esp-open-rtos/extras/bmp280

Driver for BMP280 absolute barometric pressure sensor

The driver works only with BMP280 sensor. For BMP080/BMP180 there's a separate driver. Even though BMP280 is a successor of BMP180 they are not compatible. They have different registers and different operation modes. BMP280 supports two ways of communication: spi and i2c. This driver provides only i2c communication. The driver is written for esp-open-rtos framework and requires i2c driver from it.

Features

• I2C communication.
• Forced mode (Similar to BMP180 operation).
• Normal mode. Continuous measurement.
• Soft reset.

Usage

Connect BMP280 module to you ESP8266 module and specify SCL and SDA pins:

const uint8_t scl_pin = 5;
const uint8_t sda_pin = 4;

Pull up SDO pin of BMP280 in order to have address 0x77. Or pull down SDO pin and change #define BMP280_ADDRESS 0x77 to #define BMP280_ADDRESS 0x76. Otherwise your sensor will not work. By default address 0x77 is used, so SDO pin should be high.

BMP280 supports two operation modes.

Forced mode

In forced mode, a single measurement is performed according to selected configuration. When the measurement is finished, the sensor returns to sleep mode and the measurement results can be read.

Normal mode

Normal mode continuously cycles between measurement period and standby period, whose time is defined by standby_time.

Example

Forced mode

const uint8_t scl_pin = 5;
const uint8_t sda_pin = 4;
bmp280_params_t  params;
float pressure, temperature;

bmp280_init_default_params(&params);
params.mode = BMP280_MODE_FORCED;
bmp280_init(&params, scl_pin, sda_pin);

while (1) {
    bmp280_force_measurement();
    while (bmp280_is_measuring()) {}; // wait for measurement to complete

    bmp280_read(&temperature, &pressure);
    printf("Pressure: %.2f Pa, Temperature: %.2f C\n", pressure, temperature);
    vTaskDelay(1000 / portTICK_RATE_MS);
}

Normal mode

bmp280_params_t  params;
float pressure, temperature;

bmp280_init_default_params(&params);
bmp280_init(&params, scl_pin, sda_pin);

while (1) {
    bmp280_read(&temperature, &pressure);
    printf("Pressure: %.2f Pa, Temperature: %.2f C\n", pressure, temperature);
    vTaskDelay(1000 / portTICK_RATE_MS);
}

License

The driver is released under MIT license.

Copyright (c) 2016 sheinz (https://github.com/sheinz)