XC886/888CLM
Controller Area Network (MultiCAN) Controller
User’s Manual
15-13
V1.3, 2010-02
MultiCAN, V1.0
15.1.4
Message Object List Structure
This section describes the structure of the message object lists in the MultiCAN module.
15.1.4.1
Basics
The message objects of the MultiCAN module are organized in double-chained lists,
where each message object has a pointer to the previous message object in the list as
well as a pointer to the next message object in the list. The MultiCAN module provides
eight lists. Each message object is allocated to one of these lists. In the example in
, the three message objects (3, 5, and 16) are allocated to the list with
index 2 (List Register LIST2).
Figure 15-6
Example Allocation of Message Objects to a List
Bit field LIST.BEGIN points to the first element in the list (object 5 in the example), and
bit field LIST.END points to the last element in the list (object 3 in the example). The
number of elements in the list is indicated by bit field LIST.SIZE (SIZE = number of list
elements - 1, thus SIZE = 2 for the 3 elements in the example). The bit LIST.EMPTY
indicates whether a list is empty or not (EMPTY = 0 in the example, because list 2 is not
empty).
Each message object n has a pointer MOCTRn.PNEXT that points to the next message
object in the list and a pointer MOCTRn.PPREV that points to the previous message
object in the list. PPREV of the first message object points to the message object itself
because the first message object has no predecessor (in the example message object
5 is the first message object in the list, indicated by PPREV = 5). PNEXT of the last
message object also points to the message object itself because the last message object
MultiCAN_list_basics
Message
Object 5
PPREV = 5
PNEXT = 16
LIST = 2
Message
Object 16
PPREV = 5
PNEXT = 3
LIST = 2
Message
Object 3
PPREV = 16
PNEXT = 3
LIST = 2
Register LIST2
EMPTY = 0
BEGIN = 5
END = 3
SIZE = 2
*
