Use of MSP430 MCU Watchdog

2. The clock sources that can be selected in the latter two modes are: SMCLK and ACLK.

3. When using the last two modes, pay attention to whether the watchdog can work under the state of the MCU. For example, when the MCU is in LPM3, there is only ACLK clock, and in LPM4, there is no clock available.

4. How to use the watchdog mode

When the watchdog count overflows, the program is reset. Enable the watchdog in the program, clear the watchdog before the count overflows, or reset the watchdog to make it count again. If the program runs away, the watchdog may not be cleared or reset, and it will overflow, causing the program to reset.

5. In MSP430F2274, the maximum timing in watchdog mode is 1s. If you need to reset it with a longer time, you can use other counters and execute ((void(*)())RESET_VECTOR)(); after the count is full, or write an error value to the watchdog control register or execute an invalid command after the count is full: such as ((void(*)())0x170)(); 0x170 is an address of a peripheral module and cannot be a function address, so executing this sentence will reset the program.

6. Specific use of watchdog

6.1. Stop mode: turn off the watchdog

C language implementation: WDTCTL = WDTPW + WDTHOLD

6.2. Timer mode: used as a timer, the watchdog interrupt function is executed when the counter is full and an interrupt is generated.

C language implementation:

Start the watchdog timer in the main program, such as: WDTCTL = WDT_MDLY_8;

The watchdog interrupt function is:

#pragmavector=WDT_VECTOR

__interruptvoid wATchdog_timer(void)

{

}

6.3. Watchdog mode: When the count overflows, the reset interrupt function is executed.

C language implementation:

Clear watchdog: WDTCTL = WDTPW+WDTCNTCL;

Set watchdog: WDTCTL = WDT_MRST_0_5;

or WDTCTL = WDT_ARST_1000;