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When the core is programmed to recognize internal breakpoints, you can debug all parts of
the code. However, if an internal breakpoint is recognized when MSR
and SRR1 are busy), the machine enters into a nonrestartable state. For more information
refer to Section 6.3.4.1 Restartability After An Interrupt. When working in masked mode,
all internal breakpoints that are detected when MSR
are not counted by the debug counters. Detected watchpoints are always reported on the
external pins, regardless of the value of the MSR
The core defaults to masked mode after reset. It is input in the nonmasked mode by setting
the BRKNOMSK bit in the LCTRL2 register.The BRKNOMSK bit controls all internal
breakpoints (I-breakpoints and L-breakpoints). See Section 20.6.2.7 Load/Store Support
AND-OR Control Register for more information.
20.3.1.4 IGNORE FIRST MATCH OPTION. To facilitate the debugger utilities of "continue"
and "go from x", the ignore first match option is supported for the instruction breakpoints.
When an instruction breakpoint is first enabled, the first instruction will not cause an
instruction breakpoint if the IFM bit in the instruction support control (ICTRL) register is set.
This is used for "continue" utilities. When IFM is clear, every matched instruction can cause
an instruction breakpoint. This is used for "go from x". The IFM bit is set by the software and
cleared by the hardware after the first instruction breakpoint (the match is ignored). Load/
store breakpoints and all counter-generated breakpoints (instruction and load/store) are
unaffected by this mode.
20.3.1.5 GENERATING COMPARE TYPES. Using the four compare types—equal to, not
equal to, greater than, and less than—it is possible to generate two additional compare
types:
• Greater than or equal to
• Less than or equal to
Generating the greater than or equal to compare type can be accomplished by programming
the comparator to the value in question plus or minus 1. Notice that this method does not
work for the following boundary cases:
• Less than or equal to the largest unsigned number (1111...1)
• Greater than or equal to the smallest unsigned number (0000...0)
• Less than or equal to the maximum positive number when in signed mode (0111...1)
• Greater than or equal to the maximum negative number when in signed mode (1000...)
These boundary cases do not require special support because they are considered 'always
true'. They can be programmed using the ignore option of the load/store watchpoint
programming. See Section 20.6.2.7 Load/Store Support AND-OR Control Register for
more information.
MOTOROLA
Development Capabilities and Interface
=0 are lost and detected watchpoints
RI
bit.
RI
MPC823e REFERENCE MANUAL
= 0 (registers SRR0
RI
20-15
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