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Alex
Alex

Reputation: 10126

Watchdog configuration on Stellaris Launchpad LM4F120

I try to configure the watchdog timer on Stellaris Launchpad LM4F120.

The code is the following:

void configure_watchdog(void) {
    SYSCTL_RCGCWD_R = 0x1; /* Enabling Clock for WD0 */
    WATCHDOG0_LOAD_R = 0xffffffff; /* Setting initial value */
    WATCHDOG0_CTL_R = WDT_CTL_INTEN; /* Enabling interrupt generation */
}

This supposed to be enough in accordance to the datasheet.

The problem is that controller always falls to FaultISR and resets after it. I can't understand why.

What am I doing wrong?

EDIT: The controller does not reset. It just goes to FaultISR

Upvotes: 1

Views: 659

Answers (2)

Martin Thompson
Martin Thompson

Reputation: 16812

You have to keep servicing the watchdog, otherwise it times out and calls whatever is setup for that exception. FaultISR would appear to be that in your case.

If you want the watchdog to do something else on the timeout you need to figure out how your particular toolchain connects functions to exception sources and map your new function correctly.

If you don't want the watchdog to expire (which is usually what it's there for, to catch errant code) then you need to service it regularly. The compiler vendor often provides a function or intrinsic to do this.

Upvotes: 1

bta
bta

Reputation: 45057

Jumping to an ISR when the watchdog expires sounds like the correct behavior. What exactly are you doing inside your ISR code? If you are resetting the watchdog inside the ISR, then you shouldn't be seeing the microcontroller reset itself (based on your posted configuration code, at least). After you set up the watchdog, read the configuration register back out and make sure that it holds the value that you expect. Some of the bits in that register can only be set under certain circumstances, and it's possible that you're not running with the settings that you think you're using.

You mentioned that you were trying to use the watchdog timer as a generic downcounter. Could you use one of the general-purpose timers instead of the watchdog? You would still get an interrupt when time expired, but regular timers don't have the ability to reset the entire system.

Upvotes: 2

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