HardwareTimer: Allow setting preload enable bits

cores/arduino/HardwareTimer.cpp

@@ -93,7 +93,7 @@ HardwareTimer::HardwareTimer(TIM_TypeDef *instance)
 #if defined(TIM_RCR_REP)
   _timerObj.handle.Init.RepetitionCounter = 0;
 #endif
-  _timerObj.handle.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
+  _timerObj.handle.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
   HAL_TIM_Base_Init(&(_timerObj.handle));
 }
 
@@ -442,6 +442,11 @@ uint32_t HardwareTimer::getOverflow(TimerFormat_t format)
 
 /**
   * @brief  Set overflow (rollover)
+  *
+  *         Note that by default, the new value will not be applied
+  *         immediately, but become effective at the next update event
+  *         (usually the next timer overflow). See setPreloadEnable()
+  *         for controlling this behaviour.
   * @param  overflow: depend on format parameter
   * @param  format of overflow parameter. If ommited default format is Tick
   *           TICK_FORMAT:     overflow is the number of tick for overflow
@@ -677,6 +682,29 @@ void HardwareTimer::setMode(uint32_t channel, TimerModes_t mode, PinName pin)
   }
 }
 
+/**
+  * @brief  Enable or disable preloading for overflow value
+  *         When disabled, changes to the overflow value take effect
+  *         immediately. When enabled (the default), the value takes
+  *         effect only at the next update event (typically the next
+  *         overflow).
+  *
+  *         Note that the capture/compare register has its own preload
+  *         enable bit, which is independent and enabled in PWM modes
+  *         and disabled otherwise. If you need more control of that
+  *         bit, you can use the HAL functions directly.
+  * @param  value: true to enable preloading, false to disable
+  * @retval None
+  */
+void HardwareTimer::setPreloadEnable(bool value)
+{
+  if (value) {
+    LL_TIM_EnableARRPreload(_timerObj.handle.Instance);
+  } else {
+    LL_TIM_DisableARRPreload(_timerObj.handle.Instance);
+  }
+}
+
 /**
   * @brief  Set channel Capture/Compare register
   * @param  channel: Arduino channel [1..4]

cores/arduino/HardwareTimer.h

@@ -112,15 +112,15 @@ class HardwareTimer {
     void setPWM(uint32_t channel, PinName pin, uint32_t frequency, uint32_t dutycycle, void (*PeriodCallback)(HardwareTimer *) = NULL, void (*CompareCallback)(HardwareTimer *) = NULL); // Set all in one command freq in HZ, Duty in percentage. Including both interrup.
     void setPWM(uint32_t channel, uint32_t pin, uint32_t frequency, uint32_t dutycycle, void (*PeriodCallback)(HardwareTimer *) = NULL, void (*CompareCallback)(HardwareTimer *) = NULL);
 
-
     void setCount(uint32_t val, TimerFormat_t format = TICK_FORMAT); // set timer counter to value 'val' depending on format provided
     uint32_t getCount(TimerFormat_t format = TICK_FORMAT);  // return current counter value of timer depending on format provided
 
     void setMode(uint32_t channel, TimerModes_t mode, PinName pin = NC); // Configure timer channel with specified mode on specified pin if available
     void setMode(uint32_t channel, TimerModes_t mode, uint32_t pin);
 
-    uint32_t getCaptureCompare(uint32_t channel, TimerCompareFormat_t format = TICK_COMPARE_FORMAT); // return Capture/Compare register value of specified channel depending on format provided
+    void setPreloadEnable(bool value); // Configure overflow preload enable setting
 
+    uint32_t getCaptureCompare(uint32_t channel, TimerCompareFormat_t format = TICK_COMPARE_FORMAT); // return Capture/Compare register value of specified channel depending on format provided
     void setCaptureCompare(uint32_t channel, uint32_t compare, TimerCompareFormat_t format = TICK_COMPARE_FORMAT);  // set Compare register value of specified channel depending on format provided
 
     void setInterruptPriority(uint32_t preemptPriority, uint32_t subPriority); // set interrupt priority
@@ -139,26 +139,24 @@ class HardwareTimer {
     // Refresh() is usefull while timer is running after some registers update
     void refresh(void); // Generate update event to force all registers (Autoreload, prescaler, compare) to be taken into account
 
-
     uint32_t getTimerClkFreq();  // return timer clock frequency in Hz.
 
     static void captureCompareCallback(TIM_HandleTypeDef *htim); // Generic Caputre and Compare callback which will call user callback
     static void updateCallback(TIM_HandleTypeDef *htim);  // Generic Update (rollover) callback which will call user callback
 
     // The following function(s) are available for more advanced timer options
     TIM_HandleTypeDef *getHandle();  // return the handle address for HAL related configuration
-
-  private:
-    TimerModes_t  _ChannelMode[TIMER_CHANNELS];
-    timerObj_t _timerObj;
-    void (*callbacks[1 + TIMER_CHANNELS])(HardwareTimer *); //Callbacks: 0 for update, 1-4 for channels. (channel5/channel6, if any, doesn't have interrupt)
     int getChannel(uint32_t channel);
     int getLLChannel(uint32_t channel);
     int getIT(uint32_t channel);
     int getAssociatedChannel(uint32_t channel);
 #if defined(TIM_CCER_CC1NE)
     bool isComplementaryChannel[TIMER_CHANNELS];
 #endif
+  private:
+    TimerModes_t  _ChannelMode[TIMER_CHANNELS];
+    timerObj_t _timerObj;
+    void (*callbacks[1 + TIMER_CHANNELS])(HardwareTimer *); //Callbacks: 0 for update, 1-4 for channels. (channel5/channel6, if any, doesn't have interrupt)
 };
 
 extern timerObj_t *HardwareTimer_Handle[TIMER_NUM];
@@ -168,4 +166,4 @@ extern timer_index_t get_timer_index(TIM_TypeDef *htim);
 #endif /* __cplusplus */
 
 #endif  // HAL_TIM_MODULE_ENABLED && !HAL_TIM_MODULE_ONLY
-#endif  // HARDWARETIMER_H_
+#endif  // HARDWARETIMER_H_