Revision 0:2d9d71938413, committed 2019-10-03

Comitter:

rlanders73

Date:

Thu Oct 03 18:04:23 2019 +0000

Commit message:

This is a class implementation for the STM32 watchdog timer.

Changed in this revision

diff -r 000000000000 -r 2d9d71938413 Watchdog.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Watchdog.cpp	Thu Oct 03 18:04:23 2019 +0000
@@ -0,0 +1,94 @@
+/// @file Watchdog.cpp provides the interface to the Watchdog module
+///
+/// This provides basic Watchdog service for the mbed. You can configure
+/// various timeout intervals that meet your system needs. Additionally,
+/// it is possible to identify if the Watchdog was the cause of any 
+/// system restart.
+/// 
+/// Adapted from Simon's Watchdog code from http://mbed.org/forum/mbed/topic/508/
+
+
+#include "mbed.h"
+#include "Watchdog.h"
+
+#ifdef FEATURE_COMMON_PAL
+#include "mbed_trace.h"
+#define TRACE_GROUP "WDT"
+#else
+#define tr_debug(format, ...) debug_if(_debug_trace_on, format "\n", ## __VA_ARGS__)
+#define tr_info(format, ...)  debug_if(_debug_trace_on, format "\n", ## __VA_ARGS__)
+#define tr_warn(format, ...)  debug_if(_debug_trace_on, format "\n", ## __VA_ARGS__)
+#define tr_error(format, ...) debug_if(_debug_trace_on, format "\n", ## __VA_ARGS__)
+#endif
+
+/// Watchdog gets instantiated at the module level
+Watchdog::Watchdog() {
+    // capture the cause of the previous reset
+    wdreset = __HAL_RCC_GET_FLAG(RCC_FLAG_IWDGRST);
+    //Clear source Reset Flag
+    __HAL_RCC_CLEAR_RESET_FLAGS();
+}
+
+/// Load timeout value in watchdog timer and enable
+void Watchdog::Configure(float timeout) {
+       
+    #define LsiFreq (45000)
+    uint16_t PrescalerCode;
+    uint16_t Prescaler;
+    uint16_t ReloadValue;
+    float Calculated_timeout;
+    
+    if ((timeout * (LsiFreq/4)) < 0x7FF) {
+        PrescalerCode = IWDG_PRESCALER_4;
+        Prescaler = 4;
+    }
+    else if ((timeout * (LsiFreq/8)) < 0xFF0) {
+        PrescalerCode = IWDG_PRESCALER_8;
+        Prescaler = 8;
+    }
+    else if ((timeout * (LsiFreq/16)) < 0xFF0) {
+        PrescalerCode = IWDG_PRESCALER_16;
+        Prescaler = 16;
+    }
+    else if ((timeout * (LsiFreq/32)) < 0xFF0) {
+        PrescalerCode = IWDG_PRESCALER_32;
+        Prescaler = 32;
+    }
+    else if ((timeout * (LsiFreq/64)) < 0xFF0) {
+        PrescalerCode = IWDG_PRESCALER_64;
+        Prescaler = 64;
+    }
+    else if ((timeout * (LsiFreq/128)) < 0xFF0) {
+        PrescalerCode = IWDG_PRESCALER_128;
+        Prescaler = 128;
+    }
+    else {
+        PrescalerCode = IWDG_PRESCALER_256;
+        Prescaler = 256;
+    }
+    
+    // specifies the IWDG Reload value. This parameter must be a number between 0 and 0x0FFF.
+    ReloadValue = (uint32_t)(timeout * (LsiFreq/Prescaler));
+    
+    Calculated_timeout = ((float)(Prescaler * ReloadValue)) / LsiFreq;
+    tr_debug("WATCHDOG set with prescaler:%d reload value: 0x%X - timeout:%f\n",Prescaler, ReloadValue, Calculated_timeout);
+    
+    IWDG->KR = 0x5555; //Disable write protection of IWDG registers      
+    IWDG->PR = PrescalerCode;      //Set PR value      
+    IWDG->RLR = ReloadValue;      //Set RLR value      
+    IWDG->KR = 0xAAAA;    //Reload IWDG      
+    IWDG->KR = 0xCCCC;    //Start IWDG - See more at: http://embedded-lab.com/blog/?p=9662#sthash.6VNxVSn0.dpuf       
+ 
+    Pet();
+}
+
+/// "Pet", "kick" or "feed" the dog - reset the watchdog timer
+/// by writing this required bit pattern
+void Watchdog::Pet() { 
+    IWDG->KR = 0xAAAA;         //Reload IWDG - See more at: http://embedded-lab.com/blog/?p=9662#sthash.6VNxVSn0.dpuf
+}
+
+/// get the flag to indicate if the watchdog causes the reset
+bool Watchdog::WatchdogCausedReset() {
+    return wdreset;
+}

diff -r 000000000000 -r 2d9d71938413 Watchdog.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Watchdog.h	Thu Oct 03 18:04:23 2019 +0000
@@ -0,0 +1,101 @@
+/// @file Watchdog.h provides the interface to the Watchdog module
+///
+/// This provides basic Watchdog service for the mbed. You can configure
+/// various timeout intervals that meet your system needs. Additionally,
+/// it is possible to identify if the Watchdog was the cause of any 
+/// system restart, permitting the application code to take appropriate
+/// behavior.
+/// 
+/// Adapted from Simon's Watchdog code from http://mbed.org/forum/mbed/topic/508/
+///
+/// @note Copyright © 2011 by Smartware Computing, all rights reserved.
+///     This software may be used to derive new software, as long as
+///     this copyright statement remains in the source file.
+/// @author David Smart
+///
+/// History
+/// \li v1.00 - 20110616: initial release with some documentation improvements
+///
+#ifndef WATCHDOG_H
+#define WATCHDOG_H
+#include "mbed.h"
+
+/// The Watchdog class provides the interface to the Watchdog feature
+///
+/// Embedded programs, by their nature, are usually unattended. If things
+/// go wrong, it is usually important that the system attempts to recover.
+/// Aside from robust software, a hardware watchdog can monitor the
+/// system and initiate a system reset when appropriate.
+///
+/// This Watchdog is patterned after one found elsewhere on the mbed site,
+/// however this one also provides a method for the application software
+/// to determine the cause of the reset - watchdog or otherwise.
+///
+/// example:
+/// @code
+/// Watchdog wd;
+///
+/// ...
+/// main() {
+///    if (wd.WatchdogCausedReset())
+///        pc.printf("Watchdog caused reset.\r\n");
+///      
+///    wd.Configure(3.0);       // sets the timeout interval
+///    for (;;) {
+///         wd.Service();       // kick the dog before the timeout
+///         // do other work
+///    }
+/// }
+/// @endcode
+///
+class Watchdog {
+public:
+    /// Create a Watchdog object
+    ///
+    /// example:
+    /// @code
+    /// Watchdog wd;    // placed before main
+    /// @endcode
+    Watchdog();
+    
+    /// Configure the timeout for the Watchdog
+    ///
+    /// This configures the Watchdog service and starts it. It must
+    /// be serviced before the timeout, or the system will be restarted.
+    ///
+    /// example:
+    /// @code
+    ///     ...
+    ///     wd.Configure(1.4);  // configure for a 1.4 second timeout
+    ///     ...
+    /// @endcode
+    ///
+    /// @param[in] timeout in seconds, as a floating point number
+    /// @returns none
+    ///
+    void Configure(float timeout);
+    
+    /// Service the Watchdog so it does not cause a system reset
+    ///
+    /// example:
+    /// @code
+    ///    wd.Pet();
+    /// @endcode
+    /// @returns none
+    void Pet();
+    
+    /// WatchdogCausedReset identifies if the cause of the system
+    /// reset was the Watchdog
+    ///
+    /// example:
+    /// @code
+    ///    if (wd.WatchdogCausedReset())) {
+    /// @endcode
+    ///
+    /// @returns true if the Watchdog was the cause of the reset
+    bool WatchdogCausedReset();
+private:
+    bool wdreset;
+};
+
+#endif // WATCHDOG_H
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