dht11 sensor schmatic


I have a DHT11 humidity/temperature sensor in researching how to wire the sensor up I came across two circuits 1 wiring it straight into the arduino uno board, the other using a breadboard and adding a one k resistor between pin 2 and analog pin six.

The question is why the resistor. Does the sensor generate so much current that it needs to dampened by a resistor? Why would one example have a resistor and the other not?


You need a digital pin of the Arduino, and 5V and GND.
The communication with the DHT11 is digital, but that line is an open-collector signal, therefor a pullup resistor is needed to 5V.

However, the Arduino is able to turn on a internal pullup resistor of 50k or so. That is (sometimes) enough to make the DHT11 work. But it is better to use a pullup resistor of for example 10k.

I prefer a schematic like this one : Measuring Humidity with DHT11 Sensor
And I prefer this library : https://github.com/RobTillaart/Arduino/tree/master/libraries/DHTlib