MEMS formaldehyde HCHO sensor module

The formaldehyde sensor module is a CH2O gas module developed by using MEMS micro gas sensors, It can be used to detect the content of formaldehyde gas in the environment,

and then judge the air quality. The module is aged commissioning, calibration, calibration, good response consistency and high sensitivity to formaldehyde gas.

Features
Extremely high sensitivity, excellent long-term stability
Factory calibrated, automatic preheating judgment, low power consumption, long service life, high cost performance.

Applications
air purifier, indoor environment detection, air conditioning fresh air, portable detector.

Technical parameters

Mode number			M1001
Gas sensor mode number			S1001
Detectible gas			formaldehyde CH2O
Electronicproperties	Physical connection		XH2.54-4 vertical plug
	Data output		I²C  (5V)  or URAT  (5V)
	Input voltage		5.0±0.2VDC    (  no   polarity protection  )
	Measurement range		0-3mg/m³  (resolution：0.01 mg/m³)
Sensing properties	Workingcurrent	≤20mA	Response time	≤10s
	Preheattime	60 秒	Recovery time	≤120s
Working condition	temperature	-10 --- 40℃	Storage temperature	-20 --- 60℃
	humidity	≤95％RH	Storagehumidity	≤60％RH
	sensitive	0.03 ppm	weight	About 20 g
	Outline size	24×20×15mm  (L×W×H)
	Sensitivedamping	≤1%/year	Life time	5 year

Pinout    (URAT)

Pin #	function
Pin 1	V (-)
Pin 2	V (+)
Pin 3	A  (  RX)
Pin 4	B  (  TX)

Communication protocol parameters

Baud rate	9600bps
Data bits	8
Stop bits	1
Parity	none

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

Pin #	Function
Pin 1	V (-)
Pin 2	V (+)
Pin 3	A  (CLK)
Pin 4	B  (SDA)

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

B1	B2	B3
Address	CH2O Hi	CH2O Lo
3Bh	0XXh	0XXh

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

Application sketch map

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