The collision priority management of the MPC5500 family causes lower-priority messages to be canceled by higher-priority messages if they occur at the same time. Refer to the chip documentation for details.

The messages have the following priority, from highest to lowest:

WPM → OTM → BTM → DTM

A BTM message that attempts to enter the queue at the same time as a Watchpoint Message (WPM) or Ownership Trace Message (OTM) is lost. An error message is generated indicating that the BTM was lost.

The following direct or indirect branch then queues a direct/indirect branch with sync message. The count value in this message represents the number of sequential instructions executed after the last successfully generated BTM message. This count includes the branch that did not generate a message due to the collision.

A DTM message that attempts to enter the queue at the same time as a WPM, OTM, or BTM message is lost. A subsequent read or write operation then queues a data trace read/write with sync message