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.