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56 lines
1.8 KiB
Plaintext
56 lines
1.8 KiB
Plaintext
/* Knock Sensor
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This sketch reads a piezo element to detect a knocking sound.
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It reads an analog pin and compares the result to a set threshold.
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If the result is greater than the threshold, it writes
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"knock" to the serial port, and toggles the LED on pin 13.
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The circuit:
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* + connection of the piezo attached to analog in 0
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* - connection of the piezo attached to ground
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* 1-megohm resistor attached from analog in 0 to ground
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http://www.arduino.cc/en/Tutorial/Knock
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created 25 Mar 2007
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by David Cuartielles <http://www.0j0.org>
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modified 4 Sep 2010
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by Tom Igoe
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This example code is in the public domain.
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*/
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// these constants won't change:
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const int ledPin = 13; // led connected to digital pin 13
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const int knockSensor = A0; // the piezo is connected to analog pin 0
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const int threshold = 100; // threshold value to decide when the detected sound is a knock or not
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// these variables will change:
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int sensorReading = 0; // variable to store the value read from the sensor pin
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int ledState = LOW; // variable used to store the last LED status, to toggle the light
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void setup() {
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pinMode(ledPin, OUTPUT); // declare the ledPin as as OUTPUT
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Serial.begin(9600); // use the serial port
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}
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void loop() {
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// read the sensor and store it in the variable sensorReading:
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sensorReading = analogRead(knockSensor);
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// if the sensor reading is greater than the threshold:
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if (sensorReading >= threshold) {
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// toggle the status of the ledPin:
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ledState = !ledState;
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// update the LED pin itself:
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digitalWrite(ledPin, ledState);
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// send the string "Knock!" back to the computer, followed by newline
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Serial.println("Knock!");
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}
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delay(100); // delay to avoid overloading the serial port buffer
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}
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