product name： | Digital Air Quality (Odor) Module |
Model： | MAQ400DUL |
version： | V1.0 |
Creator： | He Genwen |
reviewed by： | Yuan Chao |
1、DESCRIPTION
The air quality sensor module adopts advanced semiconductor gas sensing components, which have the characteristics of small size, low power consumption, and long service life. At the same time, it adopts a digital UART interface output and has user calibration function. The sensor is highly sensitive to formaldehyde, benzene, carbon monoxide, ammonia, hydrogen, alcohol, cigarette smoke, essence and other organic volatile gases. The module has undergone aging, debugging, calibration, and has good consistency and extremely high sensitivity.
This product has the characteristics of low power consumption, high precision, digital display, and long service life, and is widely used in related fields such as air purifiers, fresh air ventilation systems, air quality monitoring instruments, intelligent integrated ceilings, etc.
2、TECHNICAL INDEX
1.TECHNICAL INDEX
project | parameter |
Detect gas | Formaldehyde, benzene, carbon monoxide, hydrogen, alcohol, ammonia, cigarette smoke, essence, etc |
working voltage | 4 .8 ~ 5 . 2 V DC |
Working current | ≤ 70mA average |
Warm-up time | 3min |
response time | < 20s |
recovery time | < 60s |
Sensitivity attenuation | ≤ 1%/year |
output data | 0 ~9 . 999 mg/m3 |
Interface | UART 9600BAUD |
working conditions | 0 ~50 ℃/15 ~ 90 %RH( No condensation) |
Storage conditions | -20~50℃/ <60%RH(No condensation) |
weight | ≤ 20g |
size | 22.5×12×17.6 (mm) |
life | >2year |
Terminal specifications | 4 PIN 2.54mm |
Table 1. Technical indicators
2. Sensor sensitivity curve
Figure 1. Comparison of sensitivity curves for different gases
3、Appearance and structural dimensions
Figure 2. Module Structure Diagram
4、interface definition
Table 2. Interface Definition
interface | name | function |
1 | GND | Input power negative terminal |
2 | 5V | Input power positive terminal |
3 | A | UART-TXD |
4 | B | UART- RXD |
Table 3. Communication Configuration
category | parameter |
BAUD | 9600 |
Data bits | 8 |
stop bit | 1 |
check bit | not have |
5、communication protocol
0x86 –Read the concentration value of the sensor
1 | 0x86 | Read the concentration and temperature values of the sensor |
sending | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
start bit | address | command | -- | -- | -- | -- | -- | checksums |
0xFF | 0x01 | 0x86 | 00 | 00 | 00 | 00 | 00 | 79 |
EXP. | FF 01 86 00 00 00 00 00 79 |
return | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
start bit | command | Sensor concentration value | -- | -- | -- | -- | checksums |
0xFF | 0x86 | High Byte | Low Byte | 00 | 00 | 00 | 00 | -- |
EXP. | FF 86 07 17 00 00 00 00 5D |
1 、Formula：
Concentration result=(concentration value high byte * 256+concentration value low byte)/ 1000；
2 、Output Algorithm：
The above table returns a value where the high byte is 0x07, converted to decimal 7, and the low byte is 0x17, converted to decimal 23. The output result is： (7*256+23) =1815；
3、The instruction to send data is in a fixed format；
4、Calculate the checksum of the returned data：
Verification value: The sum of the first 8 digits of data added together, after removing the carry and XOR with 0xFF, the result is the verification value; 0x85- User self calibration zero point
1 | 0x85 | During user use, self calibrate 0 points, and a numerical value will be calibrated at the factory |
sending | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
start bit | address | command | -- | -- | -- | -- | -- | checksums |
0xFF | 0x01 | 0x85 | 00 | 00 | 00 | 00 | 00 | 7A |
EXP. | FF 01 85 00 00 00 00 00 7A |
return | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
start bit | command | Return results | -- | -- | -- | -- | -- | checksums |
0xFF | 0x85 | 0 perhaps 1 | 00 | 00 | 00 | 00 | 00 | -- |
EXP. | FF 85 01 00 00 00 00 00 7B |
1、The second byte returns 0 indicating calibration failure, 1 indicating calibration success, and the previous example returns a value of 01 indicating calibration success;
2、The sensor modules are calibrated for zero and concentration points when they leave the factory, and in most cases, users do not need to calibrate the zero point again. However, after being placed in harsh environments for a long time, the sensor may experience output signal drift. To ensure the effectiveness of product testing, it is recommended that users can self calibrate the zero point according to their usage needs and refer to the following four solutions:
A、Manual calibration: The device is equipped with a one click calibration interface or switch, and end users can choose to manually calibrate the zero point in clean air. This solution is applicable to all users;
B、Power on calibration: After each device is turned on and preheated, the device automatically calibrates to zero according to the current concentration. This scheme is not suitable for devices that work in environments with high pollutant concentrations for a long time, such as meeting rooms and mahjong rooms where people have been smoking;
C、 Automatic calibration: After turning on, the device continuously scans the output value of the sensor module, and considers the lowest value that appears as the zero point value;
D、Comprehensive calibration: Self calibrate the zero point every time the machine is turned on, and continuously scan the output value. If there is a lower value, it is considered as a new zero point.
6、note
The module should avoid contact with organic solvents (including silicone and other adhesives), coatings, chemicals, oils, and high concentration gases
The module cannot withstand excessive impact or vibration
The module needs to be preheated for at least 5 minutes when first powered on for use
Do not apply this module to systems involving personal safety
Do not install the module for use in strong air convection environments
Do not place the mold in high concentration organic gases for a long time
After long-term storage, it is recommended to power on for aging. The recommended aging time is shown in the tablefour
Storage time | Suggested aging time |
Less than 1 month | Not less than 48 hours |
1-6 months | Not less than 72 hours |
Over 6 months | No less than 168 hours |
Table 4. Aging time
