BME280 sensor API
Introduction
This package contains the Bosch Sensortec's BME280 pressure sensor driver (sensor API)
The sensor driver package includes bme280.c, bme280.h and bme280_defs.h files.
Version
| File | Version | Date |
|---|---|---|
| bme280.c | 3.2.0 | 21 Mar 2017 |
| bme280.h | 3.2.0 | 21 Mar 2017 |
| bme280_defs.h | 3.2.0 | 21 Mar 2017 |
Integration details
- Integrate bme280.h, bme280_defs.h and bme280.c file in to the project.
- Include the bme280.h file in your code like below.
#include "bme280.h"
File information
- bme280_defs.h : This header file has the constants, macros and datatype declarations.
- bme280.h : This header file contains the declarations of the sensor driver APIs.
- bme280.c : This source file contains the definitions of the sensor driver APIs.
Supported sensor interfaces
- SPI 4-wire
- I2C
SPI 3-wire is currently not supported in the API.
Usage guide
Initializing the sensor
To initialize the sensor, user need to create a device structure. User can do this by creating an instance of the structure bme280_dev. After creating the device strcuture, user need to fill in the various parameters as shown below.
Example for SPI 4-Wire
struct bme280_dev dev;
int8_t rslt = BME280_OK;
/* Sensor_0 interface over SPI with native chip select line */
dev.id = 0;
dev.interface = BME280_SPI_INTF;
dev.read = user_spi_read;
dev.write = user_spi_write;
dev.delay_ms = user_delay_ms;
rslt = bme280_init(&dev);
Example for I2C
struct bme280_dev dev;
int8_t rslt = BME280_OK;
dev.id = BME280_I2C_ADDR_PRIM;
dev.interface = BME280_I2C_INTF;
dev.read = user_i2c_read;
dev.write = user_i2c_write;
dev.delay_ms = user_delay_ms;
rslt = bme280_init(&dev);
Regarding compensation functions for temperature,pressure and humidity we have two implementations.
- Double precision floating point version
- Integer version
By default, integer version is used in the API. If user needs double version, user has to enable FLOATING_POINT_REPRESENTATION macro in bme280_defs.h file.
In integer compensation functions, we also have below two implementations for pressure.
- For 32 bit machine.
- For 64 bit machine.
By default, 64 bit variant is used in the API. If user wants 32 bit variant, user can disable the macro MACHINE_64_BIT in bme280_defs.h file.
Get sensor data
Get sensor data in forced mode
int8_t get_sensor_data_forced_mode(struct bme280_dev *dev)
{
int8_t rslt;
uint8_t settings_sel;
struct bme280_data comp_data;
/* Continuously get the sensor data */
while (1) {
dev->settings.osr_h = BME280_OVERSAMPLING_4X;
dev->settings.osr_p = BME280_OVERSAMPLING_4X;
dev->settings.osr_t = BME280_OVERSAMPLING_4X;
settings_sel = BME280_OSR_PRESS_SEL|BME280_OSR_TEMP_SEL|BME280_OSR_HUM_SEL;
rslt = bme280_set_sensor_settings(settings_sel, dev);
rslt = bme280_set_sensor_mode(BME280_FORCED_MODE, dev);
/* Give some delay for the sensor to go into force mode */
dev->delay_ms(5);
rslt = bme280_get_sensor_data(BME280_PRESS | BME280_HUM | BME280_TEMP, &comp_data, dev);
print_sensor_data(&comp_data);
}
return rslt;
}
void print_sensor_data(struct bme280_data *comp_data)
{
#ifdef FLOATING_POINT_REPRESENTATION
printf("%0.2f\t\t%0.2f\t\t%0.2f\t\n",comp_data->temperature, comp_data->pressure, comp_data->humidity);
#else
printf("%ld\t\t%ld\t\t%ld\t\n",comp_data->temperature, comp_data->pressure, comp_data->humidity);
#endif
}
Get sensor data in normal mode
int8_t get_sensor_data_normal_mode(struct bme280_dev *dev)
{
int8_t rslt;
uint8_t settings_sel;
struct bme280_data comp_data;
dev->settings.osr_h = BME280_OVERSAMPLING_4X;
dev->settings.osr_p = BME280_OVERSAMPLING_4X;
dev->settings.osr_t = BME280_OVERSAMPLING_4X;
settings_sel = BME280_OSR_PRESS_SEL|BME280_OSR_TEMP_SEL|BME280_OSR_HUM_SEL;
rslt = bme280_set_sensor_settings(settings_sel, dev);
rslt = bme280_set_sensor_mode(BME280_NORMAL_MODE, dev);
/* Give some delay for the sensor to go into normal mode */
dev->delay_ms(5);
while (1) {
rslt = bme280_get_sensor_data(BME280_PRESS | BME280_HUM | BME280_TEMP, &comp_data, dev);
print_sensor_data(&comp_data);
}
return rslt;
}
void print_sensor_data(struct bme280_data *comp_data)
{
#ifdef FLOATING_POINT_REPRESENTATION
printf("%0.2f\t\t%0.2f\t\t%0.2f\t\n",comp_data->temperature, comp_data->pressure, comp_data->humidity);
#else
printf("%ld\t\t%ld\t\t%ld\t\n",comp_data->temperature, comp_data->pressure, comp_data->humidity);
#endif
}