PXN20RM Datasheet, PDF (717/1376 Pages) Freescale Semiconductor, Inc – PXN20 Microcontroller

FlexRay Communication Controller (FlexRAY)
Table 26-98. Single Transmit Message Buffer Module Transitions (continued)
Transition
MA
TX
SU
STS
Condition
slot match and
CycleCounter match
slot start and
MBCCSRn[CMT] = 1
status updated
static slot start
Description
Message Available - Message buffer is assigned to next slot and cycle counter
filter matches.
Transmission Slot Start - Slot Start and commit bit CMT is set.
In case of a dynamic slot, pLatestTx is not exceeded.
Status Updated - Slot Status field and message buffer status flags updated.
Interrupt flag set.
Static Slot Start - Start of static slot.
DSS
SSS
dynamic slot start or
symbol window start or
NIT start
slot start or
symbol window start or
NIT start
Dynamic Slot or Segment Start. - Start of dynamic slot or symbol window or NIT.
Slot or Segment Start - Start of static slot or dynamic slot or symbol window or
NIT.
Transition Priorities
The application can trigger only one transition at a time. There is no need to specify priorities among them.
As shown in the first part of Table 26-99, the module transitions have a higher priority than the application
transitions. For all states except the CCMa state, both a lock/unlock transition HL/HD and a module
transition can be executed at the same time. The result state is reached by first applying the application
transition and subsequently the module transition to the intermediately reached state. For example, if the
message buffer is in the HLck state and the application unlocks the message buffer by the HU transition
and the module triggers the slot assigned transition SA, the intermediate state is Idle and the resulting state
is CCSa.
The priorities among the module transitions is given in the second part of Table 26-99.
Table 26-99. Single Transmit Message Buffer Transition Priorities
State
Idle, HLck
CCMa
Idle, HLck
CCMa
Priorities
SA > HD
MA > HD
TX > HL
MA > SA
TX > STS
TX > DSS
Description
module vs. application
Slot Assigned > Message Buffer Disable
Message Available > Message Buffer Disable
Transmission Start > Message Buffer Lock
module internal
Message Available > Slot Assigned
Transmission Slot Start > Static Slot Start
Transmission Slot Start > Dynamic Slot Start
26.6.6.2.4 Transmit Message Setup
To transmit a message over the FlexRay bus, the application writes the message data into the message
buffer data field and sets the commit bit CMT in the Message Buffer Configuration, Control, Status
Registers (MBCCSRn). The physical access to the message buffer data field is described in
Section 26.6.3.1, Individual Message Buffers.
Freescale Semiconductor
PXN20 Microcontroller Reference Manual, Rev. 1
26-103