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TC1728
Controller Area Network Controller (MultiCAN)
indicated by PPREV = 5). PNEXT of the last message object also points to the message
object itself because the last message object has no successor (in the example, object 3
is the last message object in the list, indicated by PNEXT = 3).
Bit field MOCTRn.LIST indicates the list index number to which the message object is
currently allocated. The message object of the example are allocated to list 2. Therefore,
all LIST bit fields for the message objects assigned to list 2 are set to LIST = 2.
20.3.6.2 List of Unallocated Elements
The list with list index 0 has a special meaning: it is the list of all unallocated elements.
An element is called unallocated if it belongs to list 0 (MOCTRn.LIST = 0). It is called
allocated if it belongs to a list with an index not equal to 0 (MOCTRn.LIST > 0).
After reset, all message objects are unallocated. This means that they are assigned to
the list of unallocated elements with MOCTRn.LIST = 0. After this initial allocation of the
message objects caused by reset, the list of all unallocated message objects is ordered
by message number (predecessor of message object n is object n-1, successor of object
n is object n+1).
20.3.6.3 Connection to the CAN Nodes
Each CAN node is linked to one unique list of message objects. A CAN node performs
message transfer only with the message objects that are allocated to the list of the CAN
node. This is illustrated in
Figure
20-12. Frames that are received on a CAN node may
only be stored in one of the message objects that belongs to the CAN node; frames to
be transmitted on a CAN node are selected only from the message objects that are
allocated to that node, as indicated by the vertical arrows.
There are more lists (eight) than CAN nodes (two). This means that some lists are not
linked to one of the CAN nodes. A message object that is allocated to one of these
unlinked lists cannot receive messages directly from a CAN node and it may not transmit
messages.
FIFO and gateway mechanisms refer to message numbers and not directly to a specific
list. The user must take care that the message objects targeted by FIFO/gateway belong
to the desired list. The mechanisms make it possible to work with lists that do not belong
to the CAN node.
User's Manual
20-28
V1.0, 2011-12
MultiCAN, V2.24
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