MATLAB Examples

Communicating with TM4C123G6HPM Hardware

This example shows how to tune the parameters and monitor the signals of an algorithm running on Tiva TM4C123G LaunchPad using Energia Toolchain.

Contents

Supported Hardware:

TIVA TM4C123G LaunchPad.

Available versions of this example:

Tiva TM4C123G LaunchPad : Tiva123_communication

The provided model is pre-configured for Tiva TM4C123G LaunchPad and you can run on any of the board listed in the "Supported Hardware" section, by changing the "Target Hardware" parameter in the configuration parameters of the model as described in Task 3 of this example.

Introduction

Embedded Coder Support Package for Tiva TM4C123G LaunchPad enables you to monitor and tune algorithms running on Tiva TM4C123G LaunchPad from the same Simulink® models from which you developed the algorithms.

In this example you will learn how to tune and monitor the algorithm in real time as it is executing. When you are developing algorithms, it is often necessary to determine appropriate values of critical algorithm parameters in an iterative fashion. For example, a surveillance algorithm that measures motion energy in a room may use a threshold to determine an intruder in the presence of ambient noise. If the threshold value is set too low, the algorithm may erroneously interpret any movement as an intruder. If the threshold value is set too high, the algorithm may not be able to detect any movement at all. In such cases, the right threshold value may be obtained by trying different values until the desired algorithm performance is reached. This iterative process is called parameter tuning. Simulink's External mode feature enables you to accelerate the process of parameter tuning by letting you change certain parameter values while the model is running on target hardware, without stopping the model. When you change parameter values from within Simulink, the modified parameter values are communicated to the target hardware immediately. The effects of the parameters tuning activity may be monitored by viewing algorithm signals on scopes or displays in Simulink. This example introduces the Simulink External mode feature by showing you how to:

• Set up communication between Simulink and Tiva TM4C123G Launchpad.

• Use a Simulink model to tune the parameters of an algorithm that is running on Tiva TM4C123G Launchpad.

• Use Simulink scopes to monitor the state of an algorithm running on Tiva TM4C123G LaunchPad .

Prerequisites

We recommend completing Getting Started with Tiva TM4C123G LaunchPad Hardware example.

Required Hardware

To run this example you will need the following hardware:

• Tiva TM4C123G LaunchPad

• USB cable

Model

The following figure shows the example model:

open_system('TIVA123_communication.slx');

Task 1 - Configure and Run the Model on Tiva TM4C123G LaunchPad Hardware

In this task, you will configure and run your model on the Tiva TM4C123G LaunchPad .

1. Connect the Tiva TM4C123G LaunchPad to your computer with a USB cable.

2. Open the Configuration Parameters in the model. Click the Code Generation and select ert.tlc as the System target file under Target selection. Set the Hardware implementation->Hardware board parameter to “Tiva TM4C123G LaunchPad” which is connected to your computer. You will observe “Energia Tiva” selected as a Toolchain in Code Generation pane. Do not change any other settings.

3. Click Apply and OK.

Task 2 - Simulate the Model

To simulate the model, follow these steps:

1. Observe that the model plays the motion energy recorded in a room and compares it with a threshold to detect intrusion.

2. In the model, change the Simulation mode on the toolbar to Normal. This tells Simulink to run the model on the host computer. See Task 4 below to run the model on the Tiva TM4C123G LaunchPad hardware.

3. In the model, click the Run button in the Simulink toolbar.

4. Click the Scope block. Observe that the algorithm detects multiple intrusions.

5. Click Stop button in the Simulink model.

Task 3 - Run the Model in External Mode

1. Connect a USB cable from your computer to the Tiva TM4C123G LaunchPad .

2. In the model, change the Simulation mode on the toolbar to External.

3. In the model, click the Run button on the toolbar.

Task 4 - Communicate with the Model

At this point, your model is running on Tiva TM4C123G LaunchPad . As the model runs on hardware, it communicates with Simulink model in External mode using serial connection over USB.

1. Notice that the LED attached to pin 39 is glows constantly. This means that the selected threshold is too low and that the algorithm misinterprets even a minor motion energy change as an intrusion. You need to find a more optimal value of the threshold.

2. Double-click the Threshold block in the model, increase its value, and click OK or Apply. This changes the threshold value in the model running on the board.

3. Check whether the glowing pattern of the LED has changed. The LED should light up every 10 and 11.5 seconds in a correctly tuned algorithm.

4. If there is no change in LED light pattern, repeat the Steps 2 and 3 until you find the right value of the threshold.

5. Click Stop button in the Simulink model.

A pre-configured model "TIVA123_communication" is included for your convenience.

Other Things to Try

• Monitor other signals in the model. For example, add another scope to monitor the value of the recorded motion energy.

• Improve the detection algorithm to filter out any motion energy changes that are shorter than 0.2 seconds.

Summary

This example showed a workflow for tuning and monitoring an algorithm running on Tiva TM4C123G LaunchPad . In this example you learned:

• How to tune an algorithm parameter on Tiva TM4C123G LaunchPad using the External mode feature.