NXP Semiconductors MC9S08LG16, Reference Manual

Page: 84 / 373

Chapter 5 Resets, Interrupts, and General System Control
MC9S08LG32 MCU Series, Rev. 5
84 Freescale Semiconductor
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.
7 6 5 4 3 2 1 0
R
COPE COPT STOPE
0 0 0
BKGDPE RSTPE
W
Reset: 1 1 0 0 0 0 1 u
(1)
1
u = unaffected
POR and
LVR:
1 1 0 0 0 0 1 1
= Unimplemented or Reserved
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 PTC5/BKGD/MS pin to
function as BKGD/MS. When clear, the pin functions as output only GPIO. This pin defaults to the BKGD/MS
function following any MCU reset.
0 PTC5/BKGD/MS pin functions as PTC5.
1 PTC5/BKGD/MS pin functions as BKGD/MS.
0
RSTPE
RESET Pin Enable — This write-once bit when set enables the PTC6/RESET pin to function as RESET. When
clear, the pin functions as open drain output only GPIO. This pin defaults to its RESET function following an MCU
POR or LVD. When RSTPE is set, an internal pullup device is enabled on RESET.
0 PTC6/RESET pin functions as PTC6.
1 PTC6/RESET pin functions as RESET.