Temperature, humidity and CO2 box

Description: This Arduino-based weather station measures and displays indoor temperature, humidity, and CO₂ levels. It also shows a 4-day weather forecast (THIS DATA IS NOT UPDATED) and historical graphs. The data is displayed on an SSD1306 OLED screen, and users can navigate between views using buttons.

What do you need

• Arduino nano(nanoatmega328new in my case).
• 0.96 inch OLED Display SSD1306 128*64.
• BME280 5v with temperature and humidity.
• MH-Z19B for CO2 measurements.
• 2 buttons.
• 1 RGB LED for CO2 level indication.
• VS code + PlatformIO for build project.

Pin Connection Scheme

Component	Arduino Pin	Description
BME280 Sensor	A4 (SDA)	I2C data line (shared with OLED)
	A5 (SCL)	I2C clock line (shared with OLED)
MH-Z19 CO₂ Sensor	D3 (RX)	Connect MH-Z19 RX to Arduino Pin 3
	D2 (TX)	Connect MH-Z19 TX to Arduino Pin 2
Button next screen	D4	Navigate to next screen (btn_next_screen)
Button update	D5	Refresh current graph screen or add random value for debugging if not commented(btn_update)
OLED Display (SSD1306)	A4 (SDA)	I2C data line (shared with BME280)
	A5 (SCL)	I2C clock line (shared with BME280)
LED	D9 (Red color)
	D10 (Green color)
	D11 (Blue color)

⚠️ Note: I2C devices (OLED and BME280) must share the same SDA and SCL lines. Also, MH-Z19 sensor connections are logically swapped in code (pin 3 is TX, pin 2 is RX).

libs (included)

• GyverBME280@^1.5.3: https://github.com/GyverLibs/GyverBME280
• EncButton@^3.7.2: https://github.com/GyverLibs/EncButton
• GyverOLED@^1.6.4: https://github.com/GyverLibs/GyverOLED
• mhz19_uart@^0.31: https://github.com/nara256/mhz19_uart
• GRGB@^1.4.1: https://github.com/GyverLibs/GRGB

TODO:

• remove forecast data (after creating the same but ESP based project).

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