1. Introduction to Programming in RobotC
Vex IQ

2. Build a simple structure to support each of the brain, two motors and each sensor as listed to the right. Connect them as listed
Port
Connection 1
Motor – LEFT 2
Motor – RIGHT 3
Bumper Switch 4
Touch LED 5
Color Sensor 6
Distance Sensor 7
Gyro
Set-up

3. Programming Each student will work alone
When a student thinks they have a program written to complete one of the tasks, one of the instructors will come around with a robot practice station for you to download your program and allow the instructor to check that your program works as expected.
Programming

4. Programming Everyone should complete task #3 first.
Display your name on the first line of the display and put a fun quote on the second line of the display
Programming

5. Programming Basics Open RobotC – NOT the graphical program
Set up motors and sensors
These are listed on page 3 of your packet
Give each sensor or motor a unique name
Make sure to “apply” the name given
Programming

6. Programming Programming Basics
Almost all lines of code must end with a semi colon
Most commands you need can be dragged onto the program from the “text functions” panel on the left
All parenthesis must open and close
Conditional commands use fancy brackets
Inside the fancy brackets, many individual commands can be included
Programming

7. Programming Task #3, simple
Put the following inside the fancy brackets for task main
displayTextLine(1,”your name here”);
displayTextLine(2,”Hello World”);
Everyone test that this works
Programming

8. The basics of a complete program
Programming

9. It is nice to have words in your code that tells yourself and others what the code is doing.
At the end of a line add // then everything on that line after the // will not be read as code, but is a comment
Longer comments are contained between the following /* comment goes here */
Comments

10. Programming Lets change our text to display a button being pushed
FIRST – Save the program with a new name
Programming

11. Programming To get the results of a button use the following
vexRT[BtnEUp]
Replace BtnEUp with other buttons based on the drop down list that appears
Programming

12. Buttons to the BRAIN Test this code
So, is the mathematical value of the buttons?
Buttons to the BRAIN

13. Buttons What results do the brain see when a button is changed?
Buttons send a zero when not pushed and a one when pushed
Buttons

14. Buttons to the BRAIN Try the same thing with the joysticks
So, are the mathematical values of the joysticks?
Buttons to the BRAIN

15. Conditionals Conditionals only do something when the condition is met.
Conditionals include If
While
Conditionals must be followed by fancy brackets
Conditionals

16. Button turn on light The if statement is followed by brackets
Exactly what do you expect to happen
Button turn on light

17. How could you change the code so the light goes out when the button is not pushed?
Button turn on light

18. Try this
Button turn on light

19. We can change things with variables
Just like math class, we can assign a letter (or a whole word) to represent a value
Variables

20. Programming To do more, we need to add some math Variables
Variables allow us to remember a state, however the brain needs information on what kind of variable you may use
Programming

21. What kind of information might you want to store in a variable?
String = for storing text
Int = for storing integer numbers
Float = for storing numbers with decimals
Bool = for storing a state, true or false
Char = stores a single character
Programming

22. Programming

23. Try this
Counting

24. Try this
Variables

25. Sensors What about sensors? What values do they send?
The bumper switch is very much like the buttons on the controller
Sensors

26. Bumper Switch

27. Programming How can I make the motors move? motor[Left]=vexRT[ChA];
“Left” must match the name applied in the pragma
Add to your program so both motors spin with joysticks.
Programming

28. Let’s work toward programming something to make a robot move
Can you display the results of the joysticks on the screen of your brain?
Programming

29. Tank Drive Controls

30. Arcade Drive Tank drive is easiest to write.
Most drivers prefer arcade drive.
What does it take to turn and drive forward?
Arcade Drive

31. Arcade 2 Controls

32. Your turn.
Make both motors move forward or backwards with the “a” joystick
Then
Make the “b” joystick turn the robot
Programming

33. Arcade 1 Controls

34. Distance sensor Save value to a variable int sonarDist; Get variable sonarDist = getDistanceValue(SonarSensor);
Programming

35. task main() { int sonarDist; // Initialize a variable for the sonar while(true) sonarDist = getDistanceValue(SonarSensor); displayTextLine(1,"%d",sonarDist); // Display the sonar value } // end while true } // end task main
Sonar Sensor

36. Sonar Sensor

37. How could this be used to affect the drive motors on the robot?
Sonar

38. Sonar How could this be used to affect the drive motors on the robot?
Drive slower when closer to an object
Drive faster when farther away
Sonar

39. Because the sonar values are generally large, I divided to make them smaller

40. task main() { int sonarDist; // Initialize a variable for the sonar while(true) sonarDist = getDistanceValue(SonarSensor); sonarDist = sonarDist / 5; // scale the speed to move slower if (sonarDist > 100) sonarDist = 100; // if speed is over 100, reset motor[Left] = sonarDist; // set motor value displayTextLine(1,"%d",sonarDist); // Display the sonar value } // end while true } // end task main
Sonar

41. Sonar

42. More interesting things happen when you can record and save a “state” for your robot.
The following with two variables creates a “latch” that keeps the robot in the same state until the same button is pushed again.
Programming

43. task main() {
bool buttonToggleState = false;// possible states are true or false
bool buttonPressed = false;
while(true)
// check for a button press only if we are not already pressed.
if( vexRT[ BtnFUp ] == 1 )
if( ! buttonPressed )
buttonToggleState = !buttonToggleState;// change the toggle state
buttonPressed = true;// Note the button is pressed }
else
buttonPressed = false;// the button is not pressed
// Now do something with our toggle flag
if( buttonToggleState )
displayTextLine(4,"State is On"); // Display the state
setTouchLEDColor(Touch, colorRed);// Turn LED on and Red
displayTextLine(4,"State is Off"); // Display the state
setTouchLEDColor(Touch, colorNone); // Turn LED light off
}// while-true loop
}// task main
Latch

44. Latch

45. Programming Challenge
If the bumper switch is mounted on the bumper, when the robot hits a wall, can you program it to switch to reverse?
Bump it again, and switch to forward
Programming Challenge

46. Bumper Latch task main() {
bool buttonToggleState = false;// possible states are true or false
bool buttonPressed = false;
while(true)
// check for a button press only if we are not already pressed.
if(getBumperValue(Bump) == 1 )
if( ! buttonPressed )
buttonToggleState = !buttonToggleState;// change the toggle state
buttonPressed = true;// Note the button is pressed }
}else{
buttonPressed = false;// the button is not pressed
// Now do something with our toggle flag
if( buttonToggleState )
motor[Left] = 70; // Drive Forward
motor[Right] = 70; // Drive Forward
motor[Left] = -70; // Drive Backwards
motor[Right] = -70; // Drive Backwards
}// while-true loop
}// task main
Bumper Latch

47. Bumper Latch

48. Your turn
Combine your earlier program of a “Latch” to turn the right motor on with a button
Then turn it off again with the same button
Programming

49. Color Sensor So you have a color sensor connected to port 5.
What values does this provide to your brain?
Can you write a program to figure it out?
Color Sensor

50. Can we display this color number as a color?
Color Sensor

51. Try This!!