DHT11?Learn Temperature Humidity With DHT11 With Micropython

Hi~ I'm irina but My nickname is "Y"

When we think of temperature/humidity sensors in IoT, DHT-11 comes to mind the most. So today, I would like to introduce the working principle of DHT11 to the source code.

Supplies

DHT11 x 1

W5100S-EVB-Pico x 1

Step 1: What Is DHT11?

If you look for it, surprisingly, it is a temperature/humidity sensor that is often used when you want to check the temperature and humidity of products specialized for IoT such as Arduino or Raspberry Pi.

humidity : 20~95%

temperature: 0~50ºC

As explained in the figure, the pins are in order from left to right.

VCC,Signal, NC, GND

NC is an unused pin, so only 3 pins are actually used.

When using the above product, a normal value is output only when a resistor (5K) is connected between VCC and Signal.

If there is no resistor, you can also use a module.

Since the module already has a resistor connected to the signal, the wiring is simple and easy to use.

Step 2: Operation Principle

When I first dealt with it, I didn't even know how it works and didn't write it.

As I write it, I wonder what kind of principle it is,

There are two types of electrical humidity measurement methods: capacitance sensing type nd resistance sensing type, but the capacitive sensing type sensor has high precision but is expensive.

So DHT11 uses resistance sensing type.

The two electrodes are not connected to each other, but a small amount of current flows due to the moisture in the air. So, when there is more moisture in the air, more current flows, so the resulting resistance value is measured as humidity.

In the temperature measurement of DHT11, the resistance value of the material changes according to the temperature, and a temperature sensor called thermistor is included in the DHT11 and is used together with the humidity sensor!