MPC555
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MPC556
DEVELOPMENT SUPPORT
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
21-16
When the IFM bit is clear, every matched instruction can cause an instruction break-
point (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.
21.3.1.6 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)
• Less than or equal of the maximum positive number when in signed mode
(0111...1)
• Greater than or equal of the maximum negative number when in signed mode
(1000...)
These boundary cases need no special support because they all mean ‘always true’
and can be programmed using the ignore option of the load/store watchpoint program-
ming (refer to
21.3 Watchpoints and Breakpoints Support
21.3.2 Instruction Support
There are four instruction address comparators A,B,C, and D. Each is 30 bits long,
generating two output signals: equal and less than. These signals are used to gener-
ate one of the following four events: equal, not equal, greater than, less than.
The instruction watchpoints and breakpoint are generated using these events and ac-
cording to user programming. Note that using the OR option enables “out of range” de-
tect.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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