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 BME280 
 Temperature sensors 

All-in-one environmental sensor measuring temperature, humidity, and pressure for IoT and weather monitoring systems.

 Interface
I²C

 Temperature range
-40 / 85°C

 Humidity range (Rh)
0% → 100%

 Pressure gauge (hPa)
300 → 1100

Temperature accuracy

+/- 0,5K

Humidity accuracy (rh)
+/- 3%

 Pressure accuracy
+/- 1hPa

 Internal resolution
20 bits

 Power supply voltage
1,71 → 3,6V

 Sampling rate
100Hz

 Typical current
3,6µA (active)

 Price
Medium

What is a BME280 sensor ?Operating principleTypical example of measurementPrinciple diagram (I2C connection)Application areas

What is a BME280 sensor ?

The BME280 is an integrated environmental digital sensor designed by Bosch Sensortec.

It simultaneously measures temperature, humidity, and barometric pressure, providing a reliable estimate of altitude and local atmospheric conditions.

It is one of the most widely used sensors in IoT and weather applications, thanks to its small size, low power consumption, and stability over several years.

Operating principle

The BME280 integrates three sensors:

  • a MEMS pressure sensor (piezoresistive),
  • a capacitive humidity sensor,
  • and an integrated thermal sensor for compensation.

The raw data is digitized by a 20-bit ADC and then corrected using internal calibration coefficients stored in EEPROM.

Standard Bosch equations (simplified):

P = f(raw_p, raw_t)

T = f(raw_t)

RH = f(raw_h, T)

💡 The exact formulas are provided in the Bosch documentation and are based on 6 to 9 calibration coefficients.

Typical example of measurement

Parameter 
 Gross value (hex)

Calculated value

Temperature

 0x6A90

24,8 °C
Humidity

0x5E20

46,5 % RH

Pressure

0x8A2C0

1013,2 hPa

🧮 Pressure can be converted into altitude:

Altitude (m) = 44330 × (1 − (P / 1013,25)^0,1903)

Principle diagram (I2C connection)

+3.3V
 │
[BME280]
 │ SDA ─────────┐
 │ SCL ─────────┤── [I²C Microcontroller]
 │ GND          │
 │ CSB / SDO ───┘ (config address or SPI)

💡 I²C Address: 0x76 if SDO=GND / 0x77 if SDO=VCC.

Application areas

🌤️ Connected weather stations and IoT

🚁 Drones (altimeter / air compensation)

⌚ Smartwatches and fitness trackers

🏠 Air conditioning and home automation systems

🧠 Industrial environmental monitoring

Should I choose a BME280 sensor ?

Strengths points

  • 🌍 3 sensors in 1
         → Temperature, humidity, and pressure integrated into a single housing.
  • 🎯 Stable and calibrated precision→ Each sensor is individually calibrated by Bosch.
  • 🔋 Very low consumption
         → Perfect for connected objects and wearable devices.
  • 📡 Flexible interface (I²C or SPI)
         → Compatible with most MCUs and IoT platforms.
BME280 sensors

Weaknesses points

  • 🌡️ Thermal sensitivity
         → The measurements can be influenced by the heat of the board if poorly insulated.
  • 🧱 Unprotected case
         → No built-in hydrophobic filter — sensitive to condensation and dust.
  • 📏 Complex calculations
         → The pressure/temperature/humidity conversions require the Bosch compensation equations.

Useful information

Here is some useful information regarding the BME280 sensors.

Address (hex)
 Registry Name
 Description
0xF2 ctrl_hum Humidity configuration
0xF4 ctrl_meas Temperature and pressure configuration
0xF5 config Filtering and monitoring duration
0xF7 → 0xFE Data registers Raw data (p, T, RH)
0x88 → 0xA1 Calib data Factory calibration coefficients 
i2c_start();
i2c_write(0x76 << 1);
i2c_write(0xF7);
i2c_start();
i2c_write((0x76 << 1) | 1);
read 8 bytes -> raw_p[3], raw_t[3], raw_h[2];
i2c_stop();

temp = compensate_T(raw_t);
press = compensate_P(raw_p);
hum = compensate_H(raw_h);

💡 Compensation functions are provided by Bosch in the official libraries.

3.3V ───────────┐
                │
               [BME280]
                │ SDA ───────┐
                │ SCL ───────┤── MCU (Arduino, STM32, ESP32…)
                │ CSB/SDO ───┘ (I²C/SPI)
                │ GND

💡 Provide pull-up resistors of 4.7 kΩ on SDA and SCL if not present.

Register
 Bits Function
ctrl_meas [7:5] osrs_t / [4:2] osrs_p / [1:0] mode Temperature, pressure, and mode configuration
config [7:5] t_sb / [4:2] filter / [0] spi3w_en Standby time, filtering, 3-wire SPI
ctrl_hum [2:0] osrs_h Humidity oversampling

Parameter RangeMax error
Temperature 0 → +65 °C ±0,5 K
Humidity 20 → 80 % RH ±3 % RH
Pression 300 → 1100 hPa ±1 hPa

💡 One of the best accuracies available on a compact 3-in-1 sensor.

 We integrate any sensor into any probe 

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 Waterproof

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 Atmosphere

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Stick-in

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Thread

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Jacketed

PCBA Design

PCBA design

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Winding

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