From 5d698588f244f442b55921ef04d2cd6e8993046a Mon Sep 17 00:00:00 2001
From: Alexandre Bourdiol <alexandre.bourdiol@st.com>
Date: Wed, 18 May 2022 11:46:20 +0200
Subject: [PATCH] HardwareTimer: call refresh() after parameter update when
 timer not running

In case timer is not running,
after an update of parameters (setOverflow(), setCaptureCompare(),
setPrescaleFactor()),
call refresh() to force register update independently of Preload setting.

Fixes https://www.stm32duino.com/viewtopic.php?f=7&t=1563

Signed-off-by: Alexandre Bourdiol <alexandre.bourdiol@st.com>
---
 cores/arduino/HardwareTimer.h              |  2 ++
 libraries/SrcWrapper/src/HardwareTimer.cpp | 32 ++++++++++++++++++++--
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/cores/arduino/HardwareTimer.h b/cores/arduino/HardwareTimer.h
index 2b6027a941..d975ffb1b2 100644
--- a/cores/arduino/HardwareTimer.h
+++ b/cores/arduino/HardwareTimer.h
@@ -151,6 +151,8 @@ class HardwareTimer {
     static void captureCompareCallback(TIM_HandleTypeDef *htim); // Generic Capture and Compare callback which will call user callback
     static void updateCallback(TIM_HandleTypeDef *htim);  // Generic Update (rollover) callback which will call user callback
 
+    void updateRegistersIfNotRunning(TIM_TypeDef *TIMx); // Take into account registers update immediately if timer is not running,
+
     bool isRunning(); // return true if HardwareTimer is running
     bool isRunningChannel(uint32_t channel); // return true if channel is running
 
diff --git a/libraries/SrcWrapper/src/HardwareTimer.cpp b/libraries/SrcWrapper/src/HardwareTimer.cpp
index 2f6bcf1608..9e948bc53a 100644
--- a/libraries/SrcWrapper/src/HardwareTimer.cpp
+++ b/libraries/SrcWrapper/src/HardwareTimer.cpp
@@ -471,6 +471,8 @@ void HardwareTimer::setPrescaleFactor(uint32_t prescaler)
 {
   // Hardware register correspond to prescaler-1. Example PSC register value 0 means divided by 1
   LL_TIM_SetPrescaler(_timerObj.handle.Instance, prescaler - 1);
+
+  updateRegistersIfNotRunning(_timerObj.handle.Instance);
 }
 
 /**
@@ -550,6 +552,8 @@ void HardwareTimer::setOverflow(uint32_t overflow, TimerFormat_t format)
     ARR_RegisterValue = 0;
   }
   __HAL_TIM_SET_AUTORELOAD(&_timerObj.handle, ARR_RegisterValue);
+
+  updateRegistersIfNotRunning(_timerObj.handle.Instance);
 }
 
 /**
@@ -640,7 +644,7 @@ void HardwareTimer::setMode(uint32_t channel, TimerModes_t mode, PinName pin)
 
   /* Configure some default values. Maybe overwritten later */
   channelOC.OCMode = TIMER_NOT_USED;
-  channelOC.Pulse = __HAL_TIM_GET_COMPARE(&(_timerObj.handle), timChannel);  // keep same value already written in hardware <register
+  channelOC.Pulse = __HAL_TIM_GET_COMPARE(&(_timerObj.handle), timChannel);  // keep same value already written in hardware register
   channelOC.OCPolarity = TIM_OCPOLARITY_HIGH;
   channelOC.OCFastMode = TIM_OCFAST_DISABLE;
 #if defined(TIM_CR2_OIS1)
@@ -857,6 +861,8 @@ void HardwareTimer::setCaptureCompare(uint32_t channel, uint32_t compare, TimerC
   }
 
   __HAL_TIM_SET_COMPARE(&(_timerObj.handle), timChannel, CCR_RegisterValue);
+
+  updateRegistersIfNotRunning(_timerObj.handle.Instance);
 }
 
 /**
@@ -1082,7 +1088,8 @@ bool HardwareTimer::hasInterrupt(uint32_t channel)
 
 /**
   * @brief  Generate an update event to force all registers (Autoreload, prescaler, compare) to be taken into account
-  * @note   Refresh() can only be called after a 1st call to resume() to be sure timer is initialised.
+  * @note   @note Refresh() can only be called after timer has been initialized,
+            either by calling setup() function or thanks to constructor with TIM instance parameter.
   *         It is useful while timer is running after some registers update
   * @retval None
   */
@@ -1198,6 +1205,27 @@ bool HardwareTimer::isRunningChannel(uint32_t channel)
   return (isRunning() && ret);
 }
 
+/**
+  * @brief  Take into account registers update immediately if timer is not running,
+  *         (independently from Preload setting)
+  * @param  TIMx Timer instance
+  * @retval None
+  */
+void HardwareTimer::updateRegistersIfNotRunning(TIM_TypeDef *TIMx)
+{
+  if (!isRunning()) {
+    if (LL_TIM_IsEnabledIT_UPDATE(TIMx)) {
+      // prevent Interrupt generation from refresh()
+      LL_TIM_DisableIT_UPDATE(TIMx);
+      refresh();
+      LL_TIM_ClearFlag_UPDATE(TIMx);
+      LL_TIM_EnableIT_UPDATE(TIMx);
+    } else {
+      refresh();
+    }
+  }
+}
+
 /**
   * @brief  HardwareTimer destructor
   * @retval None