Freescale Semiconductor FlexRay MFR4310 - Figure 3-111. Message Transmission Timing; Figure 3-112. Message Transmission from Hlck State with Unlock

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 Message
Buffer Segment Size and Utilization Register (MBSSUTR).
2. the message buffer data field size, as defined by the related field of the Message Buffer Data Size
Register (MBDSR)
3. the value of the PLDLEN field in the message buffer header field, as described in Section 3.4.5.2.1,
“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 start
MA
slot s
TX
SU
CCMa
CCTx
slot s+1
Idle
MT
start
Idle
slot s+2
slot start slot start slot start
MT start
message transmit
SSS
CCSu
search[s+1]
MT
st
a
rt
M
T
s
ta
r
t
MA
slot s
TX
SSS
HLckCCMa CCTx
slot s+1
HLck
M
T
st
a
r
t
Idle
slot s+2
slot start
slot start slot start
HU
CCMa
message transmit