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nuttx/drivers/sensors/bmp180.c

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/****************************************************************************
* drivers/sensors/bmp180.c
* Character driver for the Freescale BMP1801 Barometer Sensor
*
* Copyright (C) 2015 Gregory Nutt. All rights reserved.
* Copyright (C) 2015 Alan Carvalho de Assis
* Author: Alan Carvalho de Assis <acassis@gmail.com>
*
* 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 NuttX 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 COPYRIGHT HOLDERS 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
* COPYRIGHT OWNER 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdlib.h>
#include <fixedmath.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/fs/fs.h>
#include <nuttx/i2c.h>
#include <nuttx/sensors/bmp180.h>
#if defined(CONFIG_I2C) && defined(CONFIG_BMP180)
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define BMP180_ADDR 0x77
#define BMP180_FREQ 100000
#define DEVID 0x55
#define BMP180_AC1_MSB 0xaa
#define BMP180_AC1_LSB 0xab
#define BMP180_AC2_MSB 0xac
#define BMP180_AC2_LSB 0xad
#define BMP180_AC3_MSB 0xae
#define BMP180_AC3_LSB 0xaf
#define BMP180_AC4_MSB 0xb0
#define BMP180_AC4_LSB 0xb1
#define BMP180_AC5_MSB 0xb2
#define BMP180_AC5_LSB 0xb3
#define BMP180_AC6_MSB 0xb4
#define BMP180_AC6_LSB 0xb5
#define BMP180_B1_MSB 0xb6
#define BMP180_B1_LSB 0xb7
#define BMP180_B2_MSB 0xb8
#define BMP180_B2_LSB 0xb9
#define BMP180_MB_MSB 0xba
#define BMP180_MB_LSB 0xbb
#define BMP180_MC_MSB 0xbc
#define BMP180_MC_LSB 0xbd
#define BMP180_MD_MSB 0xbe
#define BMP180_MD_LSB 0xbf
#define BMP180_DEVID 0xd0
#define BMP180_SOFT_RESET 0xe0
#define BMP180_CTRL_MEAS 0xf4
#define BMP180_ADC_OUT_MSB 0xf6
#define BMP180_ADC_OUT_LSB 0xf7
#define BMP180_ADC_OUT_XLSB 0xf8
#define BMP180_READ_TEMP 0x2e
#define BMP180_READ_PRESS 0x34
#define BMP180_NOOVERSAMPLE 0x00
#define BMP180_OVERSAMPLE2X 0x70
#define BMP180_OVERSAMPLE4X 0xb0
#define BMP180_OVERSAMPLE8X 0xc0
/* Current Oversampling */
#define CURRENT_OSS (BMP180_OVERSAMPLE8X)
/****************************************************************************
* Private Type Definitions
****************************************************************************/
struct bmp180_dev_s
{
FAR struct i2c_dev_s *i2c; /* I2C interface */
uint8_t addr; /* BMP180 I2C address */
int freq; /* BMP180 Frequency <= 3.4MHz */
int16_t bmp180_cal_ac1; /* Calibration coefficients */
int16_t bmp180_cal_ac2;
int16_t bmp180_cal_ac3;
uint16_t bmp180_cal_ac4;
uint16_t bmp180_cal_ac5;
uint16_t bmp180_cal_ac6;
int16_t bmp180_cal_b1;
int16_t bmp180_cal_b2;
int16_t bmp180_cal_mb;
int16_t bmp180_cal_mc;
int16_t bmp180_cal_md;
int32_t bmp180_utemp; /* Uncompensated temperature read from BMP180 */
int32_t bmp180_upress; /* Uncompensated pressure read from BMP180 */
};
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static uint8_t bmp180_getreg8(FAR struct bmp180_dev_s *priv, uint8_t regaddr);
static uint16_t bmp180_getreg16(FAR struct bmp180_dev_s *priv, uint8_t regaddr);
static void bmp180_putreg8(FAR struct bmp180_dev_s *priv, uint8_t regaddr,
uint8_t regval);
static void bmp180_updatecaldata(FAR struct bmp180_dev_s *priv);
static void bmp180_read_press_temp(FAR struct bmp180_dev_s *priv);
static int bmp180_getpressure(FAR struct bmp180_dev_s *priv);
/* Character driver methods */
static int bmp180_open(FAR struct file *filep);
static int bmp180_close(FAR struct file *filep);
static ssize_t bmp180_read(FAR struct file *, FAR char *, size_t);
static ssize_t bmp180_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_bmp180fops =
{
bmp180_open, /* open */
bmp180_close, /* close */
bmp180_read, /* read */
bmp180_write, /* write */
0, /* seek */
0, /* ioctl */
#ifndef CONFIG_DISABLE_POLL
0, /* poll */
#endif
0 /* unlink */
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: bmp180_getreg8
*
* Description:
* Read from an 8-bit BMP180 register
*
****************************************************************************/
static uint8_t bmp180_getreg8(FAR struct bmp180_dev_s *priv, uint8_t regaddr)
{
int ret;
uint8_t regval = 0;
/* Restart the register */
ret = I2C_WRITE(priv->i2c, &regaddr, 1);
if (ret < 0)
{
sndbg("I2C_WRITE failed: %d\n", ret);
return ret;
}
/* Restart the register */
ret = I2C_READ(priv->i2c, &regval, 1);
if (ret < 0)
{
sndbg("I2C_READ failed: %d\n", ret);
return ret;
}
return regval;
}
/****************************************************************************
* Name: bmp180_getreg16
*
* Description:
* Read two 8-bit from a BMP180 register
*
****************************************************************************/
static uint16_t bmp180_getreg16(FAR struct bmp180_dev_s *priv, uint8_t regaddr)
{
int ret;
uint16_t msb, lsb;
uint16_t regval = 0;
/* Register to read */
ret = I2C_WRITE(priv->i2c, &regaddr, 1);
if (ret < 0)
{
sndbg("I2C_WRITE failed: %d\n", ret);
return ret;
}
/* Read register */
ret = I2C_READ(priv->i2c, (uint8_t *)&regval, 2);
if (ret < 0)
{
sndbg("I2C_READ failed: %d\n", ret);
return ret;
}
/* MSB and LSB are inverted */
msb = (regval & 0xFF);
lsb = (regval & 0xFF00) >> 8;
regval = (msb << 8) | lsb;
return regval;
}
/****************************************************************************
* Name: bmp180_putreg8
*
* Description:
* Write to an 8-bit BMP180 register
*
****************************************************************************/
static void bmp180_putreg8(FAR struct bmp180_dev_s *priv, uint8_t regaddr,
uint8_t regval)
{
int ret;
uint8_t data[2];
data[0] = regaddr;
data[1] = regval;
/* Restart the register */
ret = I2C_WRITE(priv->i2c, (uint8_t *) &data, 2);
if (ret < 0)
{
sndbg("I2C_WRITE failed: %d\n", ret);
return;
}
return;
}
/****************************************************************************
* Name: bmp180_checkid
*
* Description:
* Read and verify the BMP180 chip ID
*
****************************************************************************/
static int bmp180_checkid(FAR struct bmp180_dev_s *priv)
{
uint8_t devid = 0;
/* Read device ID */
devid = bmp180_getreg8(priv, BMP180_DEVID);
snvdbg("devid: 0x%02x\n", devid);
if (devid != (uint16_t) DEVID)
{
/* ID is not Correct */
sndbg("Wrong Device ID!\n");
return -ENODEV;
}
return OK;
}
/****************************************************************************
* Name: bmp180_updatecaldata
*
* Description:
* Update Calibration Coefficient Data
*
****************************************************************************/
static void bmp180_updatecaldata(FAR struct bmp180_dev_s *priv)
{
/* AC1 */
priv->bmp180_cal_ac1 = (int16_t) bmp180_getreg16(priv, BMP180_AC1_MSB);
/* AC2 */
priv->bmp180_cal_ac2 = (int16_t) bmp180_getreg16(priv, BMP180_AC2_MSB);
/* AC3 */
priv->bmp180_cal_ac3 = (int16_t) bmp180_getreg16(priv, BMP180_AC3_MSB);
/* AC4 */
priv->bmp180_cal_ac4 = bmp180_getreg16(priv, BMP180_AC4_MSB);
/* AC5 */
priv->bmp180_cal_ac5 = bmp180_getreg16(priv, BMP180_AC5_MSB);
/* AC6 */
priv->bmp180_cal_ac6 = bmp180_getreg16(priv, BMP180_AC6_MSB);
/* B1 */
priv->bmp180_cal_b1 = (int16_t) bmp180_getreg16(priv, BMP180_B1_MSB);
/* B2 */
priv->bmp180_cal_b2 = (int16_t) bmp180_getreg16(priv, BMP180_B2_MSB);
/* MB */
priv->bmp180_cal_mb = (int16_t) bmp180_getreg16(priv, BMP180_MB_MSB);
/* MC */
priv->bmp180_cal_mc = (int16_t) bmp180_getreg16(priv, BMP180_MC_MSB);
/* MD */
priv->bmp180_cal_md = (int16_t) bmp180_getreg16(priv, BMP180_MD_MSB);
}
/****************************************************************************
* Name: bmp180_read_press_temp
*
* Description:
* Read raw pressure and temperature from BMP180 and store it in the
* bmp180_dev_s structure.
*
****************************************************************************/
static void bmp180_read_press_temp(FAR struct bmp180_dev_s *priv)
{
uint8_t oss = CURRENT_OSS;
/* Issue a read temperature command */
bmp180_putreg8(priv, BMP180_CTRL_MEAS, BMP180_READ_TEMP);
/* Wait 5ms */
usleep(5000);
/* Read temperature */
priv->bmp180_utemp = bmp180_getreg16(priv, BMP180_ADC_OUT_MSB);
/* Issue a read pressure command */
bmp180_putreg8(priv, BMP180_CTRL_MEAS, (BMP180_READ_PRESS | oss));
/* Delay 25.5ms (to OverSampling 8X) */
usleep(25500);
/* Read pressure */
priv->bmp180_upress = bmp180_getreg16(priv, BMP180_ADC_OUT_MSB) << 8;
priv->bmp180_upress |= bmp180_getreg8(priv, BMP180_ADC_OUT_XLSB);
priv->bmp180_upress = priv->bmp180_upress >> (8 - (oss >> 6));
snvdbg("Uncompensated temperature = %d\n", priv->bmp180_utemp);
snvdbg("Uncompensated pressure = %d\n", priv->bmp180_upress);
}
/****************************************************************************
* Name: bmp180_getpressure
*
* Description:
* Calculate the Barometric Pressure using the temperature compensated
* See Freescale AN3785 and BMP1801 data sheet for details
*
****************************************************************************/
static int bmp180_getpressure(FAR struct bmp180_dev_s *priv)
{
int32_t x1;
int32_t x2;
int32_t x3;
int32_t b3;
int32_t b5;
int32_t b6;
int32_t press;
int32_t temp;
uint32_t b4;
uint32_t b7;
uint8_t oss = (CURRENT_OSS >> 6);
/* Check if coefficient data were read correctly */
if ((priv->bmp180_cal_ac1 == 0) || (priv->bmp180_cal_ac2 == 0) ||
(priv->bmp180_cal_ac3 == 0) || (priv->bmp180_cal_ac4 == 0) ||
(priv->bmp180_cal_ac5 == 0) || (priv->bmp180_cal_ac6 == 0) ||
(priv->bmp180_cal_b1 == 0) || (priv->bmp180_cal_b2 == 0) ||
(priv->bmp180_cal_mb == 0) || (priv->bmp180_cal_mc == 0) ||
(priv->bmp180_cal_md == 0))
{
bmp180_updatecaldata(priv);
}
/* Read temperature and pressure */
bmp180_read_press_temp(priv);
/* Calculate true temperature */
x1 = ((priv->bmp180_utemp - priv->bmp180_cal_ac6) * priv->bmp180_cal_ac5) >> 15;
x2 = (priv->bmp180_cal_mc << 11) / (x1 + priv->bmp180_cal_md);
b5 = x1 + x2;
temp = (b5 + 8) >> 4;
snvdbg("Compensated temperature = %d\n", temp);
/* Calculate true pressure */
b6 = b5 - 4000;
x1 = (priv->bmp180_cal_b2 * ((b6 * b6) >> 12)) >> 11;
x2 = (priv->bmp180_cal_ac2 * b6) >> 11;
x3 = x1 + x2;
b3 = (((((int32_t) priv->bmp180_cal_ac1) * 4 + x3) << oss) + 2) >> 2;
x1 = (priv->bmp180_cal_ac3 * b6) >> 13;
x2 = (priv->bmp180_cal_b1 * ((b6 * b6) >> 12)) >> 16;
x3 = ((x1 + x2) + 2) >> 2;
b4 = (priv->bmp180_cal_ac4 * (uint32_t) (x3 + 32768)) >> 15;
b7 = ((uint32_t) (priv->bmp180_upress - b3) * (50000 >> oss));
if (b7 < 0x80000000)
{
press = (b7 << 1) / b4;
}
else
{
press = (b7 / b4) << 1;
}
x1 = (press >> 8) * (press >> 8);
x1 = (x1 * 3038) >> 16;
x2 = (-7357 * press) >> 16;
press = press + ((x1 + x2 + 3791) >> 4);
snvdbg("Compressed pressure = %d\n", press);
return press;
}
/****************************************************************************
* Name: bmp180_open
*
* Description:
* This function is called whenever the BMP1801 device is opened.
*
****************************************************************************/
static int bmp180_open(FAR struct file *filep)
{
return OK;
}
/****************************************************************************
* Name: bmp180_close
*
* Description:
* This routine is called when the BMP180 device is closed.
*
****************************************************************************/
static int bmp180_close(FAR struct file *filep)
{
return OK;
}
/****************************************************************************
* Name: bmp180_read
****************************************************************************/
static ssize_t bmp180_read(FAR struct file *filep, FAR char *buffer,
size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR struct bmp180_dev_s *priv = inode->i_private;
FAR uint32_t *press = (FAR uint32_t *) buffer;
if (!buffer)
{
sndbg("Buffer is null\n");
return -1;
}
if ( buflen != 4)
{
sndbg("You can't read something other than 32 bits (4 bytes)\n");
return -1;
}
/* Get the pressure compensated */
*press = (int32_t) bmp180_getpressure(priv);
/* Return size of uint32_t (4 bytes) */
return 4;
}
/****************************************************************************
* Name: bmp180_write
****************************************************************************/
static ssize_t bmp180_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
return -ENOSYS;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: bmp180_register
*
* Description:
* Register the BMP180 character device as 'devpath'
*
* Input Parameters:
* devpath - The full path to the driver to register. E.g., "/dev/press0"
* i2c - An instance of the I2C interface to use to communicate with
* BMP180
*
* Returned Value:
* Zero (OK) on success; a negated errno value on failure.
*
****************************************************************************/
int bmp180_register(FAR const char *devpath, FAR struct i2c_dev_s *i2c)
{
FAR struct bmp180_dev_s *priv;
int ret;
/* Initialize the BMP180 device structure */
priv = (FAR struct bmp180_dev_s *)kmm_malloc(sizeof(struct bmp180_dev_s));
if (!priv)
{
sndbg("Failed to allocate instance\n");
return -ENOMEM;
}
priv->i2c = i2c;
priv->addr = BMP180_ADDR;
priv->freq = BMP180_FREQ;
/* Configure I2C before using it */
I2C_SETADDRESS(priv->i2c, priv->addr, 7);
I2C_SETFREQUENCY(priv->i2c, priv->freq);
/* Check Device ID */
ret = bmp180_checkid(priv);
if (ret < 0)
{
sndbg("Failed to register driver: %d\n", ret);
kmm_free(priv);
return ret;
}
/* Read the coefficient value */
bmp180_updatecaldata(priv);
/* Register the character driver */
ret = register_driver(devpath, &g_bmp180fops, 0666, priv);
if (ret < 0)
{
sndbg("Failed to register driver: %d\n", ret);
kmm_free(priv);
}
snvdbg("BMP180 driver loaded successfully!\n");
return ret;
}
#endif /* CONFIG_I2C && CONFIG_BMP180 */
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