diff --git a/chip/basic/clock.cpp b/chip/basic/clock.cpp
index 9f04344..faf1518 100644
--- a/chip/basic/clock.cpp
+++ b/chip/basic/clock.cpp
@@ -32,14 +32,43 @@ uint32_t zchip_clock_hasspassed(uint32_t ticket) {
   return UINT32_MAX - ticket + nowticket;
 }
 
+static HAL_StatusTypeDef _HAL_TIM_Base_Start(TIM_HandleTypeDef* htim) __attribute__((optimize("O2")));
+static HAL_StatusTypeDef _HAL_TIM_Base_Stop(TIM_HandleTypeDef* htim) __attribute__((optimize("O2")));
+
+static HAL_StatusTypeDef _HAL_TIM_Base_Start(TIM_HandleTypeDef* htim) {
+  uint32_t tmpsmcr;
+  /* Check the TIM state */
+  if (htim->State != HAL_TIM_STATE_READY) {
+    return HAL_ERROR;
+  }
+  htim->State = HAL_TIM_STATE_BUSY;
+  if (IS_TIM_SLAVE_INSTANCE(htim->Instance)) {
+    tmpsmcr = htim->Instance->SMCR & TIM_SMCR_SMS;
+    if (!IS_TIM_SLAVEMODE_TRIGGER_ENABLED(tmpsmcr)) {
+      __HAL_TIM_ENABLE(htim);
+    }
+  } else {
+    __HAL_TIM_ENABLE(htim);
+  }
+  return HAL_OK;
+}
+static HAL_StatusTypeDef _HAL_TIM_Base_Stop(TIM_HandleTypeDef* htim) {
+  /* Disable the Peripheral */
+  __HAL_TIM_DISABLE(htim);
+  /* Set the TIM state */
+  htim->State = HAL_TIM_STATE_READY;
+  /* Return function status */
+  return HAL_OK;
+}
+
 void __zchip_clock_early_delayus(uint32_t n) {
   volatile uint32_t counter = 0;
   __HAL_TIM_SET_COUNTER(m_usdleaytim, 0);
-  HAL_TIM_Base_Start(m_usdleaytim);
+  _HAL_TIM_Base_Start(m_usdleaytim);
   while (counter < n) {
     counter = __HAL_TIM_GET_COUNTER(m_usdleaytim);
   }
-  HAL_TIM_Base_Stop(m_usdleaytim);
+  _HAL_TIM_Base_Stop(m_usdleaytim);
 }
 void zchip_clock_early_delayus(uint32_t n) {
   uint32_t us = n % 1000;
@@ -56,12 +85,10 @@ void zchip_clock_early_delayus(uint32_t n) {
 void zchip_clock_early_delayus2(uint32_t us) { __zchip_clock_early_delayus(us); }
 void zchip_clock_early_delayus_timer_start() {
   __HAL_TIM_SET_COUNTER(m_usdleaytim, 0);
-  HAL_TIM_Base_Start(m_usdleaytim);
+  _HAL_TIM_Base_Start(m_usdleaytim);
 }
 uint32_t zchip_clock_early_delayus_timer_haspassed() {
   uint32_t counter = __HAL_TIM_GET_COUNTER(m_usdleaytim);
   return counter;
 }
-void zchip_clock_early_delayus_timer_stop(){
-  HAL_TIM_Base_Stop(m_usdleaytim);
-}
+void zchip_clock_early_delayus_timer_stop() { _HAL_TIM_Base_Stop(m_usdleaytim); }
diff --git a/chip/basic/clock.hpp b/chip/basic/clock.hpp
index 1b9e912..67b7021 100644
--- a/chip/basic/clock.hpp
+++ b/chip/basic/clock.hpp
@@ -16,8 +16,9 @@ uint32_t zchip_clock_init(zchip_clock_cfg_t* cfg);
 uint32_t zchip_clock_get_ticket(void);
 uint32_t zchip_clock_hasspassed(uint32_t ticket);
 void     zchip_clock_early_delayus(uint32_t us);
-void     zchip_clock_early_delayus2(uint32_t us);
-void     zchip_clock_early_delayus_timer_start();
-uint32_t zchip_clock_early_delayus_timer_haspassed();
-void     zchip_clock_early_delayus_timer_stop();
+
+void     zchip_clock_early_delayus2(uint32_t us) __attribute__((optimize("O2")));
+void     zchip_clock_early_delayus_timer_start() __attribute__((optimize("O2")));
+uint32_t zchip_clock_early_delayus_timer_haspassed() __attribute__((optimize("O2")));
+void     zchip_clock_early_delayus_timer_stop() __attribute__((optimize("O2")));
 }