TC1796
Peripheral Units (Vol. 2 of 2)
Controller Area Network (MultiCAN) Controller
User’s Manual
22-39
V2.0, 2007-07
MultiCAN, V2.0
•
PRI = 01
B
or PRI = 11
B
(priority by list order).
•
PRI = 00
B
and the actual matrix position in a TTCAN network matches the matrix
position(s) given in MOAMRn of MOa, i.e.
CYCLE & MCYCLE = CYCCTM.BCC & MCYCLE and
COLUMN & MCOLUMN = CYCCTM.CSM & MCOLUMN
A message object with PRI = 00
B
can be transmitted only by an active TTCAN node.
The message object that is qualified for transmission and has highest transmit priority
wins the transmit acceptance filtering, and will be transmitted first. All other message
objects lose the current transmit acceptance filtering round. They get a new chance in
subsequent acceptance filtering rounds.
The three priority rules listed before are valid for normal CAN operation (without TTCAN
functionality) as well as for arbitration windows within a TTCAN system matrix.
Figure 22-16 Effective Transmit Request of Message Object
Transmission Acceptance Filtering in TTCAN Exclusive Windows
In exclusive windows of a TTCAN, transmit acceptance filtering is performed as
described in the previous section but with the exception that only message objects with
MOARn.PRI = 00
B
can be transmitted. Message objects with other PRI values are not
taken into account. Hence the transmit acceptance filtering process selects the first
message object in the list that meets the following conditions:
1. MOARn.PRI = 00
B
a) MSGVAL & TXRQ & TXEN0 & TXEN1 = 1 (i.e. the message object qualifies for
transmission)
b) The actual matrix position in a TTCAN network matches the matrix position(s)
given in MOAMR of MOa, i.e.
CYCLE & MCYCLE = CYCCTM.BCC & MCYCLE and
COLUMN & MCOLUMN = CYCCTM.CSM & MCOLUMN
MCA05842
MSGVAL
0 = Object will not be transmitted
1 = Object is requested for transmission
TXRQ
TXEN0
TXEN1
&