mc9s08ac32 Freescale Semiconductor, Inc, mc9s08ac32 Datasheet - Page 75

• Manufacturer Part Number: mc9s08ac32
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

1
5.9.3
This register contains a single write-only control bit. A serial background command such as
WRITE_BYTE must be used to write to SBDFR. Attempts to write this register from a user program are
ignored. Reads always return 0x00.
5.9.4
This register may be read at any time. Bits 3 and 2 are unimplemented and always read 0. This is a
write-once register so only the first write after reset is honored. Any subsequent attempt to write to SOPT
(intentionally or unintentionally) is ignored to avoid accidental changes to these sensitive settings. SOPT
should be written during the user’s reset initialization program to set the desired controls even if the desired
settings are the same as the reset settings.
Freescale Semiconductor
BDFR is writable only through serial background debug commands, not from user programs.
Reset
BDFR
Field
Field
LVD
ICG
2
1
0
W
R
System Background Debug Force Reset Register (SBDFR)
System Options Register (SOPT)
Internal Clock Generation Module Reset — Reset was caused by an ICG module reset.
0 Reset not caused by ICG module.
1 Reset caused by ICG module.
Low Voltage Detect — If the LVDRE and LVDSE bits are set and the supply drops below the LVD trip voltage,
an LVD reset will occur. This bit is also set by POR.
0 Reset not caused by LVD trip or POR.
1 Reset caused by LVD trip or POR.
Background Debug Force Reset — A serial background command such as WRITE_BYTE may be used to
allow an external debug host to force a target system reset. Writing logic 1 to this bit forces an MCU reset. This
bit cannot be written from a user program.
0
0
7
Figure 5-4. System Background Debug Force Reset Register (SBDFR)
= Unimplemented or Reserved
Table 5-4. SRS Register Field Descriptions (continued)
0
0
6
Table 5-5. SBDFR Register Field Descriptions
MC9S08AC60 Series Data Sheet, Rev. 2
0
0
5
0
0
4
Description
Description
Chapter 5 Resets, Interrupts, and System Configuration
3
0
0
0
0
2
0
0
1
BDFR
0
0
0
1
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