added SHT2x third party sensor library

Author: wasn-eu

libraries/Sensor_ThirdParty/examples/SHT2x/README.md

@@ -0,0 +1 @@
+This is an Arduino library for the SHT21 / SHT25 humidity and temperature sensors.

libraries/Sensor_ThirdParty/examples/SHT2x/ReadSHT2x/ReadSHT2x.ino

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+/****************************************************************
+ * ReadSHT2x
+ *  An example sketch that reads the sensor and prints the
+ *  relative humidity to the PC's serial port
+ *
+ *  Tested with:
+ *    - SHT21-Breakout Humidity sensor from Modern Device
+ *    - SHT2x-Breakout Humidity sensor from MisensO Electronics
+ ***************************************************************/
+
+#include <Wire.h>
+#include <SHT2x.h>
+
+
+void setup()
+{
+  pinMode(Vext, OUTPUT);
+  digitalWrite(Vext, LOW);
+  delay(500);
+
+  Wire.begin();
+  Serial.begin(115200);
+}
+
+void loop()
+{
+  Serial.print("Humidity(%RH): ");
+  Serial.print(SHT2x.GetHumidity());
+  Serial.print("     Temperature(C): ");
+  Serial.println(SHT2x.GetTemperature());
+  Serial.print("     Dewpoint(C): ");
+  Serial.println(SHT2x.GetDewPoint());
+  
+  delay(1000);
+}
+

libraries/Sensor_ThirdParty/readme.md

@@ -15,3 +15,4 @@ Currently with following sensors:
 | BME280 | Seeed Studio | [Seeed Studio](https://github.com/Seeed-Studio/Grove_BME280) | Work well    |
 | BME680 | SV-Zanshin   | [SV-Zanshin](https://github.com/SV-Zanshin/BME680) | Work well  |
 | ADS1x15| Adafruit     | [Adafruit](https://github.com/adafruit/Adafruit_ADS1X15) | not tested yet |
+| SHT2x  | SodaqMoja    | [SodaqMoja](https://github.com/SodaqMoja/Sodaq_SHT2x) | not tested yet |

libraries/Sensor_ThirdParty/src/SHT2x.cpp

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+/*
+  SHT2x - A Humidity Library for Arduino.
+
+  Supported Sensor modules:
+    SHT21-Breakout Module - http://www.moderndevice.com/products/sht21-humidity-sensor
+    SHT2x-Breakout Module - http://www.misenso.com/products/001
+
+  Created by Christopher Ladden at Modern Device on December 2009.
+  Modified by Paul Badger March 2010
+  
+  Modified by www.misenso.com on October 2011:
+    - code optimisation
+    - compatibility with Arduino 1.0
+
+ * This file is part of Sodaq_SHT2x.
+ *
+ * Sodaq_SHT2x is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or(at your option) any later version.
+ *
+ * Sodaq_SHT2x is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Sodaq_SHT2x.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <math.h>
+#include <Arduino.h>
+#include <Wire.h>
+#include "SHT2x.h"
+
+// Specify the constants for water vapor and barometric pressure.
+#define WATER_VAPOR 17.62f
+#define BAROMETRIC_PRESSURE 243.5f
+
+typedef enum {
+    eSHT2xAddress = 0x40,
+} HUM_SENSOR_T;
+
+typedef enum {
+    eTempHoldCmd        = 0xE3,
+    eRHumidityHoldCmd   = 0xE5,
+    eTempNoHoldCmd      = 0xF3,
+    eRHumidityNoHoldCmd = 0xF5,
+} HUM_MEASUREMENT_CMD_T;
+
+
+/******************************************************************************
+ * Global Functions
+ ******************************************************************************/
+
+/**********************************************************
+ * GetHumidity
+ *  Gets the current humidity from the sensor.
+ *
+ * @return float - The relative humidity in %RH
+ **********************************************************/
+float SHT2xClass::GetHumidity(void)
+{
+    float value = readSensor(eRHumidityHoldCmd);
+    if (value == 0) {
+        return 0;                       // Some unrealistic value
+    }
+    return -6.0 + 125.0 / 65536.0 * value;
+}
+
+/**********************************************************
+ * GetTemperature
+ *  Gets the current temperature from the sensor.
+ *
+ * @return float - The temperature in Deg C
+ **********************************************************/
+float SHT2xClass::GetTemperature(void)
+{
+    float value = readSensor(eTempHoldCmd);
+    if (value == 0) {
+        return -273;                    // Roughly Zero Kelvin indicates an error
+    }
+    return -46.85 + 175.72 / 65536.0 * value;
+}
+
+/**********************************************************
+ * GetDewPoint
+ *  Gets the current dew point based on the current humidity and temperature
+ *
+ * @return float - The dew point in Deg C
+ **********************************************************/
+float SHT2xClass::GetDewPoint(void)
+{
+  float humidity = GetHumidity();
+  float temperature = GetTemperature();
+
+  // Calculate the intermediate value 'gamma'
+  float gamma = log(humidity / 100) + WATER_VAPOR * temperature / (BAROMETRIC_PRESSURE + temperature);
+  // Calculate dew point in Celsius
+  float dewPoint = BAROMETRIC_PRESSURE * gamma / (WATER_VAPOR - gamma);
+
+  return dewPoint;
+}
+
+/******************************************************************************
+ * Private Functions
+ ******************************************************************************/
+
+uint16_t SHT2xClass::readSensor(uint8_t command)
+{
+    uint16_t result;
+
+    Wire.beginTransmission(eSHT2xAddress);
+    Wire.write(command);
+    delay(100);
+    Wire.endTransmission();
+
+    Wire.requestFrom(eSHT2xAddress, 3);
+    uint32_t timeout = millis() + 300;       // Don't hang here for more than 300ms
+    while (Wire.available() < 3) {
+        if ((millis() - timeout) > 0) {
+            return 0;
+        }
+    }
+
+    //Store the result
+    result = Wire.read() << 8;
+    result += Wire.read();
+    result &= ~0x0003;   // clear two low bits (status bits)
+
+    //Clear the final byte from the buffer
+    Wire.read();
+
+    return result;
+}
+
+SHT2xClass SHT2x;

libraries/Sensor_ThirdParty/src/SHT2x.h

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+/*
+  SHT2x - A Humidity Library for Arduino.
+
+  Supported Sensor modules:
+    SHT21-Breakout Module - http://www.moderndevice.com/products/sht21-humidity-sensor
+    SHT2x-Breakout Module - http://www.misenso.com/products/001
+
+  Created by Christopher Ladden at Modern Device on December 2009.
+  
+  Modified by www.misenso.com on October 2011:
+    - code optimisation
+    - compatibility with Arduino 1.0
+
+ * This file is part of Sodaq_SHT2x.
+ *
+ * Sodaq_SHT2x is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or(at your option) any later version.
+ *
+ * Sodaq_SHT2x is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Sodaq_SHT2x.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+
+#ifndef SHT2X_H
+#define SHT2X_H
+
+#include <stdint.h>
+
+class SHT2xClass
+{
+  private:
+    uint16_t readSensor(uint8_t command);
+
+  public:
+    float GetHumidity(void);
+    float GetTemperature(void);
+    float GetDewPoint(void);
+};
+
+extern SHT2xClass SHT2x;
+
+#endif