added libraries and clean up

source/piezo_input/piezo_input.ino

@@ -0,0 +1,9 @@
+void setup() {
+   Serial.begin(9600);
+}
+
+void loop() {
+  int val = analogRead(5);     
+  Serial.println(val);
+  delay(100);  // we have to make a delay to avoid overloading the serial port
+}