K60P100M100SF2RM Datasheet, PDF (1359/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Arbitration process can be triggered in the following situations:
Chapter 48 CAN (FlexCAN)
• During Rx and Tx frames from CAN CRC field to end of frame. Arbitration start
point depends on instantiation parameters NUMBER_OF_MB and TASD.
Additionally, TASD value may be changed to optimize the arbitration start point.
• During CAN BusOff state from TX_ERR_CNT=124 to 128. Arbitration start point
depends on instantiation parameters NUMBER_OF_MB and TASD. Additionally,
TASD value may be changed to optimize the arbitration start point.
• During C/S write by CPU in BusIdle. First C/S write starts arbitration process and a
second C/S write during this same arbitration restarts the process. If other C/S writes
are performed, Tx arbitration process is pending. If there is no arbitration winner
after arbitration process has finished, then TX arbitration machine begins a new
arbitration process.
• • If there is a pending arbitration and BusIdle state starts then an arbitration
process is triggered. In this case the first and second C/S write in BusIdle will
not restart the arbitration process. It is possible that there is not enough time to
finish arbitration in WaitForBusIdle state and the next state is Idle. In this case
the scan is not interrupted, and it is completed during BusIdle state. During this
arbitration C/S write does not cause arbitration restart.
• Arbitration winner deactivation during a valid arbitration window.
• Upon Leave Freeze Mode (first bit of the WaitForBusIdle state). If there is a re-
synchronization during WaitForBusIdle arbitration process is restarted.
Arbitration process stops in the following situation:
• All Mailboxes were scanned.
• A Tx active Mailbox is found in case of Lowest Buffer feature enabled.
• Arbitration winner inactivation or abort during any arbitration process.
• There was not enough time to finish Tx arbitration process. For instance, a
deactivation was performed near the end of frame). In this case arbitration process is
pending.
• Error or Overload flag in the bus .
• Low Power or Freeze Mode request in Idle state
Arbitration is considered pending as described below:
• It was not possible to finish arbitration process in time.
• C/S write during arbitration if write is performed in a MB which number is lower
than the Tx arbitration pointer .
• Any C/S write if there is no Tx Arbitration process in progress.
• Rx Match has just updated a Rx Code to Tx Code.
• Entering Busoff state.
C/S write during arbitration has the following effect:
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
1359