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FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
1561
33.6.6.2.7
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 CC updates the slot status field of the message buffer
and triggers the status updated transition SU. With the SU transition, the CC sets the message buffer
interrupt flag FR_MBCCSRn[MBIF] to indicate the successful message transmission.
Depending on the transmission mode flag FR_MBCCFRn[MTM], the CC changes the commit flag
FR_MBCCSRn[CMT] and the valid flag FR_MBCCSRn[DVAL]. If the FR_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 FR_MBCCSRn[CMT] is cleared with the SU transition. If the
FR_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 CC will not clear the FR_MBCCSRn[CMT] flag at the end of transmission and will set the
valid flag FR_MBCCSRn[DVAL] to indicate that the message will be 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 (FR_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.
Message buffer status update after null frame transmission
After the transmission of a null frame, the status of the message buffer that was used for the null frame
transmission is not changed at all. The slot status field is not updated, the status and control flags are not
changed, and the interrupt flag is not set.
33.6.6.3
Receive message buffers
The section provides a detailed description of the functionality of the receive message buffers. If receive
message buffers are used it is required to configure the related receive shadow buffer as described in
Section 33.6.3.2, Receive shadow buffers
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Summary of Contents for MPC5644A
Page 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...