watchdog.h

00001 /// @file Watchdog.h provides the interface to the Watchdog module
00002 ///
00003 /// This provides basic Watchdog service for the mbed. You can configure
00004 /// various timeout intervals that meet your system needs. Additionally,
00005 /// it is possible to identify if the Watchdog was the cause of any 
00006 /// system restart, permitting the application code to take appropriate
00007 /// behavior.
00008 /// 
00009 /// Adapted from Simon's Watchdog code from http://mbed.org/forum/mbed/topic/508/
00010 ///
00011 /// @note Copyright © 2011 by Smartware Computing, all rights reserved.
00012 ///     This software may be used to derive new software, as long as
00013 ///     this copyright statement remains in the source file.
00014 /// @author David Smart
00015 ///
00016 /// History
00017 /// \li v1.00 - 20110616: initial release with some documentation improvements
00018 ///
00019 #ifndef WATCHDOG_H
00020 #define WATCHDOG_H
00021 #include "mbed.h"
00022 
00023 /// The Watchdog class provides the interface to the Watchdog feature
00024 ///
00025 /// Embedded programs, by their nature, are usually unattended. If things
00026 /// go wrong, it is usually important that the system attempts to recover.
00027 /// Aside from robust software, a hardware watchdog can monitor the
00028 /// system and initiate a system reset when appropriate.
00029 ///
00030 /// This Watchdog is patterned after one found elsewhere on the mbed site,
00031 /// however this one also provides a method for the application software
00032 /// to determine the cause of the reset - watchdog or otherwise.
00033 ///
00034 /// example:
00035 /// @code
00036 /// Watchdog wd;
00037 ///
00038 /// ...
00039 /// main() {
00040 ///    if (wd.WatchdogCausedReset())
00041 ///        pc.printf("Watchdog caused reset.\r\n");
00042 ///      
00043 ///    wd.Configure(3.0);       // sets the timeout interval
00044 ///    for (;;) {
00045 ///         wd.Service();       // kick the dog before the timeout
00046 ///         // do other work
00047 ///    }
00048 /// }
00049 /// @endcode
00050 ///
00051 class Watchdog {
00052 public:
00053     /// Create a Watchdog object
00054     ///
00055     /// example:
00056     /// @code
00057     /// Watchdog wd;    // placed before main
00058     /// @endcode
00059     Watchdog();
00060     
00061     /// Configure the timeout for the Watchdog
00062     ///
00063     /// This configures the Watchdog service and starts it. It must
00064     /// be serviced before the timeout, or the system will be restarted.
00065     ///
00066     /// example:
00067     /// @code
00068     ///     ...
00069     ///     wd.Configure(1.4);  // configure for a 1.4 second timeout
00070     ///     ...
00071     /// @endcode
00072     ///
00073     /// @param[in] timeout in seconds, as a floating point number
00074     /// @returns none
00075     ///
00076     void Configure(float timeout);
00077     
00078     /// Service the Watchdog so it does not cause a system reset
00079     ///
00080     /// example:
00081     /// @code
00082     ///    wd.Service();
00083     /// @endcode
00084     /// @returns none
00085     void Service();
00086     
00087     /// WatchdogCausedReset identifies if the cause of the system
00088     /// reset was the Watchdog
00089     ///
00090     /// example:
00091     /// @code
00092     ///    if (wd.WatchdogCausedReset())) {
00093     /// @endcode
00094     ///
00095     /// @returns true if the Watchdog was the cause of the reset
00096     bool WatchdogCausedReset();
00097 private:
00098     bool wdreset;
00099 };
00100 
00101 #endif // WATCHDOG_H