FlexRay Communication Controller (FLEXRAY)
22-154
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
22.7.5.2
Behavior in static segment
In this case, both message buffers are assigned to a slot
S
in the
static
segment.
The configuration of a transmit buffer for a static slot
S
assigns this slot to the node as a transmit slot. The
FlexRay protocol requires:
•
When a slot occurs, if the slot is assigned to a node on a channel that node must transmit either a
normal frame or a null frame on that channel. Specifically, a null frame will be sent if there is no
data ready, or if there is no match on a transmit filter (cycle counter filtering, for example).
Regardless of the availability of data and the cycle counter filter, the node will transmit a frame in the static
slot
S.
In any case, the result of the message buffer search will be the transmit message buffer
t.
The receive
message buffer
r
will not be found, no reception is possible.
22.7.5.3
Behavior in dynamic segment
In this case, both message buffers are assigned to a slot
S
in the
dynamic
segment. The FlexRay protocol
requires:
•
When a slot occurs, if a slot is assigned to a node on a channel that node only transmits a frame on
that channel if there is data ready and there is a match on relevant transmit filters (no null frames
are sent).
The transmission of a frame in the dynamic segment is determined by the availability of data and the match
of the cycle counter filter of the transmit message buffer.
22.7.5.3.1
Transmit Data Not Available
If transmit data are
not available
, i.e. the transmit buffer is not committed MBCCSR
t
[CMT]=0 and/or
locked MBCCSR
t
[LCKS]=1,
a) for the cycles in the set {4n}, which is assigned to both buffers, the receive buffer will be found
and the node can receive data, and
b) for the cycles in the set {4n+2}, which is assigned to the receive buffer only, the receive buffer
will be found and the node can receive data.
The receive cycles are shown in
Figure 22-153. Transmit Data Not Available
22.7.5.3.2
Transmit Data Available
If transmit data are
available,
i.e. the transmit buffer is committed MBCCSR
t
[CMT]=1 and not locked
MBCCSR
t
[LCKS]=0,
a) for the cycles in the set {4n}, which is assigned to both buffers, the transmit buffer will be found
and the node transmits data.
0
RX
1
2
RX
3
4
RX
5
6
RX
7
59
60
RX
61
62
RX
8
RX
63
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...
