wireless sensor / LinearAnalogSensors

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AnalogPH.h@4:61e97a2029f8, 2016-08-13 (annotated)

Committer:
wang1tao
Date:
Sat Aug 13 09:34:26 2016 +0000
Revision:
4:61e97a2029f8
Changed for Multi-channel PH measurement

Who changed what in which revision?

UserRevisionLine numberNew contents of line
wang1tao 4:61e97a2029f8 1 /* Copyright (c) <2012> <P. Patel>, MIT License
wang1tao 4:61e97a2029f8 2 *
wang1tao 4:61e97a2029f8 3 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
wang1tao 4:61e97a2029f8 4 * and associated documentation files (the "Software"), to deal in the Software without restriction,
wang1tao 4:61e97a2029f8 5 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
wang1tao 4:61e97a2029f8 6 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
wang1tao 4:61e97a2029f8 7 * furnished to do so, subject to the following conditions:
wang1tao 4:61e97a2029f8 8 *
wang1tao 4:61e97a2029f8 9 * The above copyright notice and this permission notice shall be included in all copies or
wang1tao 4:61e97a2029f8 10 * substantial portions of the Software.
wang1tao 4:61e97a2029f8 11 *
wang1tao 4:61e97a2029f8 12 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
wang1tao 4:61e97a2029f8 13 * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
wang1tao 4:61e97a2029f8 14 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
wang1tao 4:61e97a2029f8 15 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
wang1tao 4:61e97a2029f8 16 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
wang1tao 4:61e97a2029f8 17 */
wang1tao 4:61e97a2029f8 18
wang1tao 4:61e97a2029f8 19 // --------------------- Median Filtered Linear Temperature Sensor Reader ------------------------
wang1tao 4:61e97a2029f8 20
wang1tao 4:61e97a2029f8 21 #ifndef ANALOGPH
wang1tao 4:61e97a2029f8 22 #define ANALOGPH
wang1tao 4:61e97a2029f8 23
wang1tao 4:61e97a2029f8 24 #include "mbed.h"
wang1tao 4:61e97a2029f8 25 /** This library is designed to work with devices like the LM335 temperature sensor. There are only
wang1tao 4:61e97a2029f8 26 * two requirements for compatibility of a device with this library: 1) It must be a sensor device
wang1tao 4:61e97a2029f8 27 * that has an analog voltage output. 2) The physical quantity measured must vary linearly with
wang1tao 4:61e97a2029f8 28 * the analog voltage. The LM335 which creates an analog voltage proportional to temperature
wang1tao 4:61e97a2029f8 29 * can work very well with this library using the nominal multiplier of 0.0050354 and offset of
wang1tao 4:61e97a2029f8 30 * -273.15 or by providing two calibration points to the constuctor to generate a linear response. It
wang1tao 4:61e97a2029f8 31 * samples the sensor 9 times and uses the median to minimize the effect of poor ADC readings and sudden
wang1tao 4:61e97a2029f8 32 * changes.
wang1tao 4:61e97a2029f8 33 *
wang1tao 4:61e97a2029f8 34 * Example:
wang1tao 4:61e97a2029f8 35 * @code
wang1tao 4:61e97a2029f8 36 * LinearTemp mysensor(p20, 0.0050354, -273.15); // Setup a LM335 temp sensor on pin 20
wang1tao 4:61e97a2029f8 37 * DigitalOut myled(LED1);
wang1tao 4:61e97a2029f8 38 *
wang1tao 4:61e97a2029f8 39 * int main() {
wang1tao 4:61e97a2029f8 40 * while(1) {
wang1tao 4:61e97a2029f8 41 * // Light LED if filtered temperature is greater than 45 degrees Celsius
wang1tao 4:61e97a2029f8 42 * if (mysensor > 45) myled = 1;
wang1tao 4:61e97a2029f8 43 * else myled = 0;
wang1tao 4:61e97a2029f8 44 * }
wang1tao 4:61e97a2029f8 45 * }
wang1tao 4:61e97a2029f8 46 * @endcode
wang1tao 4:61e97a2029f8 47 */
wang1tao 4:61e97a2029f8 48 class AnalogPHSensor {
wang1tao 4:61e97a2029f8 49 public:
wang1tao 4:61e97a2029f8 50 /** Create a calibrated temperature sensor object connected to an Analog input pin
wang1tao 4:61e97a2029f8 51 * @param pin Analog input pin to which an LM335 or comparable linear temp sensor is connected
wang1tao 4:61e97a2029f8 52 * @param temp1 Temperature (float in degrees C or F) of first calibration point
wang1tao 4:61e97a2029f8 53 * @param read1 Mbed ADC reading (unsigned short) of first calibration point
wang1tao 4:61e97a2029f8 54 * @param temp2 Temperature (float in degrees C or F) of second calibration point
wang1tao 4:61e97a2029f8 55 * @param read2 Mbed ADC reading (unsigned short) of second calibration point
wang1tao 4:61e97a2029f8 56 */
wang1tao 4:61e97a2029f8 57 AnalogPHSensor(PinName pin, float temp1, unsigned short read1, float temp2, unsigned short read2);
wang1tao 4:61e97a2029f8 58 /** Create a calibrated temperature sensor object connected to an Analog input pin
wang1tao 4:61e97a2029f8 59 * @param pin Analog input pin to which an LM335 or comparable linear temp sensor is connected
wang1tao 4:61e97a2029f8 60 * @param multiplier Conversion multiplier to go from ADC reading as unsigned short to temperature (change in degrees / change in unsigned short)
wang1tao 4:61e97a2029f8 61 * @param offset Conversion offset (positive or negative)
wang1tao 4:61e97a2029f8 62 */
wang1tao 4:61e97a2029f8 63 AnalogPHSensor(PinName pin, float multiplier, float offset);
wang1tao 4:61e97a2029f8 64 /** Returns a new median-filtered, converted reading from the sensor
wang1tao 4:61e97a2029f8 65 * @returns New temperature (float) in degrees C or F as designated by the calibration points
wang1tao 4:61e97a2029f8 66 */
wang1tao 4:61e97a2029f8 67 float readPH();
wang1tao 4:61e97a2029f8 68 /** Return the last calculated and stored temperature
wang1tao 4:61e97a2029f8 69 * @returns Last stored PH
wang1tao 4:61e97a2029f8 70 */
wang1tao 4:61e97a2029f8 71 float getPH();
wang1tao 4:61e97a2029f8 72 #ifdef MBED_OPERATORS
wang1tao 4:61e97a2029f8 73 /** An operator shorthand for readPH() to calculate filtered PH
wang1tao 4:61e97a2029f8 74 */
wang1tao 4:61e97a2029f8 75 operator float() {
wang1tao 4:61e97a2029f8 76 return readPH();
wang1tao 4:61e97a2029f8 77 }
wang1tao 4:61e97a2029f8 78 #endif
wang1tao 4:61e97a2029f8 79 private:
wang1tao 4:61e97a2029f8 80 AnalogIn _pin;
wang1tao 4:61e97a2029f8 81 unsigned short _phArr[6];
wang1tao 4:61e97a2029f8 82 float _ph;
wang1tao 4:61e97a2029f8 83 float _multiplier;
wang1tao 4:61e97a2029f8 84 float _offset;
wang1tao 4:61e97a2029f8 85 };
wang1tao 4:61e97a2029f8 86 #endif