04-14-2025, 12:38 PM
There are several threads on here about issues with the popular DHT22 sensors, this is an attempt to summarise them in one place. To begin, there are actually multiple things sold as DHT22's, the main ones being the raw sensors with 4 pins:
and the other being DHT22 modules with 3 wires and built-in pullup resistors and decoupling capacitors:
A problem with these is that they're specced for 3.3 - 5V operation (even if some sites incorrectly claim 3 - 5V), so in theory can't be powered from the 3V output on the GPIO connector and need to be power from the 5V pin on the 433 MHz connector.
However at least for the KC868 A16v3 I've found that both the DHT22 4-pin and the DHT22 3-wire work fine on 3V (as well as 5V). However the 3-wire module is far more reliable than the 4-pin sensor, the 3-wire is immediately detected and updates consistently while the 4-pin takes several minutes to be detected and barely every updates.
It'd be interesting to hear the experiences others have had with different DHT22 sensors.
and the other being DHT22 modules with 3 wires and built-in pullup resistors and decoupling capacitors:
A problem with these is that they're specced for 3.3 - 5V operation (even if some sites incorrectly claim 3 - 5V), so in theory can't be powered from the 3V output on the GPIO connector and need to be power from the 5V pin on the 433 MHz connector.
However at least for the KC868 A16v3 I've found that both the DHT22 4-pin and the DHT22 3-wire work fine on 3V (as well as 5V). However the 3-wire module is far more reliable than the 4-pin sensor, the 3-wire is immediately detected and updates consistently while the 4-pin takes several minutes to be detected and barely every updates.
It'd be interesting to hear the experiences others have had with different DHT22 sensors.