Revision 9:84f7c088c261, committed 2015-11-11

Comitter:

salarian

Date:

Wed Nov 11 16:05:42 2015 +0000

Parent:

8:3c7d083f26b5

Commit message:

Refactored the STM32 bit variant of the functions and set the default clock to 32.768 kHz (crystal oscillator)

Changed in this revision

--- a/Watchdog.cpp	Tue Oct 27 17:04:16 2015 +0000
+++ b/Watchdog.cpp	Wed Nov 11 16:05:42 2015 +0000
@@ -76,7 +76,7 @@
 }
 
 // Compute the log2 of an integer. This is the simplest algorithm but probably is a bit slow.
-int log2(unsigned v)
+int Watchdog::log2(unsigned v)
 {
     unsigned r = 0;             
     
@@ -91,7 +91,9 @@
 void Watchdog::Configure(float s) {
     // http://www.st.com/web/en/resource/technical/document/reference_manual/CD00171190.pdf
     
-    s = s * 40000;                  // The average frequency of STM32 watchdog timer is 40 kHz but it can vary between 30 and 60 kHz
+    s = s * 32768;                  // Newer Nucleo boards have 32.768 kHz crystal. Without it, the internal 
+                                    // RC clock would have an average frequency of 40 kHz (variable between 30 and 60 kHz)
+                                    
     int scale = 1 + log2(s / 4096); // The RLR register is 12 bits and beyond that a prescaler should be used
     int residual = s / (1 << scale); // The value for the RLR register
     
@@ -99,7 +101,7 @@
         scale = 8;
         residual = 0xFFF;
     }
-        
+           
     IWDG->KR  = 0x5555;         // enable write to PR, RLR
     IWDG->PR  = scale - 2;      // Prescaler has values of multiples of 4 (i.e. 2 ^2), page 486 Reference Manual
     IWDG->RLR = residual;       // Init RLR

--- a/Watchdog.h	Tue Oct 27 17:04:16 2015 +0000
+++ b/Watchdog.h	Wed Nov 11 16:05:42 2015 +0000
@@ -102,6 +102,17 @@
     bool WatchdogCausedReset();
 private:
     bool wdreset;
+    
+    #if defined( TARGET_STM )
+    /// Logarithm in base 2
+    ///
+    /// This function is needed for the STM32 platforms to compute the prescaler
+    /// value for the watchdog timer
+    ///
+    /// @param[in] the input value as an unsigned integer (i.e. always positive)
+    /// @returns the computed log2
+    int log2(unsigned v);
+    #endif
 };
 
 #endif // WATCHDOG_H
\ No newline at end of file