#ARDUINO UNO PINOUT DEFINITION HOW TO#
To learn more about how thermistors work and how to use them on the Arduino, check out this Arduino Thermistor Temperature Sensor Tutorial. The DHT11 measures temperature with a surface mounted NTC temperature sensor (thermistor) built into the unit. Higher relative humidity decreases the resistance between the electrodes, while lower relative humidity increases the resistance between the electrodes. The change in resistance between the two electrodes is proportional to the relative humidity. When water vapor is absorbed by the substrate, ions are released by the substrate which increases the conductivity between the electrodes. The humidity sensing component is a moisture holding substrate with electrodes applied to the surface. The DHT11 detects water vapor by measuring the electrical resistance between two electrodes. How the DHT11 Measures Humidity and Temperature At 100% RH, condensation occurs, and at 0% RH, the air is completely dry. The relative humidity is expressed as a percentage. The formula to calculate relative humidity is: Cold air can hold less water vapor before it becomes saturated, and hot air can hold more water vapor before it becomes saturated. The saturation point changes with air temperature. At the saturation point, water vapor starts to condense and accumulate on surfaces forming dew. the saturation point of water vapor in the air. The relative humidity is the amount of water vapor in air vs. No more than 1 Hz sampling rate (once every second).Good for 0-50☌ temperature readings ☒☌ accuracy.Good for 20-80% humidity readings with 5% accuracy.2.5mA max current use during conversion (while requesting data).The only real downside of this sensor is you can only get new data from it once every 2 seconds, the sensor readings can be up to 2 seconds old.Ĭompared to the DHT22, this sensor is less precise, less accurate, and works in a smaller range of temperature/humidity, but it is smaller and less expensive. Its fairly simple to use, but requires careful timing to grab data. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air and spits out a digital signal on the data pin (no analog input pins needed). The DHT11 is a basic, ultra low-cost digital temperature and humidity sensor.
#ARDUINO UNO PINOUT DEFINITION CODE#
After that, I’ll show you how to connect the DHT11 to an Arduino and give you some example code so you can use the DHT11 in your own projects. In this tutorial, I’ll first go into a little background about humidity, then I’ll explain how the DHT11 measures humidity. It’s perfect for remote weather stations, home environmental control systems, and farm or garden monitoring systems. The DHT11 humidity and temperature sensor make it really easy to add humidity and temperature data to your DIY electronics projects.