Clap On Lamp

Contributors: Shawn Hymel

Programming

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language:c
/**
 * Clap On Light
 * Date: November 9, 2017
 * Author: Shawn Hymel (SparkFun Electronics)
 * 
 * Connect a servo to a lamp chain/switch to turn it on and off
 * with two successive claps (or other loud noises).
 * 
 * To complete this project, you will need parts from the
 * SparkFun Inventor's Kit v4.0: 
 * https://www.sparkfun.com/products/14265 as well as a sound
 * detector board: https://www.sparkfun.com/products/14262 along
 * with a lamp, electrical tape, hose clamp, zip ties, and a
 * paper clip.
 * 
 * This sketch was written by SparkFun Electronics, with lots of
 * help from the Arduino community. This code is completely free
 * for any use.
 */

#include <Servo.h>

// Pins
const int SERVO_PIN = 9;
const int SOUND_PIN = A0;

// Constants
const int THRESHOLD = 30;                           // Raw ADC
const unsigned long TIMEOUT = 500;                  // ms
const unsigned long TIME_BETWEEN_PULSES_MIN = 300;  // ms
const unsigned long TIME_BETWEEN_PULSES_MAX = 1000; // ms
const int PULSE_MIN = 40;                           // ms
const int PULSE_MAX = 300;                          // ms
const int SERVO_WAIT = 1000;                        // ms
const int SERVO_CCW = 0;                            // deg
const int SERVO_CW = 180;                           // deg

// Globals
unsigned long last_pulse_time = 0;
Servo servo;

void setup() {

  Serial.begin(9600);

  servo.attach(SERVO_PIN);
  servo.write(SERVO_CW);

  pinMode(SOUND_PIN, INPUT);
}

void loop() {

  // Look for pulse and take time it occured
  unsigned long pulse_length = readPulse(SOUND_PIN, THRESHOLD, TIMEOUT);
  if ( (pulse_length >= PULSE_MIN) && 
       (pulse_length <= PULSE_MAX) ) {
    unsigned long pulse_time = millis();
    Serial.println(pulse_time - last_pulse_time);

    // Check time between this pulse and the last one we saw
    if ( (pulse_time - last_pulse_time >= TIME_BETWEEN_PULSES_MIN) &&
         (pulse_time - last_pulse_time <= TIME_BETWEEN_PULSES_MAX) ) {
      Serial.println("Clap on!");
      pullChain();
    }

    last_pulse_time = pulse_time;
  }
}

// If the analog value is above the threshold, wait for it to
// drop below the threshold and return the time it was above
// the threshold. Return 0 if it's not above the threshold, and
// return the timeout value if it stays above the threshold for
// too long.
unsigned long readPulse(int pin, int threshold, unsigned long timeout) {

  unsigned long t = 0;

  // If above the threshold, wait for value to drop below it
  if ( analogRead(pin) >= threshold ) {
    unsigned long timestamp = millis();
    while ( (analogRead(pin) >= threshold) &&
            (millis() < timestamp + timeout) );
    t = millis() - timestamp;
  }

  return t;
}

// Pull the lamp chain by moving the servo far counterclockwise,
// wait 500 ms, and then move it far clockwise.
void pullChain() {
  servo.write(SERVO_CCW);
  delay(SERVO_WAIT);
  servo.write(SERVO_CW);
  delay(SERVO_WAIT);
}

What You Should See

Clap twice near the sound detector with a pause of about 1/2 second between claps. The servo should activate and pull the chain to switch the light on. Clap twice again, and the lamp should turn off.