System Development and Debugging
MPC885 PowerQUICC Family Reference Manual, Rev. 2
53-16
Freescale Semiconductor
Figure 53-4. Partially Supported Watchpoints/Breakpoint Example
53.2.4.3
Context Dependent Filter
The core can be programmed to recognize only internal breakpoints when MSR[RI] = 1 (maskable mode)
or to always recognize internal breakpoints (nonmaskable mode).
In maskable mode, when the core is programmed only to recognize internal breakpoints (when MSR[RI]
=1), it is possible to debug all parts of the code, except when SRR0 and SRR1, DAR, and DSISR are busy
as indicated by MSR[RI] = 0 (in the prologues and epilogues of exception handlers). Internal breakpoints
detected when MSR[RI] = 0 are lost and debug counters do not count detected watchpoints. Detected
watchpoints are always reported on the external pins, regardless of the value of MSR[RI].
In nonmaskable mode, when the core is programmed to recognize internal breakpoints, all parts of the code
can be debugged. However, if an internal breakpoint is recognized when MSR[RI] = 0 (SRR0 and SRR1
are busy), the machine enters a nonrestartable state. See
Section 6.1.5, “Recoverability After an
Exception.”
The core defaults to maskable mode after reset. The core is put in nonmaskable mode by setting
LCTRL2[BRKNOMSK], which controls all internal I- and L-breakpoints. See
Section 53.5.1.5,
“Load/Store Support AND-OR Control Register (LCTRL2).”
53.2.4.4
Ignore First Match
The ignore first match bit, ICTRL[IFM], facilitates the debugger’s “continue” and “go from x” utilities for
instruction breakpoints. When an instruction breakpoint is first enabled, the first instruction cannot cause
an instruction breakpoint if ICTRL[IFM] = 1. This is used for “continue” utilities. If IFM = 0, every
matched instruction causes an instruction breakpoint. This is used for “go from x”. IFM is set by software
and cleared by 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.
53.2.4.5
Generating Six Compare Types
The four compare types (equal, not equal, greater than, and less than) can be used to generate two
additional compare types—greater than or equal to and less than or equal to. The greater-than-or-equal
compare type can be generated by using the greater-than compare type and programming the comparator
to the value in question minus 1. Likewise, the less-than-or-equal compare type can be generated by using
the less-than compare type and programming the comparator to the value in question plus 1. This does not
work for the following boundary cases:
•
Less than or equal of the largest unsigned number (1111...1).
0x00000000
0x00000004
0x00000008
0x0000000c
0x00000010
Possible false detect on these half-words when using word/multiple
Summary of Contents for PowerQUICC MPC870
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Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
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Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
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Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
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