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FlexRay Module (FLEXRAYV4)
MFR4310 Reference Manual, Rev. 2
158
Freescale Semiconductor
Figure 3-111. Message Transmission Timing
Figure 3-112. Message Transmission from HLck state with unlock
The amount of message data read from the FRM and transferred to the FlexRay bus is determined by the
following three items
1. the message buffer segment that the message buffer is assigned to, as defined by the
Buffer Segment Size and Utilization Register (MBSSUTR)
.
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
“Frame Header Section Description
”
If a message buffer is assigned to message buffer segment 1, and PLDLEN is greater than MBSEG1DS,
2 * MBSEG1DS bytes are read from the message buffer data field and zero padding is used for the
remaining bytes for the FlexRay bus transfer. If PLDLEN is less than or equals MBSEG1DS, the FlexRay
module reads and transfers 2*PLDLEN bytes. The same holds for segment 2 and MBSEG2DS.
3.4.6.2.6
Null Frame Transmission
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 equaling s and MBCCFRn.CHA equaling 1 are not
committed 9MBCCSRn.CMT = 0), locked by the application (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 is used for null frame transmission.
As a result of the message buffer search described in
Section 3.4.7, “Individual Message Buffer Search
”,
the FlexRay module triggers the slot assigned transition
SA
for up to two transmit message buffers if at
search[s+1]
MT
st
art
MA
slot s
TX
SU
CCMa
CCTx
slot s+1
Idle
MT
sta
rt
Idle
slot s+2
slot star
t
slot star
t
slot star
t
MT
st
art
message transmit
SSS
CCSu
search[s+1]
MT
st
art
MT
sta
rt
MA
slot s
TX
SSS
HLckCCMa CCTx
slot s+1
HLck
MT
st
art
Idle
slot s+2
slot
st
art
slot s
tart
slot s
tart
HU
CCMa
message transmit
Summary of Contents for FlexRay MFR4310
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Page 3: ...MFR4310 Reference Manual MFR4310RM Rev 2 03 2008...
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Page 24: ...MFR4310 Reference Manual Rev 2 24 Freescale Semiconductor Table Number Title Page...
Page 28: ...Introduction MFR4310 Reference Manual Rev 2 28 Freescale Semiconductor...
Page 58: ...Device Overview MFR4310 Reference Manual Rev 2 58 Freescale Semiconductor...
Page 234: ...Clocks and Reset Generator CRG MFR4310 Reference Manual Rev 2 234 Freescale Semiconductor...
Page 260: ...Package Information MFR4310 Reference Manual Rev 2 260 Freescale Semiconductor...
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