Chapter 8 S12X Debug (S12XDBGV3) Module
MC9S12XE-Family Reference Manual , Rev. 1.19
332
Freescale Semiconductor
8.4.5.1
Trace Trigger Alignment
Using the TALIGN bits (see
) it is possible to align the trigger with the end, the middle, or
the beginning of a tracing session.
If End or Mid tracing is selected, tracing begins when the ARM bit in DBGC1 is set and State1 is entered.
The transition to Final State if End is selected signals the end of the tracing session. The transition to Final
State if Mid is selected signals that another 32 lines will be traced before ending the tracing session.
Tracing with Begin-Trigger starts at the opcode of the trigger.
8.4.5.1.1
Storing with Begin-Trigger
Storing with Begin-Trigger, data is not stored in the Trace Buffer until the Final State is entered. Once the
trigger condition is met the S12XDBG module will remain armed until 64 lines are stored in the Trace
Buffer. If the trigger is at the address of the change-of-flow instruction the change of flow associated with
the trigger will be stored in the Trace Buffer. Using Begin-trigger together with tagging, if the tagged
instruction is about to be executed then the trace is started. Upon completion of the tracing session the
breakpoint is generated, thus the breakpoint does not occur at the tagged instruction boundary.
8.4.5.1.2
Storing with Mid-Trigger
Storing with Mid-Trigger, data is stored in the Trace Buffer as soon as the S12XDBG module is armed.
When the trigger condition is met, another 32 lines will be traced before ending the tracing session,
irrespective of the number of lines stored before the trigger occurred, then the S12XDBG module is
disarmed and no more data is stored. Using Mid-trigger with tagging, if the tagged instruction is about to
be executed then the trace is continued for another 32 lines. Upon tracing completion the breakpoint is
generated, thus the breakpoint does not occur at the tagged instruction boundary.
8.4.5.1.3
Storing with End-Trigger
Storing with End-Trigger, data is stored in the Trace Buffer until the Final State is entered, at which point
the S12XDBG module will become disarmed and no more data will be stored. If the trigger is at the
address of a change of flow instruction the trigger event will not be stored in the Trace Buffer.
8.4.5.2
Trace Modes
The S12XDBG module can operate in four trace modes. The mode is selected using the TRCMOD bits in
the DBGTCR register. In each mode tracing of XGATE or CPU12X information is possible. The source
for the trace is selected using the TSOURCE bits in the DBGTCR register. The modes are described in the
following subsections. The trace buffer organization is shown in
8.4.5.2.1
Normal Mode
In Normal Mode, change of flow (COF) program counter (PC) addresses will be stored.
COF addresses are defined as follows for the CPU12X:
•
Source address of taken conditional branches (long, short, bit-conditional, and loop primitives)
•
Destination address of indexed JMP, JSR, and CALL instruction
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