diff --git a/components/step_motor_ctrl_module/step_motor_ctrl_module.cpp b/components/step_motor_ctrl_module/step_motor_ctrl_module.cpp
index 6ad0fc1..306ff35 100644
--- a/components/step_motor_ctrl_module/step_motor_ctrl_module.cpp
+++ b/components/step_motor_ctrl_module/step_motor_ctrl_module.cpp
@@ -390,8 +390,10 @@ int32_t StepMotorCtrlModule::step_motor_easy_move_to_zero() {
     return err::kstep_motor_ioindex_out_of_range;
   }
 
-  if(m_iotable[0].getHalPin())
-  
+  if (m_iotable[0].isNull()) {
+    return err::kstep_motor_ioindex_out_of_range;
+  }
+
   return do_step_motor_easy_move_to_zero();
 }
 int32_t StepMotorCtrlModule::step_motor_easy_move_to_io(int32_t ioindex, int32_t direction) {
@@ -413,6 +415,9 @@ int32_t StepMotorCtrlModule::step_motor_easy_move_to_end_point() {
   if (m_nio <= 1) {
     return err::kstep_motor_ioindex_out_of_range;
   }
+  if (m_iotable[1].isNull()) {
+    return err::kstep_motor_ioindex_out_of_range;
+  }
   return do_step_motor_easy_move_to_end_point();
 }
 
@@ -492,6 +497,13 @@ int32_t StepMotorCtrlModule::do_step_motor_easy_move_to_zero() {
 }
 
 int32_t StepMotorCtrlModule::do_step_motor_easy_move_to_io(int32_t ioindex, int32_t direction) {
+  if (ioindex < 0 || ioindex >= m_nio) {
+    return err::kstep_motor_ioindex_out_of_range;
+  }
+  if (m_iotable[ioindex].isNull()) {
+    return err::kstep_motor_ioindex_out_of_range;
+  }
+
   m_thread.stop();
   m_thread.start(
       [this, ioindex, direction]() {