Diff: sht15.hpp

Revision:

0:d55659b0c4a0

Child:

1:8465801be23f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sht15.hpp	Thu Nov 18 10:23:43 2010 +0000
@@ -0,0 +1,249 @@
+/**
+ * Copyright (c) 2010 Roy van Dam <roy@negative-black.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+ 
+#ifndef _SHT15_HPP_
+#define _SHT15_HPP_
+
+#include "mbed.h"
+#include "i2c.hpp"
+
+namespace SHTx {    
+    /**
+     * Class: SHT15
+     *  Humidity and Temperature Sensor - SHT15
+     *  High level software interface.
+     */
+    class SHT15 {
+    private:
+        I2C i2c;
+        
+        bool ready;
+        bool scale;
+    
+        uint8_t  status_register;
+        uint16_t humidity;
+        uint16_t temperature;
+
+        struct coefficients {
+            // Humidity conversion coefficients
+            float c1[2], c2[2], c3[2];
+
+            // Temperature conversion coefficients
+            float dc[2], df[2], dv[2];
+
+            // Temperature compensation coefficients
+            float t1[2], t2[2];
+
+            // Initialize table
+            coefficients(void) {
+                c1[0] = -2.046f;        c2[1] = -2.046f;
+                c2[0] =  0.036f;        c2[1] =  0.587f;
+                c3[0] = -0.0000015955f; c2[1] = -0.00040845f;
+
+                dc[0] =  0.01f;         dc[1] =  0.04f;
+                df[0] =  0.018f;        df[1] =  0.072f;
+                dv[0] = -39.7f;         dv[1] = -39.5f;
+
+                t1[0] =  0.01f;         t1[1] =  0.01f;
+                t2[0] =  0.00008f;      t2[1] =  0.00128f;
+            };
+        } coefficient;
+    
+        enum cmd_list {
+            cmd_read_temperature = 0x03,
+            cmd_read_humidity    = 0x05,
+            cmd_read_register    = 0x07,
+            cmd_write_register   = 0x06,
+            cmd_reset_device     = 0x1E
+        };
+
+        enum flag_list {
+            flag_resolution = 0x01,
+            flag_reset      = 0x02,
+            flag_heater     = 0x04,
+            flag_battery    = 0x40
+        };
+    
+    public:
+        /*
+         * Initializes I2C interface and waits
+         * the 11ms device initialization time.
+         */
+        SHT15(PinName sda, PinName scl);
+
+        /**
+         * Function: getTemperature
+         *  Returns the current temperature.
+         *
+         * Values:
+         *  returns - current temperature.
+         */
+        float getTemperature(void);
+    
+        /**
+         * Function: getHumidity
+         *  Returns the current relative humidity.
+         *
+         * Values:
+         *  returns - relative humidity.
+         */
+        float getHumidity(void);
+
+        /**
+         * Function: checkBattery
+         *  Returns true if battery voltage drops
+         *    below 2.4 volt.
+         *
+         * Values:
+         *  returns - true on low battery, false otherwise
+         */
+        bool checkBattery(void);
+    
+        /**
+         * Function: setHeater
+         *  Enable on chip heating element. The heater may 
+         *  increase the temperature of the sensor by 5C to
+         *  10C beyond ambient temperature.
+         *
+         * Values:
+         *  value - true->on, false->off
+         *  return - operation result
+         */
+        bool setHeater(bool value);
+
+        /**
+         * Function: setResolution
+         *  Set lower measurement resolution to allow
+         *  faster update frequencies.
+         *
+         * Resolutions
+         *  low:   8bit humid. - 12bit temp.
+         *  high: 12bit humid. - 14bit temp.
+         *
+         * Values:
+         *  value - true->low, false->high
+         *  return - operation result
+         */
+        bool setResolution(bool value);
+
+        /**
+         * Function: setScale
+         *  Sets output scale to fahrenheit or celcius.
+         *
+         * Values:
+         *  value - true->fahrenheit, false->celcius
+         */
+        void setScale(bool value);
+    
+        /**
+         * Function: update
+         *  Performs humidity and temperature
+         *  sensor readout of the chip.
+         *
+         * Values:
+         *  return - operation result
+         */
+        bool update(void);
+    
+        /**
+         * Function: reset
+         *  Performs full chip reset.
+         *
+         * Values:
+         *  return - operation result
+         */
+        bool reset(void);
+    
+    private:
+    
+        /**
+         * Function: convertTemperature
+         *  Convert sensor data to human readable value
+         *  on the farenheit or celcius scale.
+         *
+         * Values:
+         *  sot    - raw temperatue sensor output
+         *  res    - true->low, false->high 
+         *  scale  - true->fahrenheit, false->celcius 
+         *  return - temperature
+         */
+        float convertTemperature(uint16_t sot, bool res = false, bool scale = false);
+    
+        /**
+         * Function: convertHumidity
+         *  Convert sensor data to relative humidity
+         *  in percentage.
+         *
+         * Values:
+         *  sohr   - raw humidity sensor output
+         *  sot    - raw temperatue sensor output
+         *  res    - true->low, false->high
+         *  return - relative humidity
+         */
+        float convertHumidity(uint16_t sohr, uint16_t sot, bool res = false);
+      
+        /**
+         * Function: writeRegister
+         *  Write internal chip register.
+         *
+         * Values:
+         *  return - operation result
+         */
+        bool writeRegister(void);
+    
+        /**
+         * Function: readRegister
+         *  Reads internal chip register
+         *
+         * Values:
+         *  command - register to be accessed
+         *  return  - operation result
+         */
+        bool readRegister(cmd_list command);
+    
+        /**
+         * Function: setFlag
+         *  Modify local register flag.
+         *
+         * Values:
+         *  flag  - flag to be modified
+         *  value - value to be assigned
+         */
+        void setFlag(flag_list flag, bool value);
+    
+        /**
+         * Function: getFlag
+         *  Get local register flag.
+         *
+         * Values:
+         *  returns - flag value
+         */
+        bool getFlag(flag_list flag);
+    };
+}
+
+/* !_SHT15_HPP_ */
+#endif
\ No newline at end of file