Module Operation
1230
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
FlexRay Module
26.2.5.1 Clock Correction Failed Counter
When the Clock Correction Failed Counter reaches the “maximum without clock correction passive” limit
defined by SUCC3.WCP(3-0), the POC transits from NORMAL_ACTIVE to NORMAL_PASSIVE state.
When it reaches the “maximum without clock correction fatal” limit defined by SUCC3.WCF(3-0), it transits
NORMAL_ACTIVE or NORMAL_PASSIVE to the HALT state.
The Clock Correction Failed Counter CCEV.CCFC(3-0) allows the host to monitor the duration of the
inability of a node to compute clock correction terms after the communication controller passed protocol
startup phase. It will be incremented by 1 at the end of any odd numbered communication cycle where
either the Missing Offset Correction flag SFS.MOCS or the Missing Rate Correction flag SFS.MRCS is set.
The clock correction failed counter is reset to 0 at the end of an odd communication cycle if neither the
Missing Offset Correction flag SFS.MOCS nor the Missing Rate Correction flag SFS.MRCS is set.
The Clock Correction Failed Counter stops incrementing when the “maximum without clock correction
fatal” value SUCC3.WCF(3-0) is reached (incrementing the counter at its maximum value will not cause it
to wraparound back to 0). The clock correction failed counter will be initialized to 0 when the
communication controller enters READY state or when NORMAL_ACTIVE state is entered.
NOTE:
The transition to HALT state is prevented if SUCC1.HCSE is not set.
26.2.5.2 Passive to Active Counter
The passive to active counter controls the transition of the POC from NORMAL_PASSIVE to
NORMAL_ACTIVE state. SUCC1.SUCC1.PTA(4-0) defines the number of consecutive even / odd cycle
pairs that must have valid clock correction terms before the communication controller is allowed to transit
from NORMAL_PASSIVE to NORMAL_ACTIVE state. If SUCC1.PTA(4-0) is cleared to 0, the
communication controller is not allowed to transit from NORMAL_PASSIVE to NORMAL_ACTIVE state.
26.2.5.3 HALT Command
In case the host wants to stop FlexRay communication of the local node it can bring the communication
controller into HALT state by asserting the HALT command. This can be done by writing SUCC1.CMD(3-
0) = 0110. In order to shut down communication on an entire FlexRay network, a higher layer protocol is
required to assure that all nodes apply the HALT command at the same time.
The POC state from which the transition to HALT state took place can be read from CCSV.PSL(5-0).
When called in NORMAL_ACTIVE or NORMAL_PASSIVE state the POC transits to HALT state at the end
of the current cycle. When called in any other state SUCC1.CMD(3-0) will be reset to 0000 =
“command_not_accepted” and bit EIR.CNA in the error interrupt register is set to 1. If enabled an interrupt
to the host is generated.
26.2.5.4 FREEZE Command
In case the host detects a severe error condition it can bring the communication controller into HALT state
by asserting the FREEZE command. This can be done by writing SUCC1.CMD(3-0) = 0111. The FREEZE
command triggers the entry of the HALT state immediately regardless of the current POC state.
The POC state from which the transition to HALT state took place can be read from CCSV.PSL(5-0).