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207 lines
6.4 KiB
207 lines
6.4 KiB
// -----------------------------------------------------------------------------
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// BME280/BMP280 Sensor over I2C
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// Uses SparkFun BME280 library
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// Copyright (C) 2017 by Xose Pérez <xose dot perez at gmail dot com>
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// -----------------------------------------------------------------------------
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#pragma once
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#include "Arduino.h"
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#include "BaseSensor.h"
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#include <SparkFunBME280.h>
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#define BMX280_CHIP_BMP280 0x58
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#define BMX280_CHIP_BME280 0x60
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class BMX280Sensor : public BaseSensor {
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public:
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// ---------------------------------------------------------------------
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// Public
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// ---------------------------------------------------------------------
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void setAddress(unsigned char address) {
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if (_address != address) _dirty = true;
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_address = address;
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}
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// ---------------------------------------------------------------------
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// Sensor API
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// ---------------------------------------------------------------------
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// Initialization method, must be idempotent
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void begin() {
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if (!_dirty) return;
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_dirty = false;
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_chip = 0;
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// I2C auto-discover
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unsigned char addresses[] = {0x76, 0x77};
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_address = lock_i2c(_address, sizeof(addresses), addresses);
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if (_address == 0) return;
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// Init
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init();
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}
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// Descriptive name of the sensor
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String name() {
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char buffer[20];
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snprintf(buffer, sizeof(buffer), "%s @ I2C (0x%02X)", _chip == BMX280_CHIP_BME280 ? "BME280" : "BMP280", _address);
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return String(buffer);
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}
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// Descriptive name of the slot # index
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String slot(unsigned char index) {
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return name();
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}
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// Type for slot # index
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magnitude_t type(unsigned char index) {
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if (index < _count) {
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_error = SENSOR_ERROR_OK;
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unsigned char i = 0;
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#if BMX280_TEMPERATURE > 0
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if (index == i++) return MAGNITUDE_TEMPERATURE;
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#endif
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#if BMX280_PRESSURE > 0
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if (index == i++) return MAGNITUDE_PRESSURE;
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#endif
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#if BMX280_HUMIDITY > 0
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if (_chip == BMX280_CHIP_BME280) {
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if (index == i) return MAGNITUDE_HUMIDITY;
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}
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#endif
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}
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_error = SENSOR_ERROR_OUT_OF_RANGE;
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return MAGNITUDE_NONE;
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}
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// Pre-read hook (usually to populate registers with up-to-date data)
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virtual void pre() {
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if (_chip == 0) {
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_error = SENSOR_ERROR_UNKNOWN_ID;
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return;
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}
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#if BMX280_MODE == 1
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forceRead();
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#endif
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}
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// Current value for slot # index
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double value(unsigned char index) {
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if (index < _count) {
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_error = SENSOR_ERROR_OK;
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unsigned char i = 0;
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#if BMX280_TEMPERATURE > 0
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if (index == i++) return bme->readTempC();
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#endif
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#if BMX280_PRESSURE > 0
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if (index == i++) return bme->readFloatPressure() / 100;
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#endif
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#if BMX280_HUMIDITY > 0
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if (_chip == BMX280_CHIP_BME280) {
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if (index == i) return bme->readFloatHumidity();
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}
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#endif
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}
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_error = SENSOR_ERROR_OUT_OF_RANGE;
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return 0;
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}
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protected:
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void init() {
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// Destroy previous instance if any
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if (bme) delete bme;
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bme = new BME280();
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bme->settings.commInterface = I2C_MODE;
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bme->settings.I2CAddress = _address;
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bme->settings.runMode = BMX280_MODE;
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bme->settings.tStandby = 0;
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bme->settings.filter = 0;
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bme->settings.tempOverSample = BMX280_TEMPERATURE;
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bme->settings.pressOverSample = BMX280_PRESSURE;
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bme->settings.humidOverSample = BMX280_HUMIDITY;
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// Fix when not measuring temperature, t_fine should have a sensible value
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if (BMX280_TEMPERATURE == 0) bme->t_fine = 100000; // aprox 20ºC
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// Make sure sensor had enough time to turn on. BMX280 requires 2ms to start up
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delay(10);
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// Check sensor correctly initialized
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_chip = bme->begin();
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if ((_chip != BMX280_CHIP_BME280) && (_chip != BMX280_CHIP_BMP280)) {
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_chip = 0;
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_error = SENSOR_ERROR_UNKNOWN_ID;
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}
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#if BMX280_TEMPERATURE > 0
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++_count;
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#endif
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#if BMX280_PRESSURE > 0
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++_count;
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#endif
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#if BMX280_HUMIDITY > 0
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if (_chip == BMX280_CHIP_BME280) ++_count;
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#endif
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_measurement_delay = measurementTime();
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}
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unsigned long measurementTime() {
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// Measurement Time (as per BMX280 datasheet section 9.1)
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// T_max(ms) = 1.25
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// + (2.3 * T_oversampling)
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// + (2.3 * P_oversampling + 0.575)
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// + (2.4 * H_oversampling + 0.575)
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// ~ 9.3ms for current settings
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double t = 1.25;
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#if BMX280_TEMPERATURE > 0
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t += (2.3 * BMX280_TEMPERATURE);
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#endif
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#if BMX280_PRESSURE > 0
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t += (2.3 * BMX280_PRESSURE + 0.575);
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#endif
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#if BMX280_HUMIDITY > 0
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if (_chip == BMX280_CHIP_BME280) {
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t += (2.4 * BMX280_HUMIDITY + 0.575);
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}
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#endif
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return round(t + 1); // round up
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}
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void forceRead() {
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// We set the sensor in "forced mode" to force a reading.
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// After the reading the sensor will go back to sleep mode.
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uint8_t value = bme->readRegister(BME280_CTRL_MEAS_REG);
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value = (value & 0xFC) + 0x01;
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bme->writeRegister(BME280_CTRL_MEAS_REG, value);
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delay(_measurement_delay);
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}
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// ---------------------------------------------------------------------
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BME280 * bme;
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unsigned char _chip;
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unsigned long _measurement_delay;
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};
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