Interfacing MS5611 Pressure & Altitude with Arduino Uno

MS5611 practical reference

A high-resolution barometric sensor with centimeter-level altitude precision, frequently used in flight controllers and drones. The MS5611 measures atmospheric pressure with extremely fine resolution and converts that reading into altitude using the standard barometric formula, making it a staple in multirotor flight controllers for altitude-hold, weather stations wanting precise pressure trends, and any project needing to detect small changes in elevation that cheaper pressure sensors would miss.

Key specifications

• Sensor type: MS5611 high-resolution barometric pressure sensor with integrated 24-bit ADC
• Operating voltage: 1.8V–3.6V DC (breakout boards regulate from 3.3-5V input)
• Operating current: ~1-1.5 µA in standby, ~12.5 µA average during conversion
• Pressure range: 10 mbar to 1200 mbar
• Pressure resolution: 0.012 mbar (roughly 10cm altitude resolution)
• Temperature accuracy: ±0.8°C (also provides onboard temperature reading used to compensate pressure)
• Interface: I2C (up to 400 kHz) or SPI, selectable depending on breakout wiring
• I2C address: 0x76 or 0x77 depending on the CSB pin state

Pinout and connection notes

Most breakout boards default to I2C mode; the CSB pin's state sets which of the two possible I2C addresses (0x76 or 0x77) the sensor responds on, which is useful when combining it with another sensor sharing the same default address on one bus. For altitude calculations, remember pressure readings need to be compensated against a known sea-level reference or a recent local baseline for meaningful relative-altitude results.

• VCC: Power, 1.8–3.6V DC (most breakouts accept 3.3-5V and regulate down)
• GND: Ground
• SCL / SCLK: I2C clock or SPI clock, depending on interface mode
• SDA / SDI: I2C data or SPI data-in, depending on interface mode
• CSB: Chip select — determines I2C address (0x76/0x77) or enables SPI mode when pulled LOW
• SDO: SPI data-out (only used in SPI mode)

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.