lps22hb

Connect LPS22HB sensor on Raspberry Pi hardware I2C bus

Since R2021a

Description

The lps22hb object reads ambient temperature and absolute pressure using the STMicroelectronics^® I2C-based LPS22HB sensor interfaced with the Raspberry Pi^® hardware. Before you use the lps22hb object, ensure that the I2C interface is enabled on your Raspberry Pi kernel. You can then create a connection to the Raspberry Pi board using the raspi object and set its properties. For more information, see raspi.

Creation

Syntax

sensor = lps22hb(mypi)

sensor = lps22hb(mypi,Name,Value)

Description

sensor = lps22hb(mypi) creates a LPS22HB sensor object with default property values. The object represents a connection to the sensor on the Raspberry Pi hardware mypi.

sensor = lps22hb(mypi,Name,Value) creates a LPS22HB sensor object with properties using one or more Name,Value arguments.

Input Arguments

mypi — Raspberry Pi hardware connection

raspi object

Raspberry Pi hardware board connection specified as a raspi object.

Example: sensor = lps22hb(mypi) creates a connection to the LPS22HB sensor on the Raspberry Pi object mypi.

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Bus — I2C bus address of Raspberry Pi board

'i2c-0' | 'i2c-1'

I2C bus address of the Raspberry Pi hardware board.

Example: sensor = lps22hb(mypi, 'Bus', 'i2c-1') creates the sensor object on the 'i2c-1' bus of the Raspberry Pi board.

Data Types: char

I2CAddress — Specify I2C address of sensor

'0x5C' (default) | '0x5D'

Specify the I2C address of the sensors when multiple I2C devices with the expected address for LPS22HB are connected to the same hardware board. LPS22HB can have two I2C addresses depending on the logic level on pin SA0 of the sensor.

Pin Name	Pin State	I2C Address
SA0	Low	0x5C
	High	0x5D

You can specify the I2C address in:

• Hexadecimal, decimal, or binary format

• String of hexadecimal value of I2C Address

• Character vector of hexadecimal value of I2C Address

Example: pressureSensor = lps22hb(mypi,'I2CAddress',0x5C)

0x5C is the I2C address of the LPS22HB connected to Raspberry Pi board.

If not specified, the object will be created with one of the available I2C device address in the table. Availability of I2C device with the expected address will be determined by using scanI2CBus.

Object Functions

readTemperature	Read one sample of temperature from sensor
readPressure	Read one absolute pressure data sample from sensor

Examples

Create LPS22HB Sensor Connection

Ensure that the I2C interface on the Raspberry Pi kernel is enabled and then create an lps22hb sensor object.

You can enable the I2C interface using:

• Raspberry Pi Kernel I2C Interfacing options on Linux terminal. For more information, see Enable I2C Interface on Raspberry Pi Hardware Kernel or

• Raspberry Pi Resource Monitor App. For more information, see Enabling External Peripherals on Raspberry Pi Hardware Kernel.

Create a connection from MATLAB^® to the Raspberry Pi hardware board.

mypi = raspi('raspberrypi-hysdu8X38o','rocky','bullwinkle')

mypi = 

  Raspi with Properties:

           DeviceAddress: 'raspberrypi-hysdu8X38o'
                    Port: 18734
               BoardName: 'Raspberry Pi 3 Model B+'
           AvailableLEDs: {'led0'}
    AvailableDigitalPins: [4,5,6,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27]
    AvailableSPIChannels: {‘CE0’,’CE1’}
       AvailableI2CBuses: {'i2c-1'}
             I2CBusSpeed: 100000
        AvailabelWebCams: mmal service 16.1 (platform:bcm2835-v4l2)

Get the address of the LPS22HB sensor connected to the I2C bus 'i2c-1'.

sensor = scanI2CBus(mypi,'i2c-1');

ans =

  1×1 cell array

    {'0x5D'}

Create an lps22hb sensor object on the I2C bus 'i2c-1' on address '0x5D'.

sensor = lps22hb(mypi,'Bus','i2c-1','I2CAddress','0x5D');

sensor = 

  lps22hb with properties:

                         I2CAddress: 93 ("0x5D")
                                Bus: i2c-1

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using MATLAB® Coder™.

• Timestamp value is always returned in seconds.

• When you create an lps22hb sensor object and do not specify the I2C address in the name-value pair, the default I2C address is considered by the LPS22HB sensor. For the LPS22HB sensor, the default I2C address is '0x5C'.

Version History

Introduced in R2021a