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This carrier for ST’s LPS331AP digital barometer measures pressures from 260 mbar to 1260 mbar (26 kPa to 126 kPa) with absolute pressure accuracy over temperature down to 2 mbar (0.2 kPa) and typical RMS noise of 0.02 mbar (0.002 kPa) in high-resolution mode. These pressures can easily be converted to altitudes. The board has a 3.3 V linear regulator and integrated level shifters that allow it to work over an input voltage range of 2.5 V to 5.5 V, and the 0.1 pin spacing makes it easy to use with standard solderless breadboards and 0.1 perfboards. The sensor offers IC and SPI interfaces.
This board is a compact (0.4 0.9) carrier for ST’s LPS331AP MEMS absolute pressure sensor, or barometer; we therefore recommend careful reading of the LPS331AP datasheet (453k pdf) before using this product. The LPS331 is a great IC, but its small, leadless, LGA package makes it difficult for the typical student or hobbyist to use. It also operates at voltages below 3.6 V, which can make interfacing difficult for microcontrollers operating at 5 V. This carrier board addresses these issues by incorporating additional electronics, including a 3.3 V voltage regulator and level-shifting circuits, while keeping the overall size as compact as possible. The board ships fully populated with its SMD components, including the LPS331AP, as shown in the product picture.
The LPS331 features embedded temperature compensation and has many configurable options, including selectable resolutions, a choice of output data rates, and two programmable external interrupt signals. Its pressure output has an absolute accuracy as low as 2 mbar (0.2 kPa), with RMS noise of 0.02 mbar (0.002 kPa) in the highest-resolution mode. Pressure and temperature sensor data are available through a digital interface, which can be configured to operate in either IC or SPI mode, and can be used for altimetry. (See the Sample Code section below for an Arduino library that can be used to turn this sensor into an altimeter).
The carrier board includes a low-dropout linear voltage regulator that provides the 3.3 V required by the LPS331, which allows the sensor to be powered from a 2.5 V to 5.5 V supply. The regulator output is available on the VDD pin and can supply almost 150 mA to external devices. The breakout board also includes a circuit that shifts the IC/SPI clock and data in lines to the same logic voltage level as the supplied VIN, making it simple to interface the board with 5 V systems, and the board’s 0.1 pin spacing makes it easy to use with standard solderless breadboards and 0.1 perfboards.
For sensor fusion applications, AltIMU-10 v3 inertial measurement unit combines the LPS331AP with an L3GD20H 3-axis gyro and an LSM303D 3-axis accelerometer and 3-axis magnetometer on a single board, providing ten independent readings that can be used to calculate an absolute orientation and altitude.
This module is a lower-cost alternative to our newer LPS25H carrier, which offers improved accuracy, reduced output noise, and a built-in FIFO (First In, First Out) buffer allows the sensor to store pressure readings for burst transmission or to output a running average to further reduce output noise.
- Dimensions: 0.4 0.9 0.1 (10 mm 23 mm 3 mm)
- Weight without header pins: 0.6 g (0.02 oz)
- Operating voltage: 2.5 V to 5.5 V
- Supply current: 2 mA
- Output format (IC/SPI): 24-bit pressure reading (4096 LSb/mbar)
- Sensitivity range: 260 mbar to 1260 mbar (26 kPa to 126 kPa)
A 19 strip of 0.1" header pins and a 19 strip of 0.1" right-angle header pins are included, as shown in the picture below. You can solder the header strip of your choice to the board for use with custom cables or solderless breadboards, or you can solder wires directly to the board itself for more compact installations.
The board has one mounting hole that works with #2 and M2 screws (not included).
- Product Wiki
- LPS331AP datasheet: Datasheet for the ST LPS331AP MEMS pressure sensor.
- LPS331AP pressure/altitude sensor carrier with voltage regulator schematic diagram: Printable schematic diagram for the LPS331AP pressure/altitude sensor carrier with voltage regulator.
- AN4159: hardware and software guidelines for the LPS331AP: Application note from ST with hardware and software guidelines for use of the LPS331AP pressure sensor.
- UM10204 IÂ²C-bus specification and user manual: The official specification for the IÂ²C-bus, which is maintained by NXP.
- LPS331AP Pressure/Altitude Sensor Carrier with Voltage Regulator drill guide: This DXF drawing shows the locations of all of the board’s holes.
- LPS Arduino library: This is a library for the Arduino that interfaces with our LPS25H and LPS331AP pressure/altitude sensor carriers as well as the pressure sensor on the AltIMU-10 v3 (it also works with the original AltIMU-10). It makes it simple to read the raw pressure data from the sensor, and it provides functions to help calculate altitude based on the measured pressure.
- LPS331AP pressure sensor test flight: A blog post by Pololu president Jan MalÃ¡Å¡ek about testing the LPS331AP pressure sensor as an altimeter in an airplane.
- Big price reduction of Pololu MEMS sensor carriers and IMUs: We have some very exciting price reduction news to share with you, but first: A little background 3-axis accelerometer carrier, released 22 Apr...
- New product: LPS25H pressure/altitude sensor carrier: Weâve just released a carrier board for STâs newest pressure sensor, the LPS25H, and weâre also lowering the price of our LPS331AP carrier. Like the...
- New products: MinIMU-9 and AltIMU-10 v3: We are happy to introduce new v3 versions of our MinIMU-9 and AltIMU-10 inertial measurement units (IMUs). These sensor modules are the same...
- LPS331AP pressure sensor test flight: We expect to release a simple carrier for STâs new LPS331AP pressure sensor this week. While testing and writing example programs for the sensor,...
LPS331AP Pressure/Altitude Sensor Carrier with Voltage Regulator 
- Brand: Pololu
- Product Code: POL-2126
- Reward Points: 6
- Availability: 2
- Ex Tax: £6.95
- Price in reward points: 100