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108 lines
3.0 KiB
108 lines
3.0 KiB
# Driver for BMP280 and BME280 absolute barometric pressure sensors
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The driver works only with BMP280 and BME280 sensors. For BMP080/BMP180 there's
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a separate driver. Even though BMP280 is a successor of BMP180 they are not
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compatible. They have different registers and different operation modes.
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BMP280 supports two ways of communication: spi and i2c. This driver provides
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only i2c communication.
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The driver is written for [esp-open-rtos](https://github.com/SuperHouse/esp-open-rtos)
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framework and requires [i2c driver](https://github.com/SuperHouse/esp-open-rtos/tree/master/extras/i2c)
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from it.
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## Features
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* I2C communication.
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* Forced mode (Similar to BMP180 operation).
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* Normal mode. Continuous measurement.
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* Soft reset.
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## Usage
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Connect BMP280 or BME280 module to you ESP8266 module and initialize the I2C SCL and SDA pins:
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```
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const uint8_t bus = 0;
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const uint8_t scl_pin = 0;
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const uint8_t sda_pin = 2;
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i2c_init(bus, scl_pin, sda_pin, I2C_FREQ_100K);
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```
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Pull up SDO pin of BMP280 in order to have address 0x77 `BMP280_I2C_ADDRESS_1`.
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Or pull down SDO pin for address 0x76 `BMP280_I2C_ADDRESS_0`. Otherwise your
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sensor will not work.
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The BMP280 or BME280 are auto-detected at initialization based on the chip ID
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and this ID is stored in the device descriptor.
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BMP280 supports two operation modes.
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### Forced mode
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In forced mode, a single measurement is performed according to selected
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configuration. When the measurement is finished, the sensor returns to
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sleep mode and the measurement results can be read.
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### Normal mode
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Normal mode continuously cycles between measurement period and standby period,
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whose time is defined by standby_time.
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## Example
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### Forced mode
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```
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bmp280_params_t params;
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float pressure, temperature, humidity;
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bmp280_init_default_params(¶ms);
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params.mode = BMP280_MODE_FORCED;
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bmp280_t bmp280_dev;
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bmp280_dev.i2c_addr = BMP280_I2C_ADDRESS_0;
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bmp280_init(&bmp280_dev, ¶ms);
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bool bme280p = bmp280_dev.id == BME280_CHIP_ID;
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while(1) {
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bmp280_force_measurement(&bmp280_dev));
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// wait for measurement to complete
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while (bmp280_is_measuring(&bmp280_dev)) {};
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bmp280_read_float(&bmp280_dev, &temperature, &pressure, &humidity);
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printf("Pressure: %.2f Pa, Temperature: %.2f C", pressure, temperature);
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if (bme280p)
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printf(", Humidity: %.2f\n", humidity);
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vTaskDelay(1000 / portTICK_PERIOD_MS);
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}
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```
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### Normal mode
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```
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bmp280_params_t params;
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float pressure, temperature, humidity;
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bmp280_init_default_params(¶ms);
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bmp280_t bmp280_dev;
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bmp280_dev.i2c_addr = BMP280_I2C_ADDRESS_0;
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bmp280_init(&bmp280_dev, ¶ms);
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bool bme280p = bmp280_dev.id == BME280_CHIP_ID;
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while(1) {
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bmp280_read_float(&bmp280_dev, &temperature, &pressure, &humidity);
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printf("Pressure: %.2f Pa, Temperature: %.2f C", pressure, temperature);
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if (bme280p)
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printf(", Humidity: %.2f\n", humidity);
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else
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printf("\n");
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vTaskDelay(1000 / portTICK_PERIOD_MS);
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}
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```
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## License
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The driver is released under MIT license.
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Copyright (c) 2016 sheinz (https://github.com/sheinz)
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