bme280.h File Reference

#include <stdint.h>

Go to the source code of this file.

Functions
void	init_bme280 (void)
	Initialise the device ready for measurements to be taken. More...
int16_t	bme280_get_temperature (void)
	Fetches the latest temperature data from the sensor, compensates and formats the data in degrees Celcius * 100. More...
uint16_t	bme280_get_humidity (void)
	Fetches the latest humidity data from the sensor, compensates and formats the data as RH * 100. More...
uint16_t	bme280_get_pressure (void)
	Fetches the latest pressure data from the sensor, compensates and formats the data as Pa * 100. More...

Detailed Description

Copyright

Copyright © 2022 by Jason Duffy.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Author

Jason Duffy

Date

22nd June 2022

See also

Definition in file bme280.h.

Function Documentation

init_bme280()

void init_bme280

(

void

)

Initialise the device ready for measurements to be taken.

Definition at line 125 of file bme280.c.

{   
    // Setup I2C hardware fpr use.
    init_i2c(BUS_SPEED_100KHZ);
 
    // Perform ID check. 
    uint8_t id = bme280_read_byte(CHIP_ID_REG);
    if (id == 0x60)
    {
        log_message(&bme280_log,
                    DEBUG,
                    "In init_bme280(), Chip ID check passed.");
    }
    else
    {
        log_message(&bme280_log,
                    ERROR,
                    "In init_bme280(), Chip ID check failed.");
    }
 
    // Read compensation data from sensor and save it.
    bme280_read_comp_data();
 
    // 
    bme280_write_byte(CTRL_HUM_REG, OVERSAMPLE_x1);
 
    //
    bme280_write_byte(CONFIG_REG, 0b10100000);
 
    // oversample x1 temp, pressure off, forced mode
    bme280_write_byte(CTRL_MEAS_REG, 0b00100001);
}

bme280_get_temperature()

int16_t bme280_get_temperature

(

void

)

Fetches the latest temperature data from the sensor, compensates and formats the data in degrees Celcius * 100.

Returns

eg. A return value of 5123 = 51.23˚C (Degrees Celcius).

Definition at line 164 of file bme280.c.

{
    int32_t retval;
    uint32_t raw_temp_adc_val;
 
    // oversample x1 temp, pressure off, forced mode.
    bme280_write_byte(CTRL_MEAS_REG, 0b00100001);
    raw_temp_adc_val = bme280_get_raw_temp_val();
    retval = bme280_compensate_temp(raw_temp_adc_val);
 
    return retval;
}

bme280_get_humidity()

uint16_t bme280_get_humidity

(

void

)

Fetches the latest humidity data from the sensor, compensates and formats the data as RH * 100.

Returns

eg. A return value of 2852 = 28.50 RH (Relative Humidity).

Definition at line 207 of file bme280.c.

{
    uint32_t retval;
    uint16_t raw_hum_adc_val;
 
    // oversample x1 temp, pressure off, forced mode
    bme280_write_byte(CTRL_MEAS_REG, 0b00100001);
    raw_hum_adc_val = bme280_get_raw_hum_val();
    retval = bme280_compensate_humidity(raw_hum_adc_val);
    retval *= 100;
    retval = (retval >> 10);
 
    return retval;
}

bme280_get_pressure()

uint16_t bme280_get_pressure

(

void

)

Fetches the latest pressure data from the sensor, compensates and formats the data as Pa * 100.

Returns

eg. A return value of 96386 = 963.86 Pa (Pascals).

Definition at line 228 of file bme280.c.

{
    // Some pressure-getting code goes here.
    return 0; 
}