# Hardware

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<a href="./unit_sch_v_1_0_0_bme688_environmental_sensor_4_in_1.pdf"><img src="resources/Schematics_icon.jpg?raw=false" width="450px"><br/> Schematics</a>
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## Key Technical Specifications

- Operating Voltage: 1.71V to 3.6V
- Supply Current: 0.9 µA (sleep), 2.1 µA (ULP), ~920 µA (gas scan)
- Operating Temperature: -40°C to +85°C
- Relative Humidity Range: 0% to 100% RH
- Pressure Range: 300 hPa to 1100 hPa
- Gas Sensing: VOCs, IAQ index via integrated gas sensor
- Interfaces: I²C and SPI (up to 3.4 MHz)
- Package Size: 3.0 × 3.0 × 0.93 mm³


## Technical Specifications

| Parameter                                       | Technical Data                                             |
|-------------------------------------------------|------------------------------------------------------------|
| Package dimensions                              | 8-Pin LGA with metal<br>3.0 x 3.0 x 0.93 mm³               |
| Operation range (full accuracy)                 | Pressure: 300...1100 hPa<br>Humidity: 0…100%<br>Temperature: -40…85°C |
| Supply voltage VDDIO                            | 1.2 - 3.6 V                                              |
| Supply voltage VDD                              | 1.71 - 3.6 V                                             |
| Interface                                       | I²C and SPI                                                |
| Average current consumption                     | 2.1 µA at 1 Hz humidity and temperature<br>3.1 µA at 1 Hz pressure and temperature<br>3.7 µA at 1 Hz humidity, pressure and temperature<br>90 µA at ULP mode for p/h/T &amp; air quality<br>0.9 mA at LP mode for p/h/T &amp; air quality<br>3.9 mA in standard gas scan mode (gas scan mode &amp; scan rate can be optimized on applications with BME AI studio) |
| Gas sensor - F1 score for H₂S scanning          | 0.94                                                       |
| Gas sensor - Standard scan speed                | 10.8 s / scan                                              |
| Gas sensor - Electric charge for standard scan  | 0.18 mAh (5 scans ~ 1 min)                                 |
| Gas sensor - Response time (τ 33-63%)           | &lt; 1 s (for new sensors)                                 |
| Gas sensor - Sensor-to-sensor deviation         | +/- 15%                                                    |
| Gas sensor - Power consumption                  | &lt; 0.1 mA in ultra-low power mode                        |
| Gas sensor - Output data processing             | Major direct outputs: Index for Air Quality (IAQ), bVOC-&amp; CO₂-equivalents (ppm), Gas scan result (%) &amp; many more (all listed in datasheet in Table 20: BSEC outputs)                                                                                                       |
| Humidity sensor - Response time (τ0-63%)        | 8 s                                                        |
| Humidity sensor - Accuracy tolerance            | ± 3 % relative humidity                                    |
| Humidity sensor - Hysteresis                    | ≤ 1.5 % relative humidity                                  |
| Pressure sensor - RMS Noise                     | 0.12 Pa (equiv. to 1.7 cm)                                 |
| Pressure sensor - Sensitivity Error             | ± 0.25 % (equiv. to 1 m at 400 m height change)            |
| Pressure sensor - Temperature coefficient offset| ±1.3 Pa/K (equiv. to ±10.9 cm at 1°C temperature change)   |
| I2C Address                                     | 0x77                                                       |

## Pinout


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### **Pinout Diagram**

<a href="./unit_pinout_v_0_0_2_ue0095_bme688_4_in_1_en.pdf"><img src="resources/unit_pinout_v_0_0_2_ue0095_bme688_4_in_1_en.jpg" width="500px"><br/>Pinout</a>
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### **Pinout Details**

| Pin Label | Description                  |
|-----------|------------------------------|
| VCC       | Power supply (3.3V or 5V)    |
| GND       | Ground                       |
| SDA/SDI   | I²C data / SPI data in       |
| SCL/SCK   | I²C clock / SPI clock        |
| CSB       | Chip select (SPI, active low)|
| SDO       | SPI data out                 |

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## Topology

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<a href="./resources/unit_topology_v_1_0_0_bme688_environmental_sensor_4_in_1.png"><img src="./resources/unit_topology_v_1_0_0_bme688_environmental_sensor_4_in_1.png" width="450px"><br/> Topology</a>
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| Ref. | Description                              |
|------|------------------------------------------|
| IC1  | BME688 Environmental Sensor              |
| L1   | Power On LED                             |
| U1   | AP2112K 3V3 Regulator                    | 
| JP1  | 2.54 mm Castellated Holes                |
| J1   | QWIIC Connector (JST 1 mm pitch) for I2C |
  
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## Dimensions

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<a href="./resources/unit_dimension_v_1_0_0_bme688_environmental_sensor_4_in_1.png"><img src="./resources/unit_dimension_v_1_0_0_bme688_environmental_sensor_4_in_1.png" width="500px"><br/> Dimensions</a>
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