s908az32ag2cfue Freescale Semiconductor, Inc, s908az32ag2cfue Datasheet - Page 113

• Manufacturer Part Number: s908az32ag2cfue
• Description: M68hc08 Microcontrollers 8-bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 11
Brake Module
11.1 Introduction
The break module can generate a break interrupt that stops normal program flow at a defined address to
enter a background program.
11.2 Features
11.3 Functional Description
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.
structure of the break module.
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Accessible I/O Registers during Break Interrupts
CPU-Generated Break Interrupts
Software-Generated Break Interrupts
COP Disabling during Break Interrupts
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.
IAB[15:0]
Figure 11-1. Break Module Block Diagram
IAB[15:8]
IAB[7:0]
BREAK ADDRESS REGISTER HIGH
MC68HC908AZ32A Data Sheet, Rev. 2
BREAK ADDRESS REGISTER LOW
8-BIT COMPARATOR
8-BIT COMPARATOR
CONTROL
BREAK
Figure 11-1
shows the
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