MEMS Digital Formaldehyde Sensor Module (HCHO, CH2O)

Introduction

The formaldehyde sensor module is a CH₂O gas module developed with a MEMS micro gas sensor that can be used to detect formaldehyde gas content in the environment and thus determine air quality. The module has been aging, debugging, calibration, calibration, and has good response consistency and high sensitivity to formaldehyde gas.

Main Feature 

High sensitivity, excellent long-term stability, factory calibration, automatic preheat judgment, low power consumption, long life, high cost performance

Technical Parameter

Pinout （URAT）                            Communication protocol parameters

Serial data flow format

Note:

2Ch is module fixed address in B1

sum(B6)=unit_8(B1+B2+B3+B4+B5)

CH₂O gas concentration (mg/m3) = (CH2O High (B2)*256+ CH2O Low (B3))*0.01

Data range

For example, if reading data are: 2Ch,00h,57h,03h,0E8h,6Eh，

The results are:

sum：6Eh=2Ch+00h+57h+03h+0E8h

TVOC value：(B2*256+B3)*0.01=(00h*256+57h)*0.01=0.87mg/m³

I²C pin definition                  I²C parameters

I²C sequence

Output method

Module use 2 wire I²C bus, the default is Slave Addr=0x3B, this is only read/write address, which occupied bit7 to bit1. When read from sensor, write 0x3B<<1|0x01=77. 

I²C data format

Module pictures:

Note: R2 is load resistor, it may differ from different production batch number. Common value are: 10K, 27K, 47K, 100K and 200K. The value difference will not affect the module electro performance and sensor performance.

Outline dimension

IMPORTANT PRECAUTIONS

• Please provide preheating for more than 5-10 min in first time use.
• Avoid vibration and drop, and forbid liquid into sensor inside.
• Do not apply this module to systems involving personal safety
• Do not place the module in a high concentration of organic gas for a long time
• Do not set module in application which has strong gas flow