FlexRay Communication Controller (FLEXRAY)
22-120
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
22.6.6.4.6
Message Transmission
For double transmit message buffers, the message buffer search checks only the transmit side part. The
internal scheduling ensures, that the internal message transfer is stopped on the message buffer search start.
Thus, the transmit side of message buffer, that is not in its transmission or status update slot, is always in
the Idle state.
The message transmit behavior and transmission state changes of the transmit side of a double transmit
message buffer are the same as for single buffered transmit buffers, except that the transmit side of double
buffers can not be locked by the application, i.e. the HU and HL transition do not exist. Therefore, refer to
Section 22.6.6.2.5, Message Transmission.
22.6.6.4.7
Message Buffer Status Update
The message buffer status update behavior of the transmit side of a double transmit message buffer is the
same as for single transmit message buffers which is described in
Section 22.6.6.2.7, Message Buffer
Additionally, the slot status field of the commit side is update after the update of the slot status field of the
transmit side, even if the commit side is locked by the application. This is implemented to provide the slot
status of the most recent transmission slot.
22.6.7
Individual Message Buffer Search
This section provides a detailed description of the message buffer search algorithm.
The message buffer search determines for each enabled channel if a slot
s
in a communication cycle
c
is
assigned for frame or null frame transmission or if it is subscribed for frame reception on that channel.
The message buffer search is a sequential algorithm which is invoked at the following protocol related
events:
1. NIT start
2. slot start in the static segment
3. minislot start in the dynamic segment
The message buffer search within the NIT searches for message buffers assigned or subscribed to slot 1.
The message buffer search within slot
n
searches for message buffers assigned or subscribed to slot
n+1
.
In general, the message buffer search for the next slot
n
considers only message buffers which are
1. enabled, i.e. MBCCSRn[EDS] = 1, and
2. matches the next slot
n
, i.e. MBFIDRn[FID] =
n
, and
3. are the transmit side buffer in case of a double transmit message buffer.
On top of that, for the static segment only those message buffers are considered, that match the condition
of at least one row of
. For the dynamic segment only those message buffers are considered,
that match the condition of at least one row of
. These message buffers are called
matching
message buffers.
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...