0.1.0 initial version of I2C library for DHT12

libraries/DHT12/DHT12.cpp

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+//
+//    FILE: DHT12.cpp
+//  AUTHOR: Rob Tillaart
+// VERSION: 0.1.0
+// PURPOSE: I2C library for DHT12 for Arduino.
+//
+// HISTORY:
+// 0.1.0 - 2017-12-11 initial version
+//
+// Released to the public domain
+//
+
+#include <DHT12.h>
+
+////////////////////////////////////////////////////////////////////
+//
+// PUBLIC
+//
+DHT12::DHT12()
+{
+  _deviceAddress = DHT12_ADDRESS;
+}
+
+int8_t DHT12::read()
+{
+  // READ SENSOR
+  int status = _readSensor();
+  if (status < 0) return status;
+
+  // CONVERT AND STORE
+  humidity = bits[0] + bits[1] * 0.1;
+  temperature = (bits[2] & 0x7F) + bits[3] * 0.1;
+  if (bits[2] & 0x80)
+  {
+    temperature = -temperature;
+  }
+
+  // TEST CHECKSUM
+  uint8_t checksum = bits[0] + bits[1] + bits[2] + bits[3];
+  if (bits[4] != checksum)
+  {
+    return DHT12_ERROR_CHECKSUM;
+  }
+
+  return DHT12_OK;
+}
+
+////////////////////////////////////////////////////////////////////
+//
+// PRIVATE
+//
+
+// negative is error in communication
+// 5 is OK
+// 0..4 is too few bytes.
+int DHT12::_readSensor()
+{
+  // GET CONNECTION
+  Wire.beginTransmission(_deviceAddress);
+  Wire.write(0);
+  int rv = Wire.endTransmission();
+  if (rv < 0) return rv;
+
+  // GET DATA
+  const uint8_t length = 5;
+  int bytes = Wire.requestFrom(_deviceAddress, length);
+  if (bytes == 0) return DHT12_ERROR_CONNECT;
+  if (bytes < length) return DHT12_MISSING_BYTES;
+
+  for (int i = 0; i < bytes; i++)
+  {
+    bits[i] = Wire.read();
+  }
+
+  return bytes;
+}
+// END OF FILE

libraries/DHT12/DHT12.h

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+#ifndef DHT12_H
+#define DHT12_H
+//
+//    FILE: DHT12.h
+//  AUTHOR: Rob Tillaart
+// PURPOSE: DHT_I2C library for Arduino .
+// VERSION: 0.1.0
+// HISTORY: See DHT12.cpp
+//     URL: https://github.com/RobTillaart/Arduino/tree/master/libraries/
+//
+// Released to the public domain
+//
+
+#include "Wire.h"
+#include "Arduino.h"
+
+#define DHT12_VERSION "0.1.0"
+
+#define DHT12_OK                0
+#define DHT12_ERROR_CHECKSUM    -10
+#define DHT12_ERROR_CONNECT     -11
+#define DHT12_MISSING_BYTES     -12
+
+#define DHT12_ADDRESS           0x5C
+
+class DHT12
+{
+public:
+  DHT12();
+
+  int8_t read();
+
+  float humidity;
+  float temperature;
+
+private:
+  uint8_t _deviceAddress;
+  uint8_t bits[5];
+  int _readSensor();
+};
+
+#endif
+// END OF FILE

libraries/DHT12/examples/DHT12/DHT12.ino

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+//
+//    FILE: DHT12.ino
+//  AUTHOR: Rob Tillaart
+// VERSION: 0.1.0
+// PURPOSE: Demo for DHT12 I2C humidity & temperature sensor
+//
+// HISTORY:
+// 0.1.0 - 2017-12-11 initial version
+//
+// Released to the public domain
+//
+
+#include <DHT12.h>
+
+DHT12 DHT;
+
+void setup()
+{
+  Wire.begin();
+
+  Serial.begin(115200);
+  Serial.println(__FILE__);
+  Serial.print("DHT12 LIBRARY VERSION: ");
+  Serial.println(DHT12_VERSION);
+  Serial.println();
+
+  delay(2000);
+
+  Serial.println("Type,\tStatus,\tHumidity (%),\tTemperature (C)");
+}
+
+void loop()
+{
+  // READ DATA
+  Serial.print("DHT12, \t");
+  int status = DHT.read();
+  switch (status)
+  {
+  case DHT12_OK:
+    Serial.print("OK,\t");
+    break;
+  case DHT12_ERROR_CHECKSUM:
+    Serial.print("Checksum error,\t");
+    break;
+  case DHT12_ERROR_CONNECT:
+    Serial.print("Connect error,\t");
+    break;
+  case DHT12_MISSING_BYTES:
+    Serial.print("Missing bytes,\t");
+    break;
+  default:
+    Serial.print("Unknown error,\t");
+    break;
+  }
+  // DISPLAY DATA, sensor has only one decimal.
+  Serial.print(DHT.humidity, 1);
+  Serial.print(",\t");
+  Serial.println(DHT.temperature, 1);
+
+  delay(2000);
+}
+
+// END OF FILE

libraries/DHT12/keywords.txt

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+#######################################
+# Syntax Coloring Map For DHT_I2C
+#######################################
+
+#######################################
+# Datatypes (KEYWORD1)
+#######################################
+
+DHT12	KEYWORD1
+
+#######################################
+# Methods and Functions (KEYWORD2)
+#######################################
+
+read	KEYWORD2
+humidity	KEYWORD2
+temperature	KEYWORD2
+
+#######################################
+# Constants (LITERAL1)
+#######################################
+
+DHT12_VERSION	LITERAL2
+DHT12_OK	LITERAL2
+DHT12_ERROR_CHECKSUM	LITERAL1
+DHT12_ERROR_CONNECT	LITERAL1
+DHT12_MISSING_BYTES	LITERAL1

libraries/DHT12/library.json

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+{
+  "name": "DHT12",
+  "keywords": "Temperature Humidity DHT12 I2C",
+  "description": "I2C Library for DHT12",
+  "authors":
+  [
+    {
+      "name": "Rob Tillaart",
+      "email": "Rob.Tillaart@gmail.com",
+      "maintainer": true
+    }
+  ],
+  "repository":
+  {
+    "type": "git",
+    "url": "https://github.com/RobTillaart/Arduino.git"
+  },
+  "frameworks": "arduino",
+  "platforms": "*",
+  "export": {
+    "include": "libraries/DHT12"
+  }
+}

libraries/DHT12/library.properties

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+name=DHT12
+version=0.1.0
+author=Rob Tillaart <rob.tillaart@gmail.com>
+maintainer=Rob Tillaart <rob.tillaart@gmail.com>
+sentence=I2C Library for DHT12 Temperature and Humidity. 
+paragraph=DHT12 
+category=Sensors
+url=https://github.com/RobTillaart/Arduino/tree/master/libraries/
+architectures=*