Bosch Environmental Sensors: BMP180, BMP280 & BME280

Working Principle

The Bosch BMP280 is a MEMS barometric pressure sensor. A microscopic silicon diaphragm deflects under atmospheric pressure; piezoresistive elements on the diaphragm change resistance proportionally. An on-chip ADC and DSP compensate for temperature and convert the raw reading into calibrated pressure.

Analogy: Picture a tiny drum skin inside a chip. As air pressure changes, the drum skin flexes by nanometres, and strain gauges printed on it report the flex as an electrical signal.

Electrical Characteristics

Parameter	Value
Supply Voltage	1.71 V – 3.6 V
Pressure Range	300 – 1100 hPa
Pressure Accuracy	± 1 hPa (relative)
Temperature Range	−40 to +85 °C
Interface	I2C (addr 0x76/0x77) or SPI
Current (normal mode)	2.7 µA typical

Interfacing & Wiring

Calibration

The BMP280 stores factory calibration coefficients in internal registers. The compensation algorithm (provided in the datasheet) must be applied to raw readings. For altitude estimation, use the barometric formula:

altitude = 44330.0 * (1.0 - pow(pressure / seaLevelPressure, 0.1903))

Set seaLevelPressure from a local weather station for GPS-grade accuracy.

Code Example

/*
 * BMP280 Pressure & Altitude Reader — Arduino
 * Requires: Adafruit_BMP280 library
 * Wiring: I2C — SCL→A5, SDA→A4, VCC→3.3V
 */
#include <Wire.h>
#include <Adafruit_BMP280.h>

Adafruit_BMP280 bmp;  /* I2C interface */

void setup() {
    Serial.begin(9600);
    if (!bmp.begin(0x76)) {
        Serial.println("BMP280 not found! Check wiring.");
        while (1) delay(10);
    }
    /* Configure oversampling & filter */
    bmp.setSampling(Adafruit_BMP280::MODE_NORMAL,
                    Adafruit_BMP280::SAMPLING_X2,   /* temp */
                    Adafruit_BMP280::SAMPLING_X16,  /* pressure */
                    Adafruit_BMP280::FILTER_X16,
                    Adafruit_BMP280::STANDBY_MS_500);
}

void loop() {
    float pressure = bmp.readPressure() / 100.0F;  /* hPa */
    float altitude = bmp.readAltitude(1013.25);     /* sea-level ref */
    float tempC    = bmp.readTemperature();

    Serial.print("Pressure: "); Serial.print(pressure); Serial.println(" hPa");
    Serial.print("Altitude: "); Serial.print(altitude); Serial.println(" m");
    Serial.print("Temp: ");     Serial.print(tempC);    Serial.println(" °C");
    Serial.println();
    delay(2000);
}

Real-World Applications

BMP180: The Predecessor

The Bosch BMP180 (successor to BMP085) was the first widely adopted MEMS barometric sensor in the hobbyist community. It uses the same piezoresistive MEMS principle but with older technology:

• Pressure range: 300–1100 hPa (same as BMP280)
• Accuracy: ±1 hPa (same class, but noisier raw readings)
• Interface: I2C only (address 0x77) — no SPI option
• Resolution: 16–19 bit ADC vs BMP280’s 20-bit ADC
• Current: 12 µA at 1 Hz (vs BMP280’s 2.7 µA)
• EOL status: Discontinued by Bosch — BMP280 is the direct replacement

BME280: Adding Humidity

The Bosch BME280 is a drop-in upgrade that adds a humidity sensor to the BMP280’s pressure and temperature channels. Same footprint, same pinout, same I2C/SPI interface:

• Humidity range: 0–100% RH (±3% accuracy)
• Humidity response time: 1 second (63% step)
• Pressure & temperature: Identical specs to BMP280
• Current: 3.6 µA at 1 Hz (weather monitoring mode) — slightly higher than BMP280 due to humidity sensor
• Library: Use Adafruit_BME280 — API is nearly identical to Adafruit_BMP280 with added readHumidity()

Bosch Family Comparison

Feature	BMP180	BMP280	BME280
Pressure Range	300–1100 hPa	300–1100 hPa	300–1100 hPa
Pressure Accuracy	±1.0 hPa	±1.0 hPa	±1.0 hPa
Temperature	✓ (±1°C)	✓ (±1°C)	✓ (±1°C)
Humidity	✗	✗	✓ (±3% RH)
ADC Resolution	16–19 bit	20 bit	20 bit
Interface	I2C only	I2C + SPI	I2C + SPI
IIR Filter	✗	✓	✓
Current (1 Hz)	12 µA	2.7 µA	3.6 µA
Status	Discontinued	Active	Active

BME680 & BME688: Gas Sensing Upgrade

The BME680 adds a MOX gas sensor to the BME280’s temperature, pressure, and humidity measurements, detecting volatile organic compounds (VOCs) and outputting an Indoor Air Quality (IAQ) index. The BME688 extends this with an AI-ready 8-step gas heater profile for pattern recognition of specific gas mixtures (e.g., distinguishing cooking fumes from paint solvents).

Feature	BME280	BME680	BME688
Temperature	✓ (±1 °C)	✓ (±1 °C)	✓ (±1 °C)
Pressure	✓ (±1 hPa)	✓ (±1 hPa)	✓ (±1 hPa)
Humidity	✓ (±3% RH)	✓ (±3% RH)	✓ (±3% RH)
Gas (VOC/IAQ)	✗	✓ (single heater step)	✓ (8-step AI heater)
AI Gas Scanning	✗	✗	✓ (BME AI-Studio)
I²C Address	0x76/0x77	0x76/0x77	0x76/0x77
Current (1 Hz)	3.6 µA	~3.7 mA (gas heater on)	~3.7 mA (gas heater on)
Use Case	Weather	Indoor air quality	Odour classification

Limitations

• Altitude drift: Pressure varies with weather; without regular sea-level calibration, altitude readings drift metres per hour.
• Slow response: 16× oversampling adds latency (~40 ms) — acceptable for weather stations, too slow for shock detection.
• BMP280 lacks humidity: Upgrade to BME280 (drop-in compatible, same footprint) if humidity is also needed.
• BMP180 discontinued: No longer manufactured; use BMP280 or BME280 for new designs.
• BME680/688 gas heater: The MOX heater draws ~3.7 mA and needs 48-hour burn-in for stable IAQ readings — not suitable for ultra-low-power applications.