zic2410 California Eastern Laboratories, zic2410 Datasheet - Page 31

• Manufacturer Part Number: zic2410
• Description: Single-chip Solution, Compliant With Zigbee
• Manufacturer: California Eastern Laboratories

1.7.3 WATCHDOG TIMER
The Watchdog Timer (WDT) monitors whether the MCU is or is not operating normally. If a
problem occurs, the WDT will immediately reset the MCU.
In fact, when the system does not clear the WDT counter value, WDT considers that a problem
has occurred, and therefore, resets the MCU automatically. The WDT is used when a program
is not completed normally because a software error has been caused by the environment such
as electrical noise, unstable power or static electricity.
When Powered-up, the internal counter value of WDT is set to ‘0’ and watchdog timer is
operated. If overflow is caused in the internal counter, a system reset is initiated with a timeout
period is about 0.5 second. A user may reset the WDT by clearing WDTEN bit of WDTCON.
When WDT is operating, an application program must clear the WDT periodically to prevent the
system from being reset unwantedly.
Reset interval of WDT is calculated by the Equation 3. For example, when WDTPRE value is ‘0’
and system clock of MCU is 8MHz, reset interval of WDT is 65.536ms.
WDTCON (WATCHDOG TIMER CONTROL REGISTER, 0xD2)
Bit
7:5
1:0
4
3
2
Rev A
WDTCLR
WDTPRE
WDTWE
WDTEN
Name
Reserved
WDT Write Enable: To set WDTEN to ‘1’, this field should be set
to ‘1’.
WDT Enable: To use WDT, this bit should be set to ‘1’.
WDT Clear: Watchdog Timer resets a system when the internal
counter value is reached to the defined value by WDTPRE value.
This field does not allow system to be reset by clearing the
internal counter. When this field is set to ‘1’, this field value is
cleared automatically.
Watchdog Timer Prescaler: Sets the prescaler value of WDT.
Equation 3 – Watchdog Reset Interval Calculation
Watchdog Reset Interval =
Table 14 – Watchdog Timer Register
Document No. 0005-05-07-00-000
ZIC2410 Datasheet
Descriptions
256
×
2
f
system
(
11
+
WDTPRE
)
R/W
R/W
R/W
R/W
R/W
R/W
Page 31 of 119
Reset
Value
0
0
0
0
0