mc68hc08az60 Freescale Semiconductor, Inc, mc68hc08az60 Datasheet - Page 136

• Manufacturer Part Number: mc68hc08az60
• Description: M68hc08 Family Of 8-bit Microcontroller Units Mcus
• Manufacturer: Freescale Semiconductor, Inc

Break Module
Functional Description
MC68HC08AZ60 — Rev 1.0
136
When the internal address bus matches the value written in the break
address registers, the break module issues a breakpoint signal to the
CPU. The CPU then loads the instruction register with a software
interrupt instruction (SWI) after completion of the current CPU
instruction. The program counter vectors to $FFFC and $FFFD ($FEFC
and $FEFD in monitor mode).
The following events can cause a break interrupt to occur:
When a CPU-generated address matches the contents of the break
address registers, the break interrupt begins after the CPU completes its
current instruction. A return-from-interrupt instruction (RTI) in the break
routine ends the break interrupt and returns the MCU to normal
operation.
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A CPU-generated address (the address in the program counter)
matches the contents of the break address registers.
Software writes a logic 1 to the BRKA bit in the break status and
control register.
Figure 1
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Figure 1. Break Module Block Diagram
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Break Module
shows the structure of the break module.
BREAK ADDRESS REGISTER HIGH
BREAK ADDRESS REGISTER LOW
8-BIT COMPARATOR
8-BIT COMPARATOR
CONTROL
MOTOROLA
BREAK
2-brk