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{{bloc-etroit|text=This tutorial covers the [http://mchobby.be/PrestaShop/product.php?id_product=214 low cost DHT temperature & humidity sensors]. These sensors are very basic and slow, but are great for hobbyists who want to do some basic data logging. The DHT sensors are made of two parts, a capacitive humidity sensor and a thermistor. There is also a very basic chip inside that does some analog to digital conversion and spits out a digital signal with the temperature and humidity. The digital signal is fairly easy to read using any microcontroller.}}
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== DHT11 vs DHT22 ==
We have two versions of the DHT sensor, they look a bit similar and have the same pinout, but have different characteristics. Here are the specs:
=== DHT11 ===
* Ultra low cost
* 3 to 5V power and I/O
* 2.5mA max current use during conversion (while requesting data)
* Good for 20-80% humidity readings with 5% accuracy
* Good for 0-50°C temperature readings ±2°C accuracy
* No more than 1 Hz sampling rate (once every second)
* Body size 15.5mm x 12mm x 5.5mm
* 4 pins with 0.1" spacing
=== DHT22 ===
* Low cost
* 3 to 5V power and I/O
* 2.5mA max current use during conversion (while requesting data)
* Good for 0-100% humidity readings with 2-5% accuracy
* Good for -40 to 125°C temperature readings ±0.5°C accuracy
* No more than 0.5 Hz sampling rate (once every 2 seconds)
* Body size 15.1mm x 25mm x 7.7mm
* 4 pins with 0.1" spacing
As you can see, the [http://mchobby.be/PrestaShop/product.php?id_product=214 DHT22] is a little more accurate and good over a slightly larger range. Both use a single digital pin and are 'sluggish' in that you can't query them more than once every second or two.
Vous pouvez achetez vos DHTxx chez [http://www.mchobby.be mchobby.be]
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