MC908GR8CDWE Datasheet, PDF (93/408 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Freescale Semiconductor, Inc.
Break Module (BRK)
Functional Description
Addr. Register Name
Bit 7
6
5
4
3
2
Read: 0
0
0
1
0
0
$FE00
SIM
Break Status Register
(SBSR)
Write:
R
R
R
R
R
R
Reset: 0
0
0
1
0
0
Read:
$FE03
SIM Break Flag Control
Register (SBFCR)
Write:
BCFE
R
R
R
R
R
Reset: 0
Read:
$FE09
Break Address Register
High (BRKH)
Write:
Bit 15
14
13
12
11
10
Reset: 0
0
0
0
0
0
Read:
$FE0A
Break Address Register
Low (BRKL)
Write:
Bit 7
6
5
4
3
2
Reset: 0
0
0
0
0
0
Read:
0
0
0
0
$FE0B
Break Status and Control
Register (BRKSCR)
Write:
BRKE
BRKA
Reset: 0
0
0
0
0
0
Note: Writing a logic 0 clears BW.
= Unimplemented
R
= Reserved
Figure 6-2. I/O Register Summary
1
BW
NOTE
0
R
Bit 0
0
R
0
R
9
Bit 8
0
0
1
Bit 0
0
0
0
0
0
0
6.4.1 Flag Protection During Break Interrupts
The BCFE bit in the SIM break flag control register (SBFCR) enables
software to clear status bits during the break state.
6.4.2 CPU During Break Interrupts
The CPU starts a break interrupt by:
• Loading the instruction register with the SWI instruction
• Loading the program counter with $FFFC and $FFFD ($FEFC and
$FEFD in monitor mode)
MC68HC908GR8 — Rev 4.0
MOTOROLA
Break Module (BRK)
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Technical Data
93