diff --git a/os/hal/include/pwm.h b/os/hal/include/pwm.h
index c8095d2b7..2861cbcea 100644
--- a/os/hal/include/pwm.h
+++ b/os/hal/include/pwm.h
@@ -57,34 +57,50 @@
  * @brief   Driver state machine possible states.
  */
 typedef enum {
-  PWM_UNINIT = 0,                   /**< @brief Not initialized.            */
-  PWM_STOP = 1,                     /**< @brief Stopped.                    */
-  PWM_READY = 2,                    /**< @brief Ready.                      */
+  PWM_UNINIT = 0,                   /**< Not initialized.                   */
+  PWM_STOP = 1,                     /**< Stopped.                           */
+  PWM_READY = 2,                    /**< Ready.                             */
 } pwmstate_t;
 
 /**
  * @brief PWM logic mode.
  */
 typedef enum {
-  PWM_OUTPUT_DISABLED = 0,          /**< @brief Output not driven, callback
-                                                only.                       */
-  PWM_OUTPUT_ACTIVE_HIGH = 1,       /**< @brief Idle is logic level 0.      */
-  PWM_OUTPUT_ACTIVE_LOW = 2         /**< @brief Idle is logic level 1.      */
+  PWM_OUTPUT_DISABLED = 0,          /**< Output not driven, callback only.  */
+  PWM_OUTPUT_ACTIVE_HIGH = 1,       /**< Idle is logic level 0.             */
+  PWM_OUTPUT_ACTIVE_LOW = 2         /**< Idle is logic level 1.             */
 } pwmmode_t;
 
-/**
- * @brief   PWM notification callback type.
- *
- * @param[in] active    current channel output state
- */
-typedef void (*pwmcallback_t)(void);
-
 #include "pwm_lld.h"
 
 /*===========================================================================*/
 /* Driver macros.                                                            */
 /*===========================================================================*/
 
+/**
+ * @brief   Enables a PWM channel.
+ * @details Programs (or reprograms) a PWM channel.
+ * @note    This function has to be invoked from a lock zone.
+ *
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ * @param[in] channel   PWM channel identifier
+ * @param[in] width     PWM pulse width as clock pulses number
+ */
+#define pwmEnableChannelI(pwmp, channel, width)                             \
+  pwm_lld_enable_channel(pwmp, channel, width)
+
+/**
+ * @brief Disables a PWM channel.
+ * @details The channel is disabled and its output line returned to the
+ *          idle state.
+ * @note    This function has to be invoked from a lock zone.
+ *
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ * @param[in] channel   PWM channel identifier
+ */
+#define pwmDisableChannelI(pwmp, channel)                                   \
+  pwm_lld_disable_channel(pwmp, channel)
+
 /*===========================================================================*/
 /* External declarations.                                                    */
 /*===========================================================================*/
diff --git a/os/hal/platforms/STM32/pwm_lld.c b/os/hal/platforms/STM32/pwm_lld.c
index 472b1c15e..fbe986336 100644
--- a/os/hal/platforms/STM32/pwm_lld.c
+++ b/os/hal/platforms/STM32/pwm_lld.c
@@ -25,8 +25,9 @@
 */
 
 /**
- * @file STM32/pwm_lld.c
- * @brief STM32 PWM subsystem low level driver header.
+ * @file    STM32/pwm_lld.c
+ * @brief   STM32 PWM subsystem low level driver header.
+ *
  * @addtogroup STM32_PWM
  * @{
  */
@@ -41,32 +42,32 @@
 /*===========================================================================*/
 
 /**
- * @brief PWM1 driver identifier.
- * @note The driver PWM1 allocates the complex timer TIM1 when enabled.
+ * @brief   PWM1 driver identifier.
+ * @note    The driver PWM1 allocates the complex timer TIM1 when enabled.
  */
 #if defined(USE_STM32_PWM1) || defined(__DOXYGEN__)
 PWMDriver PWMD1;
 #endif
 
 /**
- * @brief PWM2 driver identifier.
- * @note The driver PWM2 allocates the timer TIM2 when enabled.
+ * @brief   PWM2 driver identifier.
+ * @note    The driver PWM2 allocates the timer TIM2 when enabled.
  */
 #if defined(USE_STM32_PWM2) || defined(__DOXYGEN__)
 PWMDriver PWMD2;
 #endif
 
 /**
- * @brief PWM3 driver identifier.
- * @note The driver PWM3 allocates the timer TIM3 when enabled.
+ * @brief   PWM3 driver identifier.
+ * @note    The driver PWM3 allocates the timer TIM3 when enabled.
  */
 #if defined(USE_STM32_PWM3) || defined(__DOXYGEN__)
 PWMDriver PWMD3;
 #endif
 
 /**
- * @brief PWM4 driver identifier.
- * @note The driver PWM4 allocates the timer TIM4 when enabled.
+ * @brief   PWM4 driver identifier.
+ * @note    The driver PWM4 allocates the timer TIM4 when enabled.
  */
 #if defined(USE_STM32_PWM4) || defined(__DOXYGEN__)
 PWMDriver PWMD4;
@@ -80,29 +81,12 @@ PWMDriver PWMD4;
 /* Driver local functions.                                                   */
 /*===========================================================================*/
 
-/**
- * @brief Stops all channels.
- *
- * @param[in] pwmp pointer to a @p PWMDriver object
- */
-static void stop_channels(PWMDriver *pwmp) {
-
-  pwmp->pd_enabled_channels = 0;            /* All channels disabled.       */
-  pwmp->pd_tim->CCER = 0;                   /* Outputs disabled.            */
-  pwmp->pd_tim->CCR1 = 0;                   /* Comparator 1 disabled.       */
-  pwmp->pd_tim->CCR2 = 0;                   /* Comparator 2 disabled.       */
-  pwmp->pd_tim->CCR3 = 0;                   /* Comparator 3 disabled.       */
-  pwmp->pd_tim->CCR4 = 0;                   /* Comparator 4 disabled.       */
-  pwmp->pd_tim->CCMR1 = 0;                  /* Channels 1 and 2 frozen.     */
-  pwmp->pd_tim->CCMR2 = 0;                  /* Channels 3 and 4 frozen.     */
-}
-
 #if USE_STM32_PWM2 || USE_STM32_PWM3 || USE_STM32_PWM4 || defined(__DOXYGEN__)
 /**
- * @brief Common TIM2...TIM4 IRQ handler.
- * @note It is assumed that the various sources are only activated if the
- *       associated callback pointer is not equal to @p NULL in order to not
- *       perform an extra check in a potentially critical interrupt handler.
+ * @brief   Common TIM2...TIM4 IRQ handler.
+ * @note    It is assumed that the various sources are only activated if the
+ *          associated callback pointer is not equal to @p NULL in order to not
+ *          perform an extra check in a potentially critical interrupt handler.
  */
 static void serve_interrupt(PWMDriver *pwmp) {
   uint16_t sr;
@@ -111,15 +95,15 @@ static void serve_interrupt(PWMDriver *pwmp) {
   pwmp->pd_tim->SR = ~(TIM_SR_CC1IF | TIM_SR_CC2IF | TIM_SR_CC3IF |
                        TIM_SR_CC4IF | TIM_SR_UIF);
   if ((sr & TIM_SR_CC1IF) != 0)
-    pwmp->pd_config->pc_channels[0].pcc_callback();
+    pwmp->pd_config->pc_channels[0].pcc_callback(pwmp);
   if ((sr & TIM_SR_CC2IF) != 0)
-    pwmp->pd_config->pc_channels[1].pcc_callback();
+    pwmp->pd_config->pc_channels[1].pcc_callback(pwmp);
   if ((sr & TIM_SR_CC3IF) != 0)
-    pwmp->pd_config->pc_channels[2].pcc_callback();
+    pwmp->pd_config->pc_channels[2].pcc_callback(pwmp);
   if ((sr & TIM_SR_CC4IF) != 0)
-    pwmp->pd_config->pc_channels[3].pcc_callback();
+    pwmp->pd_config->pc_channels[3].pcc_callback(pwmp);
   if ((sr & TIM_SR_UIF) != 0)
-    pwmp->pd_config->pc_callback();
+    pwmp->pd_config->pc_callback(pwmp);
 }
 #endif /* USE_STM32_PWM2 || USE_STM32_PWM3 || USE_STM32_PWM4 */
 
@@ -129,26 +113,26 @@ static void serve_interrupt(PWMDriver *pwmp) {
 
 #if USE_STM32_PWM1
 /**
- * @brief TIM1 update interrupt handler.
- * @note It is assumed that this interrupt is only activated if the callback
- *       pointer is not equal to @p NULL in order to not perform an extra
- *       check in a potentially critical interrupt handler.
+ * @brief   TIM1 update interrupt handler.
+ * @note    It is assumed that this interrupt is only activated if the callback
+ *          pointer is not equal to @p NULL in order to not perform an extra
+ *          check in a potentially critical interrupt handler.
  */
 CH_IRQ_HANDLER(VectorA4) {
 
   CH_IRQ_PROLOGUE();
 
   TIM1->SR = ~TIM_SR_UIF;
-  PWMD1.pd_config->pc_callback();
+  PWMD1.pd_config->pc_callback(&PWMD1);
 
   CH_IRQ_EPILOGUE();
 }
 
 /**
- * @brief TIM1 compare interrupt handler.
- * @note It is assumed that the various sources are only activated if the
- *       associated callback pointer is not equal to @p NULL in order to not
- *       perform an extra check in a potentially critical interrupt handler.
+ * @brief   TIM1 compare interrupt handler.
+ * @note    It is assumed that the various sources are only activated if the
+ *          associated callback pointer is not equal to @p NULL in order to not
+ *          perform an extra check in a potentially critical interrupt handler.
  */
 CH_IRQ_HANDLER(VectorAC) {
   uint16_t sr;
@@ -158,13 +142,13 @@ CH_IRQ_HANDLER(VectorAC) {
   sr = TIM1->SR & TIM1->DIER;
   TIM1->SR = ~(TIM_SR_CC1IF | TIM_SR_CC2IF | TIM_SR_CC3IF | TIM_SR_CC4IF);
   if ((sr & TIM_SR_CC1IF) != 0)
-    PWMD1.pd_config->pc_channels[0].pcc_callback();
+    PWMD1.pd_config->pc_channels[0].pcc_callback(&PWMD1);
   if ((sr & TIM_SR_CC2IF) != 0)
-    PWMD1.pd_config->pc_channels[1].pcc_callback();
+    PWMD1.pd_config->pc_channels[1].pcc_callback(&PWMD1);
   if ((sr & TIM_SR_CC3IF) != 0)
-    PWMD1.pd_config->pc_channels[2].pcc_callback();
+    PWMD1.pd_config->pc_channels[2].pcc_callback(&PWMD1);
   if ((sr & TIM_SR_CC4IF) != 0)
-    PWMD1.pd_config->pc_channels[3].pcc_callback();
+    PWMD1.pd_config->pc_channels[3].pcc_callback(&PWMD1);
 
   CH_IRQ_EPILOGUE();
 }
@@ -172,7 +156,7 @@ CH_IRQ_HANDLER(VectorAC) {
 
 #if USE_STM32_PWM2
 /**
- * @brief TIM2 interrupt handler.
+ * @brief   TIM2 interrupt handler.
  */
 CH_IRQ_HANDLER(VectorB0) {
 
@@ -186,7 +170,7 @@ CH_IRQ_HANDLER(VectorB0) {
 
 #if USE_STM32_PWM3
 /**
- * @brief TIM3 interrupt handler.
+ * @brief   TIM3 interrupt handler.
  */
 CH_IRQ_HANDLER(VectorB4) {
 
@@ -200,7 +184,7 @@ CH_IRQ_HANDLER(VectorB4) {
 
 #if USE_STM32_PWM4
 /**
- * @brief TIM4 interrupt handler.
+ * @brief   TIM4 interrupt handler.
  */
 CH_IRQ_HANDLER(VectorB8) {
 
@@ -217,7 +201,7 @@ CH_IRQ_HANDLER(VectorB8) {
 /*===========================================================================*/
 
 /**
- * @brief Low level PWM driver initialization.
+ * @brief   Low level PWM driver initialization.
  */
 void pwm_lld_init(void) {
 
@@ -267,55 +251,73 @@ void pwm_lld_init(void) {
 }
 
 /**
- * @brief Configures and activates the PWM peripheral.
+ * @brief   Configures and activates the PWM peripheral.
  *
- * @param[in] pwmp pointer to a @p PWMDriver object
+ * @param[in] pwmp      pointer to a @p PWMDriver object
  */
 void pwm_lld_start(PWMDriver *pwmp) {
   uint16_t ccer;
 
+  /* Reset channels.*/
+  pwmp->pd_enabled_channels = 0;            /* All channels disabled.       */
+
   if (pwmp->pd_state == PWM_STOP) {
-    /* Clock activation.*/
+    /* Clock activation and timer reset.*/
 #if USE_STM32_PWM1
     if (&PWMD1 == pwmp) {
-      NVICEnableVector(TIM1_UP_IRQn,
-                       CORTEX_PRIORITY_MASK(STM32_PWM1_IRQ_PRIORITY));
-      NVICEnableVector(TIM1_CC_IRQn,
-                       CORTEX_PRIORITY_MASK(STM32_PWM1_IRQ_PRIORITY));
       RCC->APB2ENR |= RCC_APB2ENR_TIM1EN;
+      RCC->APB2RSTR = RCC_APB2RSTR_TIM1RST;
+      RCC->APB2RSTR = 0;
+      NVICEnableVector(TIM1_UP_IRQn,
+                       CORTEX_PRIORITY_MASK(STM32_PWM_TIM1_IRQ_PRIORITY));
+      NVICEnableVector(TIM1_CC_IRQn,
+                       CORTEX_PRIORITY_MASK(STM32_PWM_TIM1_IRQ_PRIORITY));
     }
 #endif
 #if USE_STM32_PWM2
     if (&PWMD2 == pwmp) {
-      NVICEnableVector(TIM2_IRQn,
-                       CORTEX_PRIORITY_MASK(STM32_PWM2_IRQ_PRIORITY));
       RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;
+      RCC->APB1RSTR = RCC_APB1RSTR_TIM2RST;
+      RCC->APB1RSTR = 0;
+      NVICEnableVector(TIM2_IRQn,
+                       CORTEX_PRIORITY_MASK(STM32_PWM_TIM2_IRQ_PRIORITY));
     }
 #endif
 #if USE_STM32_PWM3
     if (&PWMD3 == pwmp) {
-      NVICEnableVector(TIM3_IRQn,
-                       CORTEX_PRIORITY_MASK(STM32_PWM3_IRQ_PRIORITY));
       RCC->APB1ENR |= RCC_APB1ENR_TIM3EN;
+      RCC->APB1RSTR = RCC_APB1RSTR_TIM3RST;
+      RCC->APB1RSTR = 0;
+      NVICEnableVector(TIM3_IRQn,
+                       CORTEX_PRIORITY_MASK(STM32_PWM_TIM3_IRQ_PRIORITY));
     }
 #endif
 #if USE_STM32_PWM4
     if (&PWMD4 == pwmp) {
-      NVICEnableVector(TIM4_IRQn,
-                       CORTEX_PRIORITY_MASK(STM32_PWM4_IRQ_PRIORITY));
       RCC->APB1ENR |= RCC_APB1ENR_TIM4EN;
+      RCC->APB1RSTR = RCC_APB1RSTR_TIM4RST;
+      RCC->APB1RSTR = 0;
+      NVICEnableVector(TIM4_IRQn,
+                       CORTEX_PRIORITY_MASK(STM32_PWM_TIM4_IRQ_PRIORITY));
     }
 #endif
   }
-  /* Reset channels.*/
-  stop_channels(pwmp);
+  else {
+    /* Driver re-configuration scenario, it must be stopped first.*/
+    /* Really required ?????????? */
+    pwmp->pd_tim->CR1  = 0;                   /* Timer stopped.               */
+    pwmp->pd_tim->CR2  = 0;                   /* Timer stopped.               */
+    pwmp->pd_tim->SMCR = 0;                   /* Slave mode disabled.         */
+    pwmp->pd_tim->CCR1 = 0;                   /* Comparator 1 disabled.       */
+    pwmp->pd_tim->CCR2 = 0;                   /* Comparator 2 disabled.       */
+    pwmp->pd_tim->CCR3 = 0;                   /* Comparator 3 disabled.       */
+    pwmp->pd_tim->CCR4 = 0;                   /* Comparator 4 disabled.       */
+    pwmp->pd_tim->CNT  = 0;
+  }
 
-  /* Configuration or reconfiguration.*/
-  pwmp->pd_tim->CR1  = 0;                   /* Timer stopped.               */
-  pwmp->pd_tim->SMCR = 0;                   /* Slave mode disabled.         */
+  /* Timer configuration.*/
   pwmp->pd_tim->CR2  = pwmp->pd_config->pc_cr2;
   pwmp->pd_tim->PSC  = pwmp->pd_config->pc_psc;
-  pwmp->pd_tim->CNT  = 0;
   pwmp->pd_tim->ARR  = pwmp->pd_config->pc_arr;
   /* Output enables and polarities setup.*/
   ccer = 0;
@@ -356,22 +358,30 @@ void pwm_lld_start(PWMDriver *pwmp) {
   pwmp->pd_tim->SR   = 0;                   /* Clear pending IRQs.          */
   pwmp->pd_tim->DIER = pwmp->pd_config->pc_callback == NULL ? 0 : TIM_DIER_UIE;
   pwmp->pd_tim->BDTR = TIM_BDTR_MOE;
-  pwmp->pd_tim->CR1  = TIM_CR1_ARPE | TIM_CR1_URS |
-                       TIM_CR1_CEN;         /* Timer configured and started.*/
+  /* Timer configured and started.*/
+  pwmp->pd_tim->CR1  = TIM_CR1_ARPE | TIM_CR1_URS | TIM_CR1_CEN;
 }
 
 /**
- * @brief Deactivates the PWM peripheral.
+ * @brief   Deactivates the PWM peripheral.
  *
- * @param[in] pwmp pointer to a @p PWMDriver object
+ * @param[in] pwmp      pointer to a @p PWMDriver object
  */
 void pwm_lld_stop(PWMDriver *pwmp) {
   /* If in ready state then disables the PWM clock.*/
   if (pwmp->pd_state == PWM_READY) {
-    stop_channels(pwmp);
-    pwmp->pd_tim->CR1 = 0;
-    pwmp->pd_tim->BDTR = 0;
-    pwmp->pd_tim->DIER = 0;
+    pwmp->pd_enabled_channels = 0;          /* All channels disabled.       */
+    pwmp->pd_tim->CR1   = 0;
+    pwmp->pd_tim->CR2   = 0;
+    pwmp->pd_tim->CCER  = 0;                /* Outputs disabled.            */
+    pwmp->pd_tim->CCR1  = 0;                /* Comparator 1 disabled.       */
+    pwmp->pd_tim->CCR2  = 0;                /* Comparator 2 disabled.       */
+    pwmp->pd_tim->CCR3  = 0;                /* Comparator 3 disabled.       */
+    pwmp->pd_tim->CCR4  = 0;                /* Comparator 4 disabled.       */
+    pwmp->pd_tim->BDTR  = 0;
+    pwmp->pd_tim->DIER  = 0;
+    pwmp->pd_tim->SR    = 0;
+    pwmp->pd_tim->EGR  = TIM_EGR_UG;        /* Update event.                */
 
 #if USE_STM32_PWM1
     if (&PWMD1 == pwmp) {
@@ -402,112 +412,42 @@ void pwm_lld_stop(PWMDriver *pwmp) {
 }
 
 /**
- * @brief Enables a PWM channel.
+ * @brief   Enables a PWM channel.
  *
  * @param[in] pwmp      pointer to a @p PWMDriver object
- * @param[in] channel   PWM channel identifier
+ * @param[in] channel   PWM channel identifier (0...PWM_CHANNELS-1)
  * @param[in] width     PWM pulse width as clock pulses number
  */
 void pwm_lld_enable_channel(PWMDriver *pwmp,
                             pwmchannel_t channel,
                             pwmcnt_t width) {
 
-  /*
-   * Changes the pulse width.
-   */
-  switch (channel) {
-  case 0:
-    pwmp->pd_tim->CCR1 = width;
-    break;
-  case 1:
-    pwmp->pd_tim->CCR2 = width;
-    break;
-  case 2:
-    pwmp->pd_tim->CCR3 = width;
-    break;
-  case 3:
-    pwmp->pd_tim->CCR4 = width;
-    break;
-  }
+  *(&pwmp->pd_tim->CCR1 + (channel * 2)) = width;   /* New duty cycle.      */
   if ((pwmp->pd_enabled_channels & (1 << channel)) == 0) {
-    /*
-     * The channel is not enabled yet.
-     */
+    /* The channel is not enabled yet.*/
     pwmp->pd_enabled_channels |= (1 << channel);
-    /*
-     * Setup the comparator, the channel is configured as PWM mode 1 with
-     * preload enabled.
-     */
-    switch (channel) {
-    case 0:
-      pwmp->pd_tim->CCMR1 = (pwmp->pd_tim->CCMR1 & 0xFF00) |
-                            TIM_CCMR1_OC1M_1 | TIM_CCMR1_OC1M_2 |
-                            TIM_CCMR1_OC1PE;
-      pwmp->pd_tim->SR = ~TIM_SR_CC1IF;
-      pwmp->pd_tim->DIER |= pwmp->pd_config->pc_channels[0].pcc_callback == NULL
-                            ? 0 : TIM_DIER_CC1IE;
-      break;
-    case 1:
-      pwmp->pd_tim->CCMR1 = (pwmp->pd_tim->CCMR1 & 0x00FF) |
-                            TIM_CCMR1_OC2M_1 | TIM_CCMR1_OC2M_2 |
-                            TIM_CCMR1_OC2PE;
-      pwmp->pd_tim->SR = ~TIM_SR_CC2IF;
-      pwmp->pd_tim->DIER |= pwmp->pd_config->pc_channels[1].pcc_callback == NULL
-                            ? 0 : TIM_DIER_CC2IE;
-      break;
-    case 2:
-      pwmp->pd_tim->CCMR2 = (pwmp->pd_tim->CCMR2 & 0xFF00) |
-                            TIM_CCMR2_OC3M_1 | TIM_CCMR2_OC3M_2 |
-                            TIM_CCMR2_OC3PE;
-      pwmp->pd_tim->SR = ~TIM_SR_CC3IF;
-      pwmp->pd_tim->DIER |= pwmp->pd_config->pc_channels[2].pcc_callback == NULL
-                            ? 0 : TIM_DIER_CC3IE;
-      break;
-    case 3:
-      pwmp->pd_tim->CCMR2 = (pwmp->pd_tim->CCMR2 & 0x00FF) |
-                            TIM_CCMR2_OC4M_1 | TIM_CCMR2_OC4M_2 |
-                            TIM_CCMR2_OC4PE;
-      pwmp->pd_tim->SR = ~TIM_SR_CC4IF;
-      pwmp->pd_tim->DIER |= pwmp->pd_config->pc_channels[3].pcc_callback == NULL
-                            ? 0 : TIM_DIER_CC4IE;
-      break;
+    /* If there is a callback associated to the channel then the proper
+       interrupt is cleared and enabled.*/
+    if (pwmp->pd_config->pc_channels[channel].pcc_callback) {
+      pwmp->pd_tim->SR    = ~(2 << channel);
+      pwmp->pd_tim->DIER |= (2 << channel);
     }
   }
 }
 
 /**
- * @brief Disables a PWM channel.
+ * @brief   Disables a PWM channel.
  * @details The channel is disabled and its output line returned to the
  *          idle state.
  *
  * @param[in] pwmp      pointer to a @p PWMDriver object
- * @param[in] channel   PWM channel identifier
+ * @param[in] channel   PWM channel identifier (0...PWM_CHANNELS-1)
  */
 void pwm_lld_disable_channel(PWMDriver *pwmp, pwmchannel_t channel) {
 
+  *(&pwmp->pd_tim->CCR1 + (channel * 2)) = 0;
+  pwmp->pd_tim->DIER = ~(2 << channel);
   pwmp->pd_enabled_channels &= ~(1 << channel);
-  switch (channel) {
-  case 0:
-    pwmp->pd_tim->CCR1 = 0;
-    pwmp->pd_tim->CCMR1 = pwmp->pd_tim->CCMR1 & 0xFF00;
-    pwmp->pd_tim->DIER &= ~TIM_DIER_CC1IE;
-    break;
-  case 1:
-    pwmp->pd_tim->CCR2 = 0;
-    pwmp->pd_tim->CCMR1 = pwmp->pd_tim->CCMR1 & 0x00FF;
-    pwmp->pd_tim->DIER &= ~TIM_DIER_CC2IE;
-    break;
-  case 2:
-    pwmp->pd_tim->CCR3 = 0;
-    pwmp->pd_tim->CCMR2 = pwmp->pd_tim->CCMR2 & 0xFF00;
-    pwmp->pd_tim->DIER &= ~TIM_DIER_CC3IE;
-    break;
-  case 3:
-    pwmp->pd_tim->CCR4 = 0;
-    pwmp->pd_tim->CCMR2 = pwmp->pd_tim->CCMR2 & 0x00FF;
-    pwmp->pd_tim->DIER &= ~TIM_DIER_CC4IE;
-    break;
-  }
 }
 
 #endif /* CH_HAL_USE_PWM */
diff --git a/os/hal/platforms/STM32/pwm_lld.h b/os/hal/platforms/STM32/pwm_lld.h
index dfbb92204..b716d77c2 100644
--- a/os/hal/platforms/STM32/pwm_lld.h
+++ b/os/hal/platforms/STM32/pwm_lld.h
@@ -10,115 +10,147 @@
 
     ChibiOS/RT is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License
-    along with this program. If not, see <http://www.gnu.org/licenses/>.
-
-                                      ---
-
-    A special exception to the GPL can be applied should you wish to distribute
-    a combined work that includes ChibiOS/RT, without being obliged to provide
-    the source code for any proprietary components. See the file exception.txt
-    for full details of how and when the exception can be applied.
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 /**
- * @file STM32/pwm_lld.h
- * @brief STM32 PWM subsystem low level driver header.
- * @addtogroup STM32_PWM
+ * @file    STM32/pwm_lld.h
+ * @brief   STM32 PWM subsystem low level driver header.
+ *
+ * @addtogroup PWM
  * @{
  */
 
 #ifndef _PWM_LLD_H_
 #define _PWM_LLD_H_
 
-#if CH_HAL_USE_PWM || defined(__DOXYGEN__)
+#if HAL_USE_PWM || defined(__DOXYGEN__)
 
 /*===========================================================================*/
 /* Driver constants.                                                         */
 /*===========================================================================*/
 
 /**
- * @brief Number of PWM channels per PWM driver.
+ * @brief   Number of PWM channels per PWM driver.
  */
-#define PWM_CHANNELS                4
+#define PWM_CHANNELS                        4
 
 /*===========================================================================*/
 /* Driver pre-compile time settings.                                         */
 /*===========================================================================*/
 
 /**
- * @brief PWM1 driver enable switch.
+ * @brief   PWM1 driver enable switch.
  * @details If set to @p TRUE the support for PWM1 is included.
- * @note The default is @p TRUE.
+ * @note    The default is @p TRUE.
  */
-#if !defined(USE_STM32_PWM1) || defined(__DOXYGEN__)
-#define USE_STM32_PWM1              TRUE
+#if !defined(STM32_PWM_USE_TIM1) || defined(__DOXYGEN__)
+#define STM32_PWM_USE_TIM1                  TRUE
 #endif
 
 /**
- * @brief PWM2 driver enable switch.
+ * @brief   PWM2 driver enable switch.
  * @details If set to @p TRUE the support for PWM2 is included.
- * @note The default is @p TRUE.
+ * @note    The default is @p TRUE.
  */
-#if !defined(USE_STM32_PWM2) || defined(__DOXYGEN__)
-#define USE_STM32_PWM2              TRUE
+#if !defined(STM32_PWM_USE_TIM2) || defined(__DOXYGEN__)
+#define STM32_PWM_USE_TIM2                  TRUE
 #endif
 
 /**
- * @brief PWM3 driver enable switch.
+ * @brief   PWM3 driver enable switch.
  * @details If set to @p TRUE the support for PWM3 is included.
- * @note The default is @p TRUE.
+ * @note    The default is @p TRUE.
  */
-#if !defined(USE_STM32_PWM3) || defined(__DOXYGEN__)
-#define USE_STM32_PWM3              TRUE
+#if !defined(STM32_PWM_USE_TIM3) || defined(__DOXYGEN__)
+#define STM32_PWM_USE_TIM3                  TRUE
 #endif
 
 /**
- * @brief PWM4 driver enable switch.
+ * @brief   PWM4 driver enable switch.
  * @details If set to @p TRUE the support for PWM4 is included.
- * @note The default is @p TRUE.
+ * @note    The default is @p TRUE.
  */
-#if !defined(USE_STM32_PWM4) || defined(__DOXYGEN__)
-#define USE_STM32_PWM4              TRUE
+#if !defined(STM32_PWM_USE_TIM4) || defined(__DOXYGEN__)
+#define STM32_PWM_USE_TIM4                  TRUE
 #endif
 
 /**
- * @brief PWM1 interrupt priority level setting.
+ * @brief   PWM5 driver enable switch.
+ * @details If set to @p TRUE the support for PWM5 is included.
+ * @note    The default is @p TRUE.
  */
-#if !defined(STM32_PWM1_IRQ_PRIORITY) || defined(__DOXYGEN__)
-#define STM32_PWM1_IRQ_PRIORITY     7
+#if !defined(STM32_PWM_USE_TIM5) || defined(__DOXYGEN__)
+#define STM32_PWM_USE_TIM5                  TRUE
 #endif
 
 /**
- * @brief PWM2 interrupt priority level setting.
+ * @brief   PWM1 interrupt priority level setting.
  */
-#if !defined(STM32_PWM2_IRQ_PRIORITY) || defined(__DOXYGEN__)
-#define STM32_PWM2_IRQ_PRIORITY     7
+#if !defined(STM32_PWM_TIM1_IRQ_PRIORITY) || defined(__DOXYGEN__)
+#define STM32_PWM_TIM1_IRQ_PRIORITY         7
 #endif
 
 /**
- * @brief PWM3 interrupt priority level setting.
+ * @brief   PWM2 interrupt priority level setting.
  */
-#if !defined(STM32_PWM3_IRQ_PRIORITY) || defined(__DOXYGEN__)
-#define STM32_PWM3_IRQ_PRIORITY     7
+#if !defined(STM32_PWM_TIM2_IRQ_PRIORITY) || defined(__DOXYGEN__)
+#define STM32_PWM_TIM2_IRQ_PRIORITY         7
 #endif
 
 /**
- * @brief PWM4 interrupt priority level setting.
+ * @brief   PWM3 interrupt priority level setting.
  */
-#if !defined(STM32_PWM4_IRQ_PRIORITY) || defined(__DOXYGEN__)
-#define STM32_PWM4_IRQ_PRIORITY     7
+#if !defined(STM32_PWM_TIM3_IRQ_PRIORITY) || defined(__DOXYGEN__)
+#define STM32_PWM_TIM3_IRQ_PRIORITY         7
+#endif
+
+/**
+ * @brief   PWM4 interrupt priority level setting.
+ */
+#if !defined(STM32_PWM_TIM4_IRQ_PRIORITY) || defined(__DOXYGEN__)
+#define STM32_PWM_TIM4_IRQ_PRIORITY         7
+#endif
+
+/**
+ * @brief   PWM5 interrupt priority level setting.
+ */
+#if !defined(STM32_PWM_TIM5_IRQ_PRIORITY) || defined(__DOXYGEN__)
+#define STM32_PWM_TIM5_IRQ_PRIORITY         7
 #endif
 
 /*===========================================================================*/
 /* Configuration checks.                                                     */
 /*===========================================================================*/
 
-#if USE_STM32_PWM4 && defined(STM32F10X_LD)
-#error "TIM4 not present in low density STM32 devices"
+#if STM32_PWM_USE_TIM1 && !STM32_HAS_TIM1
+#error "TIM1 not present in the selected device"
+#endif
+
+#if STM32_PWM_USE_TIM2 && !STM32_HAS_TIM2
+#error "TIM2 not present in the selected device"
+#endif
+
+#if STM32_PWM_USE_TIM3 && !STM32_HAS_TIM3
+#error "TIM3 not present in the selected device"
+#endif
+
+#if STM32_PWM_USE_TIM4 && !STM32_HAS_TIM4
+#error "TIM4 not present in the selected device"
+#endif
+
+#if STM32_PWM_USE_TIM5 && !STM32_HAS_TIM5
+#error "TIM5 not present in the selected device"
+#endif
+
+#if !STM32_PWM_USE_TIM1 && !STM32_PWM_USE_TIM2 &&                           \
+    !STM32_PWM_USE_TIM3 && !STM32_PWM_USE_TIM4 &&                           \
+    !STM32_PWM_USE_TIM5
+#error "PWM driver activated but no TIM peripheral assigned"
 #endif
 
 /*===========================================================================*/
@@ -126,18 +158,29 @@
 /*===========================================================================*/
 
 /**
- * @brief PWM channel type.
+ * @brief   PWM channel type.
  */
 typedef uint8_t pwmchannel_t;
 
 /**
- * @brief PWM counter type.
+ * @brief   PWM counter type.
  */
 typedef uint16_t pwmcnt_t;
 
 /**
- * @brief PWM driver channel configuration structure.
- * @note It could be empty on some architectures.
+ * @brief   Type of a structure representing an PWM driver.
+ */
+typedef struct PWMDriver PWMDriver;
+
+/**
+ * @brief   PWM notification callback type.
+ *
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ */
+typedef void (*pwmcallback_t)(PWMDriver *pwmp);
+
+/**
+ * @brief   PWM driver channel configuration structure.
  */
 typedef struct {
   /**
@@ -146,22 +189,21 @@ typedef struct {
   pwmmode_t                 pcc_mode;
   /**
    * @brief Channel callback pointer.
-   * @details This callback is invoked on the channel compare event. If set to
-   * @p NULL then the callback is disabled.
+   * @note  This callback is invoked on the channel compare event. If set to
+   *        @p NULL then the callback is disabled.
    */
   pwmcallback_t             pcc_callback;
   /* End of the mandatory fields.*/
 } PWMChannelConfig;
 
 /**
- * @brief PWM driver configuration structure.
- * @note It could be empty on some architectures.
+ * @brief   PWM driver configuration structure.
  */
 typedef struct {
   /**
    * @brief Periodic callback pointer.
-   * @details This callback is invoked on PWM counter reset. If set to
-   * @p NULL then the callback is disabled.
+   * @note  This callback is invoked on PWM counter reset. If set to
+   *        @p NULL then the callback is disabled.
    */
   pwmcallback_t             pc_callback;
   /**
@@ -179,15 +221,15 @@ typedef struct {
   uint16_t                  pc_arr;
   /**
    * @brief TIM CR2 register initialization data.
-   * @note The value of this field should normally be equal to zero.
+   * @note  The value of this field should normally be equal to zero.
    */
   uint16_t                  pc_cr2;
 } PWMConfig;
 
 /**
- * @brief Structure representing a PWM driver.
+ * @brief   Structure representing a PWM driver.
  */
-typedef struct {
+struct PWMDriver {
   /**
    * @brief Driver state.
    */
@@ -196,6 +238,9 @@ typedef struct {
    * @brief Current driver configuration data.
    */
   const PWMConfig           *pd_config;
+#if defined(PWM_DRIVER_EXT_FIELDS)
+  PWM_DRIVER_EXT_FIELDS
+#endif
   /* End of the mandatory fields.*/
   /**
    * @brief Bit mask of the enabled channels.
@@ -205,32 +250,119 @@ typedef struct {
    * @brief Pointer to the TIMx registers block.
    */
   TIM_TypeDef               *pd_tim;
-} PWMDriver;
+};
 
 /*===========================================================================*/
 /* Driver macros.                                                            */
 /*===========================================================================*/
 
+/**
+ * @brief   PWM clock prescaler initialization utility.
+ * @note    The real clock value is rounded to the lower valid value, please
+ *          make sure that the source clock frequency is a multiple of the
+ *          requested PWM clock frequency.
+ * @note    The calculated value must fit into an unsigned 16 bits integer.
+ *
+ * @param[in] clksrc    clock source frequency, depending on the target timer
+ *                      cell it can be one of:
+ *                      - STM32_TIMCLK1
+ *                      - STM32_TIMCLK2
+ *                      .
+ *                      Please refer to the STM32 HAL driver documentation
+ *                      and/or the STM32 Reference Manual for the right clock
+ *                      source.
+ * @param[in] pwmclk    PWM clock frequency in cycles
+ * @return              The value to be stored in the @p pc_psc field of the
+ *                      @p PWMConfig structure.
+ */
+#define PWM_COMPUTE_PSC(clksrc, pwmclk)                                     \
+  ((uint16_t)(((clksrc) / (pwmclk)) - 1))
+
+/**
+ * @brief   PWM cycle period initialization utility.
+ * @note    The calculated value must fit into an unsigned 16 bits integer.
+ *
+ * @param[in] pwmclk    PWM clock frequency in cycles
+ * @param[in] pwmperiod PWM cycle period in nanoseconds
+ * @return              The value to be stored in the @p pc_arr field of the
+ *                      @p PWMConfig structure.
+ */
+#define PWM_COMPUTE_ARR(pwmclk, pwmperiod)                                  \
+  ((uint16_t)(((pwmclk) / (1000000000 / (pwmperiod))) - 1))
+
+/**
+ * @brief   Converts from fraction to pulse width.
+ * @note    Be careful with rounding errors, this is integer math not magic.
+ *          You can specify tenths of thousandth but make sure you have the
+ *          proper hardware resolution by carefully choosing the clock source
+ *          and prescaler settings, see @p PWM_COMPUTE_PSC.
+ *
+ * @param[in] numerator numerator of the fraction
+ * @param[in] denominator percentage as an integer between 0 and numerator
+ * @return              The pulse width to be passed to @p pwmEnableChannel().
+ *
+ * @api
+ */
+#define PWM_FRACTION_TO_WIDTH(pwmp, numerator, denominator)                 \
+  ((uint16_t)((((uint32_t)(pwmp)->pd_config->pc_arr + 1UL) *                \
+               (uint32_t)(denominator)) / (uint32_t)(numerator)))
+
+/**
+ * @brief   Converts from degrees to pulse width.
+ * @note    Be careful with rounding errors, this is integer math not magic.
+ *          You can specify hundredths of degrees but make sure you have the
+ *          proper hardware resolution by carefully choosing the clock source
+ *          and prescaler settings, see @p PWM_COMPUTE_PSC.
+ *
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ * @param[in] degrees   degrees as an integer between 0 and 36000
+ * @return              The pulse width to be passed to @p pwmEnableChannel().
+ *
+ * @api
+ */
+#define PWM_DEGREES_TO_WIDTH(pwmp, degrees)                                 \
+  PWM_FRACTION_TO_WIDTH(pwmp, 36000, degrees)
+
+/**
+ * @brief   Converts from percentage to pulse width.
+ * @note    Be careful with rounding errors, this is integer math not magic.
+ *          You can specify tenths of thousandth but make sure you have the
+ *          proper hardware resolution by carefully choosing the clock source
+ *          and prescaler settings, see @p PWM_COMPUTE_PSC.
+ *
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ * @param[in] percentage percentage as an integer between 0 and 10000
+ * @return              The pulse width to be passed to @p pwmEnableChannel().
+ *
+ * @api
+ */
+#define PWM_PERCENTAGE_TO_WIDTH(pwmp, percentage)                           \
+  PWM_FRACTION_TO_WIDTH(pwmp, 10000, percentage)
+
 /*===========================================================================*/
 /* External declarations.                                                    */
 /*===========================================================================*/
 
-#if defined(USE_STM32_PWM1) && !defined(__DOXYGEN__)
+#if defined(STM32_PWM_USE_TIM1) && !defined(__DOXYGEN__)
 extern PWMDriver PWMD1;
 #endif
 
-#if defined(USE_STM32_PWM2) && !defined(__DOXYGEN__)
+#if defined(STM32_PWM_USE_TIM2) && !defined(__DOXYGEN__)
 extern PWMDriver PWMD2;
 #endif
 
-#if defined(USE_STM32_PWM3) && !defined(__DOXYGEN__)
+#if defined(STM32_PWM_USE_TIM3) && !defined(__DOXYGEN__)
 extern PWMDriver PWMD3;
 #endif
 
-#if defined(USE_STM32_PWM4) && !defined(__DOXYGEN__)
+#if defined(STM32_PWM_USE_TIM4) && !defined(__DOXYGEN__)
 extern PWMDriver PWMD4;
 #endif
 
+#if defined(STM32_PWM_USE_TIM5) && !defined(__DOXYGEN__)
+extern PWMDriver PWMD5;
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -245,7 +377,7 @@ extern "C" {
 }
 #endif
 
-#endif /* CH_HAL_USE_PWM */
+#endif /* HAL_USE_PWM */
 
 #endif /* _PWM_LLD_H_ */
 
diff --git a/os/hal/src/pwm.c b/os/hal/src/pwm.c
index 9211091fb..8973537d9 100644
--- a/os/hal/src/pwm.c
+++ b/os/hal/src/pwm.c
@@ -27,6 +27,7 @@
 /**
  * @file    pwm.c
  * @brief   PWM Driver code.
+ *
  * @addtogroup PWM
  * @{
  */
@@ -34,7 +35,7 @@
 #include "ch.h"
 #include "hal.h"
 
-#if CH_HAL_USE_PWM || defined(__DOXYGEN__)
+#if HAL_USE_PWM || defined(__DOXYGEN__)
 
 /*===========================================================================*/
 /* Driver exported variables.                                                */
@@ -69,6 +70,9 @@ void pwmObjectInit(PWMDriver *pwmp) {
 
   pwmp->pd_state    = PWM_STOP;
   pwmp->pd_config   = NULL;
+#if defined(PWM_DRIVER_EXT_INIT_HOOK)
+  PWM_DRIVER_EXT_INIT_HOOK(pwmp);
+#endif
 }
 
 /**
@@ -83,8 +87,7 @@ void pwmStart(PWMDriver *pwmp, const PWMConfig *config) {
 
   chSysLock();
   chDbgAssert((pwmp->pd_state == PWM_STOP) || (pwmp->pd_state == PWM_READY),
-              "pwmStart(), #1",
-              "invalid state");
+              "pwmStart(), #1", "invalid state");
   pwmp->pd_config = config;
   pwm_lld_start(pwmp);
   pwmp->pd_state = PWM_READY;
@@ -102,8 +105,7 @@ void pwmStop(PWMDriver *pwmp) {
 
   chSysLock();
   chDbgAssert((pwmp->pd_state == PWM_STOP) || (pwmp->pd_state == PWM_READY),
-              "pwmStop(), #1",
-              "invalid state");
+              "pwmStop(), #1", "invalid state");
   pwm_lld_stop(pwmp);
   pwmp->pd_state = PWM_STOP;
   chSysUnlock();
@@ -111,9 +113,10 @@ void pwmStop(PWMDriver *pwmp) {
 
 /**
  * @brief   Enables a PWM channel.
+ * @details Programs (or reprograms) a PWM channel.
  *
  * @param[in] pwmp      pointer to a @p PWMDriver object
- * @param[in] channel   PWM channel identifier
+ * @param[in] channel   PWM channel identifier (0...PWM_CHANNELS-1)
  * @param[in] width     PWM pulse width as clock pulses number
  */
 void pwmEnableChannel(PWMDriver *pwmp,
@@ -125,18 +128,18 @@ void pwmEnableChannel(PWMDriver *pwmp,
 
   chSysLock();
   chDbgAssert(pwmp->pd_state == PWM_READY,
-              "pwmEnableChannel(), #1", "invalid state");
+              "pwmEnableChannel(), #1", "not ready");
   pwm_lld_enable_channel(pwmp, channel, width);
   chSysUnlock();
 }
 
 /**
- * @brief Disables a PWM channel.
+ * @brief   Disables a PWM channel.
  * @details The channel is disabled and its output line returned to the
  *          idle state.
  *
  * @param[in] pwmp      pointer to a @p PWMDriver object
- * @param[in] channel   PWM channel identifier
+ * @param[in] channel   PWM channel identifier (0...PWM_CHANNELS-1)
  */
 void pwmDisableChannel(PWMDriver *pwmp, pwmchannel_t channel) {
 
@@ -145,7 +148,7 @@ void pwmDisableChannel(PWMDriver *pwmp, pwmchannel_t channel) {
 
   chSysLock();
   chDbgAssert(pwmp->pd_state == PWM_READY,
-              "pwmDisableChannel(), #1", "invalid state");
+              "pwmDisableChannel(), #1", "not ready");
   pwm_lld_disable_channel(pwmp, channel);
   chSysUnlock();
 }
diff --git a/os/hal/templates/pwm_lld.c b/os/hal/templates/pwm_lld.c
index 18f4110d0..a1c7b50c3 100644
--- a/os/hal/templates/pwm_lld.c
+++ b/os/hal/templates/pwm_lld.c
@@ -35,6 +35,8 @@
 #include "ch.h"
 #include "hal.h"
 
+#if CH_HAL_USE_PWM || defined(__DOXYGEN__)
+
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -98,25 +100,11 @@ bool_t pwm_lld_is_enabled(PWMDriver *pwmp, pwmchannel_t channel) {
   return FALSE;
 }
 
-/**
- * @brief   Enables a callback mode for the specified PWM channel.
- * @details The callback mode must be set before starting a PWM channel.
- *
- * @param[in] pwmp      pointer to the @p PWMDriver object
- * @param[in] channel   PWM channel identifier
- * @param[in] edge      output edge mode
- * @param[in] callback  callback function
- */
-void pwm_lld_set_callback(PWMDriver *pwmp, pwmchannel_t channel,
-                          pwmedge_t edge, pwmcallback_t callback) {
-
-}
-
 /**
  * @brief   Enables a PWM channel.
  *
- * @param[in] pwmp      pointer to the @p PWMDriver object
- * @param[in] channel   PWM channel identifier
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ * @param[in] channel   PWM channel identifier (0...PWM_CHANNELS-1)
  * @param[in] width     PWM pulse width as clock pulses number
  */
 void pwm_lld_enable_channel(PWMDriver *pwmp,
@@ -130,11 +118,13 @@ void pwm_lld_enable_channel(PWMDriver *pwmp,
  * @details The channel is disabled and its output line returned to the
  *          idle state.
  *
- * @param[in] pwmp      pointer to the @p PWMDriver object
- * @param[in] channel   PWM channel identifier
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ * @param[in] channel   PWM channel identifier (0...PWM_CHANNELS-1)
  */
 void pwm_lld_disable_channel(PWMDriver *pwmp, pwmchannel_t channel) {
 
 }
 
+#endif /* CH_HAL_USE_PWM */
+
 /** @} */
diff --git a/os/hal/templates/pwm_lld.h b/os/hal/templates/pwm_lld.h
index 8db3681fb..8605c3d8c 100644
--- a/os/hal/templates/pwm_lld.h
+++ b/os/hal/templates/pwm_lld.h
@@ -35,6 +35,8 @@
 #ifndef _PWM_LLD_H_
 #define _PWM_LLD_H_
 
+#if CH_HAL_USE_PWM || defined(__DOXYGEN__)
+
 /*===========================================================================*/
 /* Driver constants.                                                         */
 /*===========================================================================*/
@@ -69,17 +71,61 @@ typedef uint8_t pwmchannel_t;
 typedef uint16_t pwmcnt_t;
 
 /**
- * @brief   Driver configuration structure.
- * @note    It could be empty on some architectures.
+ * @brief   Type of a structure representing an PWM driver.
+ */
+typedef struct PWMDriver PWMDriver;
+
+/**
+ * @brief   PWM notification callback type.
+ *
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ */
+typedef void (*pwmcallback_t)(PWMDriver *pwmp);
+
+/**
+ * @brief   PWM driver channel configuration structure.
+ * @note    Some architectures may not be able to support the channel mode
+ *          or the callback, in this case the fields are ignored.
  */
 typedef struct {
+  /**
+   * @brief Channel active logic level.
+   */
+  pwmmode_t                 pcc_mode;
+  /**
+   * @brief Channel callback pointer.
+   * @note  This callback is invoked on the channel compare event. If set to
+   *        @p NULL then the callback is disabled.
+   */
+  pwmcallback_t             pcc_callback;
+  /* End of the mandatory fields.*/
+} PWMChannelConfig;
 
+/**
+ * @brief   Driver configuration structure.
+ * @note    Implementations may extend this structure to contain more,
+ *          architecture dependent, fields.
+ */
+typedef struct {
+  /**
+   * @brief Periodic callback pointer.
+   * @note  This callback is invoked on PWM counter reset. If set to
+   *        @p NULL then the callback is disabled.
+   */
+  pwmcallback_t             pc_callback;
+  /**
+   * @brief Channels configurations.
+   */
+  PWMChannelConfig          pc_channels[PWM_CHANNELS];
+  /* End of the mandatory fields.*/
 } PWMConfig;
 
 /**
  * @brief   Structure representing an PWM driver.
+ * @note    Implementations may extend this structure to contain more,
+ *          architecture dependent, fields.
  */
-typedef struct {
+struct PWMDriver {
   /**
    * @brief Driver state.
    */
@@ -88,13 +134,63 @@ typedef struct {
    * @brief Current configuration data.
    */
   const PWMConfig           *pd_config;
+#if defined(PWM_DRIVER_EXT_FIELDS)
+  PWM_DRIVER_EXT_FIELDS
+#endif
   /* End of the mandatory fields.*/
-} PWMDriver;
+};
 
 /*===========================================================================*/
 /* Driver macros.                                                            */
 /*===========================================================================*/
 
+/**
+ * @brief   Converts from fraction to pulse width.
+ * @note    Be careful with rounding errors, this is integer math not magic.
+ *          You can specify tenths of thousandth but make sure you have the
+ *          proper hardware resolution by carefully choosing the clock source
+ *          and prescaler settings, see @p PWM_COMPUTE_PSC.
+ *
+ * @param[in] numerator numerator of the fraction
+ * @param[in] denominator percentage as an integer between 0 and numerator
+ * @return              The pulse width to be passed to @p pwmEnableChannel().
+ *
+ * @api
+ */
+#define PWM_FRACTION_TO_WIDTH(pwmp, numerator, denominator) 0
+
+/**
+ * @brief   Converts from degrees to pulse width.
+ * @note    Be careful with rounding errors, this is integer math not magic.
+ *          You can specify hundredths of degrees but make sure you have the
+ *          proper hardware resolution by carefully choosing the clock source
+ *          and prescaler settings, see @p PWM_COMPUTE_PSC.
+ *
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ * @param[in] degrees   degrees as an integer between 0 and 36000
+ * @return              The pulse width to be passed to @p pwmEnableChannel().
+ *
+ * @api
+ */
+#define PWM_DEGREES_TO_WIDTH(pwmp, degrees)                                 \
+  PWM_FRACTION_TO_WIDTH(pwmp, 36000, degrees)
+
+/**
+ * @brief   Converts from percentage to pulse width.
+ * @note    Be careful with rounding errors, this is integer math not magic.
+ *          You can specify tenths of thousandth but make sure you have the
+ *          proper hardware resolution by carefully choosing the clock source
+ *          and prescaler settings, see @p PWM_COMPUTE_PSC.
+ *
+ * @param[in] pwmp      pointer to a @p PWMDriver object
+ * @param[in] percentage percentage as an integer between 0 and 10000
+ * @return              The pulse width to be passed to @p pwmEnableChannel().
+ *
+ * @api
+ */
+#define PWM_PERCENTAGE_TO_WIDTH(pwmp, percentage)                           \
+  PWM_FRACTION_TO_WIDTH(pwmp, 10000, percentage)
+
 /*===========================================================================*/
 /* External declarations.                                                    */
 /*===========================================================================*/
@@ -106,8 +202,6 @@ extern "C" {
   void pwm_lld_start(PWMDriver *pwmp);
   void pwm_lld_stop(PWMDriver *pwmp);
   bool_t pwm_lld_is_enabled(PWMDriver *pwmp, pwmchannel_t channel);
-  void pwm_lld_set_callback(PWMDriver *pwmp, pwmchannel_t channel,
-                            pwmedge_t edge, pwmcallback_t callback);
   void pwm_lld_enable_channel(PWMDriver *pwmp,
                               pwmchannel_t channel,
                               pwmcnt_t width);
@@ -116,6 +210,8 @@ extern "C" {
 }
 #endif
 
+#endif /* CH_HAL_USE_PWM */
+
 #endif /* _PWM_LLD_H_ */
 
 /** @} */
diff --git a/readme.txt b/readme.txt
index cd87e80c5..c5dbd8eca 100644
--- a/readme.txt
+++ b/readme.txt
@@ -61,6 +61,12 @@
 *** 2.0.8 ***
 - FIX: Fixed failed memory recovery by registry scan, improved the related
   test case (bug 3116888).
+- FIX: Fixed PWM channels going to ACTIVE state when the pulse width is
+  set to zero in the STM32 PWM driver (bug 3114481).
+- FIX: Fixed PWM channels return to IDLE state in STM32 PWM driver (bug
+  3114467).
+- CHANGE: Bugs 3114467 and 3114481 have been fixed by backporting the 2.1.x
+  PWM driver, there is a difference in the PWM callback parameters.
 
 *** 2.0.7 ***
 - FIX: Fixed typo in board name (bug 3113574).