'use strict'; this.pi = null; this.i2cBusNo = null; this.i2cAddress = null; this.i2cHand = null; this.I2C_ADDRESS_B = 0x76; this.I2C_ADDRESS_A = 0x77; this.CHIP_ID = 0x58; this.REGISTER_DIG_T1 = 0x88; this.REGISTER_DIG_T2 = 0x8A; this.REGISTER_DIG_T3 = 0x8C; this.REGISTER_DIG_P1 = 0x8E; this.REGISTER_DIG_P2 = 0x90; this.REGISTER_DIG_P3 = 0x92; this.REGISTER_DIG_P4 = 0x94; this.REGISTER_DIG_P5 = 0x96; this.REGISTER_DIG_P6 = 0x98; this.REGISTER_DIG_P7 = 0x9A; this.REGISTER_DIG_P8 = 0x9C; this.REGISTER_DIG_P9 = 0x9E; this.REGISTER_DIG_H1 = 0xA1; this.REGISTER_DIG_H2 = 0xE1; this.REGISTER_DIG_H3 = 0xE3; this.REGISTER_DIG_H4 = 0xE4; this.REGISTER_DIG_H5 = 0xE5; this.REGISTER_DIG_H6 = 0xE7; this.REGISTER_CHIPID = 0xD0; this.REGISTER_RESET = 0xE0; this.REGISTER_CONTROL_HUM = 0xF2; this.REGISTER_CONTROL = 0xF4; this.REGISTER_PRESSURE_DATA = 0xF7; this.REGISTER_TEMP_DATA = 0xFA; this.REGISTER_HUMIDITY_DATA = 0xFD; exports.init = (options) => { this.pi = require('@ocogeclub/lgpio'); this.i2cBusNo = (options && options.hasOwnProperty('i2cBusNo')) ? options.i2cBusNo : 1; this.i2cAddress = (options && options.hasOwnProperty('i2cAddress')) ? options.i2cAddress : this.BME280_DEFAULT_I2C_ADDRESS(); this.i2cHand = this.pi.i2c_open(this.i2cBusNo, this.i2cAddress); let r; r = this.pi.i2c_write_byte_data(this.i2cHand, this.REGISTER_CHIPID, 0); if (r < 0) return r; let chipId = this.pi.i2c_read_byte_data(this.i2cHand, this.REGISTER_CHIPID); if (chipId !== this.CHIP_ID_BME280() && chipId !== this.CHIP_ID1_BMP280() && chipId !== this.CHIP_ID2_BMP280() && chipId !== this.CHIP_ID3_BMP280()) { return `Unexpected BMx280 chip ID: 0x${chipId.toString(16).toUpperCase()}`; } // console.log(`Found BMx280 chip ID 0x${chipId.toString(16).toUpperCase()} on bus i2c-${this.i2cBusNo}, address 0x${this.i2cAddress.toString(16).toUpperCase()}`); this.loadCalibration((err) => { if (err) { return err; } // Humidity 16x oversampling // let r = this.pi.i2c_write_byte_data(this.i2cHand, this.REGISTER_CONTROL_HUM, 0b00000101); if (r < 0) return `Humidity 16x oversampling error: ${r}`; // Temperture/pressure 16x oversampling, normal mode // r = this.pi.i2c_write_byte_data(this.i2cHand, this.REGISTER_CONTROL, 0b10110111); if (r < 0) return `Temperture/pressure 16x oversampling error: ${r}`; return 0; }); } // reset() // // Perform a power-on reset procedure. You will need to call init() following a reset() // exports.reset = () => { const POWER_ON_RESET_CMD = 0xB6; let r = this.pi.i2c_write_byte_data(this.i2cHand, this.REGISTER_RESET, POWER_ON_RESET_CMD); if (r < 0) return `cannot power-on reset: ${r}`; else return 0; } // cancel() // // Cancels the sensor and releases resources. // exports.cancel = () => { if (this.i2cHand >= 0) { this.pi.i2c_close(this.i2cHand); this.i2cHand = 0; } } exports.readSensorData = () => { if (!this.cal) { return 'You must first call bme280.init()'; } // Grab temperature, humidity, and pressure in a single read // let buffer = this.pi.i2c_read_i2c_block_data(this.i2cHand, this.REGISTER_PRESSURE_DATA, 8); if (!buffer) return `couldn't grab data`; // Temperature (temperature first since we need t_fine for pressure and humidity) // let adc_T = this.uint20(buffer[3], buffer[4], buffer[5]); let tvar1 = ((((adc_T >> 3) - (this.cal.dig_T1 << 1))) * this.cal.dig_T2) >> 11; let tvar2 = (((((adc_T >> 4) - this.cal.dig_T1) * ((adc_T >> 4) - this.cal.dig_T1)) >> 12) * this.cal.dig_T3) >> 14; let t_fine = tvar1 + tvar2; let temperature_C = ((t_fine * 5 + 128) >> 8) / 100; // Pressure // let adc_P = this.uint20(buffer[0], buffer[1], buffer[2]); let pvar1 = t_fine / 2 - 64000; let pvar2 = pvar1 * pvar1 * this.cal.dig_P6 / 32768; pvar2 = pvar2 + pvar1 * this.cal.dig_P5 * 2; pvar2 = pvar2 / 4 + this.cal.dig_P4 * 65536; pvar1 = (this.cal.dig_P3 * pvar1 * pvar1 / 524288 + this.cal.dig_P2 * pvar1) / 524288; pvar1 = (1 + pvar1 / 32768) * this.cal.dig_P1; let pressure_hPa = 0; if (pvar1 !== 0) { let p = 1048576 - adc_P; p = ((p - pvar2 / 4096) * 6250) / pvar1; pvar1 = this.cal.dig_P9 * p * p / 2147483648; pvar2 = p * this.cal.dig_P8 / 32768; p = p + (pvar1 + pvar2 + this.cal.dig_P7) / 16; pressure_hPa = p / 100; } // Humidity (available on the BME280, will be zero on the BMP280 since it has no humidity sensor) // let adc_H = this.uint16(buffer[6], buffer[7]); let h = t_fine - 76800; h = (adc_H - (this.cal.dig_H4 * 64 + this.cal.dig_H5 / 16384 * h)) * (this.cal.dig_H2 / 65536 * (1 + this.cal.dig_H6 / 67108864 * h * (1 + this.cal.dig_H3 / 67108864 * h))); h = h * (1 - this.cal.dig_H1 * h / 524288); let humidity = (h > 100) ? 100 : (h < 0 ? 0 : h); return { temperature_C: temperature_C, humidity: humidity, pressure_hPa: pressure_hPa }; } exports.loadCalibration = (callback) => { let buffer = this.pi.i2c_read_i2c_block_data(this.i2cHand, this.REGISTER_DIG_T1, 24); // for (let i = 0; i < 24; i++) console.log(parseInt(buffer[i], 16)); if (buffer) { let h1 = this.pi.i2c_read_byte_data(this.i2cHand, this.REGISTER_DIG_H1); let h2 = this.pi.i2c_read_word_data(this.i2cHand, this.REGISTER_DIG_H2); let h3 = this.pi.i2c_read_byte_data(this.i2cHand, this.REGISTER_DIG_H3); let h4 = this.pi.i2c_read_byte_data(this.i2cHand, this.REGISTER_DIG_H4); let h5 = this.pi.i2c_read_byte_data(this.i2cHand, this.REGISTER_DIG_H5); let h5_1 = this.pi.i2c_read_byte_data(this.i2cHand, this.REGISTER_DIG_H5 + 1); let h6 = this.pi.i2c_read_byte_data(this.i2cHand, this.REGISTER_DIG_H6); this.cal = { dig_T1: this.uint16(buffer[1], buffer[0]), dig_T2: this.int16(buffer[3], buffer[2]), dig_T3: this.int16(buffer[5], buffer[4]), dig_P1: this.uint16(buffer[7], buffer[6]), dig_P2: this.int16(buffer[9], buffer[8]), dig_P3: this.int16(buffer[11], buffer[10]), dig_P4: this.int16(buffer[13], buffer[12]), dig_P5: this.int16(buffer[15], buffer[14]), dig_P6: this.int16(buffer[17], buffer[16]), dig_P7: this.int16(buffer[19], buffer[18]), dig_P8: this.int16(buffer[21], buffer[20]), dig_P9: this.int16(buffer[23], buffer[22]), dig_H1: h1, dig_H2: h2, dig_H3: h3, dig_H4: (h4 << 4) | (h5 & 0xF), dig_H5: (h5_1 << 4) | (h5 >> 4), dig_H6: h6 }; // console.log('BME280 cal = ' + JSON.stringify(this.cal, null, 2)); callback(); } } exports.BME280_DEFAULT_I2C_ADDRESS = () => { return 0x77; } exports.CHIP_ID1_BMP280 = () => { return 0x56; } exports.CHIP_ID2_BMP280 = () => { return 0x57; } exports.CHIP_ID3_BMP280 = () => { return 0x58; } exports.CHIP_ID_BME280 = () => { return 0x60; } exports.int16 = (msb, lsb) => { let val = this.uint16(msb, lsb); return val > 32767 ? (val - 65536) : val; } exports.uint16 = (msb, lsb) => { return msb << 8 | lsb; } exports.uint20 = (msb, lsb, xlsb) => { return ((msb << 8 | lsb) << 8 | xlsb) >> 4; } exports.convertCelciusToFahrenheit = (c) => { return c * 9 / 5 + 32; } exports.convertHectopascalToInchesOfMercury = (hPa) => { return hPa * 0.02952998751; } exports.convertMetersToFeet = (m) => { return m * 3.28084; } exports.calculateHeatIndexCelcius = (temperature_C, humidity) => { return -8.784695 + 1.61139411 * temperature_C + 2.33854900 * humidity + -0.14611605 * temperature_C * humidity + -0.01230809 * Math.pow(temperature_C, 2) + -0.01642482 * Math.pow(humidity, 2) + 0.00221173 * Math.pow(temperature_C, 2) * humidity + 0.00072546 * temperature_C * Math.pow(humidity, 2) + -0.00000358 * Math.pow(temperature_C, 2) * Math.pow(humidity, 2); } exports.calculateDewPointCelcius = (temperature_C, humidity) => { return 243.04 * (Math.log(humidity / 100.0) + ((17.625 * temperature_C) / (243.04 + temperature_C))) / (17.625 - Math.log(humidity / 100.0) - ((17.625 * temperature_C) / (243.04 + temperature_C))); } exports.calculateAltitudeMeters = (pressure_hPa, seaLevelPressure_hPa) => { if (!seaLevelPressure_hPa) { seaLevelPressure_hPa = 1013.25; } return (1.0 - Math.pow(pressure_hPa / seaLevelPressure_hPa, (1 / 5.2553))) * 145366.45 * 0.3048; } /* * This code was forked from skylarstein's bme280-sensor: https://github.com/skylarstein/bme280-sensor */