Introduction
DHT 11 is a temperature and humidity sensor which uses a capacitive humidity sensor and a thermistor to measure the surrounding air and spits out a digital signal on the data pin (no analog input pins needed).
How does DHT11 sensor work?
The DHT11 Humidity and Temperature Sensor consists of 3 main components. A resistive type humidity sensor, an NTC (negative temperature coefficient) thermistor (to measure the temperature) and an 8-bit microcontroller, which converts the analog signals from both the sensors and send out single digital signal.
Circuit for DHT11
The connections between humidity and temperature sensor are explained below
- + Pin is connected with the female jumper wire and the male end to the 5V power supply on evive board.
- – Pin is connected with the female jumper wire and the male end to the ground on evive board.
- OUT Pin is connected with the female jumper wire and the male end to the digital pin.
PictoBlox Program
In this example, we will display the temperature and humidity value on evive TFT Display:
- Open PictoBlox.
- Select the board as evive:
- Connect the evive.
- Create the following script using when evive starts up block:
- Upload the code onto evive:
You can download the PictoBlox program from here: Temperature and Humidity Sensor
Output
The DHT 11 humidity and temperature sensor is shown below. When we blow on the humidity sensor the sensor detects the moisture that comes with the blow and changes the value on the evive TFT display.
Libraries
- The DHT11 library can be downloaded from I2Cdev .
