Tag Archives: code

Arduino Air Pressure Measurement

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Definition

                Pressure is defined as force per unit area that a fluid exerts on its surroundings. You can measure this force by detecting the amount of deflection on a diaphragm positioned inline with the fluid. Given the known area of the diaphragm, pressure can then be calculated. Pressure sensors are packaged with a scale that provides a method to convert to engineering units. The SI unit for pressure is the Pascal (N/m2), but other common units of pressure include psi, atmospheres, bars, inches of mercury, millimeters of mercury. Continue reading Arduino Air Pressure Measurement →

Arduino Pressure Measurement – BMP180

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Definition

                Pressure is defined as force per unit area that a fluid exerts on its surroundings. You can measure this force by detecting the amount of deflection on a diaphragm positioned inline with the fluid. Given the known area of the diaphragm, pressure can then be calculated. Pressure sensors are packaged with a scale that provides a method to convert to engineering units. The SI unit for pressure is the Pascal (N/m2), but other common units of pressure include psi, atmospheres, bars, inches of mercury, millimeters of mercury. Continue reading Arduino Pressure Measurement – BMP180 →

DHT11 Humidity Temperature Sensor

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Definition

Humidity is the amount of water vapor in the air. Water vapor is the gaseous state of water and is invisible. Humidity indicates the likelihood of precipitation, dew, or fog. Higher humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin.

 DHT11 Humidity Temperature Sensor

The DHT11 humidity and temperature sensor measures relative humidity (RH) and temperature. Relative humidity is the ratio of water vapor in air vs. the saturation point of water vapor in air. The saturation point of water vapor in air changes with temperature. Cold air can hold less water vapor before it is saturated, and hot air can hold more water vapor before it is saturated. The formula for relative humidity is as follows:

Relative Humidity = (density of water vapor / density of water vapor at saturation) x 100%

Basically, relative humidity is the amount of water in the air compared to the amount of water that air can hold before condensation occurs. It’s expressed as a percentage.  For example, at 100% RH condensation (or rain) occurs, and at 0% RH, the air is completely dry.

Components Used

  1. DHT11
  2. Arduino Uno
  3. Connecting Wires

DHT11 Sensor Pinout

DHT11 Pin out
DHT11 Pin out

DHT11 Arduino Circuit Diagram

DHT11 Arduino Circuit Diagram
DHT11 Arduino Circuit Diagram

Arduino Code for DHT11 Humidity Temperature Measurement

This code requires DHT11 Library Download From: https://github.com/adafruit/DHT-sensor-library

//Humidity and Temperature Measurement
//www.circuits4you.com
#include <dht.h>

dht DHT;
#define DHT11_PIN 2

void setup(){
  Serial.begin(9600);
}

void loop()
{
  int chk = DHT.read11(DHT11_PIN);
  Serial.print("Temperature = ");
  Serial.println(DHT.temperature);
  Serial.print("Humidity = ");
  Serial.println(DHT.humidity);
  delay(1000);
}

DHT11 Humidity Temperature Measurement Result

Open serial monitor and observe the readings. Blowing air on sensor will change the humidity readings.

DHT11 Temperature Humidity Result
DHT11 Temperature Humidity Result

For more Weather related other parameters measurement see below links

  1. Barometric pressure measurement
  2. Rain Sensor interface with Arduino

Frequency Measurement using Arduino

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Definition

Frequency is the number of complete cycles per second in alternating current direction. The standard unit of frequency is the hertz, abbreviated Hz.

Frequency Measurement

                Frequency Measurement is carried out by measuring the number of cycles in one second, this method requires time of one second. Other method is to measure time period of one cycle F = 1 / T.

In this example time from first rise to the second rise is measured using interrupt on Pin 2 (INT0). It is set to detect rising pulse and at every 100mSec measured frequency is displayed on serial monitor. Continue reading Frequency Measurement using Arduino →

Capacitance Measurement using Arduino

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Definition

Capacitance is defined as the ability of a body to store an electric charge. The SI unit of capacitance is the farad (symbol: F), named after the English physicist Michael Faraday. A 1 farad capacitor, when charged with 1 coulomb of electrical charge, has a potential difference of 1 volt between its plates. Continue reading Capacitance Measurement using Arduino →