Texas Instruments MSP430x1xx - Manual (Page 134)

The Watchdog Timer
9-2
9.1 The Watchdog Timer
The primary function of the watchdog-timer module (WDT) is to perform a
controlled-system restart after a software problem occurs. If the selected time
interval expires, a system reset is generated. If the watchdog function is not
needed in an application, the module can work as an interval timer, to generate
an interrupt after the selected time interval. The WDT diagram is shown in
Figure 9–1.
Figure 9–1. Schematic of Watchdog Timer
IS0
SSEL
HOLD
NMIES
16b
Counter
Clear
4
A
B
CLK
NMI
TMSEL
CNTCL
IS1
SMCLK
ACLK
Watchdog Timer
Control Register
16
MDB
LSB
MSB
1
1
A
Q6
Q9
Q13
Q15
3
2
1
(Asyn)
EN
Write Enable
Low Byte
Password
Cmp.
EQU
R/W
PUC
0
1
0
1
1
0
1
0
WDTCTL
Y
Int.
Flag
EQU
WDTQn
See Interrupt
Definition
PUC
WDTCNT
Pulse
Generator
Features of the Watchdog Timer include:
- Eight software-selectable time intervals
- Two operating modes: as watchdog or interval timer
- Expiration of the time interval in watchdog mode, which generates a sys-
tem reset; or in timer mode, which generates an interrupt request
- Safeguards which ensure that writing to the WDT control register is only
possible using a password
- Support of ultralow-power using the hold mode