C509-L_97 SIEMENS [Siemens Semiconductor Group], C509-L_97 Datasheet - Page 221

• Manufacturer Part Number: C509-L_97
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

8.1.2 Watchdog Timer Control Flags
The watchdog timer is controlled by two control flags (located in SFR IEN0 and IEN1) and one
status flags (located in SFR IP0).
Special Function Register IEN0 (Address A8 H )
Special Function Register IEN1 (Address B8 H )
Special Function Register IP0 (Address A9 H )
Bit
WDT
SWDT
WDTS
Semiconductor Group
Bit No.
A9 H
B8 H
A8 H
EXEN2 SWDT
OWDS WDTS
MSB
7
EAL
BF H
AF H
The shaded bits are not used in controlling the watchdog timer.
WDT
6
BE H
AE H
Function
Watchdog timer refresh flag
Set to initiate a refresh of the watchdog timer. Must be set directly before
SWDT is set to prevent an unintentional refresh of the watchdog timer.
Watchdog timer start flag
Set to activate the watchdog timer. When directly set after setting WDT,
a watchdog timer refresh is performed.
Watchdog timer status flag
Set by hardware when a watchdog timer reset occurred.
Can be cleared or set by software
IP0.5
EX6
5
ET2
BD H
AD H
IP0.4
EX5
4
ES0
BC H
AC H
8-3
IP0.3
EX4
3
ET1
BB H
AB H
IP0.2
EX3
2
EX1
BA2 H
AA H
IP0.1
EX2
1
ET0
B91 H
A9 H
Fail Save Mechanisms
EADC
IP0.0
LSB
0
EX0
B8 H
A8 H
Reset Value : 00 H
Reset Value : 00 H
Reset Value : 00 H
IP0
IEN1
IEN0
1997-10-01
C509-L