Demonstration of reading digital temperature and relative humidity from DHT22 sensor with Arduino UNO. You can purchase the device here * https://www.sparkfun.com/products/10167 Based on Ben Adams driver at http://www.sparkfun.com/products/10167 Using Arduino 1.5.4 IDE I got the following compile data: Sketch uses 5,406 bytes (16%) of program st…

read-DHT22.c

// you can get the header file at http://www.sparkfun.com/products/10167
#include <DHT22.h>
// Only used for sprintf
#include <stdio.h>

// Data wire is plugged into port 2 on the Arduino
#define DHT22_PIN 2
// Ben's original code suggested a 4.7K resistor between VCC and the data pin (strong pullup)
// But I found this was not needed since the pullup can be in software

// Setup a DHT22 instance
DHT22 myDHT22(DHT22_PIN);

void setup(void)
{
  // start serial port
  Serial.begin(9600);
  // Serial.println("DHT22 Library Demo");
}

void loop(void)
{ 
  DHT22_ERROR_t errorCode;
  
  // The sensor can only be read from every 1-2s, and requires a minimum
  // nice to have a short warm-up after power-on.
  delay(5000);
  
  // Serial.print("Requesting data...");
  errorCode = myDHT22.readData();
  switch(errorCode)
  {
    case DHT_ERROR_NONE:
      // Serial.print("Got Data ");
      // convert temperature from C to F
      Serial.print(myDHT22.getTemperatureC() * 1.8 + 32);
      Serial.print("F ");
      Serial.print(myDHT22.getHumidity());
      Serial.println("%");
      // Alternately, with integer formatting which is clumsier but more compact to store and
      // can be compared reliably for equality:
      // char buf[128];
      // sprintf(buf, "Integer-only reading: Temperature %hi.%01hi C, Humidity %i.%01i %% RH",
      //             myDHT22.getTemperatureCInt()/10, abs(myDHT22.getTemperatureCInt()%10),
      //             myDHT22.getHumidityInt()/10, myDHT22.getHumidityInt()%10);
      // Serial.println(buf);
      break;
    case DHT_ERROR_CHECKSUM:
      Serial.print("check sum error ");
      Serial.print(myDHT22.getTemperatureC() * 1.8 + 32);
      Serial.print("F ");
      Serial.print(myDHT22.getHumidity());
      Serial.println("%");
      break;
    case DHT_BUS_HUNG:
      Serial.println("BUS Hung ");
      break;
    case DHT_ERROR_NOT_PRESENT:
      Serial.println("Not Present ");
      break;
    case DHT_ERROR_ACK_TOO_LONG:
      Serial.println("ACK time out ");
      break;
    case DHT_ERROR_SYNC_TIMEOUT:
      Serial.println("Sync Timeout ");
      break;
    case DHT_ERROR_DATA_TIMEOUT:
      Serial.println("Data Timeout ");
      break;
    case DHT_ERROR_TOOQUICK:
      Serial.println("Polled to quick ");
      break;
  }
}