MFR4300 Datasheet, PDF (164/266 Pages) Freescale Semiconductor, Inc – FlexRay Communication Controllers

FlexRay Module (FLEXRAYV2)
Module Transitions
The module transitions that can be triggered by the FlexRay module are described in Table 3-98. Each
transition will be triggered for certain message buffers when the related condition is fulfilled.
Table 3-98. Receive Message Buffer Module Transitions
Transition
BS
SLS
Condition
slot match and
CycleCounter match
slot start
Description
Buffer Subscribed - The message buffer filter matches next slot and cycle.
Slot Start - Start of either Static Slot or Dynamic Slot.
SNS
SSS
SU
symbol window start or
NIT start
slot start or
symbol window start or
NIT start
status updated
Symbol Window or NIT Start - Start of either Symbol Window or NIT.
Slot or Segment Start - Start of either Static Slot, Dynamic Slot, Symbol
Window, or NIT.
Status Updated - Slot Status field, message buffer status flags, header index
updated. Interrupt flag set.
Transition Priorities
The application can trigger only one transition at a time. There is no need to specify priorities among them.
As shown in Table 3-99, the module transitions have a higher priority than the application transitions. For
all states except the CCRx state, a module transition and the application lock/unlock transition HL/HU and
can be executed at the same time. The result state is reached by first applying the module transition and
subsequently the application transition to the intermediately reached state. For example, if the message
buffer is in the buffer subscribed state CCBs and the module triggers the slot start transition SLS at the
same time as the application locks the message buffer by the HL transition, the intermediate state is CCRx
and the resulting state is locked buffer subscribed state HLckCCRx.
Table 3-99. Receive Message Buffer Transition Priorities
State
Idle
HLck
CCRx
Priorities
BS > HD
BS > HD
SSS > HL
Description
module vs. application
Buffer Subscribed > Message Buffer Disable
Buffer Subscribed > Message Buffer Disable
Slot or Segment Start > Message Buffer Lock
3.4.6.3.2 Message Buffer Search
The FlexRay module starts a sequential search that checks all message buffers at the following protocol
related events:
• slot start, in the static frame segment
• minislot start, in the dynamic frame segment
• NIT start
The filters that are used for the search are described in Section 3.4.7.1, “Individual Message Buffer
Filtering”.
MFR4300 Data Sheet, Rev. 1
164
Freescale Semiconductor