Fake CO2 Meter - Teardown on ZN-2CO1 Air Quality Detector

Описание

As the pandemic on going and we stay indoor more often, monitor carbon dioxide and other harmful TVOC particle in our living space since to be a good idea.

But such sensor are usually price above 150-200 USD each, do we have a more affordable version?

When I browse the internet, I stumble upon this :
ZN-2CO1 Air Quality Detector
And it claim it can detect :
- CO2 (400-6000PPM)
- TVOC (0-2.0mg/m3)
- HCHO (0-0.6mg/m3)
and Temperature and Humidity as well.

Cost well below 30 USD, which is way to cheap, knowing how much a normal CO2 sensor will cost like.

I did a teardown, found out that
It only have 2 sensor:
DHT11 clone - Temperature and Humidity sensor, most probably clone
TPM-300A-V2.2 TVOC Air Quality sensor - using TP-401 sensor
Documentation below:
http://www.szdovelet.com/product/html/?167.html
https://solarbotics.com/wp-content/uploads/tp-401a_indoor_air_quality_gas_sensor.pdf

There is no CO2 Sensor or any precision sensor inside the product.

The MCU of the display is STM32F0 china clone GD32, a lipo charging circuit, a switching regulator for 3.3V, a 2.4" IPS LCD display.

The TPM-300A-V2.2 module actually output a data stream:

2C E4 00 5D 00 1B 01 BB 44

- 2C E4 is the module address
- 00 5D TVOC high low bit
- 00 1B CHOH high low bit
- 01 BB CO2 high low bit
- 44 Parity bit

Conclusion:

Don't buy this. the product is fake. The data read out is not the actual reading and just make out.