   if (diff > 2 * magAvg[0]) {
     digitalWrite(LED_PIN, LOW);
 
-    Serial.print("Diff:\t"); Serial.println(diff);
+    Serial.print("Prev :\t");
+    for (int i = 0; i < endIndex; i++) {
+      float phase = prevPhase[i];
+      Serial.print(phase);
+      Serial.print("\t");
+    }
+    Serial.println("");
+
+    // Serial.print("Diff:\t"); Serial.println(diff);
     Serial.print("Phase:\t");
     for (int i = 0; i < endIndex; i++) {
       float phase = phaseAvg[i];

      Serial.print("\t");
    }
    Serial.println("");

  }

  if (diff > 2 * magAvg[0] && phaseNearZero) {
    digitalWrite(LED_PIN, HIGH);

    Serial.print("BPM:\t");
    for (int i = 0; i < endIndex; i++) {

    }
    Serial.println("");

  }

  if (diff > 1 * magAvg[0] && phaseNearZero) {
    Serial.println("BEAT!");
    digitalWrite(LED_PIN, HIGH);
  } else {
    digitalWrite(LED_PIN, LOW);
  }
