7Semi BME280 Temperature, Humidity & Pressure Sensor Nano Breakout
π Overview
The breakout is based on the Bosch BME280 environmental sensor, a 3-in-1 MEMS digital sensor that measures:
Temperature
Relative Humidity
Barometric Pressure
It integrates all three sensing elements into a single compact chip, making it suitable for precise environmental monitoring.
βοΈ Working Principle
The BME280 combines three different sensing mechanisms:
1. Temperature Sensor
Based on bandgap temperature sensing
Measures ambient temperature and provides compensation data for other sensors
2. Humidity Sensor
Uses a capacitive sensing structure
Absorbs moisture β changes capacitance β converted to digital signal
3. Pressure Sensor
Uses a MEMS piezoresistive diaphragm
Air pressure deforms the diaphragm β resistance change β digital output
π All three signals are processed internally and provided as calibrated digital outputs
π Measurement Ranges
Temperature: β40Β°C to +85Β°C
Humidity: 0% to 100% RH
Pressure: 300 hPa to 1100 hPa
π Covers full environmental conditions from indoor to outdoor atmospheres.
π― Accuracy & Performance
Temperature
Accuracy: Β±0.5Β°C
Humidity
Accuracy: Β±3% RH
Response time: ~1 second
Pressure
Absolute accuracy: ~Β±1 hPa
Very low noise β enables fine altitude estimation
β‘ Electrical Characteristics
Supply voltage:
VDD: 1.71V to 3.6V
VDDIO: 1.2V to 3.6V
Current consumption (typical):
~1.8 Β΅A (Temp + Humidity)
~2.8 Β΅A (Pressure + Temp)
~3.6 Β΅A (all sensors active)
π Very low power β ideal for battery-powered systems.
π Communication Interface
IΒ²C (up to ~3.4 MHz)
SPI (3-wire / 4-wire)
π Fully digital output β no ADC required.
π§ Internal Features
β Factory Calibration
Each sensor includes pre-calibrated coefficients
No external calibration needed
β Oversampling Control
Adjustable resolution for:
Temperature
Pressure
Humidity
π Allows trade-off between:
Accuracy
Power consumption
β Built-in IIR Filter
Reduces:
Noise
Sudden environmental fluctuations
β Multiple Power Modes
Sleep mode (ultra-low power)
Forced mode (single measurement)
Normal mode (continuous measurement)
π‘οΈ Altitude Estimation
Derived from pressure readings
Based on atmospheric pressure variation
π Key point:
Requires reference pressure (sea-level)
Accuracy affected by weather changes
π¦ Physical Characteristics
Sensor size: 2.5 Γ 2.5 Γ 0.93 mm (LGA package)
Highly compact β suitable for embedded systems
π Operating Behavior
Fast response (~1 second for humidity)
Stable over temperature changes
Designed for long-term reliability and low drift
β οΈ Limitations
Measures relative humidity, not absolute moisture content
Pressure-based altitude depends on:
Weather variations
Sensitive to:
Condensation
Direct water exposure
Cannot detect gas composition (unlike gas sensors)
π§© Breakout Board Role (7Semi Nano Version)
The nano breakout board:
Provides compact pin spacing for embedded designs
Exposes:
Power pins
IΒ²C/SPI communication lines
May include:
Pull-up resistors
Basic signal routing
π Its purpose is easy integration, not altering sensor functionality.
π Summary
The 7Semi BME280 Nano Breakout is a compact, high-accuracy environmental sensing solution that:
Measures temperature, humidity, and pressure simultaneously
Uses MEMS + capacitive sensing technologies
Provides fully calibrated digital output
Offers very low power consumption
Supports flexible configuration for precision vs power trade-offs
