FlexRay Module (FLEXRAYV2)
MFR4300 Data Sheet, Rev. 1
Freescale Semiconductor
165
As a result of the message buffer search, the FlexRay module changes the state of up to two enabled receive
message buffers from either idle state
Idle
or locked state
HLck
to the either subscribed state
CCBs
or
locked buffer subscribed state
HLckCCBs
by triggering the buffer subscribed transition
BS.
If the receive message buffers for the next slot are assigned to both channels, then at most one receive
message buffer is changed to a buffer subscribed state
.
If more than one matching message buffers assigned to a certain channel, then only the message buffer
with the lowest message buffer number is in one of the states mentioned above.
3.4.6.3.3
Message Reception
With the start of the next static or dynamic slot the module trigger the slot start transition
SLS
. This
changes the state of the subscribed receive message buffers from either
CCBs
to
CCRx
or from
HLckCCBs
to
HLckCCRx,
respectively.
During the reception slot, the received frame data are written into the shadow buffers. For details on
receive shadow buffers, see
Section 3.4.6.3.6, “Receive Shadow Buffers Concept
”. The data and status of
the receive message buffers that are the
CCRx
or
HLckCCRx
are not modified in the reception slot.
3.4.6.3.4
Message Buffer Status Update
With the start of the next static or dynamic slot or with the start of the symbol window or NIT, the module
trigger the slot or segment start transition
SSS
. This transition changes the state of the receiving receive
message buffers from either
CCRx
to
CCSu
or from
HLckCCRx
to
HLck,
respectively.
If a message buffer was in the locked state
HLckCCRx
, no update will be performed. The received data
are lost. This is indicated by setting the Frame Lost Channel A/B Error Flag FRLA_EF/FRLB_EF in the
CHI Error Flag Register (CHIERFR)
.
If a message buffer was in the
CCRx
state it is now in the
CCSu
state. After the evaluation of the slot
status provided by the PE the message buffer is updated. The message buffer update depends on the slot
status bits and the segment the message buffer is assigned to. This is described in
Table 3-100
.
Table 3-100. Receive Message Buffer Update
vSS!ValidFrame
vRF!Header!NFIndicator
Update description
1
1
Valid non-null frame received.
- Message Buffer Data Field updated.
- Frame Header Field updated.
- Slot Status Field updated.
- DUP:= 1
- DVAL:= 1
- MBIF:= 1
Valid null frame received.
- Message Buffer Data Field
not
updated.
- Frame Header Field
not
updated.
- Slot Status Field updated.
- DUP:= 0
- DVAL
not
changed
- MBIF:= 1
1
0