mc9s12xf512 Freescale Semiconductor, Inc, mc9s12xf512 Datasheet - Page 564

• Manufacturer Part Number: mc9s12xf512
• Description: S12x Microcontrollers 16-bit Automotive Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 13 FlexRay Communication Controller (FLEXRAY)
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 block reads and
transfers 2*PLDLEN bytes. The same holds for segment 2 and MBSEG2DS.
13.6.6.2.6
A static slot with slot number S is assigned to the FlexRay block 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 block 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 block triggers the slot assigned transition SA for up to two transmit message buffers if at least
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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
HLck
Idle
Buffer Segment Size and Utilization Register
Register (MBDSR)
Section 13.6.5.2.1, “Frame Header Section
MA
MA
Null Frame Transmission
search[s+1]
search[s+1]
HLckCCMa
Figure 13-116. Message Transmission from HLck state with unlock
slot s
CCMa
slot s
Figure 13-115. Message Transmission Timing
MC9S12XF - Family Reference Manual, Rev.1.19
HU
CCMa
TX
TX
Description”
Section 13.6.7, “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
SU
slot s+2
slot s+2
Message
Idle
Idle
Search”,