#343 Sensors/DHT11

Reading temperature and humidity with a DHT11 sensor and ESP-01, coding with ESP8266 core for Arduino.

Notes

The DHT11 sensor is a very cheap and common sensor that provides readings of:

• relative humidity: 20-80% ±5%
• temperature: 0-50°C ±2°C

I’ve used this before with an Arduino - see LEAP#301. This time I’m testing with the most basic ESP8266 board - an ESP-01, which exposes one free GPIO.

Programming Setup

I’m using a LEAP#194 DIYDevBoard to host the ESP-01 module, and a cheap CH340G-based USB to UART adapter. With the correct drivers installed, it shows up in the tty device list.

My host computer is running MacOSX.

Required Libraries

I’m using ESP8266 core with the Arduino IDE, and the Adafruit sensor library to interface with the DHT11:

• Adafruit Unified Sensor Library
• DHT Sensor Library

These need to be installed in the Arduino IDE.

Test Sketch

The DHT11.ino sketch simply reads the sensor every 2 seconds and outputs the readings to the serial port.

Here is a test run:

Construction

Credits and References

• DHT11 Humidity & Temperature Sensor - D-Robotics UK
• ESP8266 core for Arduino
• Adafruit Unified Sensor Library
• DHT Sensor Library
• LEAP#194 DIYDevBoard - the dev board I’m using to host the ESP-01
• LEAP#301 DHT11/Basics - similar project for an Arduino
• ..as mentioned on my blog