PXS20RM Datasheet, PDF (851/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

FlexRay Communication Controller
The message buffer search within the NIT searches for message buffers assigned or subscribed to slot 1.
The message buffer search within slot n searches for message buffers assigned or subscribed to slot n+1.
In general, the message buffer search for the next slot n considers only message buffers which are
1. enabled, i.e. FR_MBCCSRn[EDS] = 1, and
2. matches the next slot n, i.e. FR_MBFIDRn[FID] = n, and
3. are the transmit side buffer in case of a double transmit message buffer.
On top of that, for the static segment only those message buffers are considered, that match the condition
of at least one row of Table 26-122. For the dynamic segment only those message buffers are considered,
that match the condition of at least one row of Table 26-123. These message buffers are called matching
message buffers.
For each enabled channel the message buffer search may identify multiple matching message buffers.
Among all matching message buffers the message buffers with highest priority according to Table 26-122
for the static segment and according to Table 26-123 for the dynamic segment are selected.
Table 26-122. Message Buffer Search Priority (static segment)
Priority MTD LCKS CMT CCFM¹
Description
(highest) 0 1
0
1
1 transmit buffer, matches cycle count, not locked and
committed
1
-
0
1 transmit buffer, matches cycle count, not committed
1
1
1
—
1 transmit buffer, matches cycle count, locked
21
-
—
— transmit buffer
30
0
n/a
1 receive buffer, matches cycle count, not locked
(lowest) 4 0
1
n/a
1 receive buffer, matches cycle count, locked
NOTES:
1 _{Cycle Counter Filter Match, see Section 26.6.7.1, Message Buffer Cycle Counter Filtering.}
Transitio
n
MA
SA
SA
SA
SB
SB
Table 26-123. Message Buffer Search Priority (dynamic segment)
Priority
MTD
LCKS
CMT
CCFM¹
Description
(highest) 0
1
0
1
1
transmit buffer,
matches cycle
count, not
locked and
committed
1
0
0
n/a
1
receive buffer,
matches cycle
count, not
locked
(lowest) 2
0
1
n/a
1
receive buffer,
matches cycle
count, locked
NOTES:
1 _{Cycle Counter Filter Match, see Section 26.6.7.1, Message Buffer Cycle Counter Filtering.}
Transition
MA
SB
SB
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
26-139