mfr4300 Freescale Semiconductor, Inc, mfr4300 Datasheet - Page 158

• Manufacturer Part Number: mfr4300
• Description: Flexray Communication Controllers
• Manufacturer: Freescale Semiconductor, Inc

FlexRay Module (FLEXRAYV2)
The amount of message data read from the FRM and transferred to the FlexRay bus is determined by the
following three items
If a message buffer is assigned to message buffer segment 1, and PLDLEN > MBSEG1DS, then
2 * MBSEG1DS bytes will be read from the message buffer data field and zero padding is used for the
remaining bytes for the FlexRay bus transfer. If PLDLEN <= MBSEG1DS, the FlexRay module reads and
transfers 2*PLDLEN bytes. The same holds for segment 2 and MBSEG2DS.
3.4.6.2.6
A static slot with slot number S is assigned to the FlexRay module for channel A, if at least one transmit
message buffer is configured with the MBFIDRn.FID set to S and MBCCFRn.CHA set to ‘1’. A Null
Frame is transmitted in the static slot S on channel A, if this slot is assigned to the FlexRay module for
channel A, and all transmit message buffers with MBFIDRn.FID = s and MBCCFRn.CHA = ‘1’ are either
not committed, i.e MBCCSRn.CMT = ‘0’, or locked by the application, i.e. MBCCSRn.LCKS = ‘1’, or
the cycle counter filter is enabled and does not match.
Additionally, the application can clear the commit bit of a message buffer that is in the CCMa state, which
is called uncommit or transmit abort. This message buffer will be used for null frame transmission.
As a result of the message buffer search described in
the FlexRay module triggers the slot assigned transition SA for up to two transmit message buffers if at
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1. the message buffer segment that the message buffer is assigned to, as defined by the
2. the message buffer data field size, as defined by the related field of the
3. the value of the PLDLEN field in the message buffer header field, as described in
Idle
HLck
Buffer Segment Size and Utilization Register
Register (MBDSR)
“Frame Header Section
MA
MA
Null Frame Transmission
search[s+1]
search[s+1]
HLckCCMa
Figure 3-113. Message Transmission from HLck state with unlock
slot s
CCMa
slot s
Figure 3-112. Message Transmission Timing
Description”
HU
CCMa
MFR4300 Data Sheet, Rev. 3
TX
TX
Section 3.4.7, “Individual Message Buffer
(MBSSUTR).
message transmit
message transmit
CCTx
CCTx
slot s+1
slot s+1
Message Buffer Data Size
SSS
SSS
Freescale Semiconductor
CCSu
Section 3.4.5.2.1,
SU
slot s+2
slot s+2
Message
Idle
Search”,
Idle