Product Name: | Digital air quality (Strange smell )Module |
Product model: | MAQ400DUL |
Version: | V1.0 |
Formulator: | He Genwen |
Reviewer: | Yuan Chao |
1. Product Description
The air quality sensor module adopts advanced semiconductor gas-sensitive components, which have the characteristics of small size, low power consumption and long life, and also uses digital UART Interface output, with user-side calibration function.The sensor has extremely high sensitivity to organic volatile gases such as formaldehyde, benzene, carbon monoxide, ammonia, hydrogen, alcohol, cigarette smoke, and flavors.The module has been aging, debugging, calibration and calibration, and has good consistency and extremely high sensitivity.
This product has the characteristics of low power consumption, high precision, digital display, long life, etc., and is widely used in related fields such as air purification machines, fresh air ventilation systems, air quality monitors, intelligent integrated ceilings, etc.
2. Technical indicators
1.Technical Indicators
project | parameter |
Detect gas | Formaldehyde, benzene, carbon monoxide, hydrogen, alcohol, ammonia, cigarettes, smoke, flavors, etc. |
Operating voltage | 4 .8 ~ 5 . 2 V DC |
Operating current | ≤ 70mA average |
Warm-up time | 3min |
Response time | < 20s |
Recovery time | < 60s |
Sensitivity attenuation | ≤ 1%/Year |
Output data | 0 ~9 . 999 mg/m3 |
Communication interface | UART 9600 Baud rate |
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 of 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 supply negative terminal |
2 | 5V | Input power supply positive terminal |
3 | A | UART-TXD |
4 | B | UART- RXD |
Table 3. Communication configuration
Category | parameter |
Baud rate | 9600 |
Data bits | 8 |
Stop position | 1 |
Check bit | none |
V. Communication Protocol
0x86 – Read the concentration value of the sensor
1 | 0x86 | Read the concentration and temperature of the sensor |
send | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
Start position | address | Order | -- | -- | -- | -- | -- | Verification value |
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 position | Order | Sensor concentration value | -- | -- | -- | -- | Verification value |
0xFF | 0x86 | High bytes | Low bytes | 00 | 00 | 00 | 00 | -- |
EXP. | FF 86 07 17 00 00 00 00 5D |
1 、Calculation formula:
Concentration results = (High concentration value bytes *256+ Low concentration )/ 1000；
2 、Output algorithm:
As shown in the above table, the return value of the high byte is 0 x07 ， Convert to decimal to 7, low byte to 0 x17 Convert to decimal to 23.The output result is: (7*256+23) =1815；
3、The instruction to send data is in a fixed format;
4、Calculate the check value of the returned data:
Check value: The sum of the first 8 bits of data, and after removing the carry, it is 0. xFF The value obtained by XOR is added to 1, and the result is the test value;0 x85 – User self-calibration zero point
1 | 0x85 | User self-calibration points during use, and a value will be calibrated when leaving the factory |
send | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
Start position | address | Order | -- | -- | -- | -- | -- | Verification value |
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 position | Order | Return result | -- | -- | -- | -- | -- | Verification value |
0xFF | 0x85 | 0 or 1 | 00 | 00 | 00 | 00 | 00 | -- |
EXP. | FF 85 01 00 00 00 00 00 7B |
1、Byte 2, return 0 to indicate the calibration failed, return 1 to indicate the calibration is successful, return 01 to indicate the calibration is successful;
2、The sensor modules have been calibrated at the zero point and concentration point when they leave the factory. In most cases, users do not need to calibrate the zero point again.However, after the sensor is placed in a relatively harsh environment for a long time, the output signal may drift. In order to ensure the product test results, it is recommended that users can calibrate the zero point by themselves according to their usage needs:
A、 Manual calibration: The device reserves a one-click calibration interface or switch, and the end user can choose to manually calibrate zero in clean air.
point, this scheme is suitable for all users;
B、 Start-up calibration: After each device is preheated, the equipment will automatically calibrate to zero according to the concentration at that time. This solution is not suitable for equipment that work in environments with high pollutant concentrations for a long time, such as: conference rooms, mahjong rooms where people have been smoking;
C、 Automatic calibration: After the power is turned on, the device continuously scans the output value of the sensor module, and regards the lowest value that appears as the zero point value;
D、 Comprehensive calibration: Each time the power is turned on, the output value is continuously scanned. If there is a lower value, it will be considered as a new zero.
6. Things to note
Module avoids contact with organic solvents (Including silicone and other adhesives )、Paints, chemicals, oils and high concentration gases
The module cannot withstand excessive impact or vibration
The module needs to be preheated for more than 5 minutes when powered on for the first time
Do not apply this module to systems involving personal safety
Do not install the module in a strong air convection environment for use
Do not place the module in high concentration organic gas for a long time
After long-term storage, it is recommended to aging. The recommended aging time is shown in the table.
4
Storage time | Recommended aging time |
Less than 1 month | No less than 48 hours |
1-6Months | No less than 72 hours |
6More than a month | No less than 168 hours |
Table 4. Aging time
