diff --git a/app/by_stepper.c b/app/by_stepper.c
index 6e71b91..f7c3ec9 100644
--- a/app/by_stepper.c
+++ b/app/by_stepper.c
@@ -116,7 +116,7 @@ void by_stepper_init(void)
   //   DWT_Delay(40U * (uint16_t)by_stepper.speed);
   // }
 
-  by_stepper_set_speed(STEPPER_SPEED_DIV1);
+  by_stepper_set_speed(STEPPER_SPEED_DIV4);
 
   while (gpio_input_data_bit_read(GPIOB, GPIO_PINS_10) == SET) {
     gpio_bits_write(GPIOA, GPIO_PINS_8, by_stepper.dir ? TRUE : FALSE);                    // DIR
@@ -138,7 +138,7 @@ void by_stepper_init(void)
 void by_stepper_loop(void)
 {
   int16_t temp = (int16_t)tmr_counter_value_get(TMR3);
-  position += (int64_t)temp;
+  position -= (int64_t)temp;
   tmr_counter_value_set(TMR3, 0);
 
   if (running_flag) {
@@ -151,10 +151,10 @@ void by_stepper_loop(void)
     } else // 正常模式
     {
       if (position_offset > 0) {
-        by_stepper_set_dir(0);
+        by_stepper_set_dir(1);
         by_stepper_run();
       } else if (position_offset < 0) {
-        by_stepper_set_dir(1);
+        by_stepper_set_dir(0);
         by_stepper_run();
       }