Lib for HP03SA atmospheric pressure sensor. Provides pressure, temperature and altitude data.
Diff: HP03SA.h
- Revision:
- 0:61bbd81782de
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/HP03SA.h Sat Jan 10 19:10:17 2015 +0000 @@ -0,0 +1,293 @@ +/* mbed HP03SA Library, for an I2C Pressure and Temperature sensor which provides derived Altitude values + * Copyright (c) 2015, v01: WH, Initial version, ported in part from Elektor weatherstation (Sept 2011), Author: W. Waetzig + * See http://www.elektor-labs.com/project/usb-long-term-weather-logger-100888.12037.html + * Code also based on several other public sources: + * See http://en.wikipedia.org/wiki/Atmospheric_pressure + * See https://learn.sparkfun.com/tutorials/bmp180-barometric-pressure-sensor-hookup-?_ga=1.94307604.888266135.1310146152 + * + * The HP03S pressure sensor from Hope Microelectronics contains a piezoresistive transducer and + * integrated 16-bit A/D converter (ADC), along with control logic and an I2C interface. + * The transducer outputs one voltage that depends on pressure and one that depends on temperature. + * These analogue values are alternately converted by the ADC and the results made available on the I2C interface. + * During the manufacturing process eleven sensor-specific calibration values with a length of two bytes are stored + * in the device’s EEPROM, and these can also be retrieved by the microcontroller. + * The correction-parameters are read out from the device in used in the calculation. + * A 32 kHz clock with an amplitude of 3 V is required to drive the ADC. This could be derived from the mbed PwmOut. + * The HP03SA has an absolute pressure range between 300-1100 hPa. Operating temp is -20 to +60 degrees Celsius. + * Note: 1 atm = 1013.25 hPa = 1013.25 mbar + * + * Unit conversions see http://www.hoperf.com/docs/guide/160.htm + * + * bar Bar convert to 100,000 Pascals exactly + * psi Pounds per Square Inch convert to 6894.76 Pascals + * mb or mbar Millibar convert to 100 Pascals (1 hPa) exactly + * hPa Hectopascal convert to 100 Pascals exactly + * kPa Kilopascal convert to 1,000 Pascals + * MPa Megapascal convert to 1,000,000 Pascals + * Kgf/cm² or kg/cm² Kilogram force per Square Centimetre convert to 98,066.5 Pascals + * N/m² Newton per Square Meter convert to 1 Pascal (SI unit for pressure) + * torr Torr convert to 133.322 Pascals + * mtorr Millitorr convert to 0.133322 Pascals + * mm Hg convert to 133.322387415 Pascals + * 1 atm 1 Atmosphere convert to 101325 Pascals exactly (760 mm Hg) + * 1 atm 1 Atmosphere convert to 1013.25 hPa exactly + * Dynes/cm² or D/cm² Dynes per Square Centimetre convert to 0.1 Pascals exactly + * oz/in² Ounces per Square Inch convert to 430.922 Pascals + * tsi (UK) or tfsi (UK) Tonnes Force per Square Inch (Long, UK) convert to 15444300 Pascals + * tsi (USA) or tfsi (USA) Ton Force per Square Inch (Short, USA) convert to 13789500 Pascals + * tsf (USA) or tfsf (USA) Tons Force per Square Foot (Short, USA) convert to 95760.5 Pascals + * psf Pounds per Square Foot convert to 47.8803 Pascals + * g/cm² or gf/cm² Grammes Force per Square Centimetre convert to 98.0665 Pascals + * + * The Altitude calculation is based on the ICAO Standard Atmosphere model ISA. The code has + * certainly not been thoroughly validated! Use at own risk. + * + * QNH is the barometric altimeter setting that causes an altimeter to read + * airfield elevation above mean sea level when on the airfield. In ISA temperature + * conditions the altimeter will read altitude above mean sea level in the vicinity of the airfield. + * Note: Remember QNH as mnemonic for "nautical height" + * Average sea-level pressure is 101.325 kPa (1013.25 hPa or mbar) or 29.92 inches (inHg) or + * 760 millimetres of mercury (mmHg). In aviation weather reports (METAR), QNH is transmitted + * around the world in hectopascals or millibars (1 hectopascal = 1 millibar), except in the + * United States, Canada, and Colombia where it is reported in inches (to two decimal places) of mercury. + * + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ +#ifndef MBED_HP03SA_H +#define MBED_HP03SA_H + +#include "mbed.h" + +/** An interface for the HP03S I2C pressure and temperature sensor + * + * @code + * #include "mbed.h" + * #include "HP03S.h" + * + * // I2C Communication + * I2C i2c(p28,p27); // SDA, SCL + * + * // Serial Communication* + * Serial pc(USBTX,USBRX); + * + * // Instantiate HP03SA + * HP03SA hp03sa(&i2c, D_XCLR); // I2C bus, XCLK Pin + * // Generate the 32kHz master clock for HP03SA + * PwmOut mclk(p21); + * + * int main() { + * pc.printf("Hello World!\n"); + * + * //Init MCLK for HP03SA + * mclk.period_us(30); //32768 KHz + * mclk.pulsewidth_us(15); //32768 KHz + * + * while(1) { + * // Take reading from sensor + * hp03sa.sample(); + * + * // Show Pressure + * pc.printf("Absolute atmospheric pressure is %.1f [hPa]\r\n", (float) hp03sa.getAbsPressure() / 10.0f); + * pc.printf("Sealevel atmospheric pressure is %.1f [hPa]\r\n", (float) hp03sa.getSeaPressure(20) / 10.0f); // About right where I live.. + * + * // Show Temperature + * pc.printf("Ambient temperature is %.1f [C]\r\n", (float) hp03sa.getTemperature() / 10.0f); + * + * // Show Altitude meters + * pc.printf("Altitude estimated at %d [m]\r\n", hp03sa.getAltitude()); + * + * // Show Altitude Ft + * pc.printf("Altitude estimated at %d [ft]\r\n", hp03sa.getAltitudeFt()); + * + * wait(1.0); + * } + * } + * @endcode + */ + +// Device I2C Slave addresses +#define HP03SA_BARO_SA 0xEE +#define HP03SA_EEPROM_SA 0xA0 + +//ISA computation constants +#define RLGM 0.19026674f // ISA Exponent (R * L) / (g * M) +#define GMRL 5.25578009f // ISA Exponent (g * M) / (R * L) +#define LBASE_X10 0.065f // ISA Temp Lapse (i.e. drop) in K per meter x10 +#define TBASE_X10 (150.0f + 2731.5f) // ISA Ref Temp in K x10 +#define PBASE_X10 (1013.25f * 10.0f) // ISA Ref Pres in hPa x10 + +/** Create an HP03SA Class instance + * + */ +class HP03SA { + +public: + + /** Create an HP03SA device instance + * + * @param i2c I2C Bus + * @param XCLR Clock enable control line + */ + HP03SA(I2C *i2c, PinName XCLR); + + /** Get Status + * + * @return bool Sensor ready + */ + bool getStatus(void); + + /** Get Pressure and Temperature sample + * + * @return none + */ + void sample(void); + + /** Get Absolute Atmospheric Pressure in hPa x 10 + * Note: sample() must be called before getAbsPressure() + * + * @return int Pressure in hPa x 10 + */ + int getAbsPressure(void); + + /** Get Sealevel Atmospheric Pressure in hPa x 10 + * Note: sample() must be called before getSeaPressure() + * + * @param int alt_meter Altitude above Mean Sea Level where measurement is taken + * @return int Pressure at sea level in hPa x 10 + */ + int getSeaPressure(int alt_meter); + + /** Get Temperature as int in °Celsius x 10 + * Note: sample() must be called before getTemperature() + * + * @return int Temperature in °Celsius x 10 + */ + int getTemperatureInt(void); + + /** Get Temperature as float in °Celsius + * Note: sample() must be called before getTemperatureFl() + * + * @return float Temperature in °Celsius + */ + float getTemperature(void); + + /** Get Altitude in meters using ISA + * Note: sample() must be called before getAltitude() + * + * @return int Altitude in meters above Mean Sea Level (MSL) + */ + int getAltitude(void); + + /** Get Altitude in feet using ISA + * Note: sample() must be called before getAltitudeFt() + * + * @return int Altitude in feet above Mean Sea Level (MSL) + */ + int getAltitudeFt(); + + /** Set QNH Pressure to calibrate sensor + * + * @param int pressure_x10 at Mean Sea Level in hPa x 10 + * The getAltitude() reading will be 0 m for the set pressure. + */ + void setPressure(int pressure_x10 = PBASE_X10); + + /** Set QNH Altitude in meter to calibrate sensor + * + * @param int alt_meter Altitude in meters above Mean Sea Level (MSL) for current pressure + * The getAltitude() reading will be 'alt_meter' m for the current pressure. + */ + void setAltitude(int alt_meter = 0); + + + /** Set QNH Altitude in feet to calibrate sensor + * + * @param int alt_feet Altitude in meters above Mean Sea Level (MSL) for current pressure + * The getAltitudeFt() reading will be 'alt_feet' ft for the current pressure. + */ + void setAltitudeFt(int alt_feet = 0); + + + /** Convert Temperature from °Celsius into °Fahrenheit + * + * @param float celsius in °Celsius + * @return float temperature in °Fahrenheit + */ + float celsiusToFahrenheit(float celsius); + +private: + + /** Init HP03SA device + * + * @return none + */ + void _init(); + + /** Read ADC value (either pressure or temperature depending on Control Register setting) + * + * @return int pressure or temperature + */ + int _readADC (void); + + /** Read Pressure and Temperature + * + * @return none + */ + void _readTempPres(void); + + /** Calculate Pressure and Temperature + * + * @return none + */ + void _calcTempPres(void); + + /** Calculate Altitude + * + * @return none + */ + void _calcAlt(void); + + //I2C interface and ADC control + I2C *_i2c; + DigitalOut _xclr; + + //Raw values, computed values + int _D1, _D2; // measured values: pressure,temperature. + int _dUT, _off; // auxiliary variables + int _sens, _x; // auxiliary variables + int _temp_x10; // temperature in Celsius x 10 + int _pres_x10; // pressure in hPa x 10 + int _alt; // altitude in m + float _pres_base_x10; + float _temp_base_x10; + + //Calibration coefficients + int _C1, //Sensitivity coefficient + _C2, //Offset coefficient + _C3, //Temp coefficient of sensitivity + _C4, //Temp coefficient of offset + _C5, //Reference temperature + _C6, //Temp coefficient of temperrature + _C7; //Offset fine tuning + //Sensor correction-parameters A, B, C, D + int _A, _B, _C, _D; +}; + +#endif \ No newline at end of file