PXS20RM Datasheet, PDF (839/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

FlexRay Communication Controller
Table 26-114. Receive Message Buffer Transition Priorities (continued)
State
CCRx
Priorities
SSS > HL
Description
Slot or Segment Start > Message Buffer Lock
26.6.6.3.2 Message Reception
As a result of the message buffer search, the CC 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.
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 26.6.6.3.5, 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.
26.6.6.3.3 Message Buffer Update
With the start of the next static or dynamic slot or with the start of the symbol window or NIT, the module
triggers 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 (FR_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 26-115.
Table 26-115. Receive Message Buffer Update
vSS!ValidFrame
1
vRF!Header!NFIn
dicator
Update description
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
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
26-127