90 lines
2.4 KiB
Markdown
90 lines
2.4 KiB
Markdown
# Driver for BMP280 absolute barometric pressure sensor
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The driver works only with BMP280 sensor. For BMP080/BMP180 there's a separate
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driver. Even though BMP280 is a successor of BMP180 they are not compatible.
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They have different registers and different operation modes.
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BMP280 supports two ways of communication: spi and i2c.
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This driver provides 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 module to you ESP8266 module and specify SCL and SDA pins:
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```
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const uint8_t scl_pin = 5;
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const uint8_t sda_pin = 4;
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```
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Pull up SDO pin of BMP280 in order to have address 0x77.
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Or pull down SDO pin and change `#define BMP280_ADDRESS 0x77` to
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`#define BMP280_ADDRESS 0x76`. Otherwise your sensor will not work.
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By default address 0x77 is used, so SDO pin should be high.
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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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const uint8_t scl_pin = 5;
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const uint8_t sda_pin = 4;
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bmp280_params_t params;
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float pressure, temperature;
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bmp280_init_default_params(¶ms);
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params.mode = BMP280_MODE_FORCED;
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bmp280_init(¶ms, scl_pin, sda_pin);
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while (1) {
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bmp280_force_measurement();
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while (bmp280_is_measuring()) {}; // wait for measurement to complete
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bmp280_read(&temperature, &pressure);
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printf("Pressure: %.2f Pa, Temperature: %.2f C\n", pressure, temperature);
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vTaskDelay(1000 / portTICK_RATE_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;
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bmp280_init_default_params(¶ms);
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bmp280_init(¶ms, scl_pin, sda_pin);
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while (1) {
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bmp280_read(&temperature, &pressure);
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printf("Pressure: %.2f Pa, Temperature: %.2f C\n", pressure, temperature);
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vTaskDelay(1000 / portTICK_RATE_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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