FlexRay Module (FLEXRAYV4)
MFR4310 Reference Manual, Rev. 2
178 Freescale Semiconductor
CCFM equaling 0 to indicate the slot assignment and to trigger the null frame transmission. In case of an
receive message buffer, this buffer is not added to the matching message buffer list.
A message buffer matches its cycle counter filter for the communication cycle with the number CYCCNT
if at least one of the following conditions evaluates to true:
Eqn. 3-8
Eqn. 3-9
3.4.7.1.3 Message Buffer Channel Assignment Consistency
The message buffer channel assignment given by the CHA and CHB bits in the Message Buffer Cycle
Counter Filter Registers (MBCCFRn) defines the channels on which the message buffer receive or
transmit. The message buffer with number n transmits or receives on channel A if
MBCCFRn.CHA equals 1 and transmits or receives on channel B if MBCCFRn.CHB equals 1.
To ensure correct message buffer operation, all message buffers assigned to the same slot must have a
consistent channel assignment. That means that all message buffers assigned to the same slot must be
assigned to only one channel, or assigned to both channels. The behavior of the message buffer search is
not defined, if both types of channel assignments occur for one slot. An inconsistent channel assignment
for message buffer 0 and message buffer 1 is depicted in Figure 3-126.
Figure 3-126. Inconsistent Channel Assignment
3.4.8 Individual Message Buffer Reconfiguration
The initial configuration of each individual message buffer can be changed even when the protocol is not
in the POC:config state. This is referred to as individual message buffer reconfiguration. The
configuration bits and fields that can be changed are given in the section on Specific Configuration Data.
The common configuration data given in the section on Specific Configuration Data can not be
reconfigured when the protocol is out of the POC:config state.
3.4.8.1 Reconfiguration Schemes
Depending on the target and destination basic state of the message buffer that is to be reconfigured, there
are three reconfiguration schemes.
3.4.8.1.1 Basic Type Not Changed (RC1)
A reconfiguration does not change the basic type of the individual message buffer, if both the message
buffer transfer direction bit MBCCSn.MTD and the message buffer type bit MBCCSn.MBT are not
changed. This type of reconfiguration is denoted by RC1 in Figure 3-127. Single transmit and receive
CYCCNT MBCCFRn CCFMSK[]∧ MBCCFRn CCFVAL[]MBCCFRn CCFMSK[]∧=
MB0
MBCCFR0.CHA = 1, MBCCFR0.CHB = 0
MB1
dual channel assignment
single channel assignment
MBFIDR0.FID = 10
MBFIDR1.FID = 10
MBCCFR1.CHA = 1, MBCCFR1.CHB = 1
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