Freescale Semiconductor FlexRay MFR4310 - Table 3-100. Receive Message Buffer Update

FlexRay Module (FLEXRAYV4)
MFR4310 Reference Manual, Rev. 2
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 idle state Idle or locked state HLck to the 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 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 CCRx to CCSu or from HLckCCRx to HLck, respectively.
If a message buffer was in the locked state HLckCCRx, no update is 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
11Valid non-null frame received.
- Message Buffer Data Field updated.
- Frame Header Field updated.
- Slot Status Field updated.
- DUP:= 1
- DVAL:= 1
- MBIF:= 1
10Valid 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