mc68hc908gr8b Freescale Semiconductor, Inc, mc68hc908gr8b Datasheet - Page 216

• Manufacturer Part Number: mc68hc908gr8b
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Development Support
When the internal address bus matches the value written in the break address registers or when software
writes a 1 to the BRKA bit in the break status and control register, the CPU starts a break interrupt by:
The break interrupt timing is:
By updating a break address and clearing the BRKA bit in a break interrupt routine, a break interrupt can
be generated continuously.
A break address should be placed at the address of the instruction opcode. When software does not
change the break address and clears the BRKA bit in the first break interrupt routine, the next break
interrupt will not be generated after exiting the interrupt routine even when the internal address bus
matches the value written in the break address registers.
18.2.1.1 Flag Protection During Break Interrupts
The system integration module (SIM) controls whether or not module status bits can be cleared during
the break state. The BCFE bit in the break flag control register (SBFCR) enables software to clear status
bits during the break state. See
subsection for each module.
18.2.1.2 TIM During Break Interrupts
A break interrupt stops the timer counter and inhibits captures.
18.2.1.3 COP During Break Interrupts
The COP is disabled during a break interrupt when V
18.2.2 Break Module Registers
These registers control and monitor operation of the break module:
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Loading the instruction register with the SWI instruction
Loading the program counter with $FFFC and $FFFD ($FEFC and $FEFD in monitor mode)
When a break address is placed at the address of the instruction opcode, the instruction is not
executed until after completion of the break interrupt routine.
When a break address is placed at an address of an instruction operand, the instruction is executed
before the break interrupt.
When software writes a 1 to the BRKA bit, the break interrupt occurs just before the next instruction
is executed.
Break status and control register (BRKSCR)
Break address register high (BRKH)
Break address register low (BRKL)
Break status register (SBSR)
Break flag control register (SBFCR)
14.7.3 SIM Break Flag Control Register
MC68HC908GR8B Data Sheet, Rev. 3.0
CAUTION
TST
is present on the RST pin.
and the Break Interrupts
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