Civil Engineering Reference
In-Depth Information
• No negative impact on the physical bus (no disturbance)
• Can be awake with a dedicated CAN frame
• Low current consumption
In addition, this solution must comply with the following three operational modes
of a vehicle and its networked system: the normal CAN communication mode, the
start up phase of the system and the vehicle, and finally the parking mode of the
vehicle with the silent system.
2.5.3.1
Normal Communication Mode
In normal CAN communication, ECUs that are not needed can be set into a special
sleep mode. All other CAN nodes can communicate and will not be disturbed by
the deactivated ECUs. With a dedicated WUF, one or more ECUs can be woken up
with a small time delay.
2.5.3.2
Start-Up Phase
During the start of CAN communication, in a CAN network, all ECUs ramp up
and, together, they will consume a lot of current. This is not necessary and with the
new approach, only the needed ECUs should be ramped up. All other nodes change
from sleep mode to a bus observation mode. After the successful ramp-up, the other
nodes can be added one by one into the communication, if necessary.
2.5.3.3
Parking Cars
If you park a car, a very low current consumption is required to unload the battery.
However, if, for example, the radio is on, all CAN ECUs located on this CAN bus
will stay active and consume a lot of current. With this new solution, only the neces-
sary ECUs are active (for example, wheel to control the radio and the radio itself)
and all other nodes are sleeping or shut off. This reduces the current consumption
dramatically.
2.5.3.4
Partial Networking
In the partial networking approach, the WUF detection unit is implemented in the
high-speed CAN transceiver. This new unit contains:
• A high precision oscillator
• A CAN message decoding unit
• An error-handling management
• A WUF configuration
