| /* | |
| Knock Sensor | |
| This sketch reads a piezo element to detect a knocking sound. | |
| It reads an analog pin and compares the result to a set threshold. | |
| If the result is greater than the threshold, it writes "knock" to the serial | |
| port, and toggles the LED on pin 13. | |
| The circuit: | |
| - positive connection of the piezo attached to analog in 0 | |
| - negative connection of the piezo attached to ground | |
| - 1 megohm resistor attached from analog in 0 to ground | |
| created 25 Mar 2007 | |
| by David Cuartielles <http://www.0j0.org> | |
| modified 30 Aug 2011 | |
| by Tom Igoe | |
| This example code is in the public domain. | |
| https://www.arduino.cc/en/Tutorial/BuiltInExamples/Knock | |
| */ | |
| // these constants won't change: | |
| const int ledPin = 13; // LED connected to digital pin 13 | |
| const int knockSensor = A0; // the piezo is connected to analog pin 0 | |
| const int threshold = 100; // threshold value to decide when the detected sound is a knock or not | |
| // these variables will change: | |
| int sensorReading = 0; // variable to store the value read from the sensor pin | |
| int ledState = LOW; // variable used to store the last LED status, to toggle the light | |
| void setup() { | |
| pinMode(ledPin, OUTPUT); // declare the ledPin as as OUTPUT | |
| Serial.begin(9600); // use the serial port | |
| } | |
| void loop() { | |
| // read the sensor and store it in the variable sensorReading: | |
| sensorReading = analogRead(knockSensor); | |
| // if the sensor reading is greater than the threshold: | |
| if (sensorReading >= threshold) { | |
| // toggle the status of the ledPin: | |
| ledState = !ledState; | |
| // update the LED pin itself: | |
| digitalWrite(ledPin, ledState); | |
| // send the string "Knock!" back to the computer, followed by newline | |
| Serial.println("Knock!"); | |
| } | |
| delay(100); // delay to avoid overloading the serial port buffer | |
| } | |