diff --git a/optical_rpm_log.ino b/optical_rpm_log.ino
new file mode 100644
index 0000000..4b28f78
--- /dev/null
+++ b/optical_rpm_log.ino
@@ -0,0 +1,84 @@
+#define SEPARATOR ","
+
+//Pins
+#define TCRT_DIG 2
+#define TCRT_ANLG A0
+
+//
+volatile int digital_val;
+int counter = 0;
+volatile unsigned prevRPM = 0;
+
+#define MIN_TIME 50000
+#define BAUD_RATE 115200
+#define RPM_CONVERSION_FACTOR 60
+#define AV_CONVERSION_FACTOR TWO_PI
+#define PRINT_DECIMALS 15
+
+volatile unsigned int rotationFlag = false;
+volatile uint32_t curTime = 0;
+volatile uint32_t prevTime = 0;
+volatile unsigned long rotations = 0;
+double prevAV = 0;
+
+void irInterrupt(){
+  uint32_t now = micros();
+  if(now - curTime >= MIN_TIME) {
+    // Switch closed and no event interrupts for the last little while
+    // Assume this is a genuine wheel rotation and not switch bounce.
+    rotations++;
+    prevTime = curTime;
+    curTime = now;
+    rotationFlag = true;
+  }
+}
+
+void setup() {
+  Serial.begin(BAUD_RATE);
+  pinMode(TCRT_DIG, INPUT_PULLUP);
+  pinMode(TCRT_ANLG, INPUT);
+  // Serial.println(F("MHP Wheel speed logging. Compiled" __TIME__ "," __DATE__));
+  Serial.println("Time_us" SEPARATOR "Rotation_Number" SEPARATOR "Rotation_Time_us" SEPARATOR "Angular_V_rad_s" SEPARATOR "Angular_A_rad_s2" SEPARATOR "RPM");
+
+  // Enable the switch
+  attachInterrupt(digitalPinToInterrupt(TCRT_DIG),irInterrupt, FALLING);
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+//  digital_val2 = digitalRead(TCRT_DIG);
+   if(rotationFlag) {
+    // Disable interrupts whilst reading to avoid race conditions.
+    
+    
+    noInterrupts();
+    unsigned long rotationTime = curTime - prevTime;
+    unsigned long rotationsCopy = rotations; // To avoid race conditions
+    unsigned long curTimeCopy = curTime;
+    interrupts();
+
+    double rotationTimeSeconds = (double)rotationTime / 1e6;
+    double rpm = RPM_CONVERSION_FACTOR / rotationTimeSeconds; // rpm if the differnce between 2 values is above 300 ignore
+    double angularV = AV_CONVERSION_FACTOR / rotationTimeSeconds;
+    double angularA = (angularV - prevAV) / rotationTimeSeconds;
+    prevAV = angularV;
+
+    
+   Serial.print(curTimeCopy);
+   Serial.write(SEPARATOR);
+   Serial.print(rotationsCopy);
+   Serial.write(SEPARATOR);
+   Serial.print(rotationTime);
+   Serial.write(SEPARATOR);
+   Serial.print(angularV, PRINT_DECIMALS);
+   Serial.write(SEPARATOR);
+   Serial.print(angularA, PRINT_DECIMALS);
+   Serial.write(SEPARATOR);
+    Serial.println(rpm, PRINT_DECIMALS);
+    
+    rotationFlag = false;
+    prevRPM = rpm; //change
+  }
+}
+// when speed up okay, there isn't a lot of chnage; but when the speed decreases very fast there are random values
+//schmitt trigger