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/*
* Copyright (C) 2014 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup driver_lps331ap
* @{
*
* @file
* @brief Device driver implementation for the LPS331AP pressure sensor
*
* @note The current driver implementation is very basic and allows only for polling the
* devices temperature and pressure values. Threshold values and interrupts are not
* used.
*
* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
* @author Peter Kietzmann <peter.kietzmann@haw-hamburg.de>
*
* @}
*/
#include <stdint.h>
#include "periph/i2c.h"
#include "lps331ap.h"
#include "lps331ap-internal.h"
/**
* @brief default I2C bus speed for this sensor
*/
#define BUS_SPEED I2C_SPEED_FAST
/**
* @brief pressure divider for norming pressure output
*/
#define PRES_DIVIDER (4096U)
/**
* @brief temperature base value and divider for norming temperature output
*/
#define TEMP_BASE (42.5f)
#define TEMP_DIVIDER (480U)
int lps331ap_init(lps331ap_t *dev, i2c_t i2c, uint8_t address, lps331ap_rate_t rate)
{
uint8_t tmp;
/* save device specifics */
dev->i2c = i2c;
dev->address = address;
/* Acquire exclusive access to the bus. */
i2c_acquire(dev->i2c);
/* initialize underlying I2C bus */
if (i2c_init_master(dev->i2c, BUS_SPEED) < 0) {
/* Release the bus for other threads. */
i2c_release(dev->i2c);
return -1;
}
/* configure device, for simple operation only CTRL_REG1 needs to be touched */
tmp = LPS331AP_CTRL_REG1_DBDU | LPS331AP_CTRL_REG1_PD |
(rate << LPS331AP_CTRL_REG1_ODR_POS);
if (i2c_write_reg(dev->i2c, dev->address, LPS331AP_REG_CTRL_REG1, tmp) != 1) {
i2c_release(dev->i2c);
return -1;
}
i2c_release(dev->i2c);
return 0;
}
int lps331ap_read_temp(lps331ap_t *dev)
{
uint8_t tmp;
int16_t val = 0;
float res = TEMP_BASE; /* reference value -> see datasheet */
i2c_acquire(dev->i2c);
i2c_read_reg(dev->i2c, dev->address, LPS331AP_REG_TEMP_OUT_L, &tmp);
val |= tmp;
i2c_read_reg(dev->i2c, dev->address, LPS331AP_REG_TEMP_OUT_H, &tmp);
i2c_release(dev->i2c);
val |= (tmp << 8);
/* compute actual temperature value in °C */
res += ((float)val) / TEMP_DIVIDER;
/* return temperature in m°C */
return (int)(res * 1000);
}
int lps331ap_read_pres(lps331ap_t *dev)
{
uint8_t tmp;
int32_t val = 0;
float res;
i2c_acquire(dev->i2c);
i2c_read_reg(dev->i2c, dev->address, LPS331AP_REG_PRESS_OUT_XL, &tmp);
val |= tmp;
i2c_read_reg(dev->i2c, dev->address, LPS331AP_REG_PRESS_OUT_L, &tmp);
val |= (tmp << 8);
i2c_read_reg(dev->i2c, dev->address, LPS331AP_REG_PRESS_OUT_H, &tmp);
i2c_release(dev->i2c);
val |= (tmp << 16);
/* see if value is negative */
if (tmp & 0x80) {
val |= (0xff << 24);
}
/* compute actual pressure value in mbar */
res = ((float)val) / PRES_DIVIDER;
return (int)res;
}
int lps331ap_enable(lps331ap_t *dev)
{
uint8_t tmp;
int status;
i2c_acquire(dev->i2c);
if (i2c_read_reg(dev->i2c, dev->address, LPS331AP_REG_CTRL_REG1, &tmp) != 1) {
i2c_release(dev->i2c);
return -1;
}
tmp |= (LPS331AP_CTRL_REG1_PD);
status = i2c_write_reg(dev->i2c, dev->address, LPS331AP_REG_CTRL_REG1, tmp);
i2c_release(dev->i2c);
return status;
}
int lps331ap_disable(lps331ap_t *dev)
{
uint8_t tmp;
int status;
i2c_acquire(dev->i2c);
if (i2c_read_reg(dev->i2c, dev->address, LPS331AP_REG_CTRL_REG1, &tmp) != 1) {
i2c_release(dev->i2c);
return -1;
}
tmp &= ~(LPS331AP_CTRL_REG1_PD);
status = i2c_write_reg(dev->i2c, dev->address, LPS331AP_REG_CTRL_REG1, tmp);
i2c_release(dev->i2c);
return status;
}