mpl115a.c

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/*
 * Copyright (c) 2012, TU Braunschweig.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/**
 * \file
 *              MPL115A Pressure Sensor (Barometer) interface implementation
 * \author
 *      Ulf Kulau <kulau@ibr.cs.tu-bs.de>
 */

/**
 *
 * \addtogroup mpl115a_interface Pressure Sensor (Barometer) MPL115A
 * @{
 */

#include "mpl115a.h"
void
mpl115a_init(void) {
  mspi_chip_release(MPL115A_CS);
  /*init mspi in mode0, at chip select pin 4 and max baud rate*/
  mspi_init(MPL115A_CS, MSPI_MODE_0, MSPI_BAUD_MAX);
}
/*---------------------------------------------------------------------------*/
uint16_t
mpl115a_get_pressure(void) {
  uint8_t press_msb;
  uint8_t press_lsb;
  uint16_t pressure = 0x0000;
  /*start pressure measurement*/
  mpl115a_cmd(MPL115A_START_P_CONV);
  _delay_ms(6);
  press_msb = mpl115a_cmd(MPL115A_PRESSURE_OUT_MSB);
  press_lsb = mpl115a_cmd(MPL115A_PRESSURE_OUT_LSB);
  pressure = (uint16_t) (press_msb << 8);
  pressure &= (0xFF00 | ((uint16_t) (press_lsb)));
  pressure = 0x03FF & (pressure >> 6);
  return pressure;
}
/*---------------------------------------------------------------------------*/
uint16_t
mpl115a_get_temp(void) {
  uint8_t temp_msb;
  uint8_t temp_lsb;
  uint16_t temperature = 0x0000;
  /*start temperature measurement*/
  mpl115a_cmd(MPL115A_START_T_CONV);
  _delay_ms(6);
  temp_msb = mpl115a_cmd(MPL115A_TEMP_OUT_MSB);
  temp_lsb = mpl115a_cmd(MPL115A_TEMP_OUT_LSB);

  temperature = (uint16_t) (temp_msb << 8);
  temperature &= (0xFF00 | ((uint16_t) (temp_lsb)));
  temperature = 0x03FF & (temperature >> 6);
  return temperature;
}
/*---------------------------------------------------------------------------*/
void
mpl115a_read_coefficients(void) {
  uint8_t i;
  int8_t coeff_tmp_msb;
  int8_t coeff_tmp_lsb;

  for (i = 0; i < 6; i++) {
    coeff_tmp_msb = mpl115a_cmd(coefficients[i].addr[0]);
    coeff_tmp_lsb = mpl115a_cmd(coefficients[i].addr[1]);
    uart_TXchar(coeff_tmp_msb);
    uart_TXchar(coeff_tmp_lsb);


    coefficients[i].value = (int16_t) (coeff_tmp_msb << 8);
    coefficients[i].value &= (0xFF00 | ((int16_t) (coeff_tmp_lsb)));
  }
  uart_TXchar('\n');
}
/*---------------------------------------------------------------------------*/
int16_t
mpl115a_get_Pcomp(void) {
  int32_t tmp1_val, tmp2_val, tmp3_val;
  int32_t tmp_help;
  uint8_t msb, lsb;
  uint16_t temperature = 0x0000;
  uint16_t pressure = 0x0000;

  /*start both, temperature and pressure measurement*/
  mpl115a_cmd(MPL115A_START_B_CONV);
  /*wait 3 ms*/
  _delay_ms(6);
  /*get temperature value*/
  msb = mpl115a_cmd(MPL115A_TEMP_OUT_MSB);
  lsb = mpl115a_cmd(MPL115A_TEMP_OUT_LSB);
  temperature = (uint16_t) (msb << 8);
  temperature &= (0xFF00 | ((uint16_t) (lsb)));
  temperature = 0x03FF & (temperature >> 6);
  /*get pressure value*/
  msb = mpl115a_cmd(MPL115A_PRESSURE_OUT_MSB);
  lsb = mpl115a_cmd(MPL115A_PRESSURE_OUT_LSB);
  pressure = (uint16_t) (msb << 8);
  pressure &= (0xFF00 | ((uint16_t) (lsb)));
  pressure = 0x03FF & (pressure >> 6);

  /* calculate the compensated pressure value with the coefficients
   * and temperature value*/
  tmp1_val = (int32_t) coefficients[MPL115A_C11].value;
  tmp2_val = (int32_t) pressure;
  /*c11x1 = tmp3_val = c11 * pressure*/
  tmp3_val = tmp1_val * tmp2_val;

  tmp1_val = (int32_t) (coefficients[MPL115A_B1].value << 14);
  tmp2_val = (int32_t) tmp3_val;
  tmp3_val = tmp1_val + tmp2_val;
  /*a11 = tmp_help = b1 + c11x1*/
  tmp_help = (int32_t) (tmp3_val >> 14);

  tmp1_val = (int32_t) coefficients[MPL115A_C12].value;
  tmp2_val = (int32_t) temperature;
  /*c12x2 = tmp3_val = c12 * temperature*/
  tmp3_val = tmp1_val * tmp2_val;

  tmp1_val = (int32_t) (tmp_help << 11);
  tmp2_val = (int32_t) tmp3_val;
  tmp3_val = tmp1_val + tmp2_val;
  /*tmp_help = a1 = a11 + c12x2*/
  tmp_help = (int32_t) (tmp3_val >> 11);

  tmp1_val = (int32_t) coefficients[MPL115A_C22].value;
  tmp2_val = (int32_t) temperature;
  /*c22x2 = tmp3_val = c22 * temperature*/
  tmp3_val = tmp1_val * tmp2_val;

  tmp1_val = (int32_t) (coefficients[MPL115A_B2].value << 15);
  tmp2_val = (int32_t) (tmp3_val >> 1);
  tmp3_val = tmp1_val + tmp2_val;

  tmp1_val = (int32_t) tmp_help;
  /*a2 = b2 + c22x2*/
  tmp_help = (int32_t) (tmp3_val >> 16);
  tmp2_val = (int32_t) pressure;
  /*a1x1 = tmp3_val = a1 * pressure*/
  tmp3_val = tmp1_val * tmp2_val;

  tmp1_val = (int32_t) (coefficients[MPL115A_A0].value << 10);
  tmp2_val = (int32_t) tmp3_val;
  tmp3_val = tmp1_val + tmp2_val;

  tmp1_val = (int32_t) tmp_help;
  /*y1 = tmp_help = a0 + a1x1*/
  tmp_help = (int32_t) (tmp3_val >> 10);
  tmp2_val = (int32_t) temperature;
  /*a2x2 = tmp3_val = a2 * temperature*/
  tmp3_val = tmp1_val * tmp2_val;

  tmp1_val = (int32_t) (tmp_help << 10);
  tmp2_val = (int32_t) tmp3_val;
  tmp3_val = tmp1_val + tmp2_val;

  return (int16_t) (tmp3_val >> 13);
}
/*---------------------------------------------------------------------------*/
uint8_t
mpl115a_cmd(uint8_t reg) {
  uint8_t data;
  mspi_chip_select(MPL115A_CS);
  mspi_transceive(reg);
  data = mspi_transceive(0x00);
  mspi_chip_release(MPL115A_CS);
  return data;
}