Optimized
Fork of LinearAnalogSensors by
AnalogPH.h
- Committer:
- wang1tao
- Date:
- 2016-08-13
- Revision:
- 4:61e97a2029f8
File content as of revision 4:61e97a2029f8:
/* Copyright (c) <2012> <P. Patel>, MIT License * * 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. */ // --------------------- Median Filtered Linear Temperature Sensor Reader ------------------------ #ifndef ANALOGPH #define ANALOGPH #include "mbed.h" /** This library is designed to work with devices like the LM335 temperature sensor. There are only * two requirements for compatibility of a device with this library: 1) It must be a sensor device * that has an analog voltage output. 2) The physical quantity measured must vary linearly with * the analog voltage. The LM335 which creates an analog voltage proportional to temperature * can work very well with this library using the nominal multiplier of 0.0050354 and offset of * -273.15 or by providing two calibration points to the constuctor to generate a linear response. It * samples the sensor 9 times and uses the median to minimize the effect of poor ADC readings and sudden * changes. * * Example: * @code * LinearTemp mysensor(p20, 0.0050354, -273.15); // Setup a LM335 temp sensor on pin 20 * DigitalOut myled(LED1); * * int main() { * while(1) { * // Light LED if filtered temperature is greater than 45 degrees Celsius * if (mysensor > 45) myled = 1; * else myled = 0; * } * } * @endcode */ class AnalogPHSensor { public: /** Create a calibrated temperature sensor object connected to an Analog input pin * @param pin Analog input pin to which an LM335 or comparable linear temp sensor is connected * @param temp1 Temperature (float in degrees C or F) of first calibration point * @param read1 Mbed ADC reading (unsigned short) of first calibration point * @param temp2 Temperature (float in degrees C or F) of second calibration point * @param read2 Mbed ADC reading (unsigned short) of second calibration point */ AnalogPHSensor(PinName pin, float temp1, unsigned short read1, float temp2, unsigned short read2); /** Create a calibrated temperature sensor object connected to an Analog input pin * @param pin Analog input pin to which an LM335 or comparable linear temp sensor is connected * @param multiplier Conversion multiplier to go from ADC reading as unsigned short to temperature (change in degrees / change in unsigned short) * @param offset Conversion offset (positive or negative) */ AnalogPHSensor(PinName pin, float multiplier, float offset); /** Returns a new median-filtered, converted reading from the sensor * @returns New temperature (float) in degrees C or F as designated by the calibration points */ float readPH(); /** Return the last calculated and stored temperature * @returns Last stored PH */ float getPH(); #ifdef MBED_OPERATORS /** An operator shorthand for readPH() to calculate filtered PH */ operator float() { return readPH(); } #endif private: AnalogIn _pin; unsigned short _phArr[6]; float _ph; float _multiplier; float _offset; }; #endif