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Interact with EV3 Brick Peripherals, Read Sensor Values, and Control Motors

This example shows you how to interact with the EV3 brick peripherals, read a sensor value, and control a motor.

Introduction

This example shows you how to use MATLAB command to:

  • Interact with the EV3 brick peripherals: display text on the LCD; play a tone on the speaker; read the button status; control the color and state of the status light.

  • Read the touch sensor value.

  • Control the speed and direction of a motor.

Prerequisites

Create a connection to the EV3 brick called mylego, as described in Getting Started with MATLAB Support Package for LEGO MINDSTORMS EV3 Hardware example.

Required Hardware

This example requires additional hardware:

  • EV3 Touch Sensor

  • EV3 Motor

Task 1 - Interact with Brick Peripherals

Use mylego to interact with the brick peripherals: LCD, speaker, buttons, and status light.

1. Clear the LCD, and then write text on row 2, column 3.

clearLCD(mylego)
writeLCD(mylego,'Hello, LEGO!',2,3)

2. Play a 500 Hz tone on the speaker for 3 seconds, with the volume level set to 20.

playTone(mylego,500,3,20)

3. Read the status of the up button. If the button is pressed, the status is 1. Otherwise, the status is 0.

readButton(mylego,'up')

4. Illuminate the status light with a red LED, and then turn it off.

writeStatusLight(mylego,'red')
writeStatusLight(mylego,'off')

For more information, enter:

help legoev3

Task 2 - Read a Sensor Value

To interact with sensors that are connected to the input ports on the EV3 brick, create a handle for the sensor. Then, use this handle to perform operations such as reading sensor values.

1. Plug a touch sensor into port #1 on the EV3 brick, and create a handle for it.

mytouch = touchSensor(mylego,1)

2. Read the value of the touch sensor - pressed (1) and not pressed (0)

readTouch(mytouch)

For more information, enter:

help touchSensor

Task 3 - Control the Speed and Direction of a Motor

To interact with motors that are connected to the output ports on the EV3 brick, create a handle for the motor. Use the Speed property to set the speed and direction of the motor. Then, use the handle to start and stop the motor.

1. Plug a motor into port #A on the EV3 brick, and create a handle for it.

mymotor = motor(mylego,'A')

2. Set the motor speed by assigning a value to the Speed property.

mymotor.Speed = 20

3. Start the motor.

start(mymotor)

4. Change the motor speed and reverse its direction.

mymotor.Speed = -10

5. Stop the motor.

stop(mymotor)

For more information, enter:

help motor

Task 4 - Clear Objects

To discard the mylego, mymotor, and mytouch object handles, use the clear function.

clear

Summary

This example showed you how to:

  • Interact with EV3 brick peripherals - LCD, speaker, buttons and status light.

  • Read the status of a touch sensor.

  • Control the speed and direction of a motor.

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