NXP Semiconductors MPC5644A, Reference Manual, Page: 1573 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor 1573
33.6.6.4.3 Message buffer transitions
Application transitions
The application transitions that can be triggered by the application using the commands described in
Table 33-119 . 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 can be issued on the transmit side only. Any enable or disable command
issued on the commit side will be ignored without notification. The transitions that will be triggered
depends on the value of the EDS bit. The enable and disable commands will affect both the commit side
and the transmit side at the same time. If the application triggers the disable transition HD while the
transmit side is in one of the states CCSa, CCSaCCITx, CCNf, CCNfCCITx, CCMa, CCMaCCITx, CCTx,
or CCSu, the disable transition has no effect (command is ignored) and the message buffer state is not
changed. No notification is given to the application.
Message Buffer Lock and Unlock
The lock and unlock commands can be issued on the commit side only. Any lock or unlock command
issued on the transmit side will be ignored and the double transmit buffer lock error flag DBL_EF in the
CCSaCCITx 1 0 — TX Slot Assigned and Internal Message Transfer –
Message buffer assigned to next static slot and Message
Buffer Data transferred from commit side to transmit side
CCNf 1 0 — TX Null Frame Transmission – Header is used for null frame
transmission
CCNfCCITx 1 0 — TX Null Frame Transmission and Internal Message
Transfer
– Header is used for null frame transmission and
Message Buffer Data transferred from commit side to
transmit side
CCMa 1 0 — — Message Available – Message buffer is assigned to next
slot and cycle counter filter matches
CCMaCCITx 1 0 — — Message Available and Internal Message Transfer –
Message buffer is assigned to next slot and cycle counter
filter matches and Message Buffer Data transferred from
commit side to transmit side.
CCTx 1 0 — TX Message Transmission – Message buffer data transmit.
Payload data from buffer transmitted
CCSu 1 0 — SS Status Update – Message buffer status update. Update of
status flags, the slot status field, and the header index.
Note: The slot status field of the commit side is updated
too, even if the application has locked the commit side.
Table 33-118. Double transmit message buffer state description (transmit side) (sheet 2 of 2) (continued)
State
FR_MBCCSRn Access region
Description
EDS LCKS Appl. Module