Package ej.hal

Class WatchdogTimer

java.lang.Object

ej.hal.WatchdogTimer

public class WatchdogTimer
extends Object

This class provides a way to handle watchdog timers. It is implemented over a low level watchdog timer and provides a checkpoint registration system. The registration system allows to add checkpoints monitored by the watchdog.

Method Summary

Modifier and Type	Method	Description
static void	checkpoint(int checkpointId)	Validates the checkpoint identified by the given checkpointId and refreshes the watchdog if all checkpoints are passed.
static int	getWatchdogTimeoutMs()	Gets the configured watchdog timeout period (in milliseconds).
static void	init()	Initializes the watchdog timer and the checkpoints registration system.
static boolean	isResetCause()	Checks whether the last reset was caused by the watchdog or not.
static int	registerCheckpoint()	Registers a watchdog checkpoint and returns its corresponding Id.
static void	start()	Starts the watchdog timer.
static void	stop()	Stops the watchdog timer and unregisters all existing checkpoints.
static void	unregisterCheckpoint(int checkpointId)	Unregisters the checkpoint with the given checkpointId.

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

init

public static void init()
                 throws WatchdogTimerException

Initializes the watchdog timer and the checkpoints registration system. This method does nothing if the watchdog is already initialized.

Throws:

WatchdogTimerException - if an error occurs.

start

public static void start()
                  throws WatchdogTimerException

Starts the watchdog timer. This method does nothing if the watchdog is already started.

Throws:

WatchdogTimerException - if the watchdog is not initialized or an error occurs.

stop

public static void stop()
                 throws WatchdogTimerException

Stops the watchdog timer and unregisters all existing checkpoints. This method does nothing if the watchdog is not started.

Throws:

WatchdogTimerException - if an error occurs.

registerCheckpoint

public static int registerCheckpoint()
                              throws WatchdogTimerException

Registers a watchdog checkpoint and returns its corresponding Id. The maximum number of checkpoints that can be registered is 32 and the checkpoint Id values are comprise between 0 and 31.

Returns:

the registered checkpoint Id.

Throws:

WatchdogTimerException - if we exceed the maximum number of registrations or if watchdog was not initialized.

unregisterCheckpoint

public static void unregisterCheckpoint(int checkpointId)
                                 throws WatchdogTimerException,
                                        IllegalArgumentException

Unregisters the checkpoint with the given checkpointId.

Parameters:

checkpointId - the checkpoint Id to unregister.

Throws:

WatchdogTimerException - if watchdog is not initialized or the checkpointId is not registered.

IllegalArgumentException - if checkpointId is out of the range.

checkpoint

public static void checkpoint(int checkpointId)
                       throws WatchdogTimerException,
                              IllegalArgumentException

Validates the checkpoint identified by the given checkpointId and refreshes the watchdog if all checkpoints are passed. Be sure that all the checkpoints are validated before the watchdog timeout expires otherwise a hardware reset will be performed.

Parameters:

checkpointId - the Id of the checkpoint to validate.

Throws:

WatchdogTimerException - if the watchdog is not initialized
if the checkpointId is not registered or an error occurs.

IllegalArgumentException - if checkpointId is out of the range.

isResetCause

public static boolean isResetCause()
                            throws WatchdogTimerException

Checks whether the last reset was caused by the watchdog or not.

Returns:

true if the last reset was caused by the watchdog; false otherwise.

Throws:

WatchdogTimerException - if an error occurs.

getWatchdogTimeoutMs

public static int getWatchdogTimeoutMs()
                                throws WatchdogTimerException

Gets the configured watchdog timeout period (in milliseconds).

Returns:

the watchdog timeout period.

Throws:

WatchdogTimerException - if an error occurs.