In Focus

Checking Temperature And Humidity Using Arduino Mega 2560

In this article I will explain about checking the Temperature and Humidity using Arduino Mega 2560.

Introduction
  • In this article I will explain about checking the temperature and humidity using Arduino Mega 2560.
  • It can accurately display the temperature in the serial monitor.
Parts Of Lists
  • Arduino Mega 2560
  • Temperature sensor
  • Hookup Wires
  • Bread Board
Temperature Sensor
  • Temperature sensor is used to find the temperature of the place.
  • It also posses the self low heating and does not cross the 0.1 degree celsius temperature rise till the air.
Figure 1: Temperature Sensor
Connection

Step 1: Connection From Temperature Sensor To ArduinoMega2560.
  • Connect the 5v of the supply to the 5v of the Arduinomega board.
  • Connect the Analog pin of the sensor to the A0 of the Analog of the board.
  • Connect the ground pin to the board of the Gnd
Programming
  1. void getCurrentTemp(int * sign, int * whole, int * fract);  
  2. char temp_string[10];  
  3. void setup()  
  4. {  
  5.     Serial.begin(9600);  
  6.     // initialize DS18B20 datapin    
  7.     digitalWrite(REF_PIN, LOW);  
  8.     pinMode(REF_PIN, INPUT); // sets the digital pin as input (logic 1)    
  9.     pinMode(A0, INPUT);  
  10. }  
  11. void loop()  
  12. {  
  13.     getCurrentTemp(temp_string);  
  14.     Serial.println(temp_string);  
  15.     delay(1000);  
  16. }  
  17. void OneWireReset(int Pin) // reset.  Should improve to act as a presence pulse    
  18.     {  
  19.         digitalWrite(Pin, LOW);  
  20.         pinMode(Pin, OUTPUT); // bring low for 500 us    
  21.         delayMicroseconds(500);  
  22.         pinMode(Pin, INPUT);  
  23.         delayMicroseconds(500);  
  24.     }  
  25. void OneWireOutByte(int Pin, byte d) // output byte d (least sig bit first).    
  26.     {  
  27.         byte n;  
  28.         for (n = 8; n != 0; n--)  
  29.         {  
  30.             if ((d & 0x01) == 1) // test least sig bit    
  31.             {  
  32.                 digitalWrite(Pin, LOW);  
  33.                 pinMode(Pin, OUTPUT);  
  34.                 delayMicroseconds(5);  
  35.                 pinMode(Pin, INPUT);  
  36.                 delayMicroseconds(60);  
  37.             }  
  38.             else  
  39.             {  
  40.                 digitalWrite(Pin, LOW);  
  41.                 pinMode(Pin, OUTPUT);  
  42.                 delayMicroseconds(60);  
  43.                 pinMode(Pin, INPUT);  
  44.             }  
  45.             d = d >> 1; // now the next bit is in the least sig bit position.    
  46.         }  
  47.     }  
  48. byte OneWireInByte(int Pin) // read byte, least sig byte first    
  49.     {  
  50.         byte d, n, b;  
  51.         for (n = 0; n < 8; n++)  
  52.         {  
  53.             digitalWrite(Pin, LOW);  
  54.             pinMode(Pin, OUTPUT);  
  55.             delayMicroseconds(5);  
  56.             pinMode(Pin, INPUT);  
  57.             delayMicroseconds(5);  
  58.             b = digitalRead(Pin);  
  59.             delayMicroseconds(50);  
  60.             d = (d >> 1) | (b << 7); // shift d to right and insert b in most sig bit position    
  61.         }  
  62.         return (d);  
  63.     }  
  64. void getCurrentTemp(char * temp)  
  65. {  
  66.     int HighByte, LowByte, TReading, Tc_100, sign, whole, fract;  
  67.     OneWireReset(REF_PIN);  
  68.     OneWireOutByte(REF_PIN, 0xcc);  
  69.     OneWireOutByte(REF_PIN, 0x44); // perform temperature conversion, strong pullup for one sec    
  70.     OneWireReset(REF_PIN);  
  71.     OneWireOutByte(REF_PIN, 0xcc);  
  72.     OneWireOutByte(REF_PIN, 0xbe);  
  73.     LowByte = OneWireInByte(REF_PIN);  
  74.     HighByte = OneWireInByte(REF_PIN);  
  75.     TReading = (HighByte << 8) + LowByte;  
  76.     sign = TReading & 0x8000; // test most sig bit    
  77.     if (sign) // negative    
  78.     {  
  79.         TReading = (TReading ^ 0xffff) + 1; // 2's comp    
  80.     }  
  81.     Tc_100 = (6 * TReading) + TReading / 4; // multiply by (100 * 0.0625) or 6.25    
  82.     whole = Tc_100 / 100; // separate off the whole and fractional portions    
  83.     fract = Tc_100 % 100;  
  84.     if (sign)  
  85.     {  
  86.         temp[0] = '-';  
  87.     }  
  88.     else  
  89.     {  
  90.         temp[0] = '+';  
  91.     }  
  92.     if (whole / 100 == 0)  
  93.     {  
  94.         temp[1] = ' ';  
  95.     }  
  96.     else  
  97.     {  
  98.         temp[1] = whole / 100 + '0';  
  99.     }  
  100.     temp[2] = (whole - (whole / 100) * 100) / 10 + '0';  
  101.     temp[3] = whole - (whole / 10) * 10 + '0';  
  102.     temp[4] = '.';  
  103.     temp[5] = fract / 10 + '0';  
  104.     temp[6] = fract - (fract / 10) * 10 + '0';  
  105.     temp[7] = '\0';  
  106. }  
Explanation
  • In this article I explained about the Checking temperature and humidity using Arduinomega2560.
  • It can accuratelly give the temperature of the place in the serial monitor.
Output

                                             Figure 2: Output