Texas Instruments MSP430x1xx manual Operation in Low-Power Modes, Software Examples

Watchdog Timer Operation

10.2.5 Operation in Low-Power Modes

The MSP430 devices have several low-power modes. Different clock signals are available in different low-power modes. The requirements of the user’s application and the type of clocking used determine how the WDT should be configured. For example, the WDT should not be configured in watchdog mode with SMCLK as its clock source if the user wants to use low-power mode 3 because SMCLK is not active in LPM3 and the WDT would not function. When the watchdog timer is not required, the WDTHOLD bit can be used to hold the WDTCNT, reducing power consumption.

10.2.6 Software Examples

Any write operation to WDTCTL must be a word operation with 05Ah (WDTPW) in the upper byte:

;Periodically clear an active watchdog

MOV #WDTPW+WDTCNTCL,&WDTCTL

;

; Change watchdog timer interval

MOV #WDTPW+WDTCNTL+SSEL,&WDTCTL

;

; Stop the watchdog

MOV #WDTPW+WDTHOLD,&WDTCTL

;

;Change WDT to interval timer mode, clock/8192 interval

MOV #WDTPW+WDTCNTCL+WDTTMSEL+WDTIS0,&WDTCTL

10-6Watchdog Timer