VEX lesson 3

1. Robotics Unit
Unit 3: Introduction to VEX

2. Cortex Microcontroller
 The “brain” of the robot
 Controls the flow of information and
power to the robot
 Controls electronic components
(motors, sensors, etc.)

3.  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.

4.  Battery pack gets plugged in here
 On/off switch
 Always turn off before you put your
robot away.

5.  VEXnet USB keys are for wireless communication
between joystick and microcontroller.
 2.4 GHz frequency band

6. 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.

7. VEXnet Joystick
 2 analog joysticks
 2 four button directional pads
 4 trigger buttons

8. VEX Microcontroller
 10 motor ports
 8 analog inputs
 12 digital I/O ports

9. VEX Clawbot
 4 motors
 Left drive
 Right drive
 Arm
 Claw

10. Clawbot Default Code Settings
Motor Motor Port
VEXnet Joystick
Control
Left Drive Motor 1 Left Joystick
Claw Motor 6
Left Shoulder
Buttons
Arm Motor 7
Right Shoulder
Buttons
Right 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.

11. Page 16 of Clawbot directions
Notice wire colors!
Black wires always face the
“outside.” Be gentle with the
pins, don’t bend them.

12. 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.

13. 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

14. 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.

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

16. 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.