Reversing Camera (RFK), Function - GF54.65-P-0005FR
Model 257, 290
up to model year 2021
with code 218 (Rear view camera)
except code 235 (Active Parking Assist)
Shown on model 257, 290
Function requirements, general
- Tml 15 ON:
The electronic ignition lock control unit sends the status of circuit 15 to the reversing camera control unit via user interface CAN.
- Function enabled through control menu on the head unit:
The head unit sends the function enable to the reversing camera control unit via user interface CAN.
- Drive position "R" engaged
- Trunk lid closed:
If the trunk lid is not closed, the picture in the Audio/COMAND display is overlaid with a warning message. The guide lines are hidden from view.
The rear SAM control unit sends information regarding the status of the trunk lid (open or closed) via interior CAN, electronic ignition lock control unit and user interface CAN to the reversing camera control unit and to the instrument cluster.
On initial startup and after being replaced, the reversing camera must be recoded using the diagnostic tester. The reversing camera is calibrated automatically after initial startup.
Reversing camera, general
The reversing camera control unit is an optical parking aid. Its tasks include the recording of images of the area to the rear of the vehicle, the generation of dynamic and static guide lines and the transmission of the picture data to the head unit. The pictures recorded by the reversing camera using an extended angle of vision of ∠ > 180° are processed accordingly by the integrated control unit. The current driving path is shown on the Audio/COMAND display in the form of guide lines based on the vehicle dimensions, vehicle speed and steering wheel angle.
The reversing camera function comprises the following subfunctions:
- Function sequence for activating/deactivating reversing camera
- Function sequence for actuating the camera cover
- Function sequence for picture recognition, picture output
Function sequence for activating/deactivating reversing camera
The reversing camera control unit is activated when gear range "R" is engaged.
Gear range "R" is engaged through the fully integrated transmission control electric controller unit control unit. The fully integrated transmission control electric controller control unit then sends the "Gear range R engaged" status to the electronic ignition lock control unit over the drive train CAN, powertrain control unit and the suspension FlexRay.
The electronic ignition lock control unit uses the incoming information to generate the "Reverse gear engaged" status that is independent of the transmission variant and sends this via user interface CAN to the reversing camera control unit.
The reversing camera control unit evaluates the input factors and activates or deactivates the reversing camera function.
The reversing camera control unit is deactivated under the following conditions:
- Vehicle speed during forward travel v > 12 km/h
- Driving distance during forward travel s > 10 m
- Time period t < 255 s when reverse gear not engaged or gear range "R" not engaged
- Gear range "P" engaged (transmission 725)
- Tml. 15 OFF
Function sequence for actuating the camera cover
In order to protect the camera lens from dirt, it is covered by a camera cover. The camera cover is automatically opened or closed according to the status of the reversing camera control unit (activated or deactivated).
The camera cover is opened and closed when requested by the reversing camera control unit. The reversing camera control unit sends this to the rear SAM control unit via user interface CAN, electronic ignition lock control unit and interior CAN. The rear SAM control unit then actuates the rear camera cover motor directly. The status of the rear camera cover (open or closed) is detected from the rear camera cover motor switch. The rear SAM control unit reads in the status of the rear camera cover motor switch directly and sends this to the reversing camera control unit via interior CAN, electronic ignition lock control unit and user interface CAN.
To allow the camera lens to be cleaned, the camera cover can be opened using the control menu of the head unit. During this, no image is shown in the Audio/COMAND display. The head unit sends the "Service mode" request to the reversing camera control unit via user interface CAN. The further course of signals corresponds to that for the opening of the camera cover when the reversing camera control unit is activated.
The camera cover is automatically closed from a speed of v > 30 km/h (irrespective of any calibration procedure) or after switching off circuit 15. During a calibration procedure, it is possible that the camera cover remains open for the duration of the calibration even after the reversing camera function has been deactivated.
Additional function requirements for picture recording and picture output
- Reversing camera control unit activated
Function sequence for picture recognition, picture output
The reversing camera control unit sends the request to display the picture data over the user interface CAN to the head unit, processes the recorded camera pictures and then sends the processed picture data over an HSVL line to the head unit. The head unit activates the Audio/COMAND display over the telematics CAN and sends the processed picture data over an HSVL line to the Audio/COMAND display. The processed picture data is then shown on the Audio/COMAND display.
The reversing camera control unit uses the steering wheel angle and stored vehicle parameters (lane and exterior contour of the vehicle) to calculate guide lines which are superimposed on the display.
The steering angle is recorded by the steering wheel angle sensor. The steering column tube module control unit reads in the signals of the steering wheel angle sensor directly and sends information regarding the steering wheel angle via chassis FlexRay, electronic ignition lock control unit and user interface CAN to the reversing camera control unit.
The reversing camera function can be operated in the following modes which the driver can select:
- Maneuvering mode
- Trailer mode (with CODE 550 (Trailer hitch))
- Wide-angle mode
The selection is made in the control menu of the head unit at the appropriate operating level. The following options are available for navigating in the control menu:
- Except with code 446 (Touchpad only), navigation can be performed using the Audio/COMAND control panel. The corresponding control signals are sent by the Audio/COMAND control panel (except code 446 (Touchpad only)) over the telematics CAN to the head unit.
- With code 446 (Touchpad only) or code 448 (Touchpad), navigation can be performed using the touchpad. The corresponding control signals are sent by the touchpad (with code 446 (Touchpad only) or code 448 (Touchpad)) over the telematics CAN to the head unit.
- Navigation can be performed by voice control. The driver hands-free system microphone is read directly by the head unit.
- Navigation can be performed via the head unit finger navigation pad and the "Back" button on the steering wheel. The head unit finger navigation pad and the "Back" button transmit the relevant control signals via the steering wheel electronics, the steering wheel CAN, the steering column tube module control unit the suspension FlexRay the electronic ignition lock control unit and the user interface CAN to the head unit.
- With code 246 (Analog clock) the control menu can be called up using the Vehicle button in the upper control panel control unit. The status of the Vehicle button is sent by the upper control panel control unit over the LCP LIN the Audio/COMAND control panel (except code 446 (Touchpad only)) or the touchpad (with code 446 (Touchpad only) or code 448 (Touchpad) and the telematics CAN to the head unit.
If the reversing camera was previously operated in maneuvering mode, the maneuvering mode is activated again when reverse gear or the "R" gear range is engaged.
Maneuvering mode:
The maneuvering mode assists the driver when reversing while parking. To do so, dynamic guide lines are shown in the display in addition to the pictures recorded by the reversing camera.
Display of dynamic and static guide lines (with steered wheels)
Virtual steering angle (yellow lane):
Yellow guide lines (virtual steering angle) are displayed when reverse gear or gear range "R" is engaged. They indicate the path which the vehicle would follow with the current steering wheel angle. The yellow guide lines are automatically adapted as the steering wheel angle changes. The distance between the two yellow guide lines is slightly more than the vehicle width.
Parking procedure:
To enter a parking space the steering wheel angle must be adapted until one of the outer yellow guide lines virtually touches the parking space marking. The parking space marking can for example be another vehicle or a line on the asphalt. The vehicle must now be reversed and the steering angle adapted accordingly until the parking space markings run parallel to the current direction of travel.
Virtual vehicle width (yellow guide lines):
Next the steering wheel must be turned back to the straight-ahead position in order to drive in a straight line up to the final park position in the parking space During this process the virtual vehicle width can be used to check whether the vehicle is in a straight position relative to the parking space and whether the parking space is wide enough.
The outer yellow guide lines symbolize the vehicle width including the outside mirrors.
The distance lines inform the driver of the distances between the rear area and obstacles.
Trailer mode (with code 550 (Trailer hitch)):
Trailer mode supports the driver when reversing to a trailer by zooming to the trailer hitch's ball head To do so special guide lines are shown in the display in addition to the pictures recorded by the reversing camera.
Display of distance lines in trailer mode (with code 550 (Trailer hitch))
Virtual steering angle (yellow guide line):
The virtual steering angle (yellow guide line) and the distance line (red guide line) are shown as soon as the driver engages reverse gear or the gear range "R" The virtual steering angle indicate to the driver the path which the vehicle would follow with the current steering wheel angle This curve is automatically adapted to the situation as the steering angle changes. The length of the guide line corresponds to approx. s = 1 m.
Distance line around the ball head (red guide line):
The distance line (red guide line) is shown with a radius of s = 0.30 m around the ball head.
All the guide lines are hidden for an attempted correction (forward travel) and shown again when the reverse gear or gear range "R" is engaged again taking the following parameters into consideration:
- Time period t < 255 s
- Vehicle speed v < 12 km/h
- Driving distance during forward travel s < 10 m
The picture displayed disappears when these parameters are exceeded. The reversing camera then remains in standby mode.
The direction of travel is defined using the wheel rotation direction. The vehicle speed is calculated from the wheel speed.
The Electronic Stability Program control unit sends the corresponding information via the suspension FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster. The instrument cluster calculates the vehicle speed to be displayed and sends it via user interface CAN to the reversing camera control unit.
Wide-angle mode:
The wide-angle mode provides assistance when reversing into traffic areas that are not clearly visible. The reversing area is shown in the Audio/COMAND display as a three-part view with an angle of ∠ > 180°. This provides a clear view into a traversing road in good time, e.g. when reversing out of a narrow lane.
View of the area to the rear of the vehicle in wide-angle mode
| Electrical function schematic, reversing camera | PE54.65-P-2051-97XBA | ||
| Overview of system components of parking assistance systems | GF54.00-P-9997FR |