If you don’t want to use pin 7 for the data signal, you can change the pin number in line 5 where it says #define DHT11_PIN 7. You should see the humidity and temperature readings displayed at one second intervals.
#Codevisionavr commands serial#
ZIP Library and select the DHTLib.zip file.Īfter it’s installed, upload this example program to the Arduino and open the serial monitor: #include It’s easy to install, just download the DHTLib.zip file below and open up the Arduino IDE. It has all the functions needed to get the humidity and temperature readings from the sensor.
#Codevisionavr commands install#
Higher relative humidity decreases the resistance between the electrodes, while lower relative humidity increases the resistance between the electrodes.ĭisplay Humidity and Temperature on the Serial Monitorīefore you can use the DHT11 on the Arduino, you’ll need to install the DHTLib library. 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 DHT11 detects water vapor by measuring the electrical resistance between two electrodes. The humidity sensing component is a moisture holding substrate with electrodes applied to the surface. How the DHT11 Measures Humidity and Temperature At 100% RH, condensation occurs, and at 0% RH, the air is completely dry.
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 air. Relative humidity is the amount of water vapor in air vs. Here are the ranges and accuracy of the DHT11:ĭHT11 Datasheet What is Relative Humidity?
It covers all of the steps, diagrams, and code you need to get started. BONUS: I made a quick start guide for this tutorial that you can download and go back to later if you can’t set this up right now.
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