3. 광센서를 이용해 야간등을 만들어보자(Cisco Lab 2.2.3.2 - Photo Resistor using Redboard and Arduino IDE)

준비물 : 아두이노, 브레드보드, 330Ω저항 1개, 10K 저항 1개, M/M 점퍼선 6개, 광센서 1개

(까먹고 사진은 못찍었는데 LED도 1개 필요합니다.)

회로도와 같이 연결해줍니다.

연결을 하면 이런 모습입니다.

※ 그러나! 저는 작동을 하지 않았는데요

1시간 동안 원인이 무엇일까 코드 분석에 전부 다 빼고 다 껴보고 하나하나 해보아서 찾아본 결과

LED가 문제였네요ㅡㅡ; 다른 LED로 고쳤더니 바로 작동해서 허무....여러분도 LED 한번 점검해보세요

아두이노 스케치 프로그램을 실행시켜서 아래와 같이 입력 후 업로드 합니다.

아래 코드는 sparkfun에서 제공하는 예제 skicode입니다.

/******************************************************************

 * SparkFun Inventor's Kit

 * Example sketch 06

 * 

 * PHOTO RESISTOR

 * 

 * Use a photoresistor (light sensor) to control the brightness

 * of a LED.

 * 

 * This sketch was written by SparkFun Electronics,

 * with lots of help from the Arduino community.

 * This code is completely free for any use.

 * Visit http://learn.sparkfun.com/products/2 for SIK information.

 * Visit http://www.arduino.cc to learn about the Arduino.

 * 

 * Version 2.0 6/2012 MDG

 * Version 2.1 9/2014 BCH

/*****************************************************************/

// As usual, we'll create constants to name the pins we're using.

// This will make it easier to follow the code below.

const int sensorPin = 0;

const int ledPin = 9;

// We'll also set up some global variables for the light level:

int lightLevel;

int calibratedlightLevel; // used to store the scaled / calibrated lightLevel

int maxThreshold = 0;     // used for setting the "max" light level

int minThreshold = 1023;   // used for setting the "min" light level

void setup()

{

  pinMode(ledPin, OUTPUT);    // Set up the LED pin to be an output.

  Serial.begin(9600);

}

void loop()

{

  lightLevel = analogRead(sensorPin);  // reads the voltage on the sensorPin

  Serial.print(lightLevel);

  autoRange();  // autoRanges the min / max values you see in your room.

  calibratedlightLevel = map(lightLevel, 0, 1023, 0, 255);  // scale the lightLevel from 0 - 1023 range to 0 - 255 range.

                                                  // the map() function applies a linear scale / offset.

                                                  // map(inputValue, fromMin, fromMax, toMin, toMax);

  Serial.print("\t");  // tab character

  Serial.print(calibratedlightLevel);   // println prints an CRLF at the end (creates a new line after)

  analogWrite(ledPin, calibratedlightLevel);    // set the led level based on the input lightLevel.

}

/******************************************************************

 * void autoRange()

 * 

 * This function sets a minThreshold and maxThreshold value for the

 * light levels in your setting. Move your hand / light source / etc

 * so that your light sensor sees a full range of values. This will

 * "autoCalibrate" to your range of input values.

/*****************************************************************/

void autoRange()

{

  if (lightLevel < minThreshold)  // minThreshold was initialized to 1023 -- so, if it's less, reset the threshold level.

    minThreshold = lightLevel;

  if (lightLevel > maxThreshold)  // maxThreshold was initialized to 0 -- so, if it's bigger, reset the threshold level.

    maxThreshold = lightLevel;

  // Once we have the highest and lowest values, we can stick them

  // directly into the map() function.

  // 

  // This function must run a few times to get a good range of bright and dark values in order to work.

  lightLevel = map(lightLevel, minThreshold, maxThreshold, 0, 255);

  lightLevel = constrain(lightLevel, 0, 255);

}

빛이 있을 경우에는 LED가 꺼지고, 어두울 경우 LED가 켜지는 야간등을 만들어 봤습니다!