weston schreiber & joshua gabrielse robotics summer training programming #1: easyc basics

Weston Schreiber & Joshua Gabrielse

Robotics Summer Training

Programming #1: EasyC Basics


Objectives: • Understand the 3 stages to programming

• Program a robot with custom controls• Build & Download program to a robot• Drive your robot!


1st Rule of Programming

Computers are stupid!!!!

They do EXACTLY what they are told,

nothing less, nothing more, and they never get the

idea.


Flowcharts(lists of instructions)

BEGIN

END

1. Put instructions on the flowchart.2. The computer (or robot) will start at

the beginning and move to the next instruction.

3. When that instruction is complete it moves to the next instruction.

4. When it gets to the end it keeps doing whatever it was last told to do.


• Break up into groups.

• Make a flowchart to make me walk out the door!

BEGIN

END

I will act like a computer (it comes naturally)

Computers do EXACTLY what they

are told, nothing less, nothing more, and they never get

the idea.


Stage 1: Planning(Algorithm, Flowchart, Pseudocode)

Stage 2: Coding(Variables, Functions, if statements, Loops)

Stage 3: Error Analysis(Syntax Errors, Logic Errors, Readdress Plan)



Flowcharts & Algorithm Planning• Two Types of Parts to a Programming Flowchart:

Actions Decisions

“Yes”

“No”

Robotics Examples“Turn on wheel motors” “Is the front bumper

pushed?”

“Lift Gripper Arm” “Has the robot turned 3 times?”

“Stop all motors” “Has the encoder registered over 1000 counts?”


Flowcharts & Algorithm PlanningPractice With Decision (Condition) Statements in Flowcharts:• Use a set of decision statements that allow the user to pick what movie they will go see:

• Prometheus (action, sci-fi)• Madagascar 3 (comedy, kids movie)


Writing Your 1st Program

1. Write a Plan for your Controller Setup

2. Start a New Program

3. Operator Control

4. Build & Download to Robot

5. Autonomous (next session)


Type in descriptions of what you’re

going to plug into each port.


8 channels:1. x-axis of right joystick

(-127 to +127)

2. y-axis of right joystick(-127 to +127)

3. y-axis of left joystick (-127 to +127)

4. x-axis of left joystick(-127 to +127)

5. left trigger buttons Up (0 or 1)Down (0 or 1)

6. right trigger buttons Up (0 or 1)Down (0 or 1)

7. left buttons Up (0 or 1)Down (0 or 1)Left (0 or 1)Right (0 or 1)

8. right buttons Up (0 or 1)Down (0 or 1)Left (0 or 1)Right (0 or 1)

VEXnet Joystick

↑ Top View ↑

↓ Front View ↓

↑ Front View ↑


EasyC Built-In Functions:

EasyC gives us functions to interact with the basic parts of the robot:

• Motor

• Servo

• Various Sensors (not this summer)


Anatomy of Functions• Name (case sensitive)

• Parameters (in order)

• Return Value (not necessary)

• Description (just for programmer)

FunctionName( param, param, param, etc. )

Examples:

RectangleArea( width, length )

DrawCircle( radius, centerX, centerY )


Anatomy of FunctionsRectangleArea( width, length )

• Name: RectangleArea• Parameters: width, length• Description: Calculates a rectangle’s area• Return Value? Area of the Rectangle

DrawCircle( radius, centerX, centerY )• Name: DrawCircle• Parameters: radius, centerX, centerY• Description: • Return Value? No return (void)


Writing Your 1st Program

1. Write a Plan for your Controller Setup

2. Start a New Program

3. Operator Control

4. Build & Download to Robot

5. Autonomous (next session)


Starting a New Program


Start a New Competition Project


Select Field Control Competition Project


Competition Projects

Initialize: This function runs when the robot is first turned on. All the motor outputs are disabled so the robot can’t move. Use to calibrate sensors.

Autonomous: This function runs after Initialize. This runs for fifteen seconds and input from joysticks is disabled.

Operator Control: This program runs after Autonomous. All inputs and outputs are enabled.

Click the tabs to access the functions.


Competition SwitchesEnable/Disable & Autonomous/Operator Control

Hardware: plug the ethernet cable into the competition port on the joystick

Software: the computer has to be connected directly to the robot controller or through VEXnet from the joystick (via the programming port)


Example Operator Control Code

Configuring the Controller


Select the Controller Configuration (F5)


Type in descriptions of what you’re going to plug into each port.

Weston Schreiber & Joshua GabrielseSelect the OperatorControl tab.


Put all control code inside the while loop.


Expand Joystick


Pick Tank or Arcade mode.

Modes

Arcade = 1 joystick drive (simpler)

Tank = 2 joystick drive (better control)

The number of motors should match your robot (2 for the CrabBot).


Drag Tank – 2 motor onto the flow chart.

Modes

I will use Tank – 2 motor since driving with two joysticks gives the driver more control.

You can use Arcade – 2 motor if you prefer to drive with one joystick.


Drag Tank – 2 motor into the WHILE loop.

WHILE Loops

Any statement placed in a while loop will execute over and over again (if the expression equals 1).

We drag the joystick block into the while loop so the program will get commands from the joystick over and over again.


For Tank drive set the Left Channel to 3 (the y-axis of your left joystick)

Tank Drive

The y-axis of the left joystick should control the left wheels and the y-axis of the right joystick should control the right wheels.


For Tank drive set the Right Channel to 2 (the y-axis of your right joystick)

Tank Drive

The y-axis of the left joystick should control the left wheels and the y-axis of the right joystick should control the right wheels.


For Arcade set the Forward/Reverse Channel to 2 (the y-axis of the right joystick).

Arcade Drive

The y-axis of your right joystick (if you’re right-handed) should control the speed (forward/reverse) of the robot.


For Arcade set the Rotate Channel to 1 (the x-axis of the right joystick).

Arcade Drive

The x-axis of your right joystick (if you’re right-handed) should control the rotation (turning) of the robot.


Select the motor number for your Left Motor.

Motor Numbers

The number of the slot/port on the robot controller that a motor is plugged into is its Motor Number.

Labels from the Controller Configuration automatically appear in green.


Select the motor number for your Right Motor.

Motor Numbers

The number of the slot/port on the robot controller that a motor is plugged into is its Motor Number.

Labels from the Controller Configuration automatically appear in green.


Arm

Arm


Arm Motor Selection

Change Joystick # to 2 for the

partner joystick.


Arm Motor Selection


Gripper

Gripper


Gripper


That’s it for Operator Control

Congratulations!


Build & Download

Build & Download your program.


Download Code to Robot

Build & Download your program.


Erasing & Writing New Code

Your program is finished downloading whenthe bar goes down (erases old code)

and goes back again (loads new code).


Save

Save your program even if it didn’t work.


The ROBOT light should be green (charged battery).The VEXnet light should be green (connected).

“My code won’t download!”(Is your robot on?)

Make sure to turn your joystick on too.

The POWER switch

should be ON.


What color is the ROBOT light on the controller?

“My code won’t download!”(Did you use a fresh battery?)

• green: okay battery • red: dead battery


• The USB A-A cable should be plugged into the robot controller in the USB port where the VEXnet key normally plugs in.

• The other end of the USB A-A cable should be plugged into a USB port on the computer.

“My code won’t download!”(Is the robot connected to the computer?)

USB A-A cable

computer

joystick

remove the VEXnet key robot controller


“My robot doesn’t drive right!”(Are the motors plugged in correctly?)

Everything should be plugged in according to the Controller Configuration


“My robot doesn’t drive right!”(Did you use servos instead of motors?)

• check the labels

• servos have two wire cords and motors have three wire codes

• motors need to be plugged into speed controllers

• motors spin continuously (360° of rotation)

• the controller sets the speed (-127 to +127)

• servos spin back and forth (120° of rotation)

• the controller sets the location (-127 to +127)

Servo(3-wire)

Motor(2-wire)


“My robot doesn’t drive right!”(Do you need to invert any of your motors?)

• Test drive your robot with all it’s wheels off the ground

• Look to see if any motors need to spin in the other direction

• Check Invert Direction to make a wheel spin in the other direction.

• Build & Download your modified code

weston schreiber & joshua gabrielse robotics summer training programming #1: easyc basics

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