Make SHTSensor a digital-sensor interface

SHT3xAnalog is now a standalone class split out from SHTSensor since
it's the only analog driver currently supported.
Support for SHTSensor integration was removed to simplify the
interface.

SHTSensor::SHTSensor and SHTSensor::init now do not take an optional
external SHTSensorDriver* anymore making internal memory management
simpler.

Other minor other code changes

Tested with SHT3x and SHTC1.
SHT3xAnalog tested without attached sensor.

Author: abrauchli

SHTSensor.cpp

@@ -1,6 +1,6 @@
 /*
  *  Copyright (c) 2016, Sensirion AG <[email protected]>
- *  Copyright (c) 2015, Johannes Winkelmann <[email protected]>
+ *  Copyright (c) 2015-2016, Johannes Winkelmann <[email protected]>
  *  All rights reserved.
  *
  *  Redistribution and use in source and binary forms, with or without
@@ -170,7 +170,7 @@ class SHT3xSensor : public SHTI2cSensor
 
   SHT3xSensor()
       : SHTI2cSensor(SHT3x_I2C_ADDRESS_44, SHT3x_ACCURACY_HIGH,
-                   -45, 175, 65535, 100, 65535)
+                     -45, 175, 65535, 100, 65535)
   {
   }
 
@@ -212,26 +212,16 @@ class SHT3xAltSensor : public SHT3xSensor
 // class SHT3xAnalogSensor
 //
 
-bool SHT3xAnalogSensor::readSample()
-{
-  readTemperature();
-  readHumidity();
-  return true;
-}
-
 float SHT3xAnalogSensor::readHumidity()
 {
   float max_adc = (float)((1 << mReadResolutionBits) - 1);
-  mHumidity = -12.5f + 125 * (analogRead(mHumidityAdcPin) / max_adc);
-  return mHumidity;
+  return -12.5f + 125 * (analogRead(mHumidityAdcPin) / max_adc);
 }
 
 float SHT3xAnalogSensor::readTemperature()
 {
   float max_adc = (float)((1 << mReadResolutionBits) - 1);
-  mTemperature = -66.875f + 218.75f *
-      (analogRead(mTemperatureAdcPin) / max_adc);
-  return mTemperature;
+  return -66.875f + 218.75f * (analogRead(mTemperatureAdcPin) / max_adc);
 }
 
 
@@ -247,36 +237,26 @@ const SHTSensor::SHTSensorType SHTSensor::AUTO_DETECT_SENSORS[] = {
 const float SHTSensor::TEMPERATURE_INVALID = NAN;
 const float SHTSensor::HUMIDITY_INVALID = NAN;
 
-bool SHTSensor::init(SHTSensorDriver *sensor)
+bool SHTSensor::init()
 {
   if (mSensor != NULL) {
     cleanup();
   }
-  mOwnSensor = (sensor == NULL);
-  if (sensor) {
-    mSensor = sensor;
-    return true;
-  }
 
   switch(mSensorType) {
     case SHT3X:
-        mSensor = new SHT3xSensor();
-        break;
+      mSensor = new SHT3xSensor();
+      break;
 
     case SHT3X_ALT:
-        mSensor = new SHT3xAltSensor();
-        break;
+      mSensor = new SHT3xAltSensor();
+      break;
 
     case SHTW1:
     case SHTW2:
     case SHTC1:
-        mSensor = new SHTC1Sensor();
-        break;
-
-    case SHT3X_ANALOG:
-        // There are no default parameters for the analog sensor.
-        // Driver instantiation must happen explicitly and be passed to init().
-        break;
+      mSensor = new SHTC1Sensor();
+      break;
 
     case AUTO_DETECT:
     {
@@ -290,7 +270,6 @@ bool SHTSensor::init(SHTSensorDriver *sensor)
           break;
         }
       }
-      // No sensor was auto detected
       if (!detected) {
         cleanup();
       }
@@ -325,7 +304,7 @@ bool SHTSensor::setI2cAddress(uint8_t newAddress)
 
 void SHTSensor::cleanup()
 {
-  if (mOwnSensor && mSensor) {
+  if (mSensor) {
     delete mSensor;
     mSensor = NULL;
   }

SHTSensor.h

@@ -1,6 +1,6 @@
 /*
  *  Copyright (c) 2016, Sensirion AG <[email protected]>
- *  Copyright (c) 2015, Johannes Winkelmann <[email protected]>
+ *  Copyright (c) 2015-2016, Johannes Winkelmann <[email protected]>
  *  All rights reserved.
  *
  *  Redistribution and use in source and binary forms, with or without
@@ -41,8 +41,9 @@ class SHTSensor
 {
 public:
   /**
-   * Enum of the supported Sensirion SHT Sensors.
-   * Using the special AutoDetect sensor causes all i2c sensors to be
+   * Enum of the supported Digital Sensirion SHT Sensors.
+   * For analog sensors, see SHT3xAnalogSensor.
+   * Using the special AUTO_DETECT sensor causes all i2c sensors to be
    * probed. The first matching sensor will then be used.
    */
   enum SHTSensorType {
@@ -55,9 +56,7 @@ class SHTSensor
     SHT3X_ALT,
     SHTC1,
     SHTW1,
-    SHTW2,
-    // Analog sensors:
-    SHT3X_ANALOG
+    SHTW2
   };
 
   /**
@@ -88,20 +87,10 @@ class SHTSensor
    * Instantiate a new SHTSensor
    * By default, the i2c bus is queried for known SHT Sensors. To address
    * a specific sensor, set the `sensorType'.
-   *
-   * Some sensor drivers require a specific parameter set and cannot be
-   * auto-detected. Those must be instantiated separately and be passed to
-   * `sensor'. In any other case sensor must be NULL.
-   *
-   * `ownSensor' describes whether the SHTSensor is responsible for freeing the
-   * memory pointed to by `sensor'. This should never need to be set explicitly.
    */
-  SHTSensor(SHTSensorType sensorType = AUTO_DETECT,
-            SHTSensorDriver *sensor = NULL,
-            bool ownSensor = false)
+  SHTSensor(SHTSensorType sensorType = AUTO_DETECT)
       : mSensorType(sensorType),
-        mSensor(sensor),
-        mOwnSensor(ownSensor),
+        mSensor(NULL),
         mTemperature(SHTSensor::TEMPERATURE_INVALID),
         mHumidity(SHTSensor::HUMIDITY_INVALID)
   {
@@ -112,11 +101,11 @@ class SHTSensor
   }
 
   /**
-   * Initialize a new Temperature and Humidity sensor driver
-   * To read out the sensor use readSample(), then use getTemperature() and
+   * Initialize the sensor driver
+   * To read out the sensor use readSample(), followed by getTemperature() and
    * getHumidity() to retrieve the values from the sample
    */
-  bool init(SHTSensorDriver *driver = NULL);
+  bool init();
 
   /**
    * Read new values from the sensor
@@ -162,7 +151,6 @@ class SHTSensor
 
   SHTSensorType mSensorType;
   SHTSensorDriver *mSensor;
-  bool mOwnSensor;
   float mTemperature;
   float mHumidity;
 };
@@ -171,7 +159,7 @@ class SHTSensor
 const uint8_t SHT3x_I2C_ADDRESS_44 = 0x44;
 const uint8_t SHT3x_I2C_ADDRESS_45 = 0x45;
 
-/** Abstract class for an SHT Sensor driver */
+/** Abstract class for a digital SHT Sensor driver */
 class SHTSensorDriver
 {
 public:
@@ -271,7 +259,7 @@ class SHTI2cSensor : public SHTSensorDriver {
                           uint8_t dataLength);
 };
 
-class SHT3xAnalogSensor : public SHTSensorDriver
+class SHT3xAnalogSensor
 {
 public:
 
@@ -281,19 +269,11 @@ class SHT3xAnalogSensor : public SHTSensorDriver
    * An optional `readResolutionBits' can be set since the Arduino/Genuino Zero
    * support 12bit precision analog readings. By default, 10 bit precision is
    * used.
-   * The analog instance can then (a) be used directly or (b) be passed to the
-   * SHTDriver instance for transparent usage accross SHT drivers:
    *
-   * Example (a):
+   * Example usage:
    * SHT3xAnalogSensor sht3xAnalog(HUMIDITY_PIN, TEMPERATURE_PIN);
    * float humidity = sht.readHumidity();
-   *
-   * Example (b):
-   * SHT3xAnalogSensor shtDriver(HUMIDITY_PIN, TEMPERATURE_PIN);
-   * SHTDriver sht(SHTDriver::SHT3xAnalog);
-   * sht.init(&shtDriver)
-   * sht.readSample();
-   * float temperature = sht.getTemperature();
+   * float temperature = sht.readTemperature();
    */
   SHT3xAnalogSensor(uint8_t humidityPin, uint8_t temperaturePin,
                     uint8_t readResolutionBits = 10)
@@ -306,8 +286,6 @@ class SHT3xAnalogSensor : public SHTSensorDriver
   {
   }
 
-  virtual bool readSample();
-
   float readHumidity();
   float readTemperature();
 

examples/sht-autodetect/sht-autodetect.ino

@@ -26,7 +26,7 @@ void loop() {
   // put your main code here, to run repeatedly:
 
   if (sht.readSample()) {
-      Serial.print("SHT:");
+      Serial.print("SHT:\n");
       Serial.print("  RH: ");
       Serial.print(sht.getHumidity(), 2);
       Serial.print("\n");