Motorola MPC533 Reference Manual page 890

Watchpoints and Breakpoints Support
status register) are busy and, therefore, MSRRI = 0, (in the prologues and epilogues of
interrupt/exception handlers).
When the CPU is programmed always to recognize internal breakpoints, it is possible to
debug all parts of the code. However, if an internal breakpoint is recognized when MSRRI
= 0 (SRR0 and SRR1 are busy), the machine enters into a non-restartable state. For more
information refer to Section 3.15.4, "Exceptions."
When working in the masked mode, all internal breakpoints detected when MSRRI = 0 are
lost. Watchpoints detected in this case are not counted by the debug counters. Watchpoints
detected are always reported on the external pins, regardless of the value of the MSRRI bit.
Out of reset, the CPU is in masked mode. Programming the CPU to be in non-masked mode
is done by setting the BRKNOMSK bit in the LCTRL2 register. Refer to Section 21.6.10,
"L-Bus Support Control Register 2." The BRKNOMSK bit controls all internal breakpoints
(I-breakpoints and L-breakpoints).
21.2.1.5 Ignore First Match
In order to facilitate the debugger utilities "continue" and "go from x", the ignore first
match option is supported for instruction breakpoints. When an instruction breakpoint is
first enabled (as a result of the first write to the instruction support control register or as a
result of the assertion of the MSRRI bit when operating in the masked mode), the first
instruction will not cause an instruction breakpoint if the ignore first match (IFM) bit in the
instruction support control register (ICTRL) is set (used for "continue").
When the IFM bit is clear, every matched instruction can cause an instruction breakpoint
(used for "go from x"). This bit is set by the software and cleared by the hardware after the
first instruction breakpoint match is ignored. Load/store breakpoints and all counter
generated breakpoints (instruction and load/store) are not affected by this mode.
21.2.1.6 Generating Six Compare Types
Using the four compare types mentioned above (equal, not equal, greater than, less than) it
is possible to generate also two more compare types: greater than or equal and less than or
equal.
• Generating the greater than or equal compare type can be done by using the greater
than compare type and programming the comparator to the needed value minus 1.
• Generating the less than or equal compare type can be done by using the less than
compare type and programming the comparator to the needed value plus 1.
This method does not work for the following boundary cases:
• Less than or equal of the largest unsigned number (1111...1)
• Greater than or equal of the smallest unsigned number (0000...0)
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