MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor 25-51
25.11.12.3 BTM Operation
25.11.12.3.1 Enabling Program Trace
Both types of branch trace messaging can be enabled in one of two ways:
• Setting the TM field of the DC1 register to enable program trace (DC1[TM])
• Using the PTS field of the WT register to enable program trace on watchpoint hits (e200z6
watchpoints are configured within the CPU)
25.11.12.3.2 Relative Addressing
The relative address feature is compliant with the IEEE
-ISTO 5001-2003 standard recommendations,
and is designed to reduce the number of bits transmitted for addresses of indirect branch messages.
The address transmitted is relative to the target address of the instruction which triggered the previous
indirect branch (or sync) message. It is generated by XOR’ing the new address with the previous address,
and then using only the results up to the most significant 1 in the result. To recreate this address, an XOR
of the (most-significant 0-padded) message address with the previously decoded address gives the current
address.
Previous address (A1) =0x0003FC01, New address (A2) = 0x0003F365
Attempted Access to Secure
Memory
For devices which implement security, any attempted branch to secure
memory locations will temporarily disable program trace & cause the
corresponding BTM to be lost. The following direct/indirect branch will queue
a direct/indirect branch with sync. message. The count value within this
message will be inaccurate because the re-enable of program trace is not
necessarily aligned on an instruction boundary.
Collision Priority All messages have the following priority: WPM -> OTM -> BTM -> DTM. A
BTM message which attempts to enter the queue at the same time as a
watchpoint message or ownership trace message will be lost. An error
message will be sent indicating the BTM was lost. The following
direct/indirect branch will queue a direct/indirect branch with sync. message.
The count value within this message will reflect the number of sequential
instructions executed after the last successful BTM Message was generated.
This count will include the branch which did not generate a message due to
the collision.
Table 25-35. Program Trace Exception Summary (Continued)
Exception Condition Exception Handling
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