Construction & implementation of a weather station

Idea of a weather station

Display of temperature and humidity values
Display of the data on a website
The possibility for a user to define threshold values
Respond to particulate matter values
Trigger events based on the sensor values

Hardware

Arduino Uno
Temperature and humidity sensor DHT22
Fine dust sensor SDS011
LCD 1602 to display sensor data and let the users define threshold values
ESP8266 (connected with the Arduino via UART) to display a website of the sensor values to wlan clients
4 pin 5V fan

Concept development

The following flowcharts describe the workflow, how the data is queried from sensors and how it is processed.

Flow chart part 1: Start query

Flow chart part 2: DHT22

Flow chart part 3: Particulate matter sensor

Flow chart part 4: ESP

Hardware structure

General structure

ESP operation

Concept of data transfer

Data integrity check between Arduino and ESP

Implemented transmission security via CRC procedure: G (x) = x^16 + x^15 + x^10 + x^3

Arduino calculates CRC-16 (Xmodem) and sends Data + CRC
ESP also calculates CRC from data
ESP checks whether CRCs are the same

Occurring challenges

Connect ESP via UART ⇒ fine dust also sends via UART
All buttons of the LCD display are only activated via a pin A0 had read
PWM signal for the fan
Data synchronization for LCD display, user website
Pin assignment due to the small number of pins

Additional Notes

Please also see our German presentation inside the folder Presentation for more information.