Revision 3:f9d3008f7e8f, committed 2014-02-05

Comitter:

takuo

Date:

Wed Feb 05 04:24:36 2014 +0000

Parent:

2:3116fe4a0079

Commit message:

Standby mode is now supported.; Conversion rate can be changed.

Changed in this revision

diff -r 3116fe4a0079 -r f9d3008f7e8f STTS751.cpp
--- a/STTS751.cpp	Sun Jan 19 03:13:38 2014 +0000
+++ b/STTS751.cpp	Wed Feb 05 04:24:36 2014 +0000
@@ -16,21 +16,24 @@
 
 #include "STTS751.h"
 
-#define SET_BITS(x,m,b) (((x) & !(m)) | (b))
+#define SET_BITS(x,m,b) (((x) & ~(m)) | (b))
 
-STTS751::STTS751(PinName sda, PinName scl, Address addr, Model model): _i2c(sda, scl), _addr(addr | model)
-{
+STTS751::STTS751(PinName sda, PinName scl, bool standby, Address addr, Model model) :
+        _i2c(sda, scl), _addr(addr | model), _standby(standby) {
     init();
 }
 
-STTS751::STTS751(I2C &i2c, Address addr, Model model): _i2c(i2c), _addr(addr | model)
-{
+STTS751::STTS751(I2C &i2c, bool standby, Address addr, Model model) :
+        _i2c(i2c), _addr(addr | model), _standby(standby) {
     init();
 }
 
-void STTS751::init()
-{
-    write8(REG_CONFIGURATION, 0x00);
+void STTS751::init() {
+    char conf = 0x00;
+    if (_standby)
+        conf |= CONF_RUNSTOP;
+    write8(REG_CONFIGURATION, conf);
+    // conversion rate = 1/sec
     write8(REG_CONV_RATE, 0x04);
 }
 
@@ -40,25 +43,57 @@
 
 STTS751::Resolution STTS751::resolution() {
     char conf = read8(REG_CONFIGURATION);
-    return (STTS751::Resolution)(conf & RES_MASK);
+    return (STTS751::Resolution) (conf & CONF_RES_MASK);
 }
 
 void STTS751::setResolution(STTS751::Resolution res) {
     char conf = read8(REG_CONFIGURATION);
-    conf = SET_BITS(conf, RES_MASK, res);
+    conf = SET_BITS(conf, CONF_RES_MASK, res);
     write8(REG_CONFIGURATION, conf);
 }
 
-float STTS751::temp()
-{
+int STTS751::conversionRate() {
+    char conv = read8(REG_CONV_RATE);
+    return conv & CONV_RATE_MASK;
+}
+
+void STTS751::setConversionRate(int rate) {
+    write8(REG_CONV_RATE, (char)(rate & CONV_RATE_MASK));
+}
+
+void STTS751::setStandbyMode(bool standby) {
+    _standby = standby;
+    char conf = read8(REG_CONFIGURATION);
+    if (_standby)
+        conf |= CONF_RUNSTOP;
+    else
+        conf &= ~CONF_RUNSTOP;
+    write8(REG_CONFIGURATION, conf);
+}
+
+void STTS751::start() {
+    if (ready())
+        write8(REG_ONESHOT, 1);
+}
+
+bool STTS751::ready() {
+    char status = read8(REG_STATUS);
+    return (status & STATUS_BUSY) == 0;
+}
+
+float STTS751::temp(bool nowait) {
+    if (_standby && !nowait) {
+        start();
+        while (!ready())
+            wait(0.01);
+    }
     signed char h = read8(REG_TEMPERATURE_H);
     unsigned char l = read8(REG_TEMPERATURE_L);
     return ((h << 8) | l) / 256.0;
 }
 
 #ifdef MBED_OPERATORS
-STTS751::operator float()
-{
+STTS751::operator float() {
     return temp();
 }
 #endif

diff -r 3116fe4a0079 -r f9d3008f7e8f STTS751.h
--- a/STTS751.h	Sun Jan 19 03:13:38 2014 +0000
+++ b/STTS751.h	Wed Feb 05 04:24:36 2014 +0000
@@ -20,6 +20,7 @@
 #include "mbed.h"
 
 /** A library for STMicroelectronics STTS751 I2C temperature sensor
+ *
  * http://www.st.com/web/catalog/sense_power/FM89/SC294/PF220116
  *
  * Example:
@@ -28,33 +29,34 @@
  * #include "STTS751.h"
  *
  * // I2C pins: p9 = sda, p10 = scl
- * STTS751 temp(p9, p10);
+ * STTS751 sensor(p9, p10);
  *
  * // You can specify an I2C object instead.
  * // I2C i2c(p2, p10);
- * // STTS751 temp(i2c);
+ * // STTS751 sensor(i2c);
  * 
  * int main() {
  *     // set the temperature resolution to 12bits
- *     temp.setResolution(STTS751::RES_12);
+ *     sensor.setResolution(STTS751::RES_12);
  *     while (true) {
- *         printf("tmp: %.4f\n", (float)temp);
+ *         printf("tmp: %.4f\n", (float)sensor);
  *         wait(1);
  *     }
  * }
  * @endcode
  */
-class STTS751
-{
+class STTS751 {
 public:
     /** Device models
      */
     enum Model {
-        MODEL_0 = 0x00,  /**< Model 0 (default) */
-        MODEL_1 = 0x40   /**< Model 1 */
+        MODEL_0 = 0x00, /**< Model 0 (default) */
+        MODEL_1 = 0x40  /**< Model 1 */
     };
 
-    /** I2C address selectors
+    /** I2C slave address selectors
+     * The I2C slave address of the device is determined by the pull up register for Addr/~Therm pin.
+     *
      */
     enum Address {
         ADDRESS_0 = (0x48 << 1), /**< pull up resistor = 7.5K */
@@ -66,34 +68,41 @@
     /** Temperature resolutions
      */
     enum Resolution {
-        RES_9  = 0x08, /**< 9 bits */
+        RES_9 = 0x08, /**<  9 bits */
         RES_10 = 0x00, /**< 10 bits (default) */
         RES_11 = 0x04, /**< 11 bits */
-        RES_12 = 0x0c  /**< 12 bits */
+        RES_12 = 0x0c /**< 12 bits */
     };
 
     /** Create an STTS751 object connected to the specified I2C pins.
      *
-     * @param sda    I2C data pin
-     * @param scl    I2C clock pin
-     * @param addr   I2C slave address (defaults to ADDRESS_3)
-     * @param model  Device model (defaults to MODEL_0)
+     * @param sda     I2C data pin
+     * @param scl     I2C clock pin
+     * @param standby Standby mode (defaults to false)
+     * @param addr    I2C slave address (defaults to ADDRESS_3)
+     * @param model   Device model (defaults to MODEL_0)
      */
-    STTS751(PinName sda, PinName scl, Address addr = ADDRESS_3, Model model = MODEL_0);
+    STTS751(PinName sda, PinName scl,
+            bool standby = false, Address addr = ADDRESS_3, Model model = MODEL_0);
+
 
     /** Create an STTS751 object connected to the specified I2C port.
      *
-     * @param i2c    I2C port
-     * @param addr   I2C slave address (defaults to ADDRESS_3)
-     * @param model  Device model (defaults to MODEL_0)
+     * @param i2c     I2C port
+     * @param standby Standby mode (defaults to false)
+     * @param addr    I2C slave address (defaults to ADDRESS_3)
+     * @param model   Device model (defaults to MODEL_0)
      */
-    STTS751(I2C &_i2c, Address addr = ADDRESS_3, Model model = MODEL_0);
+    STTS751(I2C &_i2c,
+            bool standby = false, Address addr = ADDRESS_3, Model model = MODEL_0);
 
     /** Initialize the device
      */
     void init();
 
-    /** The I2C address (8bit address) of the device
+    /** The I2C slave address (8bit) of the device
+     *
+     * @returns  The I2C slave address (8bit) of the device
      */
     int addr();
 
@@ -109,12 +118,45 @@
      */
     void setResolution(Resolution res = RES_10);
 
+    /** Get the current conversion rate
+     *
+     * @returns  The current conversion rate
+     */
+    int conversionRate();
+
+    /** Set the conversion rate
+     *  Set the number of times the temperature value is updated each second.
+     *  The conversion rate (times/second) can be calculated by 2^(rate - 4).
+     *  Note that rate should be less than 8 if the temperature resolution is 12-bit and
+     *  should be less than 9 if the temperature resolution is greater than 10-bit
+     *
+     * @param rate  Conversion rate (0 .. 9)
+     */
+    void setConversionRate(int rate);
+
+    /** Set the device mode
+     *
+     * @param standby  true : standby mode, false : continuous conversion mode
+     */
+    void setStandbyMode(bool standby);
+
+    /** Start a temperature conversion (in standby mode)
+     */
+    void start();
+
+    /** Checks that a temperature conversion has finished and the temperature value is available
+     *
+     * @returns  true if a temperature conversion has finished and the temperature value is available
+     */
+    bool ready();
+
     /** Obtain the current temperature measurement
      *
-     * @returns  The current temperature measurement in Celsius.
+     * @param nowait  If true, read the temperature value without waiting for finishing a conversion (in standby mode)
+     * @returns       The current temperature measurement in Celsius.
      */
-    float temp();
-    
+    float temp(bool nowait = false);
+
 #ifdef MBED_OPERATORS
     /** A shorthand for temp()
      *
@@ -124,6 +166,8 @@
 #endif
 
 protected:
+    /** I2C registers
+     */
     enum {
         REG_TEMPERATURE_H = 0x00,
         REG_STATUS = 0x01,
@@ -141,11 +185,48 @@
         REG_PRODUCT_ID = 0xfd,
         REG_MFG_ID = 0xfe,
         REG_REVISION_ID = 0xff,
-        RES_MASK = 0x0c
+    };
+
+    /** Configuration register (default 0x00)
+     * - b7 : MASK1
+     * - b6 : ~RUN/STOP (0 : continuous conversion mode, 1 : standby mode)
+     * - b5 : 0
+     * - b4 : RFU
+     * - b3 : Tres1
+     * - b2 : Tres0
+     * - b1-b0 : RFU
+     */
+    enum {
+        CONF_MASK1 = 0x80,
+        CONF_RUNSTOP = 0x40,
+        CONF_RES_MASK = 0x0c,
+    };
+
+    /** Status Register (default undefined)
+     * - b7 : Busy
+     * - b6 : T_HIGH
+     * - b5 : T_LOW
+     * - b4-b1 : RFU
+     * - b0 : THRM
+     */
+    enum {
+        STATUS_BUSY = 0x80,
+        STATUS_THIGH = 0x40,
+        STATUS_LOW = 0x20,
+        STATUS_THURM = 0x01
+    };
+
+    /** Conversion Rate Register (default 4)
+     * - b7-b4: 0
+     * - b3-b0: Conversion rate (0..9)
+     */
+    enum {
+        CONV_RATE_MASK = 0x0f
     };
 
     I2C _i2c;
     const int _addr;
+    bool _standby;
 
     char read8(char reg);
     void write8(char reg, char data);