Civil Engineering Reference
In-Depth Information
Fig. 3.16
Tx to Rx measurement
3.4.3.4
MultiCAN: Flexible Interrupts
MultiCAN has up to 16 interrupt nodes, called Service Request Nodes (SRN),
which can be assigned to interrupt events on the MultiCAN module. Each message
object can cause an interrupt on receive, transmit, or both. The frame counter can be
used to get time and message information. It is also having an overflow interrupt,
to enable a better monitoring of the CAN traffic. Therefore, the initialization is as-
signing interrupt events (Fig.
3.17
) to interrupt nodes. All used interrupt sources are
mapped to an interrupt node (an interrupt node can handle more than one interrupt
source). This is done via bit-field setting. It is also possible to keep some interrupt
nodes on polling, but to handle others within an interrupt routine.
By having this variety of interrupt sources and interrupt nodes, it is possible to
have, for example, status information on a lower interrupt level or to poll these, but,
for example, error situations like a bus-off (Alert, ALRT) can be handled on higher
priority levels. Therefore, an appropriate reaction to an event can be assigned.
3.4.4
The XC2000 Family in GW Applications—An Application
Example Using MultiCAN
Microcontrollers of the XC2000/XE16x family do have the “C166SV2 Core” with
MAC (multiplier-accumulator, set of digital signal processor (DSP) functions) unit.
The very high-end one even includes a cache. They are the logical progression of
the previous C16x and XC16x family. The CPU and the peripherals can run up to
128 MHz. The family members do have different MultiCAN modules, with differ-
ent amount of nodes and message objects. Most of the family members, besides
the very low-end one, do have six nodes and 256 message objects. In addition,
depending on the device, up to ten Local Interconnect Network (LIN) buses can
