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adafruit / DHT-sensor-library

Arduino library for DHT11, DHT22, etc Temperature & Humidity Sensors
https://learn.adafruit.com/dht
MIT License
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Delay in readings of DHT22 #164

Closed tormes closed 1 year ago

tormes commented 4 years ago

In the file DHT_U.cpp , in function *void DHT_Unified::setMinDelay(sensor_t sensor) , for the sensors DHT21, DHT22, the sensor->min_delay** should be 0.5 sec, not 2 secs. This sensors (they are better than the DHT11) appears to have a maximum frequency of 2 Hz = 2 times a second, so the minimum time between readings should be 0.5 secs.

RichardSHutchison commented 2 years ago

It's been 2 years and so you may have already figured this out. If you look around at the DHT22 specs, the sample rate is 0.5Hz. That stand's for half a reading per second, or one reading every two seconds. So the min_delay value of 2 seconds is actually correct.

The DHT22 has better temperature and humidity ranges and tolerances than the DHT11 but its sampling rate is slower.

Check this out: https://learn.adafruit.com/dht Or the spec sheet: https://www.electroschematics.com/wp-content/uploads/2015/02/DHT22-datasheet.pdf

caternuson commented 1 year ago

Yep. 2 seconds. From DHT22 datasheet linked above: image