Image Processing Reference
In-Depth Information
There are two Volcano calls to handle immediate frames:
•
A “transmit” call, which immediately sends the designated frame to the network
•
A “receive” call, which immediately processes the designated incoming frame if that frame
is pending
There is also a “read update bit” call to test the update bit of a subscribed signal within an
immediate frame.
The signals packed into an immediate frame can be accessed with normal read and write function
callsinthesamewayasallothernormalsignals.
The application programmer is responsible for ensuring that the transmit call is made only when
the signal values of published signals are consistent.
19.7.2 Frame Modes
In Volcano it is allowed to specify different frame modes for an ECU. A frame mode is a description
of an ECU working mode, where a set of frames (signals) can be active (input and output). he frames
canbeactiveinoneormanyframemodes.hetimingpropertiesofframesdonothavetobethe
same for different frame modes supporting the same frame.
19.8 Network Interfaces
A network interface is the device used to send and receive frames to and from networks. A network
interfaceconnectsagivenECUtothenetwork.IntheCANcasemorethanonenetworkinterface
(CAN controller) on the same ECU may be connected to the same network. Likewise, an ECU may
be connected to more than one network.
The network interface in Volcano is protocol specific. The protocols currently supported are CAN
and LIN; FlexRay and MOST are under implementation.
The network interface is managed by a standard set of Volcano calls. hese allow the interface to
be initialized or reinitialized, connected to the network (i.e., begin operating the defined protocol),
and disconnected from the network (i.e., take no further part in the defined protocol). here is also
a Volcano call to return the status of the interface.
19.9 Volcano API
The Volcano API provides a set of simple calls to manipulate signals and to control the CAN/LIN
controllers. There are also calls to control Volcano sending to, and receiving from networks. To
manipulatesignalstherearereadandwritecalls.Areadcallreturnstothecallerthelatestvalue
ofasignal;awritecallsetsthevalueofasignal.hereadandwritecallsarethesameregardlessof
the underlying network type.
19.9.1 Volcano Thread-of-Control
There are two Volcano calls that must be called at the same fixed rate: v_input() and v_output(). If the
v_gateway() function is used the same calling rate shall be used as for the v_input() and v_output()
functions. he v_output() call places the frames into the appropriate controllers. he v_input() call
takes received frames and makes the signal values available to read calls. he v_gateway() call copies
values of signals in frames received from the network to values of signals in frames sent to the
network. he v_sb_tick() call handles transmitting and receiving frames for sub-buses.
