Weather stations, indoor navigation and altitude logging all depend on the same three measurements: temperature, humidity and barometric pressure. The BME280 from Bosch Sensortec packs all three into a single LGA-8 package with an I2C and SPI interface, which is why it turns up in so many environmental sensing designs. This guide covers how to get reliable readings out of it and the layout habits that keep the data trustworthy.
One package, three measurements
Putting temperature, humidity and pressure in one package means the three readings are taken at the same physical point and at the same time. That consistency matters whenever you derive a value from more than one of them — altitude from pressure and temperature, or dew point from temperature and humidity. Sensors that are physically separate can disagree, and reconciling them in firmware is more work than most designs anticipate.
Interface and integration
- I2C — the default when the sensor shares an existing bus; remember the address pin and the pull-ups.
- SPI — a dedicated link with higher throughput and no address conflict; the right choice on a busy bus.
- Supply range — the part runs from a low-voltage rail, so it can sit directly on a modern 3.3 V MCU domain.
- Sampling — oversampling and filter settings trade power against noise; match them to how fast the environment actually changes.
Getting trustworthy readings
The single biggest cause of disappointing sensor data is the enclosure, not the silicon. Keep the sensor away from regulators, displays and other heat sources; provide the vent opening the integration guide calls for; and avoid coating the opening. Because relative humidity is computed from the temperature reading, a sensor warmed by its neighbours will report an error that looks like a humidity problem but is really a thermal one. Give the measurement a stable thermal environment and the numbers settle down.
Environmental sensors we stock
| Part | Measures | Package | Link |
|---|---|---|---|
| BME280 | Temperature / humidity / pressure (Bosch Sensortec) | LGA-8 | BME280 |
| BMP280 | Temperature / pressure (Bosch Sensortec) | LGA-8 | BMP280 |
| SHT31-DIS-B | Temperature / humidity (Sensirion) | DFN | SHT31-DIS-B |
| AHT20 | Temperature / humidity | SMD | AHT20 |
| DS18B20 | Digital temperature (1-Wire) | TO-92 / SMD | DS18B20 |
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Frequently asked questions
What does the BME280 measure?
It combines temperature, humidity and barometric pressure in one package, which is what makes it popular for weather stations, indoor navigation and altitude logging. Having all three on one die means the readings are taken at the same point and the same moment, so derived quantities such as altitude or dew point stay consistent.
Should I use I2C or SPI?
I2C is the usual choice when the sensor shares an existing two-wire bus and speed is not critical. SPI is preferred when you want a dedicated link, higher throughput, or you need to avoid address conflicts on a busy bus. Both are supported, and the choice is largely about what the rest of your board already uses.
Why does my humidity reading drift?
Humidity sensors measure the air that reaches the sensing element, so board layout matters: keep the sensor away from heat sources, leave the recommended vent opening in the enclosure, and avoid conformal coating over the opening. A part sitting near a warm regulator will read a consistently higher temperature and therefore a lower relative humidity.
Do you stock BME280 and related environmental sensors?
Yes. We stock the BME280 and a range of temperature, humidity and pressure sensors, and we can quote by quantity with date codes so you can validate before committing to volume.
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