diff --git a/bsp/stm32f4xx-HAL/drivers/drv_i2c.c b/bsp/stm32f4xx-HAL/drivers/drv_i2c.c
index f1e4ca5a5f9e3f02dcb6906a67e2c2735ebc7421..4cc04ae292e27e9ae60490d086b98f09eda50a7f 100644
--- a/bsp/stm32f4xx-HAL/drivers/drv_i2c.c
+++ b/bsp/stm32f4xx-HAL/drivers/drv_i2c.c
@@ -78,11 +78,12 @@ static rt_int32_t  drv_get_scl(void *data)
 
 static void drv_udelay(rt_uint32_t us)
 {
-    int i = (HAL_RCC_GetHCLKFreq() / 4000000 * us);
-    while (i)
+    __IO uint32_t Delay = us * (SystemCoreClock / 8U / 1000000U);
+    do 
     {
-        i--;
-    }
+        __NOP();
+    } 
+    while (Delay --);
 }
 
 static const struct rt_i2c_bit_ops drv_bit_ops =