Humidity and Temperature Sensor - Sensirion SHT1x driver
Dependents: mDot_TTN_DHT11_Boston16_CAM
Fork of SHTx by
sht15.hpp
- Committer:
- NegativeBlack
- Date:
- 2010-11-18
- Revision:
- 0:d55659b0c4a0
- Child:
- 1:8465801be23f
File content as of revision 0:d55659b0c4a0:
/** * Copyright (c) 2010 Roy van Dam <roy@negative-black.org> * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef _SHT15_HPP_ #define _SHT15_HPP_ #include "mbed.h" #include "i2c.hpp" namespace SHTx { /** * Class: SHT15 * Humidity and Temperature Sensor - SHT15 * High level software interface. */ class SHT15 { private: I2C i2c; bool ready; bool scale; uint8_t status_register; uint16_t humidity; uint16_t temperature; struct coefficients { // Humidity conversion coefficients float c1[2], c2[2], c3[2]; // Temperature conversion coefficients float dc[2], df[2], dv[2]; // Temperature compensation coefficients float t1[2], t2[2]; // Initialize table coefficients(void) { c1[0] = -2.046f; c2[1] = -2.046f; c2[0] = 0.036f; c2[1] = 0.587f; c3[0] = -0.0000015955f; c2[1] = -0.00040845f; dc[0] = 0.01f; dc[1] = 0.04f; df[0] = 0.018f; df[1] = 0.072f; dv[0] = -39.7f; dv[1] = -39.5f; t1[0] = 0.01f; t1[1] = 0.01f; t2[0] = 0.00008f; t2[1] = 0.00128f; }; } coefficient; enum cmd_list { cmd_read_temperature = 0x03, cmd_read_humidity = 0x05, cmd_read_register = 0x07, cmd_write_register = 0x06, cmd_reset_device = 0x1E }; enum flag_list { flag_resolution = 0x01, flag_reset = 0x02, flag_heater = 0x04, flag_battery = 0x40 }; public: /* * Initializes I2C interface and waits * the 11ms device initialization time. */ SHT15(PinName sda, PinName scl); /** * Function: getTemperature * Returns the current temperature. * * Values: * returns - current temperature. */ float getTemperature(void); /** * Function: getHumidity * Returns the current relative humidity. * * Values: * returns - relative humidity. */ float getHumidity(void); /** * Function: checkBattery * Returns true if battery voltage drops * below 2.4 volt. * * Values: * returns - true on low battery, false otherwise */ bool checkBattery(void); /** * Function: setHeater * Enable on chip heating element. The heater may * increase the temperature of the sensor by 5C to * 10C beyond ambient temperature. * * Values: * value - true->on, false->off * return - operation result */ bool setHeater(bool value); /** * Function: setResolution * Set lower measurement resolution to allow * faster update frequencies. * * Resolutions * low: 8bit humid. - 12bit temp. * high: 12bit humid. - 14bit temp. * * Values: * value - true->low, false->high * return - operation result */ bool setResolution(bool value); /** * Function: setScale * Sets output scale to fahrenheit or celcius. * * Values: * value - true->fahrenheit, false->celcius */ void setScale(bool value); /** * Function: update * Performs humidity and temperature * sensor readout of the chip. * * Values: * return - operation result */ bool update(void); /** * Function: reset * Performs full chip reset. * * Values: * return - operation result */ bool reset(void); private: /** * Function: convertTemperature * Convert sensor data to human readable value * on the farenheit or celcius scale. * * Values: * sot - raw temperatue sensor output * res - true->low, false->high * scale - true->fahrenheit, false->celcius * return - temperature */ float convertTemperature(uint16_t sot, bool res = false, bool scale = false); /** * Function: convertHumidity * Convert sensor data to relative humidity * in percentage. * * Values: * sohr - raw humidity sensor output * sot - raw temperatue sensor output * res - true->low, false->high * return - relative humidity */ float convertHumidity(uint16_t sohr, uint16_t sot, bool res = false); /** * Function: writeRegister * Write internal chip register. * * Values: * return - operation result */ bool writeRegister(void); /** * Function: readRegister * Reads internal chip register * * Values: * command - register to be accessed * return - operation result */ bool readRegister(cmd_list command); /** * Function: setFlag * Modify local register flag. * * Values: * flag - flag to be modified * value - value to be assigned */ void setFlag(flag_list flag, bool value); /** * Function: getFlag * Get local register flag. * * Values: * returns - flag value */ bool getFlag(flag_list flag); }; } /* !_SHT15_HPP_ */ #endif