1. ROBOTC for VEX Robotics (VEX IQ) On-Line Session 2016 Friday - Day 5
Take the first few minutes of class and watch the videos on Direct Control in the curriculum.
Heath Lauster: Instructor
Zach Deloe: Tech Assistant

2. Remote Control

3. Remote Control

4. Remote Control

5. Remote Control

6. Remote Control

7. Remote Control - Names
ROBOTC can access all of the data from the VEX IQ Remote Control by referencing the buttons and axes by their described names.
Joystick buttons return values of…
1 – Pressed
0 – Not Pressed/Released
Joystick Axis return values of…
-100 to (0 when centered)
ChA
ChD
ChB
ChC
BtnEUp
BtnEDown
BtnFUp
BtnFDown
BtnRUp
BtnRDown
BtnLUp
BtnLDown

8. Switching Controller Mode
When using the VEX IQ Remote Control, make sure to switch your “Controller Mode”
Tele-Op: Requires a Remote Control to be powered on and linked before program will run.
Autonomous: No Remote Control required, but program will not read data from the Remote Control
Switch this mode from: “Robot Menu - >VEX IQ Controller Mode”

9. Joystick Control – Tank Control
ChA
ChD

10. Joystick Control – Arcade Control
ChA
ChB

11. Joystick Control – Arm Control
BtnEUp
BtnEDown
BtnFUp
BtnFDown
BtnRUp
BtnRDown
BtnLUp
BtnLDown

12. Create a Joystick Program
Using Robot C Graphical create a new Direct Drive program with arm control.
Download it to your Clawbot
Before you download make sure the controller mode is set for TeleOp.

13. Joystick Control – Get Data
getJoystickValue(joystickChannel) This command will return the current value of a joystick axis (-100 to +100) or joystick button (0 or 1)
Parameter
Description
Default Value
joystickChannel
The name of the specified joystick component to be accessed. Valid names include:
Joystick Axis: ChA, ChB, ChC, ChD
Joystick Button: BtnEUp, BtnEDown, BtnFUp, BtnFDown, BtnLUp, BtnLDown, BtnRUp , BtnRDown
N/A
Returned Value
Value returned by the specific Axis or Button.
Joystick Axis: -100 to +100 (0 when centered)
Joystick Button: 0 (not pressed) or 1 (pressed)

14. Joystick Control - Examples
Simple Joystick Drive
Notice how ChA + ChB and ChA – ChB allows the user to turn. For example:
If I move my Joystick like this with Arcade Control:
ChA = 0 ChB = 50 Thus, the leftMotor = 50 and the rightMotor = -50
As a result, the robot turns.

15. Joystick Control - Examples
Continuous Loop for “Tank Drive”

16. Joystick Control--Examples
Adding Buttons—Control the Arm

17. Joystick Control--Examples
Adding Buttons—Control the Claw

18. Joystick Control--Advanced
What can we do to utilize all of the buttons on the Remote Control?
What are the things that we are going to do repeatedly?
How can we address those things to make our use of the Remote Control more efficient?

19. Review From Thursday

20. Playing Sounds VEX IQ Speaker
The VEX IQ system has a built in speaker that allows you to play tones and built in sounds.
You will need to make sure sound is enabled on your VEX IQ:
At the main menu, go to “Settings” (press the “X” button)
The top option in the settings should say “Sound On”
If it doesn’t press the “Check” button to toggle the sound “on”
VEX IQ Speaker

21. Playing a Sound Effect
playSound(nameOfSound); This command will play a built-in sound effect once.
Parameter
Description
Default Value
nameOfSound
Specify the name of the sound effect you would like the VEX IQ system to play. The name of the sound files are below:
soundSiren2 / soundWrongWay / soundWrongWays
soundGasFillup / soundHeadlightsOn / soundHeadlightsOff
soundTollBooth / soundCarAlarm2 / soundTada
soundGarageDoorClose / soundRatchet / soundAirWrench
soundSiren4 / soundRatchet4 / soundCarAlarm4
soundPowerOff2
N/A

22. Sound Examples Play the sound effect “Air Wrench”
playSound(soundAirWrench); sleep(500);
Play the sound effect “Tada”
playSound(soundTada); sleep(500);
Note: Sounds typically need a “Sleep” time to give them time to actually be played.

23. Playing a Sound Effect Repeatedly
playRepetitiveSound(nameOfSound, duration); This command will play a built-in sound effect multiple times for a specified amount of time.
Parameter
Description
Default Value
nameOfSound
Specify the name of the sound effect you would like the VEX IQ system to play. The name of the sound files are listed previously.
N/A
duration
This is how long to play the sound effect for. This amount of time is in 10s of milliseconds (100 = 1 second)

24. Sound Examples
Play the sound effect “Air Wrench” repeatedly for 1 second.
playRepetitiveSound(soundAirWrench, 100); sleep(1000);
Play the sound effect “Tada” repeatedly for 3 second.
playRepetitiveSound(soundTada, 300); sleep(3000);
Note: Sounds typically need a “Sleep” time to give them time to actually be played.

25. Sound Examples

26. VEX IQ LCD Screen
The VEX IQ has a LCD Screen that can be used to display text, number, or shapes/drawings to assist with programming.
The VEX IQ LCD has a specific area of the screen that is for the user to draw/write text into.
Users can choose to either write to line numbers or directly to x/y coordinates on the LCD screen.
Text Line #0
Text Line #1
Text Line #2
Text Line #3
Text Line #4
(0, 47)
(127, 47)
48 Vertical Pixels (Y)
128 Horizontal Pixels (X)
(0, 0)
(127, 0)

27. Display Text to the LCD
displayTextLine(lineNumber, “Text”); This command will display a line of text on the VEX IQ LCD Screen.
Parameter
Description
Default Value
lineNumber
The line number to write to on the VEX IQ LCD. Any previous text on the specified line number will be deleted. Line numbers range from 0-4.
N/A
“Text”
This is the text to be displayed. Because the text displayed is considered to be a ‘string’, it must be surrounded by double quotes. You can display up to 21 characters on a single line.

28. Display Text Example
Display the words “Hello World!” to the middle of the VEX IQ LCD Screen.
displayTextLine(2, "Hello World!"); sleep(1000);
Note: Display commands will need “sleep” time to allow the text to be displayed if the program is not being controlled by a loop.

29. Display Numbers to the LCD
displayTextLine(lineNumber, “Text”, variable); This command will display a line of text and the value of a variable to the VEX IQ LCD Screen.
Parameter
Description
Default Value
lineNumber
The line number to write to on the VEX IQ LCD. Any previous text on the specified line number will be deleted. Line numbers range from 0-4.
N/A
“Text”
This is the text to be displayed. Because the text displayed is considered to be a ‘string’, it must be surrounded by double quotes. The text can also display “formatting codes” to display values and variables.
variable
The name of a variable or value – this could be anything that returns a numeric value (sensors, encoders, etc.)

30. Display Text with Numbers Example
A program to constantly update the VEX IQ LCD Screen with the current value from the Gyro Sensor

31. Other LCD Commands
Erases everything in the user’s area of the VEX IQ’s LCD screen.
eraseDisplay();
Turn on and off a specific pixel at a specific x/y coordinate.
SetPixel(x, y);
ClearPixel(x, y);

32. More Display Commands
ROBOTC has over 50 different text and drawing commands available for the VEX IQ
Take a look at the descriptions/examples of more at the ROBOTC.net Wiki

33. Variables in Graphical
In Robot C Graphical the primary type of variable is the float variable. Float variable will have digits on both sides of a decimal for high accuracy. This is in contrast to a int or integer data type, which will only house a whole number.

34. Variables in Graphical
Counter Game
Physical Robot Only
We will build together
Use of touch LED to Start
Introduction to display on LCD
Introduction to sound
Get Distance Continuous
Show Program
Get Distance Reset

35. Text Based ROBOTC

36. Convert Graphical to Texted Based Robot C
At this point you have used Robot C Graphical and know how to program your robot in the areas of Movement, Sensors, Program Flow, and Direct Drive to complete various challenges.
However there are limits to Robot C Graphical and a transition to Text Robot C will allow you to expand your horizons when programming robot behaviors.
To easily see the differences between try “Convert Graphical File to Text” under the view menu.

37. Graphical File Vs. Text File

38. ROBOTC Rules/Syntax What does every program have to have?
task main()
Set of "Curly Braces“ {}
In what order does ROBOTC run a program?
Sequentially – Top to Bottom
What is whitespace?
Space in a program to make it easier for a human to read.
Simple Robot Commands (statements) always end with a…?
Semicolon ;

39. ROBOTC Rules/Syntax Paired Punctuation Control Structures Comments
Some functions have "square brackets“ [] , other have "parenthesis“ ()
How do I keep them straight?
Memorization
Functions Library
Control Structures
Just like task main, they have a set of curly braces defining their beginning and end. {}
Example?
Comments
//Necessary Evil
Get into the habit now, or you won't do it ever
Your students learn their habits from you…

40. ROBOTC Rules/Syntax Syntax is the cause of 80% of programming errors…
Most important thing to do when troubleshooting: Check Syntax
Missing Semicolons
Incorrect Braces on Structures
Misspelled words
Improper ‘case’ – motor vs. MoToR
ROBOTC is friendly about most of these errors... but can’t catch everything.

41. New Commands moveMotorTarget(motor, distance, speed);
This command will set a specific motor to move a number of degrees at a specific speed.
After the number of rotations have completed, the motor will automatically come to a stop.
waitUntilMotorStop(motor);
Because the “moveMotorTarget” is not a “blocking” command (otherwise you could only move one motor at a time), we can use the “waitUntilMotorStop” command to create a block that will wait until a specific “target movement” is complete.

42. Other Motor Commands setMotorSpeed(motor, speed);
Sets the speed of the motor (-100 to +100)
Motors will run until told otherwise or the end of the program.
Set the speed to zero (0) to turn the motor off.

43. Other Motor Commands setMotorTarget(motor, distance, speed);
motor – specifies which motor to move
distance – the distance the motor should travel in motor degrees (based on it’s total distanced moved)
Note if this value is negative, the motor will move backwards.
50 – the speed (0 to 100) the motor will travel.

44. Other Motor Commands getMotorEncoder(motor); resetMotorEncoder(motor);
Retrieves the value of a motor’s encoder (in degrees traveled) for use in a conditional statement or storing to a variable.
resetMotorEncoder(motor);
Resets the motor’s encoder back to a value of zero (0).

45. Sentry Challenge Program the robot to drive one full lap around a box.
Use any combination of the new motor commands in your solution.

46. Challenge: Labyrinth Complete the ”Labyrinth Challenge”
First “flowchart” or plan your program
Then program your robot
If finished early…
Make sure your code is commented

47. Variables What is a variable? How do they work?
A variable is a facility for storing data in a program.
How do they work?
When a variable is “declared”, the compiler sets aside a piece of memory to store the variable’s numeric value.
When the variable is called, the processor “retrieves” the numeric value of the variable and “returns” the value to be used in your program in that specific location.

48. Variables How do I create a variable?
To create (“declare”) a variable you need 3 things.
Decide the data type of the variable (more on this soon)
Give the variable a name
Assign the variable a value (optional, but recommended)
Example:
int myVariable = 1000;
Type: Integer
Name: myVariable
Value: 1000

49. Data Types There are 8 different types of variables in ROBOTC
Integer (int) – Memory Usage: 16 bits / 2 bytes
Integer Numbers Only
Ranges in value from to
Long Integer (long) – Memory Usage: 32 bits / 4 bytes
Ranges in value from to
Floating Point (float) – Memory Usage: 32 bits / 4 bytes
Integer or Decimal Numbers
Variable precision, maximum of 4 digits after decimal

50. Data Types There are 8 different types of variables in ROBOTC
Single Byte Integer (byte) – Memory Usage: 8 bits/1 byte
Integer Numbers Only
Ranges in value from -128 to +127
Unsigned Single Byte Integer (ubyte) – Memory Usage: 8 bits / 1 byte
Ranges in value from 0 to +255
Boolean Value (bool) – Memory Usage 4 bits / .5 bytes
True (1) or False (0) values only.

51. Data Types There are 8 different types of variables in ROBOTC
Single Character (char) - Memory Usage: 8 bits / 1 byte
Single ASCII Character only
Declared with apostrophe – ‘A’
String of Character (string) - Memory Usage: 160 bits / 20 bytes
Multiple ASCII Characters
Declared with quotations – “ROBOTC”
19 characters maximum per string)

52. Variables Some additional notes
Adding “const” in front of a variable will make that variable a constant.
This will prevent the variable from being changed by the program
Constants do not take up any memory on the VEX IQ
The VEX IQ has room for 7500 bytes of variables

53. Variables Some additional notes
Variable’s names must follow a specific rules:

54. Using Variables Variables can be used in your program anywhere!
Motor Speeds, If/Else Loops, Conditional Statements
Commands you know act just like variables
SensorValue – Returns the value of a sensor value
Variables are just numbers
You can perform math operations on variables
newVariable = oldVariable + 15;

55. Using Variables
VS.

56. Formatting Strings Formatting Characters:
ROBOTC supports a number of formatting characters for created a formatted string.

57. Functions
Functions are used to group together several lines of code, which can then be referenced many times in task main, or even other functions.
Convenient uses in the Sentry Challenge
Moving Forward for Distance
Turning 90 Degrees Left (or Right)
Creating Functions
Example: Moving Forward for Distance
Function Definition (Part 1 – The code that goes with the function)
Using Functions
Function Call (Part 2 – Where you want the function code to run)

58. Function Definition
The Function Definition “defines” what the function is and does
To create a Function Definition:
1. Set the “type” of function by declaring the “data type” of the function.
Void is a special data type which means no value will be returned
Commonly used when the robot is carrying out instructions
2. Give the function a name.
Following the same rules as variables, motors, and sensors
3. Add a set of parenthesis and curly braces
Parenthesis are used for “parameters”
Curly braces define the beginning and end of the function.

59. Function Call
Once you have created a Function, you can “call” it inside of task main (or another function) by referencing its name, along with a set of parenthesis and a semicolon.
Note: Keep functions above task main, or else you will have to have a “Function Prototype”

60. Functions: Program Flow
Even with functions defined, the robot starts executing code at task main
When the robot reaches a function call, the Program Flow jumps to the Function Definition and running there
When the robot finishes running the code in the function, Program Flow returns to task main

61. Function Practice Create Functions for the Sentry Challenge:
Move Forward for a Number of Rotations
Point Turn 90 Degrees Right
Point Turn 90 Degrees Left

62. Functions and Variables
Key Concept: Variable “Scope”
Variables are “local” to where they are declared.
Just because “distanceInDegrees” exists in “task main” doesn’t mean it can be used in a function.
“distanceInDegrees” is currently localized to only “task main”

63. Functions and Variables
Solution #1 – “Globalization”
Setting the variable outside any function will cause it to become a “global” variable.
This is not an ideal solution because multiple functions can use and modify this variable!
Use sparingly, but don’t be afraid to use it…

64. Functions Part 2 (Solution # 2)

65. Functions with Parameters
When working on the Sentry Challenge (or many other challenges) going forward the same distance in the function isn’t very helpful.
What is controlling the distance that the function allows the robot to move forward?
What programming tool do we have that lets us store numbers in our code?
Variables! Functions allow use for a special kind of variable, called a Parameter.
Parameters allow you to pass values into functions to account for small differences, like the number of degrees to move forward.

66. Function Definition with Parameters
A parameter is simply a variable that you are using to pass data (numbers, strings, etc.) into your function
Creating a parameter is similar to creating a variable
You must give it a “type” and a “name”
Multiple parameters can be separated by commas
Once you create a parameter, don’t forget to use it in the code of your function

67. Function Call with Parameters
Once you create a function with parameters, you must provide a value to fill those parameters in your function call
To assign a value to the parameter, simply place that value between the parenthesis of the function call
If you are using multiple parameters, you must specify their values in order!

68. Functions: Program Flow 2
Program Flow when working with Functions with Parameters is very similar to Functions without Parameters
This time, when the robot encounters the Function Call, the value (960) is passed into the “distanceInDegrees” Parameter, and used as part of the moveMotorTarget commands

69. Functions and Variables
Solution #1 – “Globalization”
Setting the variable outside any function will cause it to become a “global” variable.
This is not an ideal solution because multiple functions can use and modify this variable!
Use sparingly, but don’t be afraid to use it…

70. Functions and Variables
Solution #2 – “Passing Values”
Instead of using the variable, we can just pass the value as a parameter to our function instead.
This method is ideal because it gives you flexibility in your functions.
This requires us to edit our existing functions, however.

71. Functions and Variables
Variables are now declared inside of the parameter field of the function. Multiple variables are separated by a comma.
Variables are used inside of the function, but are localized to this function only.
Each time the function is called a different value can be passed. This promotes code flexibility and reuse!

72. Variable Locations It is important where you declare your variables:
Variables declare outside of any structure (function or task) are considered to be “global”
Variables declared inside of any structure (function to task) are considered to be “localized” to that structure.
Variables declared in a loop/conditional statement are localized to that statement block
It is always best to declare your variables in the correct location (usually at the top of your program)

73. Functions with Parameters Practice
Expand your previous functions :
Move Forward for x Degrees at Y Speed
Point Turn x Degrees Right
Point Turn x Degrees Left
Reverse for x Degrees at Y Speed

74. Sentry Challenge (Last Time)
Convert your solution to use Variables and Functions to solve

75. Other Function Types
Functions don’t always have to be a “void” function.
You can use any data type that you would assign to a variable! – int, float, bool, etc.
A special command “return” is required to return a value back to the parent function.

76. Other Function Types
Instead of “void” this function uses “int”. This tells us that this function will return an integer result.
After we add 10 to the parameter value that was passed to use by task main, we send the new value back by using the “return” command.
We assign the returned value to a variable so we can use the Debugger to verify the correct value was returned.

77. Other Function Types

78. Math with Functions

79. Final Challenge Complete the ”Minefield Challenge” If finished early…
First “flowchart” or plan your program
Then program your robot
Use Robot C Texted base with Natural Language
Use a function in the program.
If finished early…
Make sure your code is commented

80. Creating a Function Library
Make sure you save in the same place
Suppress warnings for unused functions
#pragma systemFile

81. Global Variables Debugger

82. Constant Variables
It’s best to intelligently use variables to preserve as much of this space as possible
Constant variables and #define statements can help:
Adding “const” to any variable will make it a compile-time constant and not use any variable space.
A #define statement will create an alias to a value or statement in a single variable name.

83. Constant Variables
Examples:

84. Variable Locations It is important where you declare your variables:
Variables declare outside of any structure (function or task) are considered to be “global”
Variables declared inside of any structure (function to task) are considered to be “localized” to that structure.
Variables declared in a loop/conditional statement are localized to that statement block
It is always best to declare your variables in the correct location (usually at the top of your structure)

85. Variable Locations
In this example, “test2” is not known outside of the “if” statement block.

86. Arithmetic Operators ROBOTC accepts a number of arithmetic operators:
Assignment: a = b
Addition: a + b
Subtraction: a – b
Multiplication: a * b
Division: a / b
Modulo (remainder): a % b
Increment: ++x, x++
Decrement: −−x, x−−
Unary Positive: +x
Unary Negative (inverse): −x

87. Arithmetic Operators Differences between ++i and i++
++i will increment the value of i, and then return the incremented value
i++ will increment the value of i, but return the pre-incremented value.

88. Comparison Operators
ROBOTC supports 6 different comparison/relational operators between two values:
Equal to: a == b
Not Equal to: a != b
Greater than: a > b
Less than: a < b
Greater than or equal to: a >= b
Less than or equal to: a <= b

89. Logical Operators
ROBOTC has 3 logical operators to assist when making complex decisions:
Logical Negation (NOT): !a
Logical AND: a && b
Logical OR: a || b

90. Logical Truth Tables
AND (&&)
OR (||)
NOT (!)

91. If/Else Statements
If the “while(true)” loop was missing, this code would only execute the “if” or “else” section once.

92. If/Else Statements If statements do not require an “else” statement.
If the “if” statement is false, it will just be skipped over.
You can also make a multiple decision “if/else” statements.
Example on the right 

93. Make your code more readable by using the “else if(condition)” command
“else if” Shorthand
Make your code more readable by using the “else if(condition)” command

94. If/else Shorthand
You can also have a single line “if” statement with out the need for curly braces “{“

95. For Loops
“For Loops” are important for repeating a block of a code a certain number of times.
For loops require a specific structure:

96. For Loops For Loop Syntax:
Initial – The variable that will be used to count the number of iterations through the loop
Example: int i = 0;
Condition – The conditional statement to decide how many iterations to loop through
Example: i < 10;
Increment – The statement to modify the counter variable through each iteration of the loop.
Example: i++
No semicolon at the end of this increment portion

97. For Loops
Drive and Turn – Loops 10 Times

98. For Loop Walkthough Create the for loop initial variable
Check the condition of the for loop
If true, continue onward
If false, skip the “for” loop
Run code inside of “for” loop
Run the iteration code and increment “i” by one.
Loop steps 2-4 until 2 returns false.

99. Loop Control
Two control statements are available to you when using “while” and “for” loops:
continue; - skips any remaining code below the continue statement and proceeds with the next iteration in the loop.
break; - breaks out of the current looping structure and proceeds execution of the rest of the program.

100. Loop Control
The continue statement will cause the robot to keep moving forward until the touch sensor it pressed.
The break statement will end the infinite while loop if the touch sensor is pressed