NXP Semiconductors MPC5644A, Reference Manual, Page: 1620 / 1735

FlexRay Communication Controller (FlexRay)
MPC5644A Microcontroller Reference Manual, Rev. 6
1620 Freescale Semiconductor
The required minimum CHI Clock frequency for a selected set of relevant protocol parameters and for the
LAST_MB_UTIL field in the
Message Buffer Segment Size and Utilization Register (FR_MBSSUTR) set
to 127 is given in Table 33-136 .
33.7.7 Protocol control command execution
This section considers the issues of the protocol control command execution.
The application issues any of the protocol control commands listed in the POCCMD field of Table 33-16
by writing the command to the POCCMD field of the Protocol Operation Control Register (FR_POCR) .
As a result the CC sets the BSY bit while the command is transferred to the PE. When the PE has accepted
the command, the BSY flag is cleared. All commands are accepted by the PE.
The PE maintains a protocol command vector. For each command that was accepted by the PE, the PE sets
the corresponding command bit in the protocol command vector. If a command is issued while the
corresponding command bit is set, the command is not queued and is lost.
If the command execution block of the PE is idle, it selects the next accepted protocol command with the
highest priority from the current protocol command vector according to the protocol control command
priorities given in
Table 33-137 . If the current protocol state does not allow the execution of this protocol
command (see POC state changes in FlexRay Communications System Protocol Specification, Version 2.1
Rev A ) the CC asserts the illegal protocol command interrupt flag IPC_IF in the Protocol Interrupt Flag
Register 1 (FR_PIFR1) . The protocol command is not executed in this case.
Some protocol commands may be interrupted by other commands or the detection of a fatal protocol error
as indicated by
Table 33-137 . If the application issues the FREEZE or READY command, or if the PE
detects a fatal protocol error, some commands already stored in the command vector will be removed from
this vector.
Table 33-136. Minimum f
chi
[MHz] examples (128 message buffers)
pdMicrotick
[ns]
gdMinislot
2 3 4 5 6 7
25.0 70.77 47.18 35.39 28.31 23.59 20.22
50.0 35.39 23.59 17.70 14.16 11.80 10.11
Table 33-137. Protocol control command priorities
Protocol command Priority Interrupted by Cleared and terminated by
FREEZE (highest) 1 none
READY 2
CONFIG_COMPLETE 3