Checking 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

void getCurrentTemp(int * sign, int * whole, int * fract);
char temp_string[10];
void setup()
{
    Serial.begin(9600);
    // initialize DS18B20 datapin
    digitalWrite(REF_PIN, LOW);
    pinMode(REF_PIN, INPUT); // sets the digital pin as input (logic 1)
    pinMode(A0, INPUT);
}
void loop()
{
    getCurrentTemp(temp_string);
    Serial.println(temp_string);
    delay(1000);
}
void OneWireReset(int Pin) // reset.  Should improve to act as a presence pulse
    {
        digitalWrite(Pin, LOW);
        pinMode(Pin, OUTPUT); // bring low for 500 us
        delayMicroseconds(500);
        pinMode(Pin, INPUT);
        delayMicroseconds(500);
    }
void OneWireOutByte(int Pin, byte d) // output byte d (least sig bit first).
    {
        byte n;
        for (n = 8; n != 0; n--)
        {
            if ((d & 0x01) == 1) // test least sig bit
            {
                digitalWrite(Pin, LOW);
                pinMode(Pin, OUTPUT);
                delayMicroseconds(5);
                pinMode(Pin, INPUT);
                delayMicroseconds(60);
            }
            else
            {
                digitalWrite(Pin, LOW);
                pinMode(Pin, OUTPUT);
                delayMicroseconds(60);
                pinMode(Pin, INPUT);
            }
            d = d >> 1; // now the next bit is in the least sig bit position.
        }
    }
byte OneWireInByte(int Pin) // read byte, least sig byte first
    {
        byte d, n, b;
        for (n = 0; n < 8; n++)
        {
            digitalWrite(Pin, LOW);
            pinMode(Pin, OUTPUT);
            delayMicroseconds(5);
            pinMode(Pin, INPUT);
            delayMicroseconds(5);
            b = digitalRead(Pin);
            delayMicroseconds(50);
            d = (d >> 1) | (b << 7); // shift d to right and insert b in most sig bit position
        }
        return (d);
    }
void getCurrentTemp(char * temp)
{
    int HighByte, LowByte, TReading, Tc_100, sign, whole, fract;
    OneWireReset(REF_PIN);
    OneWireOutByte(REF_PIN, 0xcc);
    OneWireOutByte(REF_PIN, 0x44); // perform temperature conversion, strong pullup for one sec
    OneWireReset(REF_PIN);
    OneWireOutByte(REF_PIN, 0xcc);
    OneWireOutByte(REF_PIN, 0xbe);
    LowByte = OneWireInByte(REF_PIN);
    HighByte = OneWireInByte(REF_PIN);
    TReading = (HighByte << 8) + LowByte;
    sign = TReading & 0x8000; // test most sig bit
    if (sign) // negative
    {
        TReading = (TReading ^ 0xffff) + 1; // 2's comp
    }
    Tc_100 = (6 * TReading) + TReading / 4; // multiply by (100 * 0.0625) or 6.25
    whole = Tc_100 / 100; // separate off the whole and fractional portions
    fract = Tc_100 % 100;
    if (sign)
    {
        temp[0] = '-';
    }
    else
    {
        temp[0] = '+';
    }
    if (whole / 100 == 0)
    {
        temp[1] = ' ';
    }
    else
    {
        temp[1] = whole / 100 + '0';
    }
    temp[2] = (whole - (whole / 100) * 100) / 10 + '0';
    temp[3] = whole - (whole / 10) * 10 + '0';
    temp[4] = '.';
    temp[5] = fract / 10 + '0';
    temp[6] = fract - (fract / 10) * 10 + '0';
    temp[7] = '\0';
}

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