FlexRay Communication Controller (FLEXRAY)
22-102
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
22.6.6.2.5
Message Transmission
As a result of the message buffer search described in
Section 22.6.7, Individual Message Buffer Search
the controller triggers the message available transition MA for up to two transmit message buffers. This
changes the message buffer state from Idle to CCMa and the message buffers can be used for message
transmission in the next slot.
The controller transmits a message from a message buffer if both of the following two conditions are
fulfilled at the start of the transmission slot:
1. the message buffer is in the message available state CCMa
2. the message data are still valid, i.e. MBCCSRn[CMT] = 1
In this case, the controller triggers the TX transition and changes the message buffer state to CCTx. A
transmit message buffer timing and state change diagram for message transmission is given in
. In this example, the message buffer with message buffer number n is Idle at the start of the
search slot, matches the slot and cycle number of the next slot, and message buffer data are valid, i.e.
MBCCSRn[CMT] = 1.
Figure 22-121. Message Transmission Timing
Figure 22-122. Message Transmission from HLck state with unlock
The amount of message data read from the flexray memory and transferred to the FlexRay bus is
determined by the following three items:
•
The message buffer segment that the message buffer is assigned to, as defined by the
Buffer Segment Size and Utilization Register (MBSSUTR)
.
•
The message buffer data field size, as defined by the related field of the
•
The value of the PLDLEN field in the message buffer header field, as described in
Section 22.6.5.2.1, Frame Header Description
search[s+1]
MT
st
art
MA
slot s
TX
SU
CCMa
CCTx
slot s+1
Idle
MT star
t
Idle
slot s+2
slot st
ar
t
slot st
ar
t
slot st
ar
t
MT
st
art
message transmit
SSS
CCSu
search[s+1]
MT st
art
MT s
tar
t
MA
slot s
TX
SSS
HLckCCMa CCTx
slot s+1
HLck
MT s
tar
t
Idle
slot s+2
sl
ot start
slot start
slot start
HU
CCMa
message transmit
Summary of Contents for PXR4030
Page 1: ...PXR40 Microcontroller Reference Manual Devices Supported PXR4030 PXR4040 PXR40RM Rev 1 06 2011...
Page 30: ...PXR40 Microcontroller Reference Manual Rev 1 Freescale Semiconductor xxx...
Page 40: ...PXR40 Microcontroller Reference Manual Rev 1 xl Freescale Semiconductor...
Page 66: ...Memory Map PXR40 Microcontroller Reference Manual Rev 1 2 4 Freescale Semiconductor...
Page 120: ...Signal Descriptions 3 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Page 860: ...FlexCAN Module 24 50 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...
Page 1167: ...Decimation Filter Freescale Semiconductor 28 53 PXR40 Microcontroller Reference Manual Rev 1...
Page 1168: ...Decimation Filter 28 54 Freescale Semiconductor PXR40 Microcontroller Reference Manual Rev 1...