MSP430G2553: How to configure watchdog timer for 1sec

Sankareswaran Muthuraj

Part Number: MSP430G2553

Hello everyone,

My task is to start the watchdog timer and run it to 1sec, between this 1 sec, I need to clear the watchdog timer every 200ms, so that watchdog timer won't reset the controller until the controller can't able to clear watchdog timer within 200ms.

I am using msp430g2553, with DCO as 8Mhz. I referred to the user manual I found the WDTCTL register (I have attached the register image below for your reference) in that register am selecting SMCLK as the clock source for the Watchdog timer by using WDTSSEL bit, and am selecting a period using WDTISx,

Let say am setting WDTISx to 00 then the time period will be --> (1/(Watchdog clock source /32768)) that is (8Mhz/32768)=244.140625 to get time 1/244.140625 will be equal to 4.096ms but I need 1sec, how can I do that and if am wrong on calculation please guide me how to archive my task.

Thanks & Regards,

Aravinth K

over 4 years ago

0 David Schultz over 4 years ago

Guru 25835 points

32KHZ ACLK

0 Sankareswaran Muthuraj over 4 years ago in reply to David Schultz

Prodigy 200 points

@David Schultz Thank you for your reply

What does mean 32Khz , I need to add 32khz externally on board ? I can't add external crystal due to my PCB design complication, I have another idea but I don't know how to do it , am planning to use VLOCLK which is 12khz but I don't know how to configure please guide me how to do it or you have an better idea please let me know.

0 David Schultz over 4 years ago in reply to Sankareswaran Muthuraj

Guru 25835 points

Use of the VLO is well documented and I can't explain it any better.

0 Cash Hao11 over 4 years ago

TI__Mastermind 46765 points

Hi,

The watchdog timer is a 16bit timer which the max count is 32768. So the largest interval of the watchdog timer should be 32768*clock cycle. If you are using a 8MHz as the clock source. The largest interval you would get is 32768/8,000,000 = 4.096ms. If you want to get an interval of 1 second, you would need to use lower clock frequency like 32.768KHz as the clock source.

Best regards,

Cash Hao

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MSP430G2553: How to configure watchdog timer for 1sec