53 lines
1.8 KiB
C++
53 lines
1.8 KiB
C++
/*
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Knock Sensor
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This sketch reads a piezo element to detect a knocking sound. It
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reads an analog pin and compares the result to a set threshold. If
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the result is greater than the threshold, it writes "knock" to the
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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 30 Jun 2009
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by Tom Igoe
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Ported to the Maple
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by LeafLabs
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*/
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// these constants won't change:
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const int knockSensor = 0; // 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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void setup() {
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Serial.begin(115200); // Ignored by Maple. But needed by boards using hardware serial via a USB to Serial adaptor
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// Declare the knockSensor as an analog input:
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pinMode(knockSensor, INPUT_ANALOG);
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// declare the built-in LED pin as an output:
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pinMode(33, OUTPUT);
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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 built-in LED
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digitalWrite(33,!digitalRead(33));// Turn the LED from off to on, or on to off
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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 printing too often
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}
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