NXP Semiconductors MPC5644A, Reference Manual, Page: 1564 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
1564 Freescale Semiconductor
33.6.6.3.1 Message buffer transitions
Application transitions
The application transitions that can be triggered by the application using the commands described in
Table 33-112 . 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 CCBs, HLckCCBs, or CCRx, 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 while the message buffer is in the
state CCRx, 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.
HLckCCBs 1 1 MSG — Locked and Buffer Subscribed – Applications access to data,
control, and status. Message buffer subscribed for reception.
CCRx 1 0 — — Message Receive – Message data received into related
shadow buffer.
HLckCCRx 1 1 MSG — Locked and Message Receive – Applications access to data,
control, and status. Message data received into related shadow
buffer.
CCSu 1 0 — RX Status Update – Message buffer status update. Update of
status flags, the slot status field, and the header index.
Table 33-111. Receive message buffer states and access (continued)
State
FR_MBCCSRn Access from
Description
EDS LCKS Appl. Module