save/restore timer registers before/after deepsleep

Author: bcostm

targets/TARGET_STM/sleep.c

@@ -36,6 +36,8 @@
 #include "mbed_error.h"
 
 extern void rtc_synchronize(void);
+extern void save_timer_ctx(void);
+extern void restore_timer_ctx(void);
 
 /*  Wait loop - assuming tick is 1 us */
 static void wait_loop(uint32_t timeout)
@@ -161,8 +163,7 @@ void hal_deepsleep(void)
     // Disable IRQs
     core_util_critical_section_enter();
 
-    // Save the timer counter value in order to reprogram it after deepsleep
-    uint32_t EnterTimeUS = us_ticker_read();
+    save_timer_ctx();
 
     // Request to enter STOP mode with regulator in low power mode
 #if TARGET_STM32L4
@@ -187,6 +188,7 @@ void hal_deepsleep(void)
 #else /* TARGET_STM32L4 */
     HAL_PWR_EnterSTOPMode(PWR_LOWPOWERREGULATOR_ON, PWR_STOPENTRY_WFI);
 #endif /* TARGET_STM32L4 */
+
     // Verify Clock Out of Deep Sleep
     ForceClockOutofDeepSleep();
 
@@ -199,12 +201,7 @@ void hal_deepsleep(void)
      *  deep sleep */
     wait_loop(500);
 
-    // Reprogram the timer counter value saved before the deepsleep
-    TIM_HandleTypeDef TimMasterHandle;
-    TimMasterHandle.Instance = TIM_MST;
-    __HAL_TIM_SET_COUNTER(&TimMasterHandle, EnterTimeUS);
-    __HAL_TIM_CLEAR_FLAG(&TimMasterHandle, TIM_FLAG_CC1);
-    __HAL_TIM_ENABLE_IT(&TimMasterHandle, TIM_IT_CC1);
+    restore_timer_ctx();
 
 #if DEVICE_RTC
     /* Wait for RTC RSF bit synchro if RTC is configured */
@@ -216,6 +213,7 @@ void hal_deepsleep(void)
         rtc_synchronize();
     }
 #endif
+
     // Enable IRQs
     core_util_critical_section_exit();
 }

targets/TARGET_STM/us_ticker.c

@@ -78,3 +78,20 @@ void us_ticker_clear_interrupt(void)
     __HAL_TIM_CLEAR_FLAG(&TimMasterHandle, TIM_FLAG_CC1);
 }
 
+uint32_t timer_cnt_reg;
+uint32_t timer_ccr1_reg;
+uint32_t timer_dier_reg;
+
+void save_timer_ctx(void)
+{
+    timer_cnt_reg = __HAL_TIM_GET_COUNTER(&TimMasterHandle);
+    timer_ccr1_reg = __HAL_TIM_GET_COMPARE(&TimMasterHandle, TIM_CHANNEL_1);
+    timer_dier_reg = TIM_MST->DIER;
+}
+
+void restore_timer_ctx(void)
+{
+    __HAL_TIM_SET_COUNTER(&TimMasterHandle, timer_cnt_reg);
+    __HAL_TIM_SET_COMPARE(&TimMasterHandle, TIM_CHANNEL_1, timer_ccr1_reg);
+    TIM_MST->DIER = timer_dier_reg;
+}