지자계 센서 사용하기

핸드폰에도 들어 있는 콤파스 역할을 하는 지자계 센서를 다뤄 보겠습니다.

드론에도 GPS 와 같이 지자계 센서가 들어 있어 웨이포인트를 설정하여 자동비행에 이용되기도 합니다.

지자계 센서로 HMC5883L 을 이용해 보겠습니다. 이 모듈도 I2C 포트를 이용합니다.

라이브러리를 첨부된 파일을 압축을 푼후 직접 복사해서 넣으면 됩니다.

이건 I2Cdev 라이브러리도 필요하네요. 

// I2C device class (I2Cdev) demonstration Arduino sketch for HMC5883L class

// 10/7/2011 by Jeff Rowberg <jeff@rowberg.net>

// Updates should (hopefully) always be available at https://github.com/jrowberg/i2cdevlib

//

// Changelog:

//     2013-05-04 - Added Heading Calculation in degrees

//     2011-10-07 - initial release

/* ============================================

I2Cdev device library code is placed under the MIT license

Copyright (c) 2011 Jeff Rowberg

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in

all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

THE SOFTWARE.

===============================================

*/

// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation

// is used in I2Cdev.h

#include "Wire.h"

// I2Cdev and HMC5883L must be installed as libraries, or else the .cpp/.h files

// for both classes must be in the include path of your project

#include "I2Cdev.h"

#include "HMC5883L.h"

// class default I2C address is 0x1E

// specific I2C addresses may be passed as a parameter here

// this device only supports one I2C address (0x1E)

HMC5883L mag;

int16_t mx, my, mz;

#define LED_PIN 13

bool blinkState = false;

void setup() {

    // join I2C bus (I2Cdev library doesn't do this automatically)

    Wire.begin();

    // initialize serial communication

    // (38400 chosen because it works as well at 8MHz as it does at 16MHz, but

    // it's really up to you depending on your project)

    Serial.begin(38400);

    // initialize device

    Serial.println("Initializing I2C devices...");

    mag.initialize();

    // verify connection

    Serial.println("Testing device connections...");

    Serial.println(mag.testConnection() ? "HMC5883L connection successful" : "HMC5883L connection failed");

    // configure Arduino LED for

    pinMode(LED_PIN, OUTPUT);

}

void loop() {

    // read raw heading measurements from device

    mag.getHeading(&mx, &my, &mz);

    // display tab-separated gyro x/y/z values

    Serial.print("mag:\t");

    Serial.print(mx); Serial.print("\t");

    Serial.print(my); Serial.print("\t");

    Serial.print(mz); Serial.print("\t");

    

// To calculate heading in degrees. 0 degree indicates North

    float heading = atan2(my, mx);

    if(heading < 0)

      heading += 2 * M_PI;

    Serial.print("heading:\t");

    Serial.println(heading * 180/M_PI);

    // blink LED to indicate activity

    blinkState = !blinkState;

    digitalWrite(LED_PIN, blinkState);

    delay(500);

}