mfr4300 Freescale Semiconductor, Inc, mfr4300 Datasheet - Page 176

• Manufacturer Part Number: mfr4300
• Description: Flexray Communication Controllers
• Manufacturer: Freescale Semiconductor, Inc

FlexRay Module (FLEXRAYV2)
3.4.6.4.6
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 3.4.6.2.5, “Message Transmission”
3.4.6.4.7
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
Status Update”.
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.
3.4.7
This section provides a detailed description of the message buffer search algorithm.
The message buffer search checks all enabled individual message buffer to determine if a certain slot is
assigned to this node for transmission or if this node is subscribed to a certain slot for reception. The
message buffer search is a sequential algorithm and is started at the following protocol related events:
The search within the NIT searches for message buffers assigned or subscribed to slot 1. The search within
slot n searches for message buffers assigned or subscribed to slot n+1.
If the message buffer search is running while the next message buffer search start event appears, the
message buffer search is stopped and the Message Buffer Search Error Flag MSB_EF is set in the
Error Flag Register
message buffers within the NIT or a minislot. The message buffer result is not defined in this case. For
more details see
The filters criteria used for the message buffer search described in
Buffer
During the search, a list of all matching message buffers is created. If all message buffers assigned or
subscribed to the next slot are assigned to only one channel, then two lists of matching message buffer will
be created, one for each channel. If all message buffers assigned or subscribed to the next slot are assigned
to both channels, only one sorted list of matching message buffers is created.
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Filtering”. For double transmit message buffers only the transmit side is included in the search.
each NIT start
each slot start in the static frame segment
each minislot start in the dynamic frame segment
Individual Message Buffer Search
Message Transmission
Message Buffer Status Update
Section 3.5.2, “Number of Usable Message Buffers”.
(CHIERFR). This appears only if the CHI frequency is to low to search through all
MFR4300 Data Sheet, Rev. 3
Section 3.4.6.2.7, “Message Buffer
Section 3.4.7.1, “Individual Message
Freescale Semiconductor
CHI