Datasheet

Chapter 5 Resets, Interrupts, and General System Control
MC9S08QD4 Series MCU Data Sheet, Rev. 6
Freescale Semiconductor 61
5.8.4 System Options Register 1 (SOPT1)
This high-page register is a write-once register so only the first write after reset is honored. It can be read
at any time. Any subsequent attempt to write to SOPT1 (intentionally or unintentionally) is ignored to
avoid accidental changes to these sensitive settings. SOPT1 must 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.
7654
1
3210
R
COPE COPT STOPE
00
BKGDPE RSTPE
W
Reset:1101001U
POR:11010010
= Unimplemented or Reserved U = unaffected
1
Bit 4 is reserved, writes will change the value but will have no effect on this MCU.
Figure 5-5. System Options Register 1 (SOPT1)
Table 5-6. SOPT1 Register Field Descriptions
Field Description
7
COPE
COP Watchdog Enable — This write-once bit selects whether the COP watchdog is enabled.
0 COP watchdog timer disabled.
1 COP watchdog timer enabled (force reset on timeout).
6
COPT
COP Watchdog Timeout — This write-once bit selects the timeout period of the COP. COPT along with
COPCLKS in SOPT2 defines the COP timeout period.
0 Short timeout period selected.
1 Long timeout period selected.
5
STOPE
Stop Mode Enable — This write-once bit is used to enable stop mode. If stop mode is disabled and a user
program attempts to execute a STOP instruction, an illegal opcode reset is forced.
0 Stop mode disabled.
1 Stop mode enabled.
1
BKGDPE
Background Debug Mode Pin Enable — This write-once bit when set enables the
PTA4/TPM2CH0O/BKGD/MS pin to function as BKGD/MS. When clear, the pin functions as one of its output only
alternative functions. This pin defaults to the BKGD/MS function following any MCU reset.
0 PTA4/TPM2CH0O/BKGD/MS pin functions as PTA4 or TPM2CH0O.
1 PTA4/TPM2CH0O/BKGD/MS pin functions as BKGD/MS.
0
RSTPE
RESET
Pin Enable — This write-once bit when set enables the PTA5/TPM2CH0I/IRQ/RESET pin to function as
RESET
. When clear, the pin functions as one of its input only alternative functions. This pin defaults to its
input-only port function following an MCU POR. When RSTPE is set, an internal pullup device is enabled on
RESET
.
0 PTA5/TPM2CH0I/IRQ/RESET
pin functions as PTA5, IRQ or TPM2CH0I.
1 PTA5/TPM2CH0I/IRQ/RESET
pin functions as RESET.