Communication protocol:
The DIP switch has 4 positions, but only 3 positions are used; the fourth position can be ignored as it is not read by the microcontroller.
Pins 1, 2, and 3 correspond to b0, b1, and b2, respectively. As shown in the diagram, toggling the switch upwards (ON direction) sets the corresponding bit to high, while toggling it downwards sets the bit to low.
The address code is calculated as:
Address Code=(b0∣b1<<1∣b2<<2)(Avoid using 00 if possible)text{Address Code} = (b0 | b1 << 1 | b2 << 2) quad (text{Avoid using 00 if possible})
| Byte | Name | Description |
|---|---|---|
| B1 | Frame Header 1 | Fixed value 3Ch |
| B2 | Frame Header 2 | Fixed value 02h |
| B3 | Data | eCO₂ High Byte |
| B4 | Data | eCO₂ Low Byte |
| B5 | Data | eCH₂O High Byte |
| B6 | Data | eCH₂O Low Byte |
| B7 | Data | TVOC High Byte |
| B8 | Data | TVOC Low Byte |
| B9 | Data | PM2.5 High Byte |
| B10 | Data | PM2.5 Low Byte |
| B11 | Data | PM10 High Byte |
| B12 | Data | PM10 Low Byte |
| B13 | Data | Temperature Integer Part |
| B14 | Data | Temperature Decimal Part |
| B15 | Data | Humidity Integer Part |
| B16 | Data | Humidity Decimal Part |
| B17 | Checksum | Checksum |
Note: The checksum in B17 is equal to the sum of the values in B1 + B2 + B3 + … + B16, and only the lower 8 bits are taken.
When the temperature data in B13 has bit 7 set to 1, it indicates a negative temperature. When bit 7 is 0, it indicates a positive temperature. For example, if B13 = 9Bh, bit 7 is 1, indicating a negative temperature, so the actual temperature is -27°C. If B13 = 1Bh, bit 7 is 0, indicating a positive temperature, so the actual temperature is 27°C.
Feature:
- Real-Time Monitoring: Provides instant data output for CO₂, CH₂O, and TVOC, with other parameters available after a brief preheating period.
- Compact and Durable Design: With external dimensions of 62×49×15mm, it is compact and easy to integrate into various systems.
- Wide Application: Suitable for use in HVAC systems, dehumidifiers, consumer products, automobiles, automation control, weather stations, and home appliances.
- User-Friendly Interface: Simple setup and easy-to-read output data make it suitable for both professional and consumer-level applications.
- High Sensitivity: Capable of detecting low concentrations of gases and particulates for accurate environmental monitoring.
Application
This seven-in-one air quality detection module is widely used in HVAC systems, dehumidifier testing and detection equipment, consumer products, automobiles, automation control, data loggers, weather stations, home appliances, and temperature regulation.
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