Receive Process - NXP Semiconductors freescale KV4 Series Reference Manual

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Functional description

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 exiting Freeze mode (first bit of the WaitForBusIdle state). If there is a re-

synchronization during WaitForBusIdle, the arbitration process is restarted.

Arbitration process stops in the following situations:

• 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, when a

deactivation was performed near the end of frame). In this case arbitration process is

• 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 whose 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:

• If C/S write is performed in the arbitration winner, a new process is restarted

immediately.

• If C/S write is performed in a MB whose number is higher than the Tx arbitration

pointer, the ongoing arbitration process will scan this MB as normal.

43.5.3 Receive process

To be able to receive CAN frames into a Mailbox, the CPU must prepare it for reception

by executing the following steps:

1. If the Mailbox is active (either Tx or Rx) inactivate the Mailbox (see

inactivation), preferably with a safe inactivation (see

KV4x Reference Manual, Rev. 2, 02/2015

Transmission abort

Freescale Semiconductor, Inc.