added support for sht4x

Author: ndml28

README.md

@@ -8,6 +8,7 @@ Repository for Sensirion humidity and temperature sensor support on Arduino
 - SHT3x-DIS (I2C)
 - SHT3x-ARP (ratiometric analog voltage output)
 - SHT85
+- SHT4x
 
 ## Installation
 

SHTSensor.cpp

@@ -51,7 +51,6 @@ bool SHTSensorDriver::readSample()
 // class SHTI2cSensor
 //
 
-const uint8_t SHTI2cSensor::CMD_SIZE             = 2;
 const uint8_t SHTI2cSensor::EXPECTED_DATA_SIZE   = 6;
 
 bool SHTI2cSensor::readFromI2c(uint8_t i2cAddress,
@@ -110,12 +109,13 @@ uint8_t SHTI2cSensor::crc8(const uint8_t *data, uint8_t len)
 bool SHTI2cSensor::readSample()
 {
   uint8_t data[EXPECTED_DATA_SIZE];
-  uint8_t cmd[CMD_SIZE];
+  uint8_t cmd[mCmd_Size];
 
   cmd[0] = mI2cCommand >> 8;
+  //is omitted for SHT4x Sensors
   cmd[1] = mI2cCommand & 0xff;
 
-  if (!readFromI2c(mI2cAddress, cmd, CMD_SIZE, data,
+  if (!readFromI2c(mI2cAddress, cmd, mCmd_Size, data,
                    EXPECTED_DATA_SIZE, mDuration)) {
     return false;
   }
@@ -133,12 +133,12 @@ bool SHTI2cSensor::readSample()
   mTemperature = mA + mB * (val / mC);
 
   val = (data[3] << 8) + data[4];
-  mHumidity = mX * (val / mY);
+  mHumidity = mX + mY * (val / mZ);
 
-  return true;
+  return true; 
+  
 }
 
-
 //
 // class SHTC1Sensor
 //
@@ -148,7 +148,7 @@ class SHTC1Sensor : public SHTI2cSensor
 public:
     SHTC1Sensor()
         // clock stretching disabled, high precision, T first
-        : SHTI2cSensor(0x70, 0x7866, 15, -45, 175, 65535, 100, 65535)
+        : SHTI2cSensor(0x70, 0x7866, 15, -45, 175, 65535, 0, 100, 65535, 2)
     {
     }
 };
@@ -176,7 +176,7 @@ class SHT3xSensor : public SHTI2cSensor
   SHT3xSensor(uint8_t i2cAddress = SHT3X_I2C_ADDRESS_44)
       : SHTI2cSensor(i2cAddress, SHT3X_ACCURACY_HIGH,
                      SHT3X_ACCURACY_HIGH_DURATION,
-                     -45, 175, 65535, 100, 65535)
+                     -45, 175, 65535, 0, 100, 65535, 2)
   {
   }
 
@@ -203,6 +203,55 @@ class SHT3xSensor : public SHTI2cSensor
 };
 
 
+//
+// class SHT4xSensor
+//
+
+class SHT4xSensor : public SHTI2cSensor
+{
+private:
+  static const uint16_t SHT4X_ACCURACY_HIGH    = 0xFD00;
+  static const uint16_t SHT4X_ACCURACY_MEDIUM  = 0xF600;
+  static const uint16_t SHT4X_ACCURACY_LOW     = 0xE000;
+
+  static const uint8_t SHT4X_ACCURACY_HIGH_DURATION   = 10;
+  static const uint8_t SHT4X_ACCURACY_MEDIUM_DURATION = 4;
+  static const uint8_t SHT4X_ACCURACY_LOW_DURATION    = 2;
+
+public:
+  static const uint8_t SHT4X_I2C_ADDRESS_44 = 0x44;
+  static const uint8_t SHT4X_I2C_ADDRESS_45 = 0x45;
+
+  SHT4xSensor(uint8_t i2cAddress = SHT4X_I2C_ADDRESS_44)
+      : SHTI2cSensor(i2cAddress, SHT4X_ACCURACY_HIGH,
+                     SHT4X_ACCURACY_HIGH_DURATION,
+                     -45, 175, 65535, -6, 125, 65535, 1)
+  {
+  }
+
+  virtual bool setAccuracy(SHTSensor::SHTAccuracy newAccuracy)
+  {
+    switch (newAccuracy) {
+      case SHTSensor::SHT_ACCURACY_HIGH:
+        mI2cCommand = SHT4X_ACCURACY_HIGH;
+        mDuration = SHT4X_ACCURACY_HIGH_DURATION;
+        break;
+      case SHTSensor::SHT_ACCURACY_MEDIUM:
+        mI2cCommand = SHT4X_ACCURACY_MEDIUM;
+        mDuration = SHT4X_ACCURACY_MEDIUM_DURATION;
+        break;
+      case SHTSensor::SHT_ACCURACY_LOW:
+        mI2cCommand = SHT4X_ACCURACY_LOW;
+        mDuration = SHT4X_ACCURACY_LOW_DURATION;
+        break;
+      default:
+        return false;
+    }
+    return true;
+  }
+};
+
+
 //
 // class SHT3xAnalogSensor
 //
@@ -227,7 +276,8 @@ float SHT3xAnalogSensor::readTemperature()
 const SHTSensor::SHTSensorType SHTSensor::AUTO_DETECT_SENSORS[] = {
   SHT3X,
   SHT3X_ALT,
-  SHTC1
+  SHTC1,
+  SHT4X
 };
 const float SHTSensor::TEMPERATURE_INVALID = NAN;
 const float SHTSensor::HUMIDITY_INVALID = NAN;
@@ -252,14 +302,17 @@ bool SHTSensor::init()
     case SHTC1:
       mSensor = new SHTC1Sensor();
       break;
-
+    case SHT4X:
+      mSensor = new SHT4xSensor();
+      break;
     case AUTO_DETECT:
     {
       bool detected = false;
       for (unsigned int i = 0;
            i < sizeof(AUTO_DETECT_SENSORS) / sizeof(AUTO_DETECT_SENSORS[0]);
            ++i) {
         mSensorType = AUTO_DETECT_SENSORS[i];
+        delay(40);
         if (init()) {
           detected = true;
           break;

SHTSensor.h

@@ -56,7 +56,8 @@ class SHTSensor
     SHT3X_ALT,
     SHTC1,
     SHTW1,
-    SHTW2
+    SHTW2,
+    SHT4X
   };
 
   /**
@@ -146,10 +147,12 @@ class SHTSensor
    */
   bool setAccuracy(SHTAccuracy newAccuracy);
 
+  SHTSensorType mSensorType;
+
 private:
   void cleanup();
 
-  SHTSensorType mSensorType;
+  
   SHTSensorDriver *mSensor;
   float mTemperature;
   float mHumidity;
@@ -197,7 +200,7 @@ class SHTSensorDriver
 class SHTI2cSensor : public SHTSensorDriver {
 public:
   /** Size of i2c commands to send */
-  static const uint8_t CMD_SIZE;
+  
 
   /** Size of i2c replies to expect */
   static const uint8_t EXPECTED_DATA_SIZE;
@@ -210,14 +213,14 @@ class SHTI2cSensor : public SHTSensorDriver {
    * the formula: temperature = a + b * (rawTemperature / c)
    * and the values `x' and `y' to convert the fixed-point humidity value
    * received by the sensor to a floating point value using the formula:
-   * humidity = x * (rawHumidity / y)
+   * humidity = x + y * (rawHumidity / z)
    * duration is the duration in milliseconds of one measurement
    */
   SHTI2cSensor(uint8_t i2cAddress, uint16_t i2cCommand, uint8_t duration,
                float a, float b, float c,
-               float x, float y)
+               float x, float y, float z, uint8_t cmd_Size)
       : mI2cAddress(i2cAddress), mI2cCommand(i2cCommand), mDuration(duration),
-        mA(a), mB(b), mC(c), mX(x), mY(y)
+        mA(a), mB(b), mC(c), mX(x), mY(y), mZ(z), mCmd_Size(cmd_Size)
   {
   }
 
@@ -235,6 +238,8 @@ class SHTI2cSensor : public SHTSensorDriver {
   float mC;
   float mX;
   float mY;
+  float mZ;
+  uint8_t mCmd_Size;
 
 private:
   static uint8_t crc8(const uint8_t *data, uint8_t len);