修正delay_us被优化的错误

Core/Src/syscalls.c

@@ -64,7 +64,7 @@ GETCHAR_PROTOTYPE
 
 void delay_us(uint16_t us)
 {
-    uint32_t delay = (HAL_RCC_GetHCLKFreq() / 4000000 * us);
+    volatile uint32_t delay = (HAL_RCC_GetHCLKFreq() / 4000000 * us);
     while (delay--);
 }
 

Peripheral/Src/servo.c

@@ -3,6 +3,7 @@
 
 void SERVO_Init()
 {
+    __HAL_TIM_SetCompare(&htim1, TIM_CHANNEL_4, 150);
     HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_4);
 }