MC68HC08GZ32 Datasheet, PDF (280/320 Pages) Freescale Semiconductor, Inc – Microcontrollers

Development Support
By updating a break address and clearing the BRKA bit in a break interrupt routine, a break interrupt can
be generated continuously.
CAUTION
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.
20.2.1.1 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 (BFCR) enables software to clear status
bits during the break state. See 15.7.3 SIM Break Flag Control Register and the Break Interrupts
subsection for each module.
20.2.1.2 TIM During Break Interrupts
A break interrupt stops the timer counter.
20.2.1.3 COP During Break Interrupts
The COP is disabled during a break interrupt when V_TST is present on the RST pin.
20.2.2 Break Module Registers
These registers control and monitor operation of the break module:
• Break status and control register (BRKSCR)
• Break address register high (BRKH)
• Break address register low (BRKL)
• Break status register (BSR)
• Break flag control register (BFCR)
20.2.2.1 Break Status and Control Register
The break status and control register (BRKSCR) contains break module enable and status bits.
Address: $FE0B
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
0
0
BRKE BRKA
Write:
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 20-4. Break Status and Control Register (BRKSCR)
BRKE — Break Enable Bit
This read/write bit enables breaks on break address register matches. Clear BRKE by writing a 0 to
bit 7. Reset clears the BRKE bit.
1 = Breaks enabled on 16-bit address match
0 = Breaks disabled
MC68HC08GZ32 Data Sheet, Rev. 3
280
Freescale Semiconductor