iCC 2003 CAN in Automation
03-1
MultiCAN – a step to CAN and TTCAN
Ursula Kelling, Infineon Technologies
MultiCAN is a new CAN module, which is building up a bridge between TTCAN level 1
& 2 and normal CAN network. On one hand it has advanced features to mould the
system matrix within the build-in scheduler on the other hand it has an improved list
feature, a hardware gateway and additional features for CAN diagnostics. This paper
compares and shows the improvement between the TwinCAN implementation and the
new MultiCAN implementation. Finally it shows how to build up the system matrix and
how to use the alternative message, in case the information for exclusive time
windows is not ready.
MultiCAN – An Introduction
MultiCAN is a new scalable module, which
will become the new Infineon family CAN.
This module supports from one, up to
eight CAN nodes, with one of them fully
hardware supporting TTCAN (level 1 & 2).
The number of message objects can be up
to 256 message objects, shared for all
nodes. The current implementation
supports four independent nodes with 128
message objects fully CAN 2.0b compliant
and one node TTCAN level 1 and 2
compliant. All nodes support an analyzer
feature, which allows to connect to the bus
system as a passive member of the bus.
Message objects can be concatenated
form of a FIFO or to a hardware supported
gateway.
Message
Object
Buffer
128
Message
Objects
Message
Object
Buffer
128
Message
Objects
Linked List
Control
CAN Node
3
CAN Node
2
CAN Node
1
CAN Node
0
CAN Control
Time Triggered Extension
Timing Control and Synchronization
Scheduler
Schedule Timing Data Memory
MultiCAN Module Kernel
Clock
Control
Address
Decoder
Interrupt
Control
f
CAN
f
OSC
TXDC3
RXDC3
TXDC3
RXDC3
ECTT[7..1]
INT_O
[15..0]
Port
Control
TXDC1
RXDC1
TXDC2
RXDC2
Figure 1: Overview of the MultiCAN Module
with Time-Triggered Extension
TTCAN and CAN nodes
All nodes support CAN, but one node
additionally supports TTCAN level 1 and 2
by hardware. This node offers a built in
scheduler to support the system matrix.
For each message object 'connected' to
the TTCAN system, an emergency
message (alternative message) is
supported. The alternative message can
be sent, if in an exclusive time window the
information for this time window is not
ready. Additionally to these features,
global timing is available and a timing
related interrupt, which can wake up the
system, e.g. out of the gap mode.
Differences: TwinCAN – MultiCAN
MultiCAN as a successor of TwinCAN,
gives advanced features. On TwinCAN
only two nodes were possible. Now more
nodes are supported as before a shared
message object memory part are possible
to give a flexible environment. To provide
the flexibility in terms of number of
message objects per node, a single bit
had to be set, to provide the node
information. Now, having more nodes and
additionally double chained lists a bitfield
became necessary. The list (node)
information can be found in every
message object, to give a decision
parameter for the CAN controller and an
overview of the actual position of every
message object for the user. In Figure 2
an example for this list – node connection
is given.