
Chapter 13 FlexRay Communication Controller (FLEXRAY)
MC9S12XF - Family Reference Manual, Rev.1.19
Freescale Semiconductor
561
13.6.6.2.3
Message Buffer Transitions
Application Transitions
The application transitions can be triggered by the application using the commands described in
Table 13-executed immediately. If the command is ignored, it must be issued again.
The enable and disable commands issued by writing 1 to the trigger bit MBCCSRn.EDT. The transition
that will be triggered by each of these command depends on the current value of the status bit
MBCCSRn.EDS. If the command triggers the disable transition HD and the message buffer is in one of
the states CCSa, HLckCCSa, CCMa, HLckCCMa, CCNf, HLckCCNf, or CCTx, the disable transition has
no effect (command is ignored) and the message buffer state is not changed. No notication is given to the
application.
The lock and unlock commands issued by writing 1 to the trigger bit MBCCSRn.LCKT. The transition that
will be triggered by each of these commands depends on the current value of the status bit
MBCCSRn.LCKS. If the command triggers the lock transition HL and the message buffer is in the state
CCTx, the lock transition has no effect (command is ignored) and message buffer state is not changed. In
CCSa
10––
Slot Assigned - Message buffer assigned to next static slot.
Ready for Null Frame transmission.
HLckCCSa
1
MSG
–
Locked and Slot Assigned - Applications access to data, control,
and status.Message buffer assigned to next static slot
CCNf
1
0
–
NF
Null Frame Transmission
Header is used for null frame transmission.
HLckCCNf
1
MSG
NF
Locked and Null Frame Transmission - Applications access to
data, control, and status. Header is used for null frame transmission.
CCMa
1
0
–
CM
Message Available - Message buffer is assigned to next slot and
cycle counter lter matches.
HLckCCMa
1
MSG
–
Locked and Message Available - Applications access to data,
control, and status. Message buffer is assigned to next slot and cycle
counter lter matches.
CCTx
1
0
–
TX
Message Transmission - Message buffer data transmit. Payload
data from buffer transmitted
CCSu
1
0
–
TX
Status Update - Message buffer status update. Update of status
ags, the slot status eld, and the header index.
Table 13-95. Single Transmit Message Buffer Application Transitions
Transition
Command
Condition
Description
HE
MBCCSRn.EDT:= 1
MBCCSRn.EDS = 0 Application triggers message buffer enable.
HD
MBCCSRn.EDS = 1 Application triggers message buffer disable.
Table 13-94. Single Transmit Message Buffer State Description (Sheet 2 of 2)
State
MBCCSRn
Access Region
Description
EDS
LCKS
Appl.
Module