Product description: LPS25HB - 126kPa I2C/SPI 2.5-5.5V pressure and height sensor - Pololu 2867 - soldered connectors
The module containsST'sLPS25HMEMS pressure sensor, which operatesfrom 26 kPa to 126 kPa. Compared to theLPS331APversion with which it is compatible, it featureshigher accuracy(up to 0.02 kPa)andlower noise (0.001 kPa). It also has a built-inFIFO bufferin which measurement data can be stored before transmission. The board also includes the necessarypassive componentsanda low-droput voltage regulatorthat allows the sensor to operate with3.3 V and 5 Vsystems.
Product compatible with Arduino
The LPS25H chip(documentation) has integrated temperature compensation and many configurable options including: selectable resolution and two programmable external interrupts. The communication interface is anI2CorSPIbus.
Connection of LPS25HB sensor
A power supply in the range of2.5 V to 5.5 Vshould be connected to the VIN and GND pins. When using a system powered by 3.3 V, the VIN pin can be left unconnected and power should be applied directly to the chip via the VDD pin. The chip communicates via I2C or SPI digital interface. The voltage of the bus logic signals should have the same value as the supply voltage applied to VIN. In case of using I2C bus, SCL and SDA pins should be connected. SPI requires connection of 4 pins: SDI, SDO, SPC and CS.
|I2C bus data line, SPI input data line (SDO in 3-wire mode).|
|SCL SPC||I2C bus clock line.|
|SDO SA0||SPI bus output data line (data-out) or address change for I2C. These pins do not have voltage converter - they work only with 3.3 V.|
|CS||Chip select - SPI Enable. The pin is in high state by default (I2C intref interface active), to start SPI communication a low state must be given.|
|INT1||Programmable interrupt. These leads do not have a voltage converter - they work only with 3.3 V.|
|VIN||Supply voltage from 2.5 V to 5.5 V.|
|VDD||When the supply voltage is higher than 3.3 V, this pin can be used as a 3.3 V voltage output with up to 150 mA current capacity.|
|GND||The ground potential of the chip.|
By default the chip uses I2C interface - CS pin is in high state by default, to start SPI communication a low state must be given. Details of I2C communication can be found in thedocumentationand in NXP's I2C bus specificationnote.
The sensor has a 7-bit address, the youngest bit of which is determined by the state on the SA0 pin. By default this pin is pulled up to VDD through a 10 kΩ resistor, which sets the address to 1011101b.
The bus operates correctly at 400 MHz (fast mode), higher values may work correctly but have not been tested.
To select communication via SPI, set the CS pin low (connect to ground). Transmission details and registers description are included in the circuitdocumentation.
Instructions for first use
All necessary information on communication and operation of the module can be found in thedocumentation. Below are some of the most important facts:
- By default, the pressure sensor is in low power mode, to activate it, the appropriate value must be entered into the CTRL_REG1 register.
- It is possible to multi-read and multi-write with a single I2C command by setting the most significant bit of the address (start autoincrement).
- It is possible to start autoincrement in SPI mode by setting MS bit - seedocumentationfor details.
- Supply voltage: 2.5 V to 5.5 V
- Current consumption: 2 mA
- Communication interface: I2C (TWI) or SPI
- Measurement ranges: 26 kPa to 126 kPa (260 mbar to 1260 mbar)
- Data format: 24-bits
- Built-in FIFO buffer
- For temperature: 20 to 60 °C: +/- 0.02 kPa
- for temperature: 0 to 80 °C: +/- 0.1 kPa
- Module size: 10.2 x 23.0 x 2.54 mm
- Weight: 0.6 g