XC908AS60ACFU Motorola Semiconductor Products, XC908AS60ACFU Datasheet - Page 204

• Manufacturer Part Number: XC908AS60ACFU
• Description: MC68HC908AZ60A, MC68HC908AS60A Hcmos Microcontroller Unit Technical Data
• Manufacturer: Motorola Semiconductor Products

Break Module (BRK)
13.4 Functional Description
Technical Data
204
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.
•
•
IAB[15:0]
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 13-1
Figure 13-1. Break Module Block Diagram
Break Module (BRK)
IAB[15:8]
IAB[7:0]
BREAK ADDRESS REGISTER HIGH
BREAK ADDRESS REGISTER LOW
shows the structure of the break module.
8-BIT COMPARATOR
8-BIT COMPARATOR
MC68HC908AZ60A — Rev 2.0
CONTROL
MOTOROLA
BREAK