LM75B.h

00001 /* LM75B Driver Library
00002  * Copyright (c) 2013 Neil Thiessen
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *     http://www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00017 #ifndef LM75B_H
00018 #define LM75B_H
00019 
00020 #include "mbed.h"
00021 
00022 /** LM75B class.
00023  *  Used for controlling an LM75B temperature sensor connected via I2C.
00024  *
00025  * Example:
00026  * @code
00027  * #include "mbed.h"
00028  * #include "LM75B.h"
00029  *
00030  * //Create an LM75B object at the default address (ADDRESS_0)
00031  * LM75B sensor(p28, p27);
00032  *
00033  * int main()
00034  * {
00035  *     //Try to open the LM75B
00036  *     if (sensor.open()) {
00037  *         printf("Device detected!\n");
00038  *
00039  *         while (1) {
00040  *             //Print the current temperature
00041  *             printf("Temp = %.3f\n", (float)sensor);
00042  *
00043  *             //Sleep for 0.5 seconds
00044  *             wait(0.5);
00045  *         }
00046  *     } else {
00047  *         error("Device not detected!\n");
00048  *     }
00049  * }
00050  * @endcode
00051  */
00052 class LM75B
00053 {
00054 public:
00055     /** Represents the different I2C address possibilities for the LM75B
00056      */
00057     enum Address {
00058         ADDRESS_0 = (0x48 << 1),    /**< A[2:0] pins = 000 */
00059         ADDRESS_1 = (0x49 << 1),    /**< A[2:0] pins = 001 */
00060         ADDRESS_2 = (0x4A << 1),    /**< A[2:0] pins = 010 */
00061         ADDRESS_3 = (0x4B << 1),    /**< A[2:0] pins = 011 */
00062         ADDRESS_4 = (0x4C << 1),    /**< A[2:0] pins = 100 */
00063         ADDRESS_5 = (0x4D << 1),    /**< A[2:0] pins = 101 */
00064         ADDRESS_6 = (0x4E << 1),    /**< A[2:0] pins = 110 */
00065         ADDRESS_7 = (0x4F << 1)     /**< A[2:0] pins = 111 */
00066     };
00067 
00068     /** Represents the power mode of the LM75B
00069      */
00070     enum PowerMode {
00071         POWER_NORMAL,   /**< Chip is enabled and samples every 100ms */
00072         POWER_SHUTDOWN  /**< Chip is in low-power shutdown mode */
00073     };
00074 
00075     /** Represents OS pin mode of the LM75B
00076      */
00077     enum OSMode {
00078         OS_COMPARATOR,  /**< OS is asserted when the temperature reaches the alert threshold, and de-asserted when the temperature drops below the alert hysteresis threshold */
00079         OS_INTERRUPT    /**< OS is asserted when the temperature reaches the alert threshold, or drops below the alert hysteresis threshold, and only de-asserted when a register has been read */
00080     };
00081 
00082     /** Represents OS pin polarity of the LM75B
00083      */
00084     enum OSPolarity {
00085         OS_ACTIVE_LOW,  /**< OS is a logic low when asserted, and a logic high when de-asserted */
00086         OS_ACTIVE_HIGH  /**< OS is a logic high when asserted, and a logic low when de-asserted */
00087     };
00088 
00089     /** Represents OS pin fault queue length of the LM75B
00090      */
00091     enum OSFaultQueue {
00092         OS_FAULT_QUEUE_1,   /**< OS is asserted after 1 fault */
00093         OS_FAULT_QUEUE_2,   /**< OS is asserted after 2 consecutive faults */
00094         OS_FAULT_QUEUE_4,   /**< OS is asserted after 4 consecutive faults */
00095         OS_FAULT_QUEUE_6    /**< OS is asserted after 6 consecutive faults */
00096     };
00097 
00098     /** Create an LM75B object connected to the specified I2C pins with the specified I2C slave address
00099      *
00100      * @param sda The I2C data pin.
00101      * @param scl The I2C clock pin.
00102      * @param addr The I2C slave address (defaults to ADDRESS_0).
00103      * @param hz The I2C bus frequency (defaults to 400kHz).
00104      */
00105     LM75B(PinName sda, PinName scl, Address addr = ADDRESS_0, int hz = 400000);
00106 
00107     /** Probe for the LM75B and indicate if it's present on the bus
00108      *
00109      * @returns
00110      *   'true' if the device exists on the bus,
00111      *   'false' if the device doesn't exist on the bus.
00112      */
00113     bool open();
00114 
00115     /** Get the current power mode of the LM75B
00116      *
00117      * @returns The current power mode as a PowerMode enum.
00118      */
00119     LM75B::PowerMode powerMode();
00120 
00121     /** Set the power mode of the LM75B
00122      *
00123      * @param mode The new power mode as a PowerMode enum.
00124      */
00125     void powerMode(PowerMode mode);
00126 
00127     /** Get the current OS pin mode of the LM75B
00128      *
00129      * @returns The current OS pin mode as an OSMode enum.
00130      */
00131     LM75B::OSMode osMode();
00132 
00133     /** Set the OS pin mode of the LM75B
00134      *
00135      * @param mode The new OS pin mode as an OSMode enum.
00136      */
00137     void osMode(OSMode mode);
00138 
00139     /** Get the current OS pin polarity of the LM75B
00140      *
00141      * @returns The current OS pin polarity as an OSPolarity enum.
00142      */
00143     LM75B::OSPolarity osPolarity();
00144 
00145     /** Set the OS pin polarity of the LM75B
00146      *
00147      * @param polarity The new OS pin polarity as an OSPolarity enum.
00148      */
00149     void osPolarity(OSPolarity polarity);
00150 
00151     /** Get the current OS pin fault queue length of the LM75B
00152      *
00153      * @returns The current OS pin fault queue length as an OSFaultQueue enum.
00154      */
00155     LM75B::OSFaultQueue osFaultQueue();
00156 
00157     /** Set the OS pin fault queue length of the LM75B
00158      *
00159      * @param queue The new OS pin fault queue length as an OSFaultQueue enum.
00160      */
00161     void osFaultQueue(OSFaultQueue queue);
00162 
00163     /** Get the current alert temperature threshold of the LM75B
00164      *
00165      * @returns The current alert temperature threshold in °C.
00166      */
00167     float alertTemp();
00168 
00169     /** Set the alert temperature threshold of the LM75B
00170      *
00171      * @param temp The new alert temperature threshold in °C.
00172      */
00173     void alertTemp(float temp);
00174 
00175     /** Get the current alert temperature hysteresis threshold of the LM75B
00176      *
00177      * @returns The current alert temperature hysteresis threshold in °C.
00178      */
00179     float alertHyst();
00180 
00181     /** Set the alert temperature hysteresis threshold of the LM75B
00182      *
00183      * @param temp The new alert temperature hysteresis threshold in °C.
00184      */
00185     void alertHyst(float temp);
00186 
00187     /** Get the current temperature measurement of the LM75B
00188      *
00189      * @returns The current temperature measurement in °C.
00190      */
00191     float temp();
00192 
00193 #ifdef MBED_OPERATORS
00194     /** A shorthand for temp()
00195      *
00196      * @returns The current temperature measurement in °C.
00197      */
00198     operator float();
00199 #endif
00200 
00201 private:
00202     //I2C register addresses
00203     enum Register {
00204         REG_TEMP    = 0x00,
00205         REG_CONF    = 0x01,
00206         REG_THYST   = 0x02,
00207         REG_TOS     = 0x03
00208     };
00209 
00210     //Member variables
00211     I2C m_I2C;
00212     const int m_ADDR;
00213 
00214     //Internal functions
00215     char read8(char reg);
00216     void write8(char reg, char data);
00217     unsigned short read16(char reg);
00218     void write16(char reg, unsigned short data);
00219     float readAlertTempHelper(char reg);
00220     void writeAlertTempHelper(char reg, float temp);
00221 };
00222 
00223 #endif