MAX31850.h

00001 /* mbed MAX31850
00002  Library, for the Dallas (Maxim) 1-Wire Digital Thermometer
00003  * Copyright (c) 2010, Michael Hagberg Michael@RedBoxCode.com
00004  *
00005  * Permission is hereby granted, free of charge, to any person obtaining a copy
00006  * of this software and associated documentation files (the "Software"), to deal
00007  * in the Software without restriction, including without limitation the rights
00008  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00009  * copies of the Software, and to permit persons to whom the Software is
00010  * furnished to do so, subject to the following conditions:
00011  *
00012  * The above copyright notice and this permission notice shall be included in
00013  * all copies or substantial portions of the Software.
00014  *
00015  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00016  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00017  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00018  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00019  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00020  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00021  * THE SOFTWARE.
00022  * 
00023  * 
00024  * This library has been adapted from the DS1820 library to work with MAX31850 thermocouple sensor
00025  * Chris Roberts (croberts21@my.whitworth.edu)
00026  * Craig Russell (crussell21@my.whitworth.edu)
00027  * 
00028  * For our application, we modified readAll() (previously convertTemperature) to force a small 
00029  * wait rather than it being optional, and removed the ability to select a single sensor.
00030  * 
00031  * getTemp() (previously temperature) has been updated to deal with the correct number of bits that 
00032  * the temperature is stored in as well as updated convertions to all four units
00033  * 
00034  *  as well as adding a setUnits() function to set the 
00035  * units that the sensor will return.
00036  * 
00037  * We removed some functionality that dealt with parasite power. 
00038  * 
00039  *
00040  */
00041 
00042 #ifndef MBED_MAX31850_H
00043 #define MBED_MAX31850_H
00044 
00045 #include "mbed.h"
00046 #include "LinkedList.h"
00047 
00048 #define C 0 //celsius 
00049 #define K 1 //Kelvin
00050 #define F 2 //fahrenheit
00051 #define R 3 //Rankin
00052 
00053 extern Serial pc;
00054 
00055 /** MAX31850
00056  *
00057  * Example:
00058  * @code
00059  * #include "mbed.h"
00060  * #include "MAX31850.h"
00061  *
00062  * MAX31850 probe(DATA_PIN);
00063  *  
00064  * int main() {
00065  *     while(true) {
00066  *         probe.convertTemperature(true, MAX31850::all_devices); //Start temperature conversion, wait until ready
00067  *         printf("It is %3.1foC\r\n", probe.temperature());
00068  *         wait(1);
00069  *     }
00070  * }
00071  * @endcode
00072  */
00073 class MAX31850
00074  {
00075 public:
00076     enum devices{
00077         this_device,     // command applies to only this device
00078         all_devices };   // command applies to all devices
00079     
00080     enum {
00081         invalid_conversion = -1000
00082     };
00083 
00084     /** Create a probe object connected to the specified pins
00085     * 
00086     * The probe might either by regular powered or parasite powered. If it is parasite
00087     * powered and power_pin is set, that pin will be used to switch an external mosfet connecting
00088     * data to Vdd. If it is parasite powered and the pin is not set, the regular data pin
00089     * is used to supply extra power when required. This will be sufficient as long as the 
00090     * number of probes is limitted.
00091     * 
00092     * For our application, we have the functions set up to only use external power. The constructor still supports
00093     * parasite power but the functions to not support it.
00094     */
00095     MAX31850 (PinName data_pin, PinName power_pin = NC, bool power_polarity = 0); // Constructor with parasite power pin
00096   
00097     ~MAX31850();
00098 
00099     /** Function to see if there are MAX31850
00100      *  devices left on a pin which do not have a corresponding MAX31850
00101      *  object
00102     *
00103     * @return - true if there are one or more unassigned devices, otherwise false
00104       */
00105     static bool unassignedProbe(PinName pin);
00106 
00107     /** This routine will initiate the temperature conversion within
00108       *  all MAX31850
00109       *  probes. 
00110       */
00111     void readAll();
00112 
00113     /** This function will return the probe temperature. Approximately 10ms per
00114       * probe to read its scratchpad, do CRC check and convert temperature on the LPC1768.
00115       *
00116       * @scratchpad scale, may be either 'c', 'f', 'k', and 'r'
00117       * @returns temperature for that scale, or MAX31850::invalid_conversion (-1000) if CRC error detected.
00118       */
00119     float getTemp(int scale = 4);     
00120 
00121     /** This function returns the 64 bit address associated with a
00122       * particular DS18B20.
00123       *
00124       * Contributed by John M. Larkin (jlarkin@whitworth.edu)
00125       *
00126       * @returns unsigned long long
00127       */
00128     unsigned long long getId();
00129 
00130 
00131     /** This function sets the _units variable to the 
00132      * users desired temperature units
00133      */
00134     void setUnits(int);
00135     
00136 
00137 private:
00138     bool _parasite_power;
00139     bool _power_mosfet;
00140     bool _power_polarity;
00141     
00142     static char CRC_byte(char _CRC, char byte );
00143     static bool onewire_reset(DigitalInOut *pin);
00144     void match_ROM();
00145     void skip_ROM();
00146     static bool search_ROM_routine(DigitalInOut *pin, char command, char *ROM_address);
00147     static void onewire_bit_out (DigitalInOut *pin, bool bit_data);
00148     void onewire_byte_out(char data);
00149     static bool onewire_bit_in(DigitalInOut *pin);
00150     char onewire_byte_in();
00151     static bool ROM_checksum_error(char *_ROM_address);
00152     bool scratchpad_checksum_error();
00153     void read_scratchpad();
00154     static bool unassignedProbe(DigitalInOut *pin, char *ROM_address);
00155 
00156     DigitalInOut _datapin;
00157     DigitalOut _parasitepin;
00158     
00159     char _ROM[8];
00160     char scratchpad[9];
00161     int _units;
00162     
00163     static LinkedList<node>  probes;
00164 };
00165 #endif