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FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
1575
Transition priorities
The application can trigger only one transition at a time. There is no need to specify priorities among them.
, the module transitions have a higher priority than the
application transitions. The priorities among the CC transitions and the related states are given in the
second part of
. These priorities apply only to the transmit side. The internal message transmit
start transition IS has tho lowest priority.
33.6.6.4.4
Message preparation
The application provides the message data through the commit side. The transmission itself is executed
from the transmit side. The transfer of the message data from the commit side to the transmit side is done
by the
Internal Message Transfer
Section 33.6.6.4.5, Internal message transfer
To transmit a message over the FlexRay bus, the application writes the message data into the message
buffer data field of the commit side and sets the commit bit CMT in the
Control, Status Registers (FR_MBCCSRn)
. The physical access to the message buffer data field is
described in
Section 33.6.3.1, Individual message buffers
”.
, the application shall write to the message buffer data field and change the
commit bit CMT only if the transmit message buffer is in one of the states HDis, HDisLck, or HLck. The
application can change the state of a message buffer if it issues the appropriate commands shown in
. The state change is indicated through the FR_MBCCSRn[EDS] and
FR_MBCCSRn[LCKS] status bits.
DSS
Dynamic slot start or
symbol window start or
NIT start
Dynamic Slot or Segment Start
– Start of dynamic slot or symbol window or
NIT
SSS
Slot start or
symbol window start or
NIT start
Slot or Segment Start
– Start of static slot or dynamic slot or symbol window
or NIT
Table 33-121. Double transmit message buffer transition priorities
State
Priority
Description
Module versus application
Idle
IS > HD
IS > HL
Internal Message Transfer Start > Message Buffer Disable
Internal Message Transfer Start > Message Buffer Lock
Module internal
Idle
MA > SA
Message Available > Slot Assigned
CCMa
TX > STS
TX > DSS
Transmission Slot Start > Static Slot Start
Transmission Slot Start > Dynamic Slot Start
Table 33-120. Double transmit message buffer module transitions
Transition
Condition
Description
Summary of Contents for MPC5644A
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