Hello and welcome to another arduino tutorial

In this project we will learn how to build a simple weather station using DHT11 Sensor and OLED display.

This project micro controller is Arduino Uno R3.

This foundational project merges two different data-collection architectures and requires formatting the results for display.

Analog vs. Digital Sensor Protocols

You cannot analogRead() a DHT11 sensor! The components in this system use fundamentally different communication methods.

1. The DHT11 Temperature & Humidity Sensor: This is a digital sensor with its own internal processor. It transmits a 40-bit data stream representing its readings.

   • You MUST use the <DHT.h> library to communicate with it.
   • Data is read using specific library commands: float temperature = dht.readTemperature(); and float humidity = dht.readHumidity();.

2. The Light Dependent Resistor (LDR): This is a purely analog, physical component. Its resistance changes based on light intensity.

   • It MUST be used in a Voltage Divider circuit with a fixed resistor (e.g., 10K Ohm).
   • The Arduino reads it as a simple analog voltage: int lightValue = analogRead(A0); (Outputs a value from 0 to 1023).

Formatting Data for the Display

The microcontroller reads values like temperature = 25.0 and humidity = 60.0. A character display has limited space, so data must be organized carefully.

• A 16x2 Character LCD (especially with an I2C backpack to simplify wiring) has exactly 32 character positions.
• Execution: You must control the cursor position precisely to format the output:

  lcd.setCursor(0, 0); // Start at the beginning of the first line
  lcd.print("T: "); lcd.print(temperature); lcd.print("C");
  
  lcd.setCursor(0, 1); // Move to the beginning of the second line
  lcd.print("H: "); lcd.print(humidity); lcd.print("%");
  

• To display additional data (like from the LDR) on the same small screen, you can create a simple pagination system. Use delay(3000); lcd.clear(); to wipe the screen every few seconds and cycle through different data screens.

Standard Climate Station Components

• Arduino Uno R3 / Nano (Provides standard execution speed and I/O).
• DHT11 Temperature & Humidity Sensor (The DHT22 is a more precise alternative, providing decimal readings).
• Light Dependent Resistor (LDR) Photocell.
• 16x2 LCD Character Display + I2C Backpack (The I2C interface drastically reduces the number of required connecting wires from 16 to just 4).

You can make your own adaptations since the system is versatile [Challenge for the reader: minimize the system ;) ].

Take care, Roy.