Adafruit_BMP183_U.cpp

/*!
 * @file Adafruit_BMP183_U.cpp
 *
 *  @mainpage Adafruit BMP183 Unified
 *
 *  @section intro_sec Introduction
 *
 *  This is a library for the BMP183 orientation sensor
 *
 *  Designed specifically to work with the Adafruit BMP183 055 Breakout.
 *
 *  Pick one up today in the adafruit shop!
 *  ------> https://www.adafruit.com/product/1900
 *
 *  These sensors use SPI to communicate, 4 pins are required to interface.
 *
 *  Adafruit invests time and resources providing this open source code,
 *  please support Adafruit andopen-source hardware by purchasing products
 *  from Adafruit!
 *
 *  @section author Author
 *
 *  K.Townsend (Adafruit Industries)
 *
 *  @section license License
 *
 *  MIT license, all text above must be included in any redistribution
 */

#include "Arduino.h"
#include "SPI.h"
#include <limits.h>
#include <math.h>

#include "Adafruit_BMP183_U.h"

#define BMP183_USE_DATASHEET_VALS (0) /**< Set to 1 for sanity check **/

/** SPI object **/
SPIClass *_spi;

/*!
 *  @brief  Instantiates a new Adafruit_BMP183_Unified class using hardware SPI
 *  @param  SPICS
 *          cs pin
 *  @param  sensorID
 *          id helpful to identify sensor
 *  @param  *theSPI
 *          optional SPI object
 */
Adafruit_BMP183_Unified::Adafruit_BMP183_Unified(int8_t SPICS, int32_t sensorID,
                                                 SPIClass *theSPI) {
  _cs = SPICS;
  _clk = _miso = _mosi = -1;

  _sensorID = sensorID;
  _spi = theSPI;
}

/*!
 *  @brief  Instantiates a new Adafruit_BMP183_Unified class using hardware SPI
 *  @param  SPICLK
 *          SPI chip clock
 *  @param  SPIMISO
 *          SPI MISO (Data to microcontroller from sensor)
 *  @param  SPIMOSI
 *          SPI MOSI (Data from microcontroller to sensor)
 *  @param  SPICS
 *          SPI CS PIN
 *  @param  sensorID
 *          id helpful to identify sensor
 */
Adafruit_BMP183_Unified::Adafruit_BMP183_Unified(int8_t SPICLK, int8_t SPIMISO,
                                                 int8_t SPIMOSI, int8_t SPICS,
                                                 int32_t sensorID) {
  _cs = SPICS;
  _clk = SPICLK;
  _miso = SPIMISO;
  _mosi = SPIMOSI;

  _sensorID = sensorID;
}

/***************************************************************************
 PRIVATE FUNCTIONS
 ***************************************************************************/

uint8_t Adafruit_BMP183_Unified::SPIxfer(uint8_t x) {
  if (_clk == -1) {
    return _spi->transfer(x);
  } else {
    // Serial.println("Software SPI");
    uint8_t reply = 0;
    for (int i = 7; i >= 0; i--) {
      reply <<= 1;
      digitalWrite(_clk, LOW);
      digitalWrite(_mosi, x & (1 << i));
      digitalWrite(_clk, HIGH);
      if (digitalRead(_miso))
        reply |= 1;
    }
    return reply;
  }
}

/*!
 *  @brief  Writes an 8 bit value over SPI
 */
void Adafruit_BMP183_Unified::writeCommand(byte reg, byte value) {
  digitalWrite(_cs, LOW);
  SPIxfer(reg & 0x7F);
  SPIxfer(value);
  digitalWrite(_cs, HIGH);
}

/*!
 *  @brief  Reads an 8 bit value over I2C
 */
uint8_t Adafruit_BMP183_Unified::read8(byte reg) {
  uint8_t value;

  digitalWrite(_cs, LOW);
  SPIxfer(0x80 | reg);
  value = SPIxfer(0x00);
  digitalWrite(_cs, HIGH);

  return value;
}

/*!
 *  @brief  Reads a 16 bit value over I2C
 */
uint16_t Adafruit_BMP183_Unified::read16(byte reg) {
  uint16_t value;

  digitalWrite(_cs, LOW);
  SPIxfer(0x80 | reg);
  value = SPIxfer(0x00);
  value <<= 8;
  value |= SPIxfer(0x00);
  digitalWrite(_cs, HIGH);

  return value;
}

/*!
 *  @brief  Reads a signed 16 bit value over I2C
 */
int16_t Adafruit_BMP183_Unified::readS16(byte reg) {
  return (int16_t)read16(reg);
}

/*!
 *  @brief  Reads the factory-set coefficients
 */
void Adafruit_BMP183_Unified::readCoefficients(void) {
#if BMP183_USE_DATASHEET_VALS
  _bmp183_coeffs.ac1 = 408;
  _bmp183_coeffs.ac2 = -72;
  _bmp183_coeffs.ac3 = -14383;
  _bmp183_coeffs.ac4 = 32741;
  _bmp183_coeffs.ac5 = 32757;
  _bmp183_coeffs.ac6 = 23153;
  _bmp183_coeffs.b1 = 6190;
  _bmp183_coeffs.b2 = 4;
  _bmp183_coeffs.mb = -32768;
  _bmp183_coeffs.mc = -8711;
  _bmp183_coeffs.md = 2868;
  _bmp183Mode = 0;
#else
  _bmp183_coeffs.ac1 = readS16(BMP183_REGISTER_CAL_AC1);
  _bmp183_coeffs.ac2 = readS16(BMP183_REGISTER_CAL_AC2);
  _bmp183_coeffs.ac3 = readS16(BMP183_REGISTER_CAL_AC3);
  _bmp183_coeffs.ac4 = read16(BMP183_REGISTER_CAL_AC4);
  _bmp183_coeffs.ac5 = read16(BMP183_REGISTER_CAL_AC5);
  _bmp183_coeffs.ac6 = read16(BMP183_REGISTER_CAL_AC6);
  _bmp183_coeffs.b1 = readS16(BMP183_REGISTER_CAL_B1);
  _bmp183_coeffs.b2 = readS16(BMP183_REGISTER_CAL_B2);
  _bmp183_coeffs.mb = readS16(BMP183_REGISTER_CAL_MB);
  _bmp183_coeffs.mc = readS16(BMP183_REGISTER_CAL_MC);
  _bmp183_coeffs.md = readS16(BMP183_REGISTER_CAL_MD);
#endif
}

int16_t Adafruit_BMP183_Unified::readRawTemperature() {
#if BMP183_USE_DATASHEET_VALS
  return 27898;
#else
  writeCommand(BMP183_REGISTER_CONTROL, BMP183_REGISTER_READTEMPCMD);
  delay(5);
  return read16(BMP183_REGISTER_TEMPDATA);
#endif
}

int32_t Adafruit_BMP183_Unified::readRawPressure() {
#if BMP183_USE_DATASHEET_VALS
  *pressure = 23843;
#else
  uint8_t p8;
  uint16_t p16;
  int32_t p32;

  writeCommand(BMP183_REGISTER_CONTROL,
               BMP183_REGISTER_READPRESSURECMD + (_bmp183Mode << 6));
  switch (_bmp183Mode) {
  case BMP183_MODE_ULTRALOWPOWER:
    delay(5);
    break;
  case BMP183_MODE_STANDARD:
    delay(8);
    break;
  case BMP183_MODE_HIGHRES:
    delay(14);
    break;
  case BMP183_MODE_ULTRAHIGHRES:
  default:
    delay(26);
    break;
  }

  p16 = read16(BMP183_REGISTER_PRESSUREDATA);
  p32 = (uint32_t)p16 << 8;
  p8 = read8(BMP183_REGISTER_PRESSUREDATA + 2);
  p32 += p8;
  p32 >>= (8 - _bmp183Mode);

  return p32;
#endif
}

/*!
 *  @brief  Setups the HW
 *  @param  mode
 *          selected bmp183 mode
 *  @return true if successful
 */
bool Adafruit_BMP183_Unified::begin(bmp183_mode_t mode) {

  // Enable SPI
  if (_clk == -1) {
    _spi->begin();
    _spi->beginTransaction(SPISettings(500000, MSBFIRST, SPI_MODE0));
  } else {
    pinMode(_clk, OUTPUT);
    digitalWrite(_clk, HIGH);
    pinMode(_mosi, OUTPUT);
    digitalWrite(_mosi, HIGH);
    pinMode(_miso, INPUT);
  }
  pinMode(_cs, OUTPUT);
  digitalWrite(_cs, HIGH);

  /* Mode boundary check */
  if ((mode > BMP183_MODE_ULTRAHIGHRES) || (mode < 0)) {
    mode = BMP183_MODE_ULTRAHIGHRES;
  }

  /* Make sure we have the right device */
  uint8_t id;
  id = read8(BMP183_REGISTER_CHIPID);
  if (id != 0x55) {
    return false;
  }

  /* Set the mode indicator */
  _bmp183Mode = mode;

  /* Coefficients need to be read once */
  readCoefficients();

  getPressure();

  return true;
}

/*!
 *  @brief  Gets the compensated pressure level in kPa
 *  @return pressure value in hPa
 */
float Adafruit_BMP183_Unified::getPressure() {
  int32_t ut = 0, up = 0, compp = 0;
  int32_t x1, x2, b5, b6, x3, b3, p;
  uint32_t b4, b7;

  /* Get the raw pressure and temperature values */
  ut = readRawTemperature();
  up = readRawPressure();

  /* Temperature compensation */
  x1 = (ut - (int32_t)(_bmp183_coeffs.ac6)) * ((int32_t)(_bmp183_coeffs.ac5)) /
       pow(2, 15);
  x2 = ((int32_t)(_bmp183_coeffs.mc * pow(2, 11))) /
       (x1 + (int32_t)(_bmp183_coeffs.md));
  b5 = x1 + x2;

  /* Pressure compensation */
  b6 = b5 - 4000;
  x1 = (_bmp183_coeffs.b2 * ((b6 * b6) >> 12)) >> 11;
  x2 = (_bmp183_coeffs.ac2 * b6) >> 11;
  x3 = x1 + x2;
  b3 = (((((int32_t)_bmp183_coeffs.ac1) * 4 + x3) << _bmp183Mode) + 2) >> 2;
  x1 = (_bmp183_coeffs.ac3 * b6) >> 13;
  x2 = (_bmp183_coeffs.b1 * ((b6 * b6) >> 12)) >> 16;
  x3 = ((x1 + x2) + 2) >> 2;
  b4 = (_bmp183_coeffs.ac4 * (uint32_t)(x3 + 32768)) >> 15;
  b7 = ((uint32_t)(up - b3) * (50000 >> _bmp183Mode));

  if (b7 < 0x80000000) {
    p = (b7 << 1) / b4;
  } else {
    p = (b7 / b4) << 1;
  }

  x1 = (p >> 8) * (p >> 8);
  x1 = (x1 * 3038) >> 16;
  x2 = (-7357 * p) >> 16;
  compp = p + ((x1 + x2 + 3791) >> 4);

  /* Assign compensated pressure value */
  return compp;
}

/*!
 *  @brief  Reads the temperatures in degrees Celsius
 *  @return temperature in Celsius
 */
float Adafruit_BMP183_Unified::getTemperature() {
  int32_t UT, X1, X2, B5; // following ds convention
  float t;

  UT = readRawTemperature();

#if BMP183_USE_DATASHEET_VALS
  // use datasheet numbers!
  UT = 27898;
  _bmp183_coeffs.ac6 = 23153;
  _bmp183_coeffs.ac5 = 32757;
  _bmp183_coeffs.mc = -8711;
  _bmp183_coeffs.md = 2868;
#endif

  // step 1
  X1 = (UT - (int32_t)_bmp183_coeffs.ac6) * ((int32_t)_bmp183_coeffs.ac5) /
       pow(2, 15);
  X2 = ((int32_t)_bmp183_coeffs.mc * pow(2, 11)) /
       (X1 + (int32_t)_bmp183_coeffs.md);
  B5 = X1 + X2;
  t = (B5 + 8) / pow(2, 4);
  t /= 10;

  return t;
}

/*!
 *   @brief  Calculates the altitude (in meters) from the specified atmospheric
 *           pressure (in hPa), sea-level pressure (in hPa), and temperature (in
 * �C)
 *   @param  seaLevel      Sea-level pressure in hPa
 *   @param  atmospheric   Atmospheric pressure in hPa
 *   @param  temp          Temperature in degrees Celsius
 *   @return               Altitude value in meters
 */
float Adafruit_BMP183_Unified::pressureToAltitude(float seaLevel,
                                                  float atmospheric,
                                                  float temp) {
  /* Hyposometric formula:                      */
  /*                                            */
  /*     ((P0/P)^(1/5.257) - 1) * (T + 273.15)  */
  /* h = -------------------------------------  */
  /*                   0.0065                   */
  /*                                            */
  /* where: h   = height (in meters)            */
  /*        P0  = sea-level pressure (in hPa)   */
  /*        P   = atmospheric pressure (in hPa) */
  /*        T   = temperature (in �C)           */

  return (((float)pow((seaLevel / atmospheric), 0.190223F) - 1.0F) *
          (temp + 273.15F)) /
         0.0065F;
}

/*!
 *   @brief  Calculates the Sea-level pressure (in hPa) from the specified
 * atmospheric pressure (in hPa), sea-level pressure (in hPa), and temperature
 * (in �C)
 *   @param  altitude      Altitude in meters
 *   @param  atmospheric   Atmospheric pressure in hPa
 *   @param  temp          Temperature in degrees Celsius
 *   @return               Sea Level pressure (hPa)
 */
float Adafruit_BMP183_Unified::seaLevelForAltitude(float altitude,
                                                   float atmospheric,
                                                   float temp) {
  /* Hyposometric formula:                      */
  /*                                            */
  /* P0=((((h*0.0065)/(temp + 273.15F))+1)^(^/0.190223F))*P */
  /*                                            */
  /* where: h   = height (in meters)            */
  /*        P0  = sea-level pressure (in hPa)   */
  /*        P   = atmospheric pressure (in hPa) */
  /*        T   = temperature (in �C)           */

  return (float)pow((((altitude * 0.0065) / (temp + 273.15F)) + 1),
                    (1.0 / 0.190223F)) *
         atmospheric;
}

/*!
 *  @brief  Provides the sensor_t data for this sensor
 */
void Adafruit_BMP183_Unified::getSensor(sensor_t *sensor) {
  /* Clear the sensor_t object */
  memset(sensor, 0, sizeof(sensor_t));

  /* Insert the sensor name in the fixed length char array */
  strncpy(sensor->name, "BMP183", sizeof(sensor->name) - 1);
  sensor->name[sizeof(sensor->name) - 1] = 0;
  sensor->version = 1;
  sensor->sensor_id = _sensorID;
  sensor->type = SENSOR_TYPE_PRESSURE;
  sensor->min_delay = 0;
  sensor->max_value = 1100.0F; // 300..1100 hPa
  sensor->min_value = 300.0F;
  sensor->resolution = 0.01F; // Datasheet states 0.01 hPa resolution
}

/*!
 *   @brief  Reads the sensor and returns the data as a sensors_event_t
 *   @param  event
 *           sensors_event_t event that you want to assign to
 *   @return true if successful
 */
bool Adafruit_BMP183_Unified::getEvent(sensors_event_t *event) {
  /* Clear the event */
  memset(event, 0, sizeof(sensors_event_t));

  event->version = sizeof(sensors_event_t);
  event->sensor_id = _sensorID;
  event->type = SENSOR_TYPE_PRESSURE;
  event->timestamp = 0;
  event->pressure = getPressure() / 100.0F;

  return true;
}