DIY CO2 meter for home and office use v.2

Real-time display of current CO2 level. Alarm indicator. Automatic display brightness. Powered from accumulator. USB charging.

Components

• LGT8F328P LQFP32 MiniEVB 5V pro-mini
• SCD40 CO2 sensor
• BMP180 pressure sensor
• TM1637 display
• TP4056 charging board
• 18650 accumulator
• SS12F15 G6 1P2T switch
• 5516 photoresistor and 10K resistor
• 3 mm. led and 330 Ohm resistor
• 7 M3x6 and 2 M2x4 screws
• Dupont wires

3D printed case

Get it from my thingiverse

Schematics

Display

D7 to TM1637 CLK
D8 to TM1637 DIO

Signal led

D9 to signal led

Light sensor

D10 to 5516 photoresistor
A0 between 5516 photoresistor and 10k resistor
GND to 10k resistor

I2C sensors

A4 to SDA of SCD40 and BMP180
A5 to SCL of SCD40 and BMP180

Power

5V and GND to TP4056 output

More info

See at my website in Russian or translated to English.