diff --git a/IteadDualStepperShield.cpp b/IteadDualStepperShield.cpp
index d297323..7300c45 100644
--- a/IteadDualStepperShield.cpp
+++ b/IteadDualStepperShield.cpp
@@ -50,7 +50,8 @@ void IteadDualStepperShield::_micro (uint8_t motor) {
 void IteadDualStepperShield::_single (uint8_t motor) {
 	uint8_t stepPin = motor == 0 ? _stepA : _stepB;
 	uint32_t usStep = motor == 0 ? _usStepA : _usStepB;
-	for (uint8_t i = 0; i < _microsteps; i++) {
+	uint8_t mode = motor == 0 ? _modeA : _modeB;
+	for (uint8_t i = 0; i < mode; i++) {
 		digitalWrite(stepPin, HIGH);
 		delayMicroseconds(usStep);
 		digitalWrite(stepPin, LOW);
diff --git a/IteadDualStepperShield.h b/IteadDualStepperShield.h
index 627dd56..ed72342 100644
--- a/IteadDualStepperShield.h
+++ b/IteadDualStepperShield.h
@@ -22,7 +22,9 @@
 
 class IteadDualStepperShield {
   private:
-  const uint8_t _microsteps = 8;   //8 or 16
+
+  
+
   const uint8_t _directionA = 3;
   const uint8_t _directionB = 7;
   const uint8_t _stepA = 2;
@@ -33,14 +35,19 @@ class IteadDualStepperShield {
   const uint8_t _settingsB1 = 8;
   const uint8_t _settingsB2 = 9;
 
+  volatile uint32_t _usStepA = 300;
+  volatile uint32_t _usStepB = 300;
+
+  //const uint8_t _microsteps = 8;   //8 or 16
+  volatile uint8_t _modeA = 1;   //1, 2, 4, or 8
+  volatile uint8_t _modeB = 1;
+
   void _single(uint8_t motor);
   void _micro(uint8_t motor);
   void _both();
 
-  uint32_t _usStepA = 300;
-  uint32_t _usStepB = 300;
-
   public:
+
   IteadDualStepperShield();
 
   uint16_t revsteps = 200; // # steps per revolution