We already learnt about DHT11 with previous article. In this new article we will tell you everything about DHT 22 generally at first glance the only difference between DHT11 and DHT22 is that the former comes in a blue shell and the latter is white, in fact they are both brothers of the same sensor family.
DHT11 is the little brother that is it has same deficiencies or less benefits compared to the DHT22 and therefore a higher price for their DHT22 when compared both. The DHT11 can be used for projects where you don’t required high Precision measurement but it does have more than acceptable features for most DIY projects.
What is DHT22?
The DHT22 , or AM2302 is a factory calibrated digital temperature and humidity sensor, it consists of a microprocessor that uses a capacitive humidity sensor, to measure the relative humidity of the air, the closer the value is to 100%, the more humid the Measured environment, also includes a thermistor to measure the surrounding air, and calculate the temperature of it, displays the data using a digital signal on the data pin. New data can be obtained once every 2 seconds.
The good thing about these devices is, on the one hand, their low cost and, on the other, being able to sense two analog parameters such as temperature and humidity digitally, since the sensor does the conversions.
Technical characteristics of a Dht22
- Power: 3.3Vdc ≤ Vcc ≤ 6Vdc
- Temperature measurement range: -40 ° C to +80 ° C
- Temperature measurement accuracy: ± 0.5 ° C error
- Resolution Temperature: 0.1 ° C
- Humidity measurement range: 0 to 100% RH
- Humidity measurement accuracy: 2% RH
- Humidity Resolution: 0.1% RH
- Sensing time: 2s
In the previous image you can see a comparison of the pinout of the DHT22 and DHT11 , and as you can see they are identical in terms of pins. Therefore, its assembly would be exactly the same, and the best thing, you could replace at any time the DHT11 with a DHT22, and vice versa, in your project without making too many changes.
Remember that they have 3 pins that you must use: GND, Vcc and Data . Pin # 3 is not used and in the modules it is canceled, that is, you will only see three pins. If you want to see more details about the product you have purchased, you can search the datasheets of the specific model and manufacturer to get all the complete information. Although most values may look the same to you, there could be some slight variation from one to the other.
DHT22 transmits digitally through its Data pin. There is no need to generate code in Arduino IDE to go from analog to understandable values for humans, but you can directly treat the digital signal to pass it to degrees or percentage of relative humidity.
Libraries required for Arduino IDE:
DHT Sensor Library latest version – Download