esp8266-meteo/components/bmp280/README.md

Driver for BMP280 and BME280 absolute barometric pressure sensors

The driver works only with BMP280 and BME280 sensors. 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 or BME280 module to you ESP8266 module and initialize the I2C SCL and SDA pins:

const uint8_t bus = 0;
const uint8_t scl_pin = 0;
const uint8_t sda_pin = 2;
i2c_init(bus, scl_pin, sda_pin, I2C_FREQ_100K);

Pull up SDO pin of BMP280 in order to have address 0x77 BMP280_I2C_ADDRESS_1. Or pull down SDO pin for address 0x76 BMP280_I2C_ADDRESS_0. Otherwise your sensor will not work.

The BMP280 or BME280 are auto-detected at initialization based on the chip ID and this ID is stored in the device descriptor.

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

bmp280_params_t  params;
float pressure, temperature, humidity;

bmp280_init_default_params(&params);
params.mode = BMP280_MODE_FORCED;

bmp280_t bmp280_dev;
bmp280_dev.i2c_addr = BMP280_I2C_ADDRESS_0;
bmp280_init(&bmp280_dev, &params);
bool bme280p = bmp280_dev.id == BME280_CHIP_ID;

while(1) {
  bmp280_force_measurement(&bmp280_dev));
  // wait for measurement to complete
  while (bmp280_is_measuring(&bmp280_dev)) {};

  bmp280_read_float(&bmp280_dev, &temperature, &pressure, &humidity);
  printf("Pressure: %.2f Pa, Temperature: %.2f C", pressure, temperature);
  if (bme280p)
    printf(", Humidity: %.2f\n", humidity);
  vTaskDelay(1000 / portTICK_PERIOD_MS);
}

Normal mode

bmp280_params_t  params;
float pressure, temperature, humidity;

bmp280_init_default_params(&params);

bmp280_t bmp280_dev;
bmp280_dev.i2c_addr = BMP280_I2C_ADDRESS_0;
bmp280_init(&bmp280_dev, &params);
bool bme280p = bmp280_dev.id == BME280_CHIP_ID;

while(1) {
  bmp280_read_float(&bmp280_dev, &temperature, &pressure, &humidity);
  printf("Pressure: %.2f Pa, Temperature: %.2f C", pressure, temperature);
  if (bme280p)
    printf(", Humidity: %.2f\n", humidity);
  else
    printf("\n");
  vTaskDelay(1000 / portTICK_PERIOD_MS);
}

License

The driver is released under MIT license.

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