Robotics UnitUnit 3: Introduction to VEX

Cortex Microcontroller

The “brain” of the robot

Controls the flow of information and power to the robot

Controls electronic components (motors, sensors, etc.)

VEX programs are downloaded from the computer to the microcontroller using the orange USB cable.

Note: You should use the USB port that is located in the front of your computer.

Battery pack gets plugged in here

On/off switch

Always turn off before you put your robot away.

VEXnet USB keys are for wireless communication between joystick and microcontroller.

2.4 GHz frequency band

VEXnet Joystick

Refer to the Cortex Microcontroller and VEXnet Joystick User Guide to setup the VEXnet Wireless Link. This document is a very valuable resource when working with any VEX robot. Make sure to read it thoroughly and keep a copy handy. It includes many troubleshooting tips.

Allows you to control the robot manually using a wireless link.

Turn power off when not in use so batteries don’t get used up.

VEXnet Joystick

2 analog joysticks

2 four button directional pads

4 trigger buttons

VEX Microcontroller

10 motor ports

8 analog inputs

12 digital I/O ports

VEX Clawbot

4 motors Left drive

Right drive

Arm

Claw

Clawbot Default Code Settings

Motor Motor PortVEXnet Joystick

ControlLeft Drive Motor 1 Left Joystick

Claw Motor 6Left Shoulder

Buttons

Arm Motor 7Right Shoulder

ButtonsRight Drive Motor 10 Right Joystick

You will use default code (code that is already written) that determines how the joystick controls the behavior of the robot. The code uses the port settings shown in the table.

Page 16 of Clawbot directions

Notice wire colors!Black wires always face the “outside.” Be gentle with the pins, don’t bend them.

Installing Batteries and VEXnet Keys

Plug a 7.2v VEX battery into the 7.2v battery port on the front of the Cortex Microcontroller, next to the on/off switch. This is a keyed connection, so there is only one way to plug this wire in.

Plug a VEXnet key to the Cortex Microcontroller into the USB slot on the top of the Cortex Microcontroller.

Using a Phillips head screw driver or VEX 3/32 Allen Wrench (depending on which version of the Joystick is used), remove the screws that attach the battery cover to the VEXnet Joystick. Remove the battery cover.

Install six (6) identical AAA batteries into the VEXnet Joystick. DO NOT mix different types of batteries.

Reinstall the battery cover by inserting the two tabs of the battery cover along the back edge to aid in installation, and then reattach the screws that were removed earlier.

Plug a VEXnet key to the VEXnet Joystick into the USB slot above the battery cover.

Joystick Controls

Tank Drive Mode (uses 2 joysticks to move forward/backward) To go forward, push both joysticks up.

To go backward, push both joysticks down.

Left turn: push right stick up, left stick down

Right turn: push left stick up, right stick down

Downloading Default Code

After you are done building your robot and using the online window to test the motors, then Mrs. McNamara or Mrs. Frohn will show you how to download the EasyC Default Code onto your microcontroller so it can communicate with a wireless Joystick.

The Can Cleanup Challenge

Objective: Within 2 minutes pick up as many cans (or blocks) as possible and put them in a specified container.

Homework: Unit 3 Quiz

On Schoology take the Robotics Lesson 3 Quiz.

You can take it up to 5 times.

Your highest score will be saved.

You have until the end of the day on Friday, April 11th to take it.