PXR40RM Datasheet, PDF (703/1434 Pages) Freescale Semiconductor, Inc – PXR40 Microcontroller

FlexRay Communication Controller (FLEXRAY)
An example of a streaming commit mode state change diagram is given in Figure 22-134. 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.
HL
HU
IS
IE
HL
HU
Idle
HLck
Idle CCITx Idle
Idle
CCITx
HLck
Idle
no internal message transfer,
until message transmitted
Idle
search[s+1]
slot s
slot s+1
Figure 22-134. Internal Message Transfer in Streaming Commit Mode
slot s+2
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 will be 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, i.e. MBCCSR(2n)[CMT] = 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 22-135. 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.
HL
HU
IS
IE
HL
HU
IS
IE
Idle
HLck
Idle CCITx Idle
Idle
CCITx
HLck
Idle
Idle CCITx ^Idle
internal message transfer
overwrites non-transmitted message
CCITx Idle
search[s+1]
slot s
slot s+1
Figure 22-135. Internal Message Transfer in Immediate Commit Mode
slot s+2
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
22-119