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lsm9ds1

Connect to LSM9DS1 sensor on Arduino hardware I2C bus

Description

The lsm9ds1 object reads acceleration, angular velocity, and magnetic field using the STMicroelectronics® LSM9DS1 sensor. The LSM9DS1 is a 9 degree of freedom (DOF) inertial measurement unit (IMU) used to read acceleration, angular velocity, and magnetic field in all three dimensions.

The lsm9ds1 object represents a connection to the device on the Arduino® hardware I2C bus. Attach an LSM9DS1 sensor to the I2C pins on the Arduino hardware. You can read the data from your sensor in MATLAB®using the object functions.

Before you use the lsm9ds1 object, create an Arduino object using arduino and set its properties. When you create the Arduino object, make sure that you include the I2C library. For more information, see Connect to Arduino Hardware.

Creation

Syntax

imu = lsm9ds1(a)
imu = lsm9ds1(a,Name,Value)

Description

imu = lsm9ds1(a) creates a sensor object with default property values. The object represents the connection to the sensor on the Arduino hardware, a.

imu = lsm9ds1(a,Name,Value) creates a sensor object with properties using one or more Name,Value pair arguments.

Example: imu = lsm9ds1(a,'SampleRate',150,'SamplesPerRead',5,'ReadMode','latest');

Input Arguments

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Arduino hardware connection created using arduino, specified as an object.

Example: imu = lsm9ds1(a) creates a connection to the LSM9DS1 sensor on the Arduino object, a.

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

Specify the I2C address of a sensor when multiple sensors are connected to the same hardware board. LSM9DS1 has two slave addresses which depends on the logic level on pins SDO_A/G and SDO_M of the sensor. For example, if SDO_M and SDO_A/G are low, the I2C address is {'0x6A','0x1C'}.

Example: imu = lsm9ds1(a,'I2CAddress',{'0x6A','0x1C'})

'0x6A' is the I2C address of the accelerometer and gyroscope of LSM9DS1. '0x1C' is the I2C address of the magnetometer of LSM9DS1.

Data Types: cell array of character vector

Properties

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Unless otherwise indicated, properties are nontunable, which means you cannot change their values after calling the object. Objects lock when you call them, and the release function unlocks them.

If a property is tunable, you can change its value at any time.

For more information on changing property values, see System Design in MATLAB Using System Objects (MATLAB).

Note

The properties SampleRate, SamplesPerRead, ReadMode, OutputFormat, TimeFormat, SamplesAvailable, and SamplesRead are available only with the Sensor Fusion and Tracking Toolbox™. These properties can be set while you create the sensor object.

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

Tunable: No

Data Types: double

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

Tunable: No

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.

Tunable: No

Data Types: character vector | string

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

  • AngularVelocity — N-by-3 array in units of rad/s

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

When the OutputFormat is set to matrix, the data is returned as matrices of acceleration, angular velocity, magnetic field, and time stamps. The units for the sensor readings are the same as the timetable format. The size of each matrix is N-by-3.

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.

Tunable: Yes

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.

Tunable: Yes

Data Types: character vector | string

Usage

Create LSM9DS1 Sensor Connection

Create an Arduino object and include the I2C library.

a = arduino();

Or, you can explicitly specify it in the Libraries Name-Value pair while creating the Arduino object.

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

Create the sensor object.

imu = lsm9ds1(a)
imu = 

  lsm9ds1 with properties: 

                 I2CAddress: 107  ("0x6B")
                           : 30   ("0x1E")
                     SCLPin: "A5" 
                     SDAPin: "A4" 

      AvailableMeasurements: ["Acceleration", "AngularVelocity","MagneticField"]

Create LSM9DS1 Sensor Connection (with Sensor Fusion and Tracking Toolbox)

Create a sensor object with properties available only with the Sensor Fusion and Tracking Toolbox.

clear imu;
imu = lsm9ds1(a,'SampleRate',50,'SamplesPerRead',5,'ReadMode','Latest')
imu = 

  lsm9ds1 with properties: 

                 I2CAddress: 107  ("0x6B")
                           : 30   ("0x1E") 
                     SCLPin: "A5" 
                     SDAPin: "A4" 

                 SampleRate: 50  (Samples/s)
             SamplesPerRead: 5  
                   ReadMode: 'latest'            
                SamplesRead: 0      
           SamplesAvailable: 0 
      AvailableMeasurements: ["Acceleration", "AngularVelocity","MagneticField"]

Object Functions

readAccelerationRead one sample of acceleration from sensor
readAngularVelocityRead one sample of angular velocity from sensor
readMagneticFieldRead one sample of magnetic field from sensor
readRead acceleration, angular velocity, magnetic field, time, and overrun data
releaseRelease the IMU object
flushFlush the host buffer
infoRead output data rate and bandwidth setting of sensor

Introduced in R2019a