Freescale Semiconductor FlexRay MFR4310 - Figure 3-116. Null Frame Transmission from Idle State with Locking

FlexRay Module (FLEXRAYV4)
MFR4310 Reference Manual, Rev. 2
160 Freescale Semiconductor
Figure 3-116. Null Frame Transmission from Idle State with locking
3.4.6.2.7 Message Buffer Status Update
After the end of each slot, the PE generates the slot status vector. Depending on the this status, the
transmitted frame type, and the amount of transmitted data, the message buffer status is updated.
Message Buffer Status Update after Complete Message Transmission
The term complete message transmission refers to the fact that all payload data stored in the message
buffer were send to FlexRay bus. In this case, the FlexRay module updates the slot status field of the
message buffer and triggers the status updated transition SU. With the SU transition, the FlexRay module
sets the message buffer interrupt flag MBCCSn.MBIF to indicate the successful message transmission.
Depending on the transmission mode flag MBCCFRn.MTM, the FlexRay module changes the commit
flag MBCCSRn.CMT and the valid flag MBCCSRn.DVAL. If the MBCCFRn.MTM flag is negated, the
message buffer is in the event transmission mode. In this case, each committed message is transmitted only
once. The commit flag MBCCSRn.CMT is cleared with the SU transition. If the MBCCFRn.MTM flag is
asserted, the message buffer is in the state transmission mode. In this case, each committed message is
transmitted as long as the application provides new data or locks the message buffers. The FlexRay module
does not clear the MBCCSRn.CMT flag at the end of transmission and sets the valid flag
MBCCSRn.DVAL to indicate the message is transmitted again.
Message Buffer Status Update after Incomplete Message Transmission
The term incomplete message transmission refers to the fact that not all payload data that should be
transmitted were send to FlexRay bus. This may be caused by the following regular conditions in the
dynamic segment:
1. The transmission slot starts in a minislot with a minislot number greater than pLatestTx.
2. The transmission slot did not exist in the dynamic segment at all.
Additionally, an incomplete message transmission can be caused by internal communication errors. If
those error occur, the Protocol Engine Communication Failure Interrupt Flag PECF_IF is set in the
Protocol Interrupt Flag Register 1 (PIFR1).
In any of these two cases, the status of the message buffer is not changed at all with the SU transition. The
slot status field is not updated, the status and control flags are not changed, and the interrupt flag is not set.
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