Interfacing BMP180 Pressure & Altitude with Arduino Uno

BMP180 practical reference

An earlier-generation barometric pressure sensor, still widely used in altimeter and weather-station projects thanks to abundant library support. The BMP180 measures atmospheric pressure and temperature over I2C, and because pressure decreases predictably with altitude, its readings can be converted into a fairly accurate relative-altitude estimate — a long-standing staple for DIY weather stations, altitude-hold drone code, and any project needing a simple 'how high up am I' or 'is the weather changing' reading.

Key specifications

• Sensor type: Bosch BMP180 barometric pressure and temperature sensor
• Operating voltage: 1.8V–3.6V DC (breakout boards regulate from 3.3-5V input)
• Operating current: ~5 µA at 1 sample/second in standard mode
• Pressure range: 300 hPa to 1100 hPa (equivalent to roughly 9000m below to 500m above sea level)
• Pressure resolution: 0.01 hPa in ultra-high-resolution mode (roughly ~0.1m altitude resolution)
• Temperature accuracy: ±2°C typical
• Interface: I2C, up to 3.4MHz
• I2C address: 0x77 (fixed)

Pinout and connection notes

Add standard 4.7kΩ pull-up resistors on SDA/SCL if not already present on the breakout board. Because altitude is calculated from relative pressure, calibrate against a known local sea-level pressure reading (or a recent baseline reading at a known altitude) for meaningful absolute altitude results, since raw pressure alone only gives relative changes.

• VIN: Power, 3.3–5V DC depending on breakout regulator
• GND: Ground
• SCL: I2C clock line
• SDA: I2C data line

Integration checklist

1. Confirm the exact part number and breakout-board revision.
2. Verify supply voltage, current demand, logic levels, and signal direction against the datasheet.
3. Check controller pin assignments and bus address or interface mode against the example code.
4. Power up with external loads disconnected, then test signals before full integration.
5. If readings or communication fail, check power and ground first, then pin mapping, interface settings, and library initialization.

Troubleshooting and reproducibility

Record the board used, wiring, library/version, supply arrangement, and measured behavior. Use the selected board-specific wiring example as the source of truth. Never assume visually similar modules share identical voltage tolerance or pin order.