Michael Ball / Thermistor

Thermistor to Temperature library, using Steinhart-Hart algorithm

This is a Thermistor to Temperature conversion library

Much thanks to @Adafruit for this tutorial: https://learn.adafruit.com/thermistor/using-a-thermistor

The 100K Thermistor is configured with a 4.7k series resistor tied to vcc (3.3v) like this:

+3.3v

\ / 4.7k series resistor \ /

.---O To Anlog pin on FRDM board

\ / Thermistor 100k Nominal \ /

- GND

author Michael J. Ball unix_guru at hotmail.com @unix_guru on Twitter March 2016

Thermistor.h@1:601e1435dfb8, 2016-03-09 (annotated)

Committer:
unix_guru
Date:
Wed Mar 09 13:56:37 2016 +0000
Revision:
1:601e1435dfb8
Parent:
0:000a8be2414d 
Updated documentation

Who changed what in which revision?

UserRevisionLine numberNew contents of line
unix_guru 0:000a8be2414d 1 #ifndef THERMISTOR_H
unix_guru 0:000a8be2414d 2 #define THERMISTOR_H
unix_guru 0:000a8be2414d 3 ///
unix_guru 0:000a8be2414d 4 /// @mainpage Thermistor Temperature library
unix_guru 0:000a8be2414d 5 ///
unix_guru 0:000a8be2414d 6 /// This is a Thermistor to Temerature conversion library
unix_guru 0:000a8be2414d 7 ///
unix_guru 0:000a8be2414d 8 /// Much thanks to @Adafruit for this tutorial:
unix_guru 0:000a8be2414d 9 /// https://learn.adafruit.com/thermistor/using-a-thermistor
unix_guru 0:000a8be2414d 10 ///
unix_guru 0:000a8be2414d 11 /// The 100K Thermistor is configured with a 4.7k series resistor
unix_guru 0:000a8be2414d 12 /// tied to vcc (3.3v) like this:
unix_guru 0:000a8be2414d 13 ///
unix_guru 0:000a8be2414d 14 /// +3.3v
unix_guru 0:000a8be2414d 15 /// |
unix_guru 0:000a8be2414d 16 /// \
unix_guru 0:000a8be2414d 17 /// / 4.7k series resistor
unix_guru 0:000a8be2414d 18 /// \
unix_guru 0:000a8be2414d 19 /// /
unix_guru 0:000a8be2414d 20 /// |
unix_guru 0:000a8be2414d 21 /// .-----------O To Anlog pin on FRDM board
unix_guru 0:000a8be2414d 22 /// |
unix_guru 0:000a8be2414d 23 /// \
unix_guru 0:000a8be2414d 24 /// /
unix_guru 0:000a8be2414d 25 /// Thermistor 100k Nominal
unix_guru 0:000a8be2414d 26 /// \
unix_guru 0:000a8be2414d 27 /// /
unix_guru 0:000a8be2414d 28 /// |
unix_guru 0:000a8be2414d 29 /// ---
unix_guru 0:000a8be2414d 30 /// GND
unix_guru 0:000a8be2414d 31 ///
unix_guru 0:000a8be2414d 32 ///
unix_guru 0:000a8be2414d 33 /// @author Michael J. Ball
unix_guru 0:000a8be2414d 34 /// unix_guru at hotmail.com
unix_guru 0:000a8be2414d 35 /// @unix_guru on Twitter
unix_guru 0:000a8be2414d 36 /// March 2016
unix_guru 0:000a8be2414d 37 ///
unix_guru 0:000a8be2414d 38 /// @code
unix_guru 1:601e1435dfb8 39 /// #include "mbed.h"
unix_guru 1:601e1435dfb8 40 /// #include "Thermistor.h"
unix_guru 1:601e1435dfb8 41 ///
unix_guru 1:601e1435dfb8 42 /// Serial pc(USBTX, USBRX);
unix_guru 1:601e1435dfb8 43 ///
unix_guru 0:000a8be2414d 44 /// Thermistor bed(PTB10);
unix_guru 1:601e1435dfb8 45 /// Thermistor extruder(PTB11);
unix_guru 1:601e1435dfb8 46 ///
unix_guru 1:601e1435dfb8 47 /// int main()
unix_guru 1:601e1435dfb8 48 /// {
unix_guru 1:601e1435dfb8 49 /// pc.baud(115200);
unix_guru 1:601e1435dfb8 50 /// pc.printf("\r\nThermistor Test - Build " __DATE__ " " __TIME__ "\r\n");
unix_guru 1:601e1435dfb8 51 ///
unix_guru 1:601e1435dfb8 52 /// while(1) {
unix_guru 1:601e1435dfb8 53 /// pc.printf("Bed Temperature %f *C\r\n",bed.get_temperature());
unix_guru 1:601e1435dfb8 54 /// wait(.5);
unix_guru 1:601e1435dfb8 55 /// pc.printf("Extruder Temperature %f *C\r\n",extruder.get_temperature());
unix_guru 1:601e1435dfb8 56 /// wait(.5);
unix_guru 1:601e1435dfb8 57 /// }
unix_guru 1:601e1435dfb8 58 /// }
unix_guru 1:601e1435dfb8 59
unix_guru 0:000a8be2414d 60 /// ...
unix_guru 0:000a8be2414d 61 /// @endcode
unix_guru 0:000a8be2414d 62 ///
unix_guru 0:000a8be2414d 63 /// @license
unix_guru 0:000a8be2414d 64 /// Licensed under the Apache License, Version 2.0 (the "License");
unix_guru 0:000a8be2414d 65 /// you may not use this file except in compliance with the License.
unix_guru 0:000a8be2414d 66 /// You may obtain a copy of the License at
unix_guru 0:000a8be2414d 67 ///
unix_guru 0:000a8be2414d 68 /// http://www.apache.org/licenses/LICENSE-2.0
unix_guru 0:000a8be2414d 69 ///
unix_guru 0:000a8be2414d 70 /// Unless required by applicable law or agreed to in writing, software
unix_guru 0:000a8be2414d 71 /// distributed under the License is distributed on an "AS IS" BASIS,
unix_guru 0:000a8be2414d 72 /// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
unix_guru 0:000a8be2414d 73 /// See the License for the specific language governing permissions and
unix_guru 0:000a8be2414d 74 /// limitations under the License.
unix_guru 0:000a8be2414d 75 ///
unix_guru 0:000a8be2414d 76
unix_guru 0:000a8be2414d 77
unix_guru 0:000a8be2414d 78 #include "mbed.h"
unix_guru 0:000a8be2414d 79
unix_guru 0:000a8be2414d 80
unix_guru 0:000a8be2414d 81 #define THERMISTORNOMINAL 100000 // 100k default
unix_guru 0:000a8be2414d 82 // temp. for nominal resistance (almost always 25 C)
unix_guru 0:000a8be2414d 83 #define TEMPERATURENOMINAL 25
unix_guru 0:000a8be2414d 84 // The beta coefficient of the thermistor (usually 3000-4000)
unix_guru 0:000a8be2414d 85 #define BCOEFFICIENT 3950
unix_guru 0:000a8be2414d 86 // the value of the 'other' resistor
unix_guru 0:000a8be2414d 87 #define SERIESRESISTOR 4700
unix_guru 0:000a8be2414d 88
unix_guru 0:000a8be2414d 89
unix_guru 0:000a8be2414d 90 class Thermistor {
unix_guru 0:000a8be2414d 91 public:
unix_guru 0:000a8be2414d 92 Thermistor(PinName pin);
unix_guru 0:000a8be2414d 93 /** Receives a PinName variable.
unix_guru 0:000a8be2414d 94 * @param pin mbed pin to which the thermistor is connected
unix_guru 0:000a8be2414d 95 */
unix_guru 0:000a8be2414d 96
unix_guru 0:000a8be2414d 97
unix_guru 0:000a8be2414d 98 float get_temperature();
unix_guru 0:000a8be2414d 99 /** This is the workhorse routine that calculates the temperature
unix_guru 0:000a8be2414d 100 * using the Steinhart-Hart equation for thermistors
unix_guru 0:000a8be2414d 101 * https://en.wikipedia.org/wiki/Steinhart%E2%80%93Hart_equation
unix_guru 0:000a8be2414d 102 */
unix_guru 0:000a8be2414d 103 void init(); // Set default Steinhart-Hart values
unix_guru 0:000a8be2414d 104 void set_ThermistorNominal(float thermnom); // Change the thermistors nominal resistance
unix_guru 0:000a8be2414d 105 void set_TemperatureNominal(float tempnom); // Change the thermistors nominal temperature
unix_guru 0:000a8be2414d 106 void set_BCoefficient(float bcoefficient); // Change the thermistors BCoefficient
unix_guru 0:000a8be2414d 107 void set_SeriesResistor(float resistor); // Change the value of the series resistor
unix_guru 0:000a8be2414d 108
unix_guru 0:000a8be2414d 109 private:
unix_guru 0:000a8be2414d 110 AnalogIn _pin;
unix_guru 0:000a8be2414d 111 float ThermistorNominal;
unix_guru 0:000a8be2414d 112 float TemperatureNominal;
unix_guru 0:000a8be2414d 113 float BCoefficient;
unix_guru 0:000a8be2414d 114 float SeriesResistor;
unix_guru 0:000a8be2414d 115 };
unix_guru 0:000a8be2414d 116
unix_guru 0:000a8be2414d 117 #endif