EASYC for VEX Cortex Llano Estacado RoboRaiders FRC Team 1817

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EASYC for VEX CortexLlano Estacado RoboRaiders
FRC Team 1817
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Humans and Machines

• Machines are built to perform useful tasks.
• The way a Machine works depends entirely on the
  way the Human build it.
• Since Machines and Robots need a medium of
  communication, a language called Programming
  Language is used.
• EASYC, ROBOTC, C, C all are programming
  languages.
• The instructions in the language are called
  Programs and the human that writes the
  instructions is called the Programmer.

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• Task of Programmer Understand Problem, Find a
  solution, Write a program to solve the problem in
  the required Programming language.
• Task of Machine Follow the program provided.
• A ROBOT is a Machine.

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Planning and Behavior

• Behavior Action the Robot has to take.
• Big Behavior Solving a maze
• Small Behavior Turn Left, Move Forward, etc.
• Big Behavior is made up of Smaller Behaviors.
• Plan a Solution to the problem.
• Break down the plan into detailed smaller steps.
• Each step is a behavior the robot needs to
  follow.
• Sequence of these steps in English is called
  pseudo-code.

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• Flow charts are a visual representation of the
  program flow.
• Start and End Rounded Rectangles. They contain
  the word Start or End, but can be more
  specific such as Power Robot Off or Stop All
  Motors.
• Actions Rectangles. They act as basic commands
  and process steps.
• Decision blocks Diamonds. These typically
  contain Yes/No questions. Based on the choice,
  the next step is determined.

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Introduction to C Programming

• EasyC is based on the the principles of C
  Programming.
• We will cover the following concepts
• 1. Basic Components of a C Program
• 2. Data Types and Variables
• 2. Conditional operators
• 3. Control Structures and Loops
• 4. Methods and Functions

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A Basic C Program

• includeltstdio.hgt // Header File
• void main(void) // Main function
• // Body of the main function
• Header file Includes all the required words and
  instructions needed to write a program
• Main function Execution starts from here
• Body stepwise Instructions to the Robot

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• Each Instruction to the robot is also called a
  Statement.
• When the list of instruction is send to the VEX
  cortex, it read them from top to bottom and left
  to right.
• Different Commands use different paired
  Punctuations such as ()
• .. defines a body of one or more
  instructions. Also called a Compound Statement.
• Every instruction in the body ends with a .
  It shows the end of a instruction.

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• Comments are for the programmer to understand
  what a particular statement does.
• Two kinds of comments
• 1. // This is a one line comment
• 2. / This is a more than one line
• Comment./
• C language is case sensitive Upper and lower
  cases are considered different.

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Data types and Variables

• A Variable is a place to store a value.
• A variable has a Type and a Name
• Type deals with the type of Data the variable
  will hold.
• Type of Data
• Int Whole Numbers. Positive, Negative, Zero
• float(Floating Point) Decimal Point Numbers.
  Positive and Negative.
• String Text. Letters, Spaces and characters.

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• char(Characters) Single characters
• bool(Boolean) True and False values
• Declare a variable
• int Age
• float Score
• string Name
• char Grade
• bool Pass

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• Assign a variable
• Age 18
• Score 90.5
• Name William
• Grade 'A'
• Pass True
• Declare and assign
• int Age 18
• float Score 90.5
• string Name William
• char Grade 'A'
• bool Pass True

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• Variable Naming Rules
• A variable name can not have spaces in it.
• A variable name can not have symbols in it.
• A variable name can not start with a number.
• A variable name can not be the same as an
  existing reserved word.
• Scope of a Variable
• Local variables Within a certain block of code
  or function. Cannot be accessed outside.
• Global variables Can be accessed anywhere in the
  code.

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• Using Variables in a print to screen function
• When printing a variable on the screen, the
  following syntax is used
• Print to screen function(type,Variable)
• Signed and - , unsigned - , short less
  range , long more range

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• Conditional Operators
• Comparison operators

Relational Operator Example
gt (Greater Than) 7 gt 5
gt (Greater Than or Equal To) 7 gt 5 , 7 gt 7
lt (Less Than) 5 lt 7
lt (Less Than or Equal To) 5 lt 7 , 7lt7
(Equal To) 7 7
! (Not Equal To) 7 ! 5
(Assignment Operator) number 7
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• Logical operators
• Boolean Truth Table
• Joining two or more statements using And and
  Or

A Its a Sunny Day B My Car is working Can I go out? (A and B) Can I go out? (A or B)
Yes Yes Yes Yes
Yes No No Yes
No Yes No Yes
No No No No
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• And
• Or
• Not !

A B !A A B A B
True True False True True
True False False False True
False True True False True
False False True False False
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Control Structures and Loops

• Control Structure
• IF statements
• if(condition)
• Instructions, if condition is True

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• IF-ELSE Statements
• if(condition)
• // Instructions, if condition is true
• else
• // Instructions, if condition is false

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• ELSE-IF Statements
• if(condition1)
• // Instructions, if condition 1 is true
• else if(condition 2)
• // Instructions, if condition 2 is true
• else
• // Instructions, if condition 1 and condition
  2 are false

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• Switch Statements
• switch(expression) //expression can only be an
  int or char
• case Value-1
• // Instructions, if expression Value-1
• break
• case Value-2
• // Instructions, if expression Value-2
• break
• default
• // Instructions, if expression does not match any
  Value

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• Example
• char Grade 'A'
• switch(Grade)
• case A
• Your Grade is A
• break
• case B
• Your Grade is B
• break
• default
• This is the default
  choice

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• Loops
• While loops
• while(condition)
• // Instructions, if condition is true
• Note Control Structures execute only once. On
  the other hand, while loops execute continuously
  until the condition is false.
• If the condition in the loop is always true, the
  loop never ends. Such a loop is called an
  Infinite Loop.
• A loop will end only when the condition is false
  or there is a break statement.

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• Example
• int count 0 //Initialization
• while(count lt 2) //Condition
• PrintToScreen( I have d apple \n, count)
• count count 1 //Increment
• Output I have 0 apple
• I have 1 apple
• I have 2 apple

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• For Loop
• for(initialization condition increment)
• // Instructions, If condition is true
• Similar to a while loop except that the
  initialization and increment are all together.
• Note Initialization is done only when the loop
  first starts. After that it is skipped.

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• Example
• int count
• for(count 0 count lt 2 count count 1)
• PrintToScreen( I have d apple \n, count)
• Output I have 0 apple
• I have 1 apple
• I have 2 apple
• Note \n is called new lines. It prints the next
  sentence in a new line.

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Methods and function

• Functions are named sections of code that can be
  called from other sections of code.
• Also called subroutines.
• Every executable statement in C must live in a
  function.
• Functions have a Data type, name and input
  values.
• Input values are called Parameters. They are the
  values you want the function to work with.

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• The function definition specifies the return
  value and the parameters of the function
• ltdata typegt FunctionName(ltparam1gt, ltparam2gt, ...)
• ltfunction bodygt
• ltreturn typegt
• Return type and Data type should be of the same
  kind.
• Return type is void if nothing is to be
  returned.
• Parameters is void if nothing is to be passed
  in.

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• Example
• int addition(int x, int y)
• int z
• z x y
• return z
• void main(void)
• addition(2, 3)

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Some Useful terms

• Compiler Turns C program into the machine
  language for the controller.
• Loader Loads the machine language output of the
  compiler (along with other stuff) into the robot
  controller.
• Machine Language What the robot controller
  actually understands. Found in .HEX files.
• 10110100
• 11100101
• 00001011

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Download EASYC

• Download Link EASYC V2.0 for VEX
• http//www.intelitekdownloads.com/easyCV4/

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Updating EASYC

• If the website says you need to update EasyC, you
  can do that by going to
• Help-gtCheck for updates

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Updating the Firmware on the Cortex Controller
and Remote Controller

• Firmware is a piece of sofware that access the
  operating system on the processor and allows it
  to perform its task.
• Step 1 Connect the Cortex/Remote Controller and
  your computer using the A-A USB cable. The LED
  should start flashing

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• Step 2 On your computer's taskbar, goto
• Start -gt All Programs -gt easyC v4 For Cortex -gt
  IFI VEXNet Firmware Utility

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• Step 3 Select SEARCH if the response is
  (Upgrade required) then BOOTLOAD and YES

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• Step 4 Then click DOWNLOAD

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• Step 5 Afterward you should see the following

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Connecting the Cortex Controller and Remote
Controller

• Connect the two devices together and then turn
  on the Remote Controller or micro controller.
  Wait until the VEXNet LED turns solid green.

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EASYC First Look

• Step 1 File -gt New Standalone Project-gtJoystick
  Project(Wifi)

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• 1. Function Block(Left) You can all the
  available functions and your project file
  information.
• 2. Main (Middle) Drag and Drop the functions
  here to see how they connect and get a visual
  look for the code. All You need to work with is
  the area between Variables and End.
• 3. Project Pane (Right) See your project files
  and other files.
• 4. Build information (Bottom) See any code
  building information here.

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• When running the Robot, the real time values in
  each port can be seen in the Online Window
• Step 1 EASYC-gt Build Download -gt Online Window

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• When running the Robot, any print to screen
  values can be seen in the Terminal Window
• Step 1 EASYC-gt Build Download -gt Terminal
  Window

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• You can open the controller configuration
  (Marked with a Red Arrow) and write down what you
  are going to plug in each port.

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VEX Cortex Controller

• The VEX Cortex Micro controller has the
  following ports
• 8 Analog ports
• 12 Digital ports
• 6 Interrupt ports
• 8 Motor ports

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VEX Remote Controller

• Vex Remote control provides you with two
  joysticks (each having a x- axis and y-axis),
  eight buttons on the front and four additional
  buttons on the top.

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• Each set of buttons or a pair of joystick has an
  assigned channel number written next to it as
  shown in the figure. Each of these controls are
  accessed using the channel number they belong to.

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Incorporating C Programming baics in EASYC

• We start by placing the needed module between
  the Variables and End modules.
• Creating a While loop
• Step 1 Click the sign next to the Program
  Flow on your Function Panel (Left)
• Step 2 Click and drag the While loop on to the
  Main panel (Middle) and place it between the two
  modules you need it to.

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• Step 3 In the While loop Window, enter the
  condition and click OK.
• NOTE For an infinite loop, we use condition 1
  .i.e. while(1), because 1 will always be 1 and so
  this condition will always be true.
• Similarly, we can do for a if statement, else-if
  statements, switch statements and For Loops.

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• Creating Variables
• Step 1 Click on the Variables module in the
  Main panel.
• Step 2 Enter the details of the Variable in the
  next Local variables Window and click OK.

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• Step 3 The variable is now stored in the
  Variables module. If you click on it again, you
  can see your variable.
• Now, whenever trying to use the variable weather
  to set its value or get its value, it will appear
  in the drop down list of the inputs and outputs
  for the other control modules like sensors.

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• Creating User Functions
• Creating a new Function
• Step 1 Project -gt Add New Function
• Step 2 Enter the Return type, name,
• Arguments/Parameter list (if any)

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• Adding an existing Function
• Step 1 Project -gt Add Existing Function
• Step 2 Enter the Details and location
• And a Search will be done.

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Building and Downloading a Program

• After writing your program, you need to build it
  and download it on to the robot.
• Step 1 Connect your robot and your computer
  using the A-A USB Cable. Make sure your cortex is
  turned off right now as a safety precaution.
• Step 2 Build and Download ? Build and Download

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• Step 3 Click Yes on the Hex file build
  successful message window and your code will be
  downloaded.

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Drives

• Simple Tank Drive
• Tank Drive involves the use of both joysticks.
• Step 1 Click the next to the Joystick Module
  in the Left Pane and drop Tank- 2 Motor in the
  Middle Pane.

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• Step 2 Enter the Joystick Number(Joystick 1 is
  your primary remote Controller, Joystick 2 is
  used if you are using another remote controller
  to control your robot), the left and right
  joystick channels, the left and right motor port
  numbers and if you need to invert a motor, change
  the value to 1.

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• Simple Arcade Drive
• Arcade Drive uses one joystick to drive the
  robot.
• Step 1 Click the next to the Joystick Module
  in the Left Pane and drop Arcade 2 Motor in the
  Middle Pane.

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• Step 2 Enter the Joystick Number(Joystick 1 is
  your primary remote Controller, Joystick 2 is
  used if you are using another remote controller
  to control your robot), the joystick channel (Set
  the Rotate Channel to 1), the left and right
  motor port numbers and if you need to invert a
  motor, change the value to 1.

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Motor Control

• The buttons on you remote controller can be used
  to control motors on your robot.
• Step 1 Click the next to the Joystick Module
  and drag and drop the Joystick Digital to motor
  in the middle pane.

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• Step 2 Enter the joystick number, Channel number
  for the button group, the button number and the
  motor value -127(Backward) to 127(Forward). 0
  makes the value stop. Finally, enter the motor
  port number.

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Turning of Motors

• Assigning Positive power Values(127) on both
  motors makes the robot go forward.
• Lower speed of robot by assigning values less
  than full power(127).
• Assigning negative power values(-127) on both
  motors makes the robot go reverse.
• Assigning zero power values(0) on both motors
  makes the robot stay in place.

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• Point Turn Turn in place (-63 and 63)
• Swing Turn Making one motor on and the other off
  makes the robot swing around the stationary
  wheels. (0 and 63)

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Shaft Encoders/Rotation Sensor

• Manual adjustments of power are not same for all
  robots and as the battery power drains, the robot
  is move shorter distances.
• Shaft Encoders are used to control how far the
  Robot Moves.
• Number of counts per Revolution on a axle mounted
  through the encoder center.
• Max 360 up for forward movements and 360 down for
  reverse movements.

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• Encoders need to be set to zero before you use
  them. Clear the encoders for better consistency
  and precision on your robots movements.
• Step 1 You can find the Quadrature encoder
  modules by clicking the next to the inputs
  modules in the left panel.

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• The corresponding text functions for the
  Quadrature modules are as follows
• Start the Encoder
• StartQuadEncoder(port number)
• It is good practice to preset the value of
  encoder to 0 before use.
• PresetQuadEncoder(port number, 0)
• Get the number of ticks passed
• ticks GetQuadEncoder(port number)

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• Limit Switch
• Limit Switch is a Digital Sensor(0 and 1)
• When pressed, it provides a sensor value 1, when
  released, it provides a sensor value 0.
• Step 1 The limit switch module is in the Inputs
  modules in the left panel.
• ?? GetDigitalInput(port number)

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• Potentiometers
• A potentiometer is a Analog Sensor.
• It measures rotation between 0 to 250 (not 360
  due to internal mechanical stops) degrees and
  return value ranging from 0 to approximately
  4095.
• ?? GetAnalogInput(port number)

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Ultrasonic Range Finder

• Ultrasonic Range Finder allows us to sense
  obstacles in the path of the robot and avoid
  bumping into them.

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• It measures distance to the obstacle using sound
  waves. It calculates the Distance depending on
  how long it takes for the sound wave to bounce
  back.
• Distance Speed Time / 2
• Step 1 Click the next to the inputs and drag
  and drop the Ultrasonic sensor in the middle
  panel.

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• Step 2 Choose if you want to start or stop the
  sensor or get its value. Enter the interrupt port
  and the digital output port.

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• The corressponding text functions will be as
  follows
• StartUltrasonic(interrupt port numer, digital
  port number)
• ?? GetUltrasonic((interrupt port numer, digital
  port number)

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Timers

• Timers are like Stopwatches.
• Used in competition to know how long the robot
  has been working.
• You have access to 6 software Timers. The time is
  in Microseconds (1 sec 1000 ms)
• Step 1 Click the next to the Program Flow
  module and drag and drop the Timer module.

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• Step 2 Choose if you want to start, preset, get
  a value or stop the Timer. It is a good practice
  to Clear the Timer before use.

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Wait

• When Wait is used, the program execution is sidle
  for that period of time.
• Step 1 Click the next to the Program flow
  and Drag and drop the wait module. The wait
  module takes time in Microseconds.

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Line Tracking Sensors

• Below is shown a set of three Line tracking
  Sensors. Line tracking sensors work on the bases
  of Infrared Light. Each sensor has an Infrared
  LED and an Infrared Light sensor.

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• The LED emits light and the sensor detects the
  amount the light reflected back.
• Light Surfaces Low Sensor Reading
• Dark Surfaces High Sensor Reading

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• The cortex gives a Sensor reading from 0 to 4095.
  The value does not correspond to any unit of
  measurement.
• Thus it is important to take care of lighting
  conditions around the robot and the height at
  which the sensors are placed in order to
  determine the threshold of reading.

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• Using all three sensors allows us to detect the
  line as well as border of the line, corners and
  intersections, which is not possible if you use
  just one line tracking sensor.

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• Step 1 The Line tracking Module is present in
  the Input modules in the Left panel. Set the
  Analog Input and retrieve the value returned by
  the Line follower.

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Create Competition Code

• Step 1 File-gtNew Competition Project-gtTimed
  Competition Project

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• The Autonomous Time and operator controlled time
  are in seconds. Each define the number of seconds
  the Autonomous code and the Operator control will
  run for.
• Put down your autonomous and operator controlled
  code in the corresponding file modules. You can
  also change the running times for the autonomous
  and operator control mode by clicking on the
  modules.

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• That's all for EasyC for Cortex programming.
• Thank you!