Magnetometer

Measure magnetic field along X, Y, and Z axes

Add-On Required: This feature requires the Simulink Support Package for Android Devices add-on.

Libraries:
Simulink Support Package for Android Devices / Sensors

Description

The Magnetometer block reads the strength of the magnetic field around an Android™ device. The built-in magnetometer sensor on the Android device measures the magnetic field along the X, Y, and Z axes. The block outputs the magnetic field as a 1-by-3 vector in microtesla (μT).

This illustration shows the orientation of the X, Y, and Z axes for a typical Android mobile phone.

This illustration shows the orientation of the X, Y, and Z axes for a typical Android tablet.

Note

During simulations without hardware, this block outputs zeros. For more information, see Block Produces Zeros or Does Nothing in Simulation.

Ports

Output

expand all

Port_1 — Strength of magnetic field around Android device
vector

The block outputs the strength of the magnetic field as a 1-by-3 vector. The elements of the vector represent the measurements of the magnetic field in μT along the X, Y, and Z axes of the magnetometer sensor on the Android device.

Data Types: single

Parameters

expand all

Sample time — How often the block reads data
`0.1` (default) | `-1` | any positive integer

Specify how often the block reads data from the magnetometer, measured in seconds. When you specify this parameter as -1, Simulink^® determines the best sample time for the block based on the block context within the model.

Read Magnetic Field Strength from Android Device

This example shows how to read the strength of the magnetic field around an Android device.

This Simulink model includes a Magnetometer block and a Data Display block. The Magnetometer block reads the strength of the magnetic field from the built-in magnetometer sensor on your Android device. The block outputs the magnetic field as a 1-by-3 vector. The Data Display block accepts the vector and displays the values on your Android device.

To run the model:

Connect an Android device to your computer with a USB cable.
Install the Simulink Support Package for Android Devices as described in Install Support for Android Devices.
In the Modeling tab of the toolstrip, select Model Settings.
In the Configuration Parameters dialog box, select Hardware Implementation.
Set the Hardware board parameter to Android Device. This selection automatically populates the parameters in the Hardware board settings with the default values for Android.
From the Groups list under Target hardware resources, select Device options.
From the Device list, select your Android device. If your device is not listed, click Refresh.
Note
If your device is not listed even after clicking the Refresh button, ensure that you have enabled the USB debugging option on your device. To enable USB debugging, enter androidhwsetup in the MATLAB^® Command Window and follow the onscreen instructions.
Click Apply to save your changes. Click OK.
On the Simulink editor toolbar, click the Build Model button . The model is loaded and starts running on the device. The values from the magnetometer are displayed on the device screen. Move your Android device and observe the change in the magnetic strength along all three axes.