Freescale Semiconductor FlexRay MFR4310 - Figure 3-124. Internal Message Transfer in Streaming Commit Mode; Figure 3-125. Internal Message Transfer in Immediate Commit Mode

FlexRay Module (FLEXRAYV4)
MFR4310 Reference Manual, Rev. 2
Freescale Semiconductor 175
An example of a streaming commit mode state change diagram is given in Figure 3-124. In this example,
both the commit and the transmit side do not contain valid message data and the application provides two
messages. The message buffer does not match the next slot.
Figure 3-124. Internal Message Transfer in Streaming Commit Mode
Immediate Commit Mode
The intention of the immediate commit mode is to transmit the latest data provided by the application. This
implies that it is not guaranteed that each provided message is transmitted at least once.
The immediate commit mode is configured by setting the message buffer commit mode bit MCM in the
Message Buffer Configuration, Control, Status Registers (MBCCSRn).
In this mode, the internal message transfer from the commit side to the transmit side is started for one
double transmit message buffer when all of the following conditions are fulfilled
1. the commit side is in the idle state
2. the commit site message data are valid, MBCCSR[2n].CMT equals 1
3. the transmit side is in one of the states idle, CCSa, or CCMa
It is not checked whether the transmit side contains no valid message data or valid message data were
transmitted at least once. If message data are valid and not transmitted, they may be overwritten.
An example of a streaming commit mode state change diagram is given in Figure 3-125. In this example,
both the commit and the transmit side do not contain valid message data, and the application provides two
messages and the first message is gets overwritten. The message buffer does not match the next slot.
Figure 3-125. Internal Message Transfer in Immediate Commit Mode
Idle
CommitTra ns mit
Idle
HL
HLck
Side Side
slot s slot s+1 slot s+2
search[s+1]
slot start
slot start slot start
HU
CCITx
Idle
IS
CCITx
IE
Idle
HL
HLck
HU
Idle
Idle
no internal message transfer,
until message transmitted
Idle
CommitTra ns mi t
Idle
HL
HLck
Side Side
slot s slot s+1 slot s+2
search[s+1]
slot start
slot start slot start
HU
CCITx
Idle
IS
CCITx
IE
Idle
HL
HLck
HU
Idle
CCITx
Idle
IS
CCITx
IE
Idle
Idle
internal message transfer
overwrites non-transmitted message