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lsm303c

Connect to LSM303C sensor Arduino hardware I2C bus

Since R2021a

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Add-On Required: This feature requires the MATLAB Support Package for Arduino Hardware add-on.

Description

The lsm303c object reads linear acceleration, magnetic field strength, and temperature using the LSM303C sensor connected to the I2C bus of the hardware. The LSM303C is an inertial measurement unit (IMU) used to read acceleration and magnetic field in all three dimensions. The LSM303C also has an embedded temperature sensor. Attach an LSM303C sensor to the I2C pins on the hardware. You can read the data from your sensor in MATLAB® using the Object Functions.

Creation

Syntax

imu = lsm303c(a)
imu = lsm303c(a,Name,Value)

Description

imu = lsm303c(a) creates a sensor object with default property values.

Example: imu = lsm303c(a);.

imu = lsm303c(a,Name,Value) creates a sensor object with properties using one or more Name,Value pair arguments.

Example: imu = lsm303c(a, 'Bus', 1);.

Input Arguments

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Connection to the hardware specified as an object.

Example: imu = lsm303c(a) creates a connection to the LSM303C sensor on the hardware represented as an object, a.

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.

I2C bus number, specified as 0 or 1. The default value is 0.

Data Types: double

Properties

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Note

Except for TimeFormat, all the other properties are non-tunable, which means you cannot change their values once the object is locked. Objects are locked when you call the read function, and the release function unlocks them. If a property is tunable, you can change its value at any time.

The rate in samples/s at which data is read from the sensor.

Data Types: double

Number of samples read from the sensor in a single execution of the read function.

Data Types: double

Specify whether to return the latest or the oldest data samples. The number of samples depends on the SamplesPerRead value. The data read from the sensor is stored in the MATLAB buffer.

  • latest —

    Provides the latest data samples available in the buffer. All previous data samples in the buffer are discarded. For example, if SamplesPerRead = 3, the latest three data samples read by the sensor are returned.

    The following figure illustrates how latest data samples are returned assuming S1 is the first sensor data stored in the buffer, S2 is the second data and so on and Sn is the last data stored in the buffer and SamplesPerRead property is set to 3 during sensor object creation.

  • oldest —

    Provides the oldest data samples available in the buffer. In this case, no data samples are discarded. For example, if SamplesPerRead = 3, the first three data samples read are returned for the first read, the next three data samples are returned for the second read, and so on.

    The following figure illustrates how oldest data samples are returned assuming S1 is the first sensor data stored in the buffer, S2 is the second data and so on and Sn is the last data stored in the buffer and SamplesPerRead property is set to 3 during sensor object creation.

Data Types: character vector | string

This property is read-only.

Samplesread property outputs the values of samples read so far by executing read function. Samplesread is set to 0, when the object is created or when you release the object.

Data Types: double

This property is read-only.

Samples available in the host buffer. The data read from the sensor is stored in the MATLAB buffer. SamplesAvailable property shows the number of SamplesAvailable in this host buffer. When you release the object, SamplesAvailable is set to 0. When the ReadMode of sensor is set as latest, SamplesAvailable will always be 0.

Data Types: double

Set the output format of the data returned by executing the read function.

When the OutputFormat is set to timetable, the data returned has the following fields:

  • Time — Time stamps in datetime or duration format

  • Acceleration — N-by-3 array in units of m/s2

  • MagneticField — N-by-3 array in units of µT

  • Temperature — N-by-1 array in units of degree Celsius

When the OutputFormat is set to matrix, the data is returned as matrices of acceleration, magnetic field, temperature, and time stamps. The units and size for the sensor readings are the same as the timetable format.

N is the number of samples per read specified by SamplesPerRead. The three columns of each field represent the measurements in x, y, and z axes.

Data Types: character vector | string

Set the format of the time displayed when the sensor data is read.

  • datetime — Displays the date and time at which the data is read.

  • duration — Displays the time elapsed in seconds after the sensor object is locked. The sensor object gets locked at the first call of the read function either after the object creation or after the execution of the release function.

Data Types: character vector | string

Object Functions

readAccelerationRead one sample of acceleration from sensor
readMagneticFieldRead one sample of magnetic field from sensor
readTemperatureRead one sample of temperature from sensor
readRead real-time sensor data at a specified rate
releaseRelease the sensor object
flushFlush the host buffer
infoRead information related to sensor

Examples

Create Connection to LSM303C Sensor

Create an arduino object with the I2C library.

a = arduino('COM4', 'Uno', 'Libraries', 'I2C');

Create the sensor object.

imu = lsm303c(a)
imu = 

  lsm303c with properties:

                 I2CAddress: 29 ("0x1D")
                           : 30 ("0x1E")
                        Bus: 0 
                     SCLPin: "D21" 
                     SDAPin: "D20" 

                 SampleRate: 100  (Samples/s)
             SamplesPerRead: 10  
                   ReadMode: 'latest'            
                SamplesRead: 0      
           SamplesAvailable: 0 
Show all properties, functions

Show all properties all functions

Create LSM303C Sensor Connection with Additional Name-Value Pair Arguments

Create a sensor object with additional properties specified as name-value pair arguments.

clear imu;
imu = lsm303c(a,'SampleRate',110,'SamplesPerRead',3,'ReadMode','oldest')
imu =

  lsm303c with properties:

                         I2CAddress: 107 ("0x6B")
                                Bus: 0
                             SCLPin: "A5"
                             SDAPin: "A4"

                         SampleRate: 110 (samples/s)
                     SamplesPerRead: 3
                           ReadMode: "oldest"
                        SamplesRead: 0
                   SamplesAvailable: 0

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More About

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Version History

Introduced in R2021a

See Also

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