🔍 BME280 Humidity & Temperature Sensor Probe -7Semi

🔍 Overview
The probe is based on the Bosch BME280 environmental sensor IC, integrated inside a sealed probe enclosure with a cable interface.
Measures:
Temperature
Relative Humidity
(Internally also pressure, though probe is mainly used for temp & humidity monitoring)
Designed for remote sensing applications, where the sensing element must be placed away from electronics.
👉 The key difference from standard breakout boards is the probe-style packaging, not the sensing technology.
⚙️ Internal Working Principle
The probe internally uses the same sensing technologies as the BME280 IC:
🌡️ Temperature
Bandgap-based sensing element
Provides temperature data for:
Direct output
Compensation of humidity readings
💧 Humidity
Capacitive polymer sensing layer
Absorbs moisture → dielectric constant changes → capacitance change → digital output
🌬️ Pressure (internal)
MEMS diaphragm senses atmospheric pressure changes
👉 All signals are processed using internal calibration coefficients stored in the chip.
📊 Measurement Characteristics
Temperature range: −40°C to +85°C
Humidity range: 0% to 100% RH (non-condensing)
Pressure range: 300 hPa to 1100 hPa
Accuracy
Temperature: ±0.5°C (typical)
Humidity: ±3% RH (typical)
Pressure: ±1 hPa (typical)
⚡ Electrical Characteristics
Supply voltage: 1.7V to 3.6V (typically 3.3V)
Current consumption: ~3.6 µA (typical active mode)
Interface: I²C digital communication
👉 The probe outputs fully calibrated digital data, eliminating the need for external ADC.
🔗 Communication & Data Output
I²C address: 0x76 or 0x77 selectable
Output resolution: 16-bit digital data
Data includes:
Compensated temperature
Compensated humidity
Pressure (optional use)
🧩 Probe Design Characteristics
✔ Sealed Probe Structure
Encased in plastic + metal or MRS-type enclosure
Protects sensor from:
Dust
Mechanical damage
Environmental exposure
✔ Cable-Based Interface
Typical cable length: ~1 meter
Pre-wired connections:
VCC
GND
SDA
SCL
👉 Enables remote placement of sensing element without signal degradation.
🌡️ Environmental Behavior
✔ Fast Response
Humidity response time: ~1 second
✔ Stability
Factory calibrated → stable over long-term use
Low drift under normal conditions
✔ Compensation
Internal temperature compensation improves humidity accuracy
🧠 Internal Processing Features
Built-in calibration coefficients
Digital compensation algorithms
Optional oversampling and filtering
Low-noise measurement output
⚠️ Limitations
Measures relative humidity, not absolute moisture content
Accuracy affected by:
Condensation
Poor airflow around probe
Pressure readings may be less relevant depending on probe enclosure design
Requires proper placement for accurate readings (air exposure is critical)
🔄 Operating Behavior
Works best in:
Continuous measurement mode
Stable airflow conditions
Important considerations:
Avoid water condensation on probe
Avoid sealed environments without airflow
🏁 Summary
The 7Semi BME280 Sensor Probe is a remote environmental sensing solution that:
Integrates temperature, humidity, and pressure sensing in a sealed probe
Provides high-accuracy calibrated digital output via I²C
Supports remote placement using a cable interface
Offers low power consumption and fast response
Is optimized for reliable environmental monitoring in distributed systems