Added final arduino code.

Arduino/sketch.ino

@@ -0,0 +1,79 @@
+
+const int LEFT_ENABLE_PIN = 8; // EN
+const int LEFT_STEP_PIN = 9; // STEP
+const int LEFT_DIRECTION_PIN = 7; // DIR
+
+const int RIGHT_ENABLE_PIN = 6; // EN
+const int RIGHT_STEP_PIN = 5; // STEP
+const int RIGHT_DIRECTION_PIN = 4; // DIR
+
+
+String commandBuffer;
+
+void setup() {
+  Serial.begin(9600);
+
+  pinMode(LEFT_ENABLE_PIN, OUTPUT); 
+  pinMode(LEFT_STEP_PIN, OUTPUT); 
+  pinMode(LEFT_DIRECTION_PIN, OUTPUT);
+
+  pinMode(RIGHT_ENABLE_PIN, OUTPUT); 
+  pinMode(RIGHT_STEP_PIN, OUTPUT); 
+  pinMode(RIGHT_DIRECTION_PIN, OUTPUT);
+
+  digitalWrite(LEFT_ENABLE_PIN, LOW);
+  delayMicroseconds(300);
+  digitalWrite(RIGHT_ENABLE_PIN, LOW);
+  delayMicroseconds(300);
+}
+
+void loop() {
+  if (Serial.available() > 0) {
+    commandBuffer = Serial.readString();
+
+    if (commandBuffer.charAt(0) == 'M'){
+      char targetMotor = commandBuffer.charAt(1);
+      char motorDirection = commandBuffer.charAt(2);
+      char steps_char = commandBuffer.charAt(3);
+      int steps = steps_char - 48;
+
+      int motorPin = -1;
+      int directionPin = -1;
+
+      int UP = HIGH;
+      int DOWN = LOW;
+
+      if (targetMotor == 'R') {
+        motorPin = RIGHT_STEP_PIN;
+        directionPin = RIGHT_DIRECTION_PIN;
+      } else if (targetMotor == 'L') {
+        motorPin = LEFT_STEP_PIN;
+        directionPin = LEFT_DIRECTION_PIN;
+        UP = LOW;
+        DOWN = HIGH;
+      }
+
+      if (motorPin > -1){
+        if (motorDirection == '+') {
+          digitalWrite(directionPin, UP); 
+        } else {
+          digitalWrite(directionPin, DOWN); 
+        }
+        for (int i=0; i< 5 * steps; i++){
+          digitalWrite(motorPin, HIGH); 
+          delayMicroseconds(300); 
+          digitalWrite(motorPin, LOW); 
+          delayMicroseconds(10000);
+        }
+      }
+    }
+    else if (commandBuffer.charAt(0) == 'S') {
+        digitalWrite(LEFT_ENABLE_PIN, LOW);
+        delayMicroseconds(300);
+        digitalWrite(RIGHT_ENABLE_PIN, LOW);
+        delayMicroseconds(300);
+    }
+    Serial.print(commandBuffer);
+    Serial.flush();
+  }
+}