Freescale Semiconductor FlexRay MFR4310, Reference Manual

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FlexRay Module (FLEXRAYV4)
MFR4310 Reference Manual, Rev. 2
186 Freescale Semiconductor
3.4.11 External Clock Synchronization
The application of the external rate and offset correction is triggered when the application writes to the
EOC_AP and ERC_AP fields in the
Protocol Operation Control Register (POCR) . The PE applies the
external correction values in the next even-odd cycle pair as shown in Figure 3-132 and Figure 3-133 .
NOTE
The values provided in the EOC_AP and ERC_AP fields are the values that
were written from the application most recently. If these value were already
applied, they are not applied in the current cycle pair again.
If the offset correction applied in the NIT of cycle 2n+1 shall be affect by the external offset correction,
the EOC_AP field must be written to after the start of cycle 2n and before the end of the static segment of
cycle 2n+1. If this field is written to after the end of the static segment of cycle 2n+1, it is not guaranteed
that the external correction value is applied in cycle 2n+1. If the value is not applied in cycle 2n+1, the
value is applied in the cycle 2n+3. Refer to
Figure 3-132 for timing details.
Figure 3-132. External Offset Correction Write and Application Timing
If the rate correction for the cycle pair [2n+2, 2n+3] shall be affect by the external offset correction, the
ERC_AP field must be written to after the start of cycle 2n and before the end of the static segment start
of cycle 2n+1. If this field is written to after the end of the static segment of cycle 2n+1, it is not guaranteed
that the external correction value is applied in cycle pair [2n+2, 2n+3]. If the value is not applied for cycle
pair [2n+2, 2n+3], the value is be applied for cycle pair [2n+4, 2n+5]. Refer to
Figure 3-133 for details.
Figure 3-133. External Rate Correction Write and Application Timing
3.4.12 Sync Frame ID and Sync Frame Deviation Tables
The FlexRay protocol requires the provision of a snapshot of the Synchronization Frame ID tables for the
even and odd communication cycle for both channels. The FlexRay module provides the means to write a
copy of these internal tables into the FRM and ensures application access to consistent tables by means of
table locking. After the application has locked the table successfully, the FlexRay module does not
overwrite these tables and the application can read a consistent snapshot.
static segment NIT static segment NIT
EOC_AP write window EOC_AP application
cycle 2n cycle 2n+1
static segment NIT
ERC_AP write window ERC_AP application
cycle 2n
static segment NIT
cycle 2n+1
static segment NIT
cycle 2n+2
static segment NIT
cycle 2n+3