Add SHT4x example

Author: Fototux

SDP8xx_I2C_minimal_example/SDP8xx_I2C_minimal_example.ino

@@ -31,8 +31,9 @@
 
 #include <Wire.h>
 
-// SDP810 500 Pa
-const int16_t SDP810_ADDRESS = 0x25;
+// SDP8xx with I2C address = 0x25
+// depending on the sensor type this could be alternatively 0x26
+const int16_t SDP8xx_ADDRESS = 0x25;
 
 void setup() {
   Serial.begin(115200);
@@ -52,7 +53,7 @@ void setup() {
 
   // start up sensor, sensor will go to continuous measurement mode
   // differential pressure mode with averaging till read 
-  Wire.beginTransmission(SDP810_ADDRESS);
+  Wire.beginTransmission(SDP8xx_ADDRESS);
   Wire.write(0x36);
   Wire.write(0x15);
   Wire.endTransmission();
@@ -68,7 +69,7 @@ void loop() {
   uint8_t data[9], counter;
 
   // read measurement data, after two bytes a CRC follows
-  Wire.requestFrom(SDP810_ADDRESS, 9);
+  Wire.requestFrom(SDP8xx_ADDRESS, 9);
   counter = 0;
   while (Wire.available()) {
     data[counter++] = Wire.read();

SHT4x_I2C_minimal_example/SHT4x_I2C_minimal_example.ino

@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2020, Sensirion AG
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice, this
+ *   list of conditions and the following disclaimer.
+ *
+ * * 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.
+ *
+ * * Neither the name of Sensirion AG nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
+ */
+
+#include <Wire.h>
+
+// SHT4x with I2C address A (SHT4x-AD1B) = 0x44
+// SHT40 with I2C address A (SHT40-BD1B) = 0x45
+const int16_t SHT_ADDRESS = 0x44;
+
+void setup() {
+  Serial.begin(115200);
+  // wait for serial connection from PC
+  // comment the following line if you'd like the output
+  // without waiting for the interface being ready
+  while(!Serial);
+
+  // output format
+  Serial.println("RelativeHumidity(percent)\tTemperature(degC)");
+  
+  // init I2C
+  Wire.begin();
+
+  // wait until sensors are ready, < 1 ms according to datasheet
+  delay(1);
+}
+
+void loop() {
+  float temperature, humidity;
+  uint8_t data[6], counter;
+
+  // start sht measurement in high prescision
+  Wire.beginTransmission(SHT_ADDRESS);
+  Wire.write(0xFD);
+  Wire.endTransmission();
+
+  // wait for measurement has finished according to datasheet > 8.2 ms
+  delay(9);
+
+  // read measurement data sht: 2 bytes T, 1 byte CRC, 2 bytes RH, 1 byte CRC
+  Wire.requestFrom(SHT_ADDRESS, 6);
+  counter = 0;
+  while (Wire.available()) {
+    data[counter++] = Wire.read();
+  }
+  
+  // floating point conversion according to datasheet
+  // convert T in degC
+  temperature = -45 + 175 * (float)((uint16_t)data[0] << 8 | data[1]) / 65535;
+  // convert RH in %
+  humidity = -6 + 125 * (float)((uint16_t)data[3] << 8 | data[4]) / 65535;
+  
+  Serial.print(humidity);
+  Serial.print("\t");
+  Serial.print(temperature);
+  Serial.println();
+
+  // wait 1 s for next measurement
+  delay(1000);
+}