NXP Semiconductors MPC5644A, Reference Manual, Page: 1556 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
1556 Freescale Semiconductor
33.6.6.2.3 Message buffer transitions
Application transitions
The application transitions can be triggered by the application using the commands described in
Table 33-107 . The application issues the commands by writing to the Message Buffer Configuration,
Control, Status Registers (FR_MBCCSRn) . Only one command can be issued with one write access. Each
command is executed immediately. If the command is ignored, it must be issued again.
Message Buffer Enable and Disable
The enable and disable commands issued by writing 1 to the trigger bit FR_MBCCSRn[EDT]. The
transition that will be triggered by each of these command depends on the current value of the status bit
FR_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 notification is given
to the application.
If the communication controller is started as a non-coldstart node, and the message buffers are configured
and enabled in the POC config state for Slot 1, then the message buffer cannot be disabled in the
INTEGRATION_LISTEN state by directly writing 1 to the EDT bit. To facilitate this, a FREEZE
command needs to be issued just before running the message buffer disable for slot 1. Executing this
command enables the message buffer disable during the LISTEN states.
Message Buffer Lock and Unlock
The lock and unlock commands issued by writing 1 to the trigger bit FR_MBCCSRn[LCKT]. The
transition that will be triggered by each of these commands depends on the current value of the status bit
FR_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 this case, the message buffer lock error flag LCK_EF in the
CHI Error Flag Register (FR_CHIERFR)
is set.
HLckCCMa 1 1 MSG — Locked and Message Available – Applications access to data,
control, and status. Message buffer is assigned to next slot and
cycle counter filter 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 flags, the slot status field, and the header index.
Table 33-106. Single transmit message buffer state description (Sheet 1 of 2) (continued)
State
FR_MBCCSRn Access region
Description
EDS LCKS Appl. Module