positions, Function
- with CODE (CL4) Multifunction steering wheel with trip computer
Multifunction steering wheel controls
S110s1 + and - button
S110s3 Accept/terminate phone call button
S111s1 Scroll forward/back button
S111s3 System selection button
S111s5 Signaling horn button
A resistor having a different graduation (ohmage) is integrated upstream of each of the following: the scroll forward/back button, the system selection button, the + and - button as well as the accept/terminate phone call button.
This graduation determines the priority ranks within the left multifunction steering wheel button group (S111) and the right multifunction steering wheel button group (S110) of the MFL.
Priorities
If a number of buttons are actuated simultaneously within the left multifunction steering wheel button group and the right multifunction steering wheel button group, only one function is activated.
Partitioning of valences
Within the left multifunction steering wheel button group, the following priorities exist:
- 1. System selection button
- 2. Scroll forward/back button
Within the right multifunction steering wheel button group, the following priorities exist:
- 1. Accept/terminate phone call button
- 2. + and - button
Example
If "Terminate" on the accept/terminate phone call button is pressed and at the same time volume (-) is pressed on the + and - button, then only the actuation of the accept/terminate phone call button is relayed.
Signal transmission
The left multifunction steering wheel button group and the right multifunction steering wheel button group are read in voltage-coded over 2 direct lines. Voltage coding of the various button functions using only various resistances corresponding to the incrementation would not ensure sufficient insensitivity to interference. For this reason, the voltage generated for checking the keys continuously changes its polarity.
The left multifunction steering wheel button group and the right multifunction steering wheel button group are each connected in series with a diode, whose polarity differs. The left multifunction steering wheel button group or the right multifunction steering wheel button group is checked alternately depending on the polarity of the voltage.
The actual voltage coding is accomplished only within the left multifunction steering wheel button group and the right multifunction steering wheel button group.
The control signals are transmitted voltage-coded from the left multifunction steering wheel button group and right multifunction steering wheel button group on the MFL to the MRM control unit (N80). The MRM control unit converts the signals into messages (e.g. "MFL_ST_WIPPE_1_1 (MFL status, top left button up)") and places them on the Controller Area Network bus class C (engine compartment) (CAN-C). The instrument cluster reads in these messages (e.g. "MFL_ST_WIPPE_1_1 (MFL status, top left button up)") and evaluates them.
The instrument cluster then places the processed messages (e.g. "RT_EIN (switch on dynamometer test mode for Electronic Stability Program (ESP))") on the Controller Area Network bus class B (interior) (CAN-B) or the processed messages (e.g. "UFB_EIN (ambient illumination on)") on CAN-C, where they can be retrieved by other control units.
Preparation of button statuses on MFL
The function of the buttons of the MFL depends partly on the current content of the multifunction display in the instrument cluster. For this reason, the button statuses are interpreted in relation to the current display content in the instrument cluster.
