MC908QY8CDWE Datasheet, PDF (196/232 Pages) Freescale Semiconductor, Inc – Addendum to MC68HC908QB8, rev. 3

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17.2.2 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)
17.2.2.1 Break Status and Control Register
The break status and control register (BRKSCR) contains break module enable and status bits.
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 17-3. 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
BRKA — Break Active Bit
This read/write status and control bit is set when a break address match occurs. Writing a 1 to BRKA
generates a break interrupt. Clear BRKA by writing a 0 to it before exiting the break routine. Reset
clears the BRKA bit.
1 = Break address match
0 = No break address match
17.2.2.2 Break Address Registers
The break address registers (BRKH and BRKL) contain the high and low bytes of the desired breakpoint
address. Reset clears the break address registers.
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 15
Bit 14
Bit 13
Bit 12
Bit 11
Bit 10
Bit 9
Bit 8
Write:
Reset: 0
0
0
0
0
0
0
0
Figure 17-4. Break Address Register High (BRKH)
Bit 7
6
5
4
3
2
1
Bit 0
Read:
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Write:
Reset: 0
0
0
0
0
0
0
0
Figure 17-5. Break Address Register Low (BRKL)
MC68HC908QB8 Data Sheet, Rev. 3
194
Freescale Semiconductor