ak8975.hpp

/*
 * Author: Jon Trulson <jtrulson@ics.com>
 * Copyright (c) 2015 Intel Corporation.
 *
 * 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.
 */
#pragma once

#include <string>
#include <mraa/common.hpp>
#include <mraa/i2c.hpp>

#define AK8975_I2C_BUS 0
#define AK8975_DEFAULT_I2C_ADDR 0x0c

namespace upm {

  class AK8975 {
  public:

    typedef enum {
      REG_WIA                   = 0x00, // device id

      REG_INFO                  = 0x01, // undocumented (AK proprietary data)

      REG_ST1                   = 0x02, // status 1

      REG_HXL                   = 0x03, // magnetometer data, X axis low byte
      REG_HXH                   = 0x04, // magnetometer data, X axis high byte
      REG_HYL                   = 0x05,
      REG_HYH                   = 0x06,
      REG_HZL                   = 0x07,
      REG_HZH                   = 0x08,

      REG_ST2                   = 0x09, // status 2

      REG_CNTL                  = 0x0a, // control

      // REG_RSV 0x0b reserved

      REG_ASTC                  = 0x0c, // self test (internal mag field)

      // REG_TS1, REG_TS2 0x0d, 0x0e reserved/factory test

      // REG_I2CDIS 0x0f, I2C disable.  Not a good idea to use or support.
      //  write a 0x1b to disable i2c.  This requires a power cycle to undo.

      // These registers hold factory calibrated co-efficients needed to
      // properly compensate for production variations.  They can only be
      // read when device is in fuse mode.  They are used to adjust the
      // measured mag field values.
      REG_ASAX                  = 0x10, // X calibration
      REG_ASAY                  = 0x11,
      REG_ASAZ                  = 0x12
    } AK8975_REG_T;

    typedef enum {
      ST1_DRDY                  = 0x01 // data ready bit
    } ST1_BITS_T;

    typedef enum {
      ST2_DERR                  = 0x04, // data error
      ST2_HOFL                  = 0x08  // measurement overflow
    } ST2_BITS_T;

    typedef enum {
      CNTL_PWRDWN               = 0x00, // power down
      CNTL_MEASURE              = 0x01, // single measurement
      CNTL_SELFTEST             = 0x08,
      CNTL_FUSE_ACCESS          = 0x0f  // access fuse (coeff) registers
    } CNTL_MODES_T;

    typedef enum {
      ASTC_SELF                 = 0x40 // enable self test
    } ASTC_BITS_T;

    AK8975(int bus=AK8975_I2C_BUS, uint8_t address=AK8975_DEFAULT_I2C_ADDR);

    ~AK8975();

    bool init();

    bool setMode(CNTL_MODES_T mode);

    bool isReady();

    bool waitforDeviceReady();

    bool update(bool selfTest=false);

    bool selfTest();

    void getMagnetometer(float *x, float *y, float *z);


  protected:
    float adjustValue(float value, float adj);

    // compensation coefficients (factory set) for this device
    float m_xCoeff;
    float m_yCoeff;
    float m_zCoeff;

    // uncompensated magnetometer readings
    float m_xData;
    float m_yData;
    float m_zData;

  private:
    mraa::I2c m_i2c;
    uint8_t m_addr;

  };
}