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224 lines
6.5 KiB
C
224 lines
6.5 KiB
C
/*
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* Copyright (C) 2016 Kees Bakker, SODAQ
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @defgroup drivers_bme280 BME280
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* @ingroup drivers_sensors
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* @brief Device driver interface for the BME280 sensor
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*
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* @{
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* @file
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* @brief Device driver interface for the BME280 sensor.
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*
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* @details There are three sensor values that can be read: temperature,
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* pressure and humidity. The BME280 device usually measures them
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* all at once. It is possible to skip measuring either of the
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* values by changing the oversampling settings. The driver is
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* written in such a way that a measurement is only started from
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* the function that reads the temperature. In other words, you
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* always have to call bme280_read_temperature, and then optionally
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* you can call the other two.
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*
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* @author Kees Bakker <kees@sodaq.com>
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*/
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#ifndef BME280_H
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#define BME280_H
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#include "saul.h"
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#include "periph/i2c.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Calibration struct for the BME280 sensor
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*
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* This must be read from the device at startup.
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*/
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typedef struct {
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uint16_t dig_T1; /**< T1 coefficient */
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int16_t dig_T2; /**< T2 coefficient */
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int16_t dig_T3; /**< T3 coefficient */
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uint16_t dig_P1; /**< P1 coefficient */
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int16_t dig_P2; /**< P2 coefficient */
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int16_t dig_P3; /**< P3 coefficient */
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int16_t dig_P4; /**< P4 coefficient */
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int16_t dig_P5; /**< P5 coefficient */
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int16_t dig_P6; /**< P6 coefficient */
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int16_t dig_P7; /**< P7 coefficient */
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int16_t dig_P8; /**< P8 coefficient */
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int16_t dig_P9; /**< P9 coefficient */
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uint8_t dig_H1; /**< H1 coefficient */
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int16_t dig_H2; /**< H2 coefficient */
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uint8_t dig_H3; /**< H3 coefficient */
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int16_t dig_H4; /**< H4 coefficient */
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int16_t dig_H5; /**< H5 coefficient */
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int8_t dig_H6; /**< H6 coefficient */
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} bme280_calibration_t;
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/**
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* @brief Values for t_sb field of the BME280 config register
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*/
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typedef enum {
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BME280_SB_0_5 = 0,
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BME280_SB_62_5 = 1,
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BME280_SB_125 = 2,
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BME280_SB_250 = 3,
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BME280_SB_500 = 4,
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BME280_SB_1000 = 5,
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BME280_SB_10 = 6,
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BME280_SB_20 = 7
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} bme280_t_sb_t;
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/**
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* @brief Values for filter field of the BME280 config register
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*/
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typedef enum {
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BME280_FILTER_OFF = 0,
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BME280_FILTER_2 = 1,
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BME280_FILTER_4 = 2,
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BME280_FILTER_8 = 3,
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BME280_FILTER_16 = 4,
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} bme280_filter_t;
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/**
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* @brief Values for mode field of the BME280 ctrl_meas register
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*/
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typedef enum {
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BME280_MODE_SLEEP = 0,
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BME280_MODE_FORCED = 1,
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BME280_MODE_FORCED2 = 2, /* Same as FORCED */
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BME280_MODE_NORMAL = 3
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} bme280_mode_t;
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/**
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* @brief Values for oversampling settings
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*
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* These values are used for:
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* - osrs_h field of the BME280 ctrl_hum register
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* - osrs_t field of the BME280 ctrl_meas register
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* - osrs_p field of the BME280 ctrl_meas register
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*/
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typedef enum {
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BME280_OSRS_SKIPPED = 0,
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BME280_OSRS_X1 = 1,
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BME280_OSRS_X2 = 2,
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BME280_OSRS_X4 = 3,
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BME280_OSRS_X8 = 4,
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BME280_OSRS_X16 = 5,
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} bme280_osrs_t;
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/**
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* @brief Parameters for the BME280 sensor
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*
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* These parameters are needed to configure the device at startup.
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*/
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typedef struct {
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/* I2C details */
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i2c_t i2c_dev; /**< I2C device which is used */
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uint8_t i2c_addr; /**< I2C address */
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/* Config Register */
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bme280_t_sb_t t_sb; /**< standby */
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bme280_filter_t filter; /**< filter coefficient */
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uint8_t spi3w_en; /**< Enables 3-wire SPI interface */
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/* ctrl_meas */
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bme280_mode_t run_mode; /**< ctrl_meas mode */
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bme280_osrs_t temp_oversample; /**< ctrl_meas osrs_t */
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bme280_osrs_t press_oversample; /**< ctrl_meas osrs_p */
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/* ctrl_hum */
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bme280_osrs_t humid_oversample; /**< ctrl_hum osrs_h */
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} bme280_params_t;
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/**
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* @brief Device descriptor for the BME280 sensor
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*/
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typedef struct {
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bme280_params_t params; /**< Device Parameters */
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bme280_calibration_t calibration; /**< Calibration Data */
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} bme280_t;
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/**
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* @brief Status and error return codes
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*/
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enum {
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BME280_OK = 0, /**< everything was fine */
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BME280_ERR_I2C = -1, /**< error initializing the I2C bus */
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BME280_ERR_NODEV = -2, /**< did not detect BME280 */
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BME280_ERR_NOCAL = -3, /**< could not read calibration data */
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};
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/**
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* @brief export SAUL endpoints
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* @{
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*/
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extern const saul_driver_t bme280_temperature_saul_driver;
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extern const saul_driver_t bme280_relative_humidity_saul_driver;
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extern const saul_driver_t bme280_pressure_saul_driver;
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/** @} */
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/**
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* @brief Initialize the given BME280 device
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*
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* @param[out] dev Initialized device descriptor of BME280 device
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* @param[in] params The parameters for the BME280 device (sampling rate, etc)
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*
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* @return BME280_OK on success
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* @return BME280_ERR_I2C
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* @return BME280_ERR_NODEV
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* @return BME280_ERR_NOCAL
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*/
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int bme280_init(bme280_t* dev, const bme280_params_t* params);
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/**
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* @brief Read temperature value from the given BME280 device, returned in centi °C
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*
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* @param[in] dev Device descriptor of BME280 device to read from
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*
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* @returns The temperature in centi Celsius. In case of an error
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* it returns INT16_MIN.
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*/
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int16_t bme280_read_temperature(bme280_t* dev);
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/**
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* @brief Read humidity value from the given BME280 device, returned in centi %RH
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*
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* @details This function should only be called after doing bme280_read_temperature
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* first.
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*
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* @param[in] dev Device descriptor of BME280 device to read from
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*
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* @returns Humidity in centi %RH (i.e. the percentage times 100)
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*/
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uint16_t bme280_read_humidity(bme280_t *dev);
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/**
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* @brief Read air pressure value from the given BME280 device, returned in PA
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*
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* @details This function should only be called after doing bme280_read_temperature
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* first.
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*
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* @param[in] dev Device descriptor of BME280 device to read from
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*
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* @returns The air pressure in Pa
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*/
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uint32_t bme280_read_pressure(bme280_t *dev);
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#ifdef __cplusplus
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}
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#endif
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#endif /* BME280_H */
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/** @} */
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