Civil Engineering Reference
In-Depth Information
levels) to guarantee the correct reception. The analyser feature can also be applied to
disconnect a failing node which permanently disturbs communication from the bus
in order to enable the remaining still functional system to continue communication.
3.4.2.7
The Interrupt System
TwinCAN has 72 interrupt sources; 32 interrupt sources are for reception and another
32 for transmission, as the very same message object can trigger a receive as well
as a transmit interrupt. (In case of a remote frame) For each CAN node, four status
and error interrupts are existing. The interrupt generation of the TwinCAN module
allows to have up to eight independent interrupt routines as eight interrupt nodes can
be assigned. Therefore, it is quite easy to have a well-defined prioritization among the
events. Thus, it is possible to assign a Peripheral Event Controller (PEC) or Direct
Memory Access (DMA) to a special message object, without having a complete inter-
rupt routine and having a fast copy process from the TwinCAN to the needed memories.
The successor of the TwinCAN module is the MultiCAN module. The Multi-
CAN module can be found on the XC2000/XE16x family, the XC8xx family, and
on all devices of the Audo Next Generation, Audo Future, and Audo MAX family.
By having the same CAN module over all families, the software compatibility of
over 8-, 16-, and 32-bit microcontrollers is given to a high extent.
3.4.3
MultiCAN
Like for the TwinCAN module, first the core functions of the module will be ex-
plained briefly before discussing the most important point in very detail.
The MultiCAN module offers:
• CAN functionality, which is V2.0B active.
• A CAN bus analyser mode and baud rate detection mechanisms for each CAN
node.
• Up to 256 (dependent on the device) message objects that
− can be assigned to the CAN nodes
− can be used for transmission or reception
− offer the remote monitoring mode in case of GW
− have “Frame Counter Monitoring”.
• Acceptance filtering:
− Each message has its own local mask, which allows to receive a group of
messages.
− Each message object is able to receive and transmit messages in standard or
extended format, and by masking also both types can be received via the very
same message object.
− It is possible to have different prioritization rules on the internal arbiter, run-
ning on the message objects.
