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FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
1576
Freescale Semiconductor
33.6.6.4.5
Internal message transfer
The internal message transfer transfers the message data from the commit side to the transmit side. The
internal message transfer is implemented as the swapping of the content of the
of the commit side and the transmit side. After the swapping, the commit side
CMT bit is cleared, the commit side interrupt flag MBIF is set, the transmit side CMT bit is set, and the
transmit side DVAL bit is cleared.
The conditions and the point in time when the internal message transfer is started are controlled by the
message buffer commit mode bit MCM in the
Message Buffer Configuration, Control, Status Registers
. The MCM bit configures the message buffer for either the streaming commit mode or
the immediate commit mode. A detailed description is given in
. The Internal Message Transfer is triggered with the transition IS. Both sides of the message
buffer enter one of the CCITx states. The internal message transfer is finished with the transition IE.
Streaming commit mode
The intention of the streaming commit mode is to ensure that each committed message is transmitted
at
least once
. The CC will not start the Internal Message Transfer for a message buffer as long as the message
data on the transmit side is not transmitted at least once.
The streaming commit mode is configured by clearing the message buffer commit mode bit MCM in the
Message Buffer Configuration, Control, Status Registers (FR_MBCCSRn)
.
In this mode, the internal message transfer from the commit side to the transmit side is started for a 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, that is, FR_MBCCSR(2n)[CMT] = 1
3. the transmit side is in one of the states Idle, CCSa, or CCMa
4. the transmit side contains either no valid message data, that is, FR_MBCCSR(2n+1)[CMT] = 0 or
the message data were transmitted at least once, that is, FR_MBCCSR(2n+1)[DVAL] = 1
An example of a streaming commit mode state change diagram is given in
. 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 33-144. Internal message transfer in streaming commit mode
Idle
Co
mmi
t
T
ransm
it
Idle
HL
HLck
S
ide
Side
slot s
slot s+1
slot s+2
search[s+1]
sl
ot st
art
slot s
tart
slot s
tart
HU
CCITx
Idle
IS
CCITx
IE
Idle
HL
HLck
HU
Idle
Idle
no internal message transfer,
until message transmitted
Summary of Contents for MPC5644A
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Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...