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libraries/DHT20/examples/DHT20_I2C_speed/DHT20_I2C_speed.ino

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+//
+//    FILE: DHT20_I2C_speed.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: Demo for DHT20 I2C humidity & temperature sensor
+//     URL: https://github.com/RobTillaart/DHT20
+//
+//  Always check datasheet - front view
+//
+//          +--------------+
+//  VDD ----| 1            |
+//  SDA ----| 2    DHT20   |
+//  GND ----| 3            |
+//  SCL ----| 4            |
+//          +--------------+
+
+//  NOTE datasheet states 400 KHz as maximum
+
+
+#include "DHT20.h"
+
+DHT20 DHT;
+
+uint32_t start, stop;
+
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("DHT20 LIBRARY VERSION: ");
+  Serial.println(DHT20_LIB_VERSION);
+  Serial.println();
+
+  Serial.println("\nNOTE: datasheet states 400 KHz as maximum.\n");
+
+  Wire.begin();
+  DHT.begin();  //  ESP32 default pins 21, 22
+  delay(2000);
+
+  for (uint32_t speed = 50000; speed < 850000; speed += 50000)
+  {
+    Wire.setClock(speed);
+    Serial.print(speed);
+    Serial.print("\t");
+    Serial.print(DHT.read());  // status
+    Serial.print("\t");
+    Serial.print(DHT.getHumidity(), 1);
+    Serial.print("\t");
+    Serial.print(DHT.getTemperature(), 1);
+    Serial.println();
+    delay(1000);
+  }
+
+  Serial.println();
+  for (uint32_t speed = 50000; speed < 850000; speed += 50000)
+  {
+    Wire.setClock(speed);
+    start = micros();
+    DHT.read();
+    stop = micros();
+
+    Serial.print(speed);
+    Serial.print("\t");
+    Serial.print(stop - start);  //  time
+    Serial.print("\t");
+    Serial.print(DHT.getHumidity(), 1);
+    Serial.print("\t");
+    Serial.print(DHT.getTemperature(), 1);
+    Serial.println();
+    delay(1000);
+  }
+
+
+  Serial.println();
+  for (uint32_t speed = 50000; speed < 850000; speed += 50000)
+  {
+    DHT.requestData();
+    while (DHT.isMeasuring());
+    Wire.setClock(speed);
+    start = micros();
+    DHT.readData();
+    stop = micros();
+    DHT.convert();
+    Serial.print(speed);
+    Serial.print("\t");
+    Serial.print(stop - start);  // time
+    Serial.print("\t");
+    Serial.print(DHT.getHumidity(), 1);
+    Serial.print("\t");
+    Serial.print(DHT.getTemperature(), 1);
+    Serial.println();
+    delay(1000);
+  }
+
+  Serial.println("\ndone...");
+}
+
+
+void loop()
+{
+}
+
+
+//  -- END OF FILE --