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Breakpoints
18.5 Breakpoints
Hardware breakpoints are used to debug software on the
MC68HC912DG128 by comparing actual address and data values to
predetermined data in setup registers. A successful comparison will
place the CPU in background debug mode (BDM) or initiate a software
interrupt (SWI). Breakpoint features designed into the
MC68HC912DG128 include:
• Mode selection for BDM or SWI generation
• Program fetch tagging for cycle of execution breakpoint
• Second address compare in dual address modes
• Range compare by disable of low byte address
• Data compare in full feature mode for non-tagged breakpoint
• Byte masking for high/low byte data compares
• R/W compare for non-tagged compares
• Tag inhibit on BDM TRACE
18.5.1 Breakpoint Modes
Three modes of operation determine the type of breakpoint in effect.
• Dual address-only breakpoints, each of which will cause a
software interrupt (SWI)
• Single full-feature breakpoint which will cause the part to enter
background debug mode (BDM)
• Dual address-only breakpoints, each of which will cause the part
to enter BDM
Breakpoints will not occur when BDM is active.
MC68HC912DG128 — Rev 3.0
Technical Data
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