STTS751.h

00001 /* A library for STMicroelectronics STTS751 I2C temperature sensor
00002  * Copyright 2014, Takuo WATANABE (wtakuo)
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 STTS751_H
00018 #define STTS751_H
00019 
00020 #include "mbed.h"
00021 
00022 /** A library for STMicroelectronics STTS751 I2C temperature sensor
00023  *
00024  * http://www.st.com/web/catalog/sense_power/FM89/SC294/PF220116
00025  *
00026  * Example:
00027  * @code
00028  * #include "mbed.h"
00029  * #include "STTS751.h"
00030  *
00031  * // I2C pins: p9 = sda, p10 = scl
00032  * STTS751 sensor(p9, p10);
00033  *
00034  * // You can specify an I2C object instead.
00035  * // I2C i2c(p2, p10);
00036  * // STTS751 sensor(i2c);
00037  * 
00038  * int main() {
00039  *     // set the temperature resolution to 12bits
00040  *     sensor.setResolution(STTS751::RES_12);
00041  *     while (true) {
00042  *         printf("tmp: %.4f\n", (float)sensor);
00043  *         wait(1);
00044  *     }
00045  * }
00046  * @endcode
00047  */
00048 class STTS751 {
00049 public:
00050     /** Device models
00051      */
00052     enum Model {
00053         MODEL_0 = 0x00, /**< Model 0 (default) */
00054         MODEL_1 = 0x40  /**< Model 1 */
00055     };
00056 
00057     /** I2C slave address selectors
00058      * The I2C slave address of the device is determined by the pull up register for Addr/~Therm pin.
00059      *
00060      */
00061     enum Address {
00062         ADDRESS_0 = (0x48 << 1), /**< pull up resistor = 7.5K */
00063         ADDRESS_1 = (0x49 << 1), /**< pull up resistor = 12K */
00064         ADDRESS_2 = (0x38 << 1), /**< pull up resistor = 20K */
00065         ADDRESS_3 = (0x39 << 1)  /**< pull up resistor = 33K or GND (default) */
00066     };
00067 
00068     /** Temperature resolutions
00069      */
00070     enum Resolution {
00071         RES_9 = 0x08, /**<  9 bits */
00072         RES_10 = 0x00, /**< 10 bits (default) */
00073         RES_11 = 0x04, /**< 11 bits */
00074         RES_12 = 0x0c /**< 12 bits */
00075     };
00076 
00077     /** Create an STTS751 object connected to the specified I2C pins.
00078      *
00079      * @param sda     I2C data pin
00080      * @param scl     I2C clock pin
00081      * @param standby Standby mode (defaults to false)
00082      * @param addr    I2C slave address (defaults to ADDRESS_3)
00083      * @param model   Device model (defaults to MODEL_0)
00084      */
00085     STTS751(PinName sda, PinName scl,
00086             bool standby = false, Address addr = ADDRESS_3, Model model = MODEL_0);
00087 
00088 
00089     /** Create an STTS751 object connected to the specified I2C port.
00090      *
00091      * @param i2c     I2C port
00092      * @param standby Standby mode (defaults to false)
00093      * @param addr    I2C slave address (defaults to ADDRESS_3)
00094      * @param model   Device model (defaults to MODEL_0)
00095      */
00096     STTS751(I2C &_i2c,
00097             bool standby = false, Address addr = ADDRESS_3, Model model = MODEL_0);
00098 
00099     /** Initialize the device
00100      */
00101     void init();
00102 
00103     /** The I2C slave address (8bit) of the device
00104      *
00105      * @returns  The I2C slave address (8bit) of the device
00106      */
00107     int addr();
00108 
00109     /** Get the current temperature resolution
00110      *
00111      * @returns  The current temperature resolution
00112      */
00113     Resolution resolution();
00114 
00115     /** Set the temperature resolution
00116      *
00117      * @param res  Resolution (defaults to RES_10)
00118      */
00119     void setResolution(Resolution res = RES_10);
00120 
00121     /** Get the current conversion rate
00122      *
00123      * @returns  The current conversion rate
00124      */
00125     int conversionRate();
00126 
00127     /** Set the conversion rate
00128      *  Set the number of times the temperature value is updated each second.
00129      *  The conversion rate (times/second) can be calculated by 2^(rate - 4).
00130      *  Note that rate should be less than 8 if the temperature resolution is 12-bit and
00131      *  should be less than 9 if the temperature resolution is greater than 10-bit
00132      *
00133      * @param rate  Conversion rate (0 .. 9)
00134      */
00135     void setConversionRate(int rate);
00136 
00137     /** Set the device mode
00138      *
00139      * @param standby  true : standby mode, false : continuous conversion mode
00140      */
00141     void setStandbyMode(bool standby);
00142 
00143     /** Start a temperature conversion (in standby mode)
00144      */
00145     void start();
00146 
00147     /** Checks that a temperature conversion has finished and the temperature value is available
00148      *
00149      * @returns  true if a temperature conversion has finished and the temperature value is available
00150      */
00151     bool ready();
00152 
00153     /** Obtain the current temperature measurement
00154      *
00155      * @param nowait  If true, read the temperature value without waiting for finishing a conversion (in standby mode)
00156      * @returns       The current temperature measurement in Celsius.
00157      */
00158     float temp(bool nowait = false);
00159 
00160 #ifdef MBED_OPERATORS
00161     /** A shorthand for temp()
00162      *
00163      * @returns  The current temperature measurement in Celsius.
00164      */
00165     operator float();
00166 #endif
00167 
00168 protected:
00169     /** I2C registers
00170      */
00171     enum {
00172         REG_TEMPERATURE_H = 0x00,
00173         REG_STATUS = 0x01,
00174         REG_TEMPERATURE_L = 0x02,
00175         REG_CONFIGURATION = 0x03,
00176         REG_CONV_RATE = 0x04,
00177         REG_HIGH_LIMIT_H = 0x05,
00178         REG_HIGH_LIMIT_L = 0x06,
00179         REG_LOW_LIMIT_H = 0x07,
00180         REG_LOW_LIMIT_L = 0x08,
00181         REG_ONESHOT = 0x0f,
00182         REG_THERM = 0x20,
00183         REG_THERM_HYSTERESIS = 0x21,
00184         REG_SMBUS_TIMEOUT = 0x22,
00185         REG_PRODUCT_ID = 0xfd,
00186         REG_MFG_ID = 0xfe,
00187         REG_REVISION_ID = 0xff,
00188     };
00189 
00190     /** Configuration register (default 0x00)
00191      * - b7 : MASK1
00192      * - b6 : ~RUN/STOP (0 : continuous conversion mode, 1 : standby mode)
00193      * - b5 : 0
00194      * - b4 : RFU
00195      * - b3 : Tres1
00196      * - b2 : Tres0
00197      * - b1-b0 : RFU
00198      */
00199     enum {
00200         CONF_MASK1 = 0x80,
00201         CONF_RUNSTOP = 0x40,
00202         CONF_RES_MASK = 0x0c,
00203     };
00204 
00205     /** Status Register (default undefined)
00206      * - b7 : Busy
00207      * - b6 : T_HIGH
00208      * - b5 : T_LOW
00209      * - b4-b1 : RFU
00210      * - b0 : THRM
00211      */
00212     enum {
00213         STATUS_BUSY = 0x80,
00214         STATUS_THIGH = 0x40,
00215         STATUS_LOW = 0x20,
00216         STATUS_THURM = 0x01
00217     };
00218 
00219     /** Conversion Rate Register (default 4)
00220      * - b7-b4: 0
00221      * - b3-b0: Conversion rate (0..9)
00222      */
00223     enum {
00224         CONV_RATE_MASK = 0x0f
00225     };
00226 
00227     I2C _i2c;
00228     const int _addr;
00229     bool _standby;
00230 
00231     char read8(char reg);
00232     void write8(char reg, char data);
00233 };
00234 
00235 #endif