BMP280 sensor API

Introduction
Version and date
Driver files information
Sensor interfaces
Integration Examples

Introduction

This package contains the Bosch Sensortec's BMP280 sensor driver (sensor API)

The sensor driver package includes bmp280.h, bmp280.c and bmp280_defs.h files

Version and date

Driver files	Version	Date
bmp280.c	3.0.0	3 Apr 2018
bmp280.h	3.0.0	3 Apr 2018
bmp280_defs.h	3.0.0	3 Apr 2018

Driver files information

bmp280.c : This source file contains the function definitions of the sensor API interfaces.
bmp280.h : This header file contains the function declarations of the sensor API interfaces.
bmp280_defs.h : This header file has the constants, macros and data type declarations.

Sensor interfaces

SPI 4-wire, SPI 3-wire interface
I2C interface

Integration Examples

Initializing the sensor

To initialize the sensor, you will first need to create a device structure. You can do this by creating an instance of the structure bmp280_dev. Then update the various parameters in structure as shown below.

Initialization for SPI 4-Wire interface

int8_t rslt;
struct bmp280_dev bmp;

/* Sensor interface over SPI with native chip select line */
bmp.dev_id  =  0;
bmp.intf = BMP280_SPI_INTF;
bmp.read = user_spi_read;
bmp.write = user_spi_write;
bmp.delay_ms = user_delay_ms;

rslt = bmp280_init(&bmp);

if (rslt == BMP280_OK) {
  /* Sensor chip ID will be printed if initialization was successful */
  printf("\n Device found with chip id 0x%x", bmp.chip_id);
}

Initialization for I2C interface

int8_t rslt;
struct bmp280_dev bmp;
/* Sensor interface over I2C with primary slave address  */
bmp.dev_id = BMP280_I2C_ADDR_PRIM;
bmp.intf = BMP280_I2C_INTF;
bmp.read = user_i2c_read;
bmp.write = user_i2c_write;
bmp.delay_ms = user_delay_ms;

rslt = bmp280_init(&bmp);

if (rslt == BMP280_OK) {
  /* Sensor chip ID will be printed if initialization was successful */
  printf("\n Device found with chip id 0x%x", bmp.chip_id);
}

Sensor Configuration settings

Pre-requisite : Initialize the sensor in SPI or I2C

struct bmp280_config bmp;

/* Always read the current settings before writing, especially when
 * all the configuration is not modified 
 */
rslt = bmp280_get_config(&conf, &bmp);
/* Check if rslt == BMP280_OK, if not, then handle accordingly */

/* Overwrite the desired settings */
conf.filter = BMP280_FILTER_COEFF_2;
conf.os_pres = BMP280_OS_16X;
conf.os_temp = BMP280_OS_4X;
conf.odr = BMP280_ODR_1000_MS;

rslt = bmp280_set_config(&conf, &bmp);
/* Check if rslt == BMP280_OK, if not, then handle accordingly */

/* Always set the power mode after setting the configuration */
rslt = bmp280_set_power_mode(BMP280_NORMAL_MODE, &bmp);
/* Check if rslt == BMP280_OK, if not, then handle accordingly */

Example for data read out

Pre-requisite : Initialize the sensor in SPI or I2C and set sensor mode and sensor settings

struct bmp280_uncomp_data ucomp_data;
uint8_t meas_dur = bmp280_compute_meas_time(&bmp);

printf("Measurement duration: %dms\r\n", meas_dur);

/* Loop to read out 10 samples of data */ 
for (uint8_t i = 0; (i < 10) && (rslt == BMP280_OK); i++) {
    bmp.delay_ms(meas_dur); /* Measurement time */

    rslt = bmp280_get_uncomp_data(&ucomp_data, &bmp);
    /* Check if rslt == BMP280_OK, if not, then handle accordingly */

    int32_t temp32 = bmp280_comp_temp_32bit(ucomp_data.uncomp_temp, &bmp);
    uint32_t pres32 = bmp280_comp_pres_32bit(ucomp_data.uncomp_press, &bmp);
    uint32_t pres64 = bmp280_comp_pres_64bit(ucomp_data.uncomp_press, &bmp);
    double temp = bmp280_comp_temp_double(ucomp_data.uncomp_temp, &bmp);
    double pres = bmp280_comp_pres_double(ucomp_data.uncomp_press, &bmp);

    printf("UT: %d, UP: %d, T32: %d, P32: %d, P64: %d, P64N: %d, T: %f, P: %f\r\n", \
      ucomp_data.uncomp_temp, ucomp_data.uncomp_press, temp32, \
      pres32, pres64, pres64 / 256, temp, pres);

    bmp.delay_ms(1000); /* Sleep time between measurements = BMP280_ODR_1000_MS */
}

ydogg/BMP280_driver