ROBOT C for VEX On-Site Professional Development

1. ROBOTC for VEXOn-Site Professional Development

2. Troubleshooting • Student: My robot won’t stop turning.

3. Troubleshooting • Student: I used the auto straightening code, and it compiles, it isn’t working, it’s just being weird.

4. Troubleshooting • Student: One of my encoders is counting down even though it’s spinning forward.

5. Troubleshooting • Student: My code won’t compile.

6. Radio Control

7. Radio Control • An out-of-box VEX Microcontroller comes with basic built-in Radio Control functionality • The Radio Control Transmitter can be configured to allow some customization of that built-in functionality • Still very limited customizability and usefulness! • The ROBOTC firmware enables full customization of how the Radio Control Transmitter signals controls the VEX • By default ROBOTC turns off reception from the transmitter to save battery life during autonomous programming • One line of code turns it back on

8. Radio Control • One Transmitter continuously sends out 6 separate values over 6 separate channels • Values range from -127 to 127 • Doesn’t something else have values that range from -127 to 127? • The “crystal” number must match on the transmitter and receiver • The crystal is what controls the frequency of the transmission • One transmitter can control multiple robots, so be careful in your classrooms • 13 different crystals/frequencies are available

9. Radio Control Reset • Since the Radio Control Transmitter can be configured, there’s the possibility that it’s configured inappropriately for our purposes. • Watch the Radio Control Setup and Values and Axes (Part 1) Videos in TRC4V, found in Radio Control > Control Mapping • Be sure to follow along with the Radio Control Setup Video!

10. Radio Control Signals

11. Radio Control • Direct Value Mapping • Values from the transmitter are directly used to control the motors (1:1 ratio) • Program Flow Tracing • Radio Control with Wait States • Radio Control with a Loop (real-time control) • Indirect Value Mapping • Values from the transmitter are modified before being used to control motors • Can make the robot easier to control • Appropriate in situations that require more “delicate” movements • Notice: the robot reads the right side of the equal sign first

12. Advanced Radio Control • Attach the Arm! • Use the Transmitter buttons to control the arm • The Transmitter buttons send values of -127, 0, or 127 • Would direct mapping or indirect mapping be most appropriate for controlling the arm? Why? • More loop control please? • Is remote controlling the robot forever always appropriate? • Question: Where would the wait statement go if we wanted the robot to be remote controlled for a controlled amount of time? • Answer: Nowhere! We need something else. • Solution: Timers • Can be thought of as internal stopwatches (4 available) • Like encoders, timers should be “cleared” anytime before they are used • Watch where you clear them!

13. Advanced Radio Control • Wasting Time? • The time it takes to turn on the VEX and start Radio Control is wasted time. • Could we make the robot wait to start it’s timer until we were ready? Any ideas? • Wait for a Transmitter Button press • The robot won’t start the timer until we say so • The robot also can’t move until we says so • Program Flow Trace • Could this idea also be used to make a “more friendly” start button on a non-radio controlled robot? • Other ideas of how to improve radio control? • Use the buttons to initiate common actions • Turn 90 degrees, move straight forward, ect

14. Advanced Radio Control • Assigning a function to a button press • Auto pickup

15. Radio Control Challenges • TRC4V Videos (recommended) • Watch remaining Control Mapping videos 3-5 • Race to the Finish • Remember to Journal • Remember to Pseudocode • Shut off your transmitter when it’s not in use! • Drastically saves the battery life (and your ears) • The transmitter is always transmitting, even if the robot isn’t on

16. Advanced Radio Control Challenges • TRC4V Videos (recommended) • Watch remaining Radio Control Videos (Control Mapping, Timers, Buttons sections) • Minefield Level 1 Challenge • Remember to Pseudocode • Remember to Journal • RoboDunk • First try it Tele-Operated, then Autonomously

17. Competition Templates • VEX Competitions have a “Field Management System” in place • Manages when robots are enabled/disabled • Determines whether the robots are in autonomous/tele-operated mode • A Competition Template is available that can be programmed in to work with the Field Management System • Contains autonomous and tele-operated sections • Found in the Sample Programs > Competition folder

18. Troubleshooting • Student: My loop should only be running for 1 minute, but it never stops.

19. Touch Sensors • Touch Sensor Check • Front sensor plugged into A/D 1 • Rear Sensor plugged into A/D 4 • How they work • Digital sensor - Pressed or Released • Watch out for “bouncing” • Two Types • Limit Switches – on Squarebot 3.0 • Bumper Switches • Setting them up • ROBOTC Motors and Sensors Setup window • Using them • The SensorValue[] command

20. Touch Sensors • Start Button • Remember back to how we used the Transmitter button to start the timer portion of the program. How would we implement the same thing with the limit switch? • Fine-tuned arm control • Using the limit switches to tell the robot when it has reached it’s minimum and maximum points

21. Touch Sensor Challenges • Quick-tap Challenge • Incorporating Sensors, Variables, Loops, If Statements, Timers, Boolean Logic, Pseudocoding, and FUN all into one activity • Addition & Subtraction • Everything you just learned, but with another twist

22. The Ultrasonic Rangefinder • Ultrasonic Rangefinder Check • Input wire plugged into A/D Port 5 • Output wire plugged into INT Port 1 • How they work • Similar to how bats and submarines work • Digital sensor – but returns distance values between 0 & 255 • (Can also return values of -1 or -2 if used improperly) • Resolution is in inches (a value of 5 = 5 inches away) • Setting them up • ROBOTC Motors and Sensors Setup window • Using them • Be careful not to use them immediately as your program starts – they take time to initialize and will return negative values • The SensorValue[] command

23. The Ultrasonic Rangefinder • Forward until Near • Move forward until the robot is “near” an object, then stop • Thresholds • Automatic Pick-up • Forward until Near + picking up the mine • Assign to a button

24. Sensor Challenges • TRC4V Videos (recommended) • Watch Remaining Sensing Section Videos • Minefield Level 2 Challenge • Remember to Pseudocode • Remember to Journal • The two are not mutually exclusive! • The Speed of Sound • Sonic Scanner Level 2 (Start)

25. Potentiometers • Potentiometer Check • Sensor plugged into A/D 1 • How they work • Analog sensor • Measures rotation of a shaft between 0 and ~265 degrees • Returns values 0 – ~1023 • Internal mechanical stop • Setting them up • ROBOTC Motors and Sensors Setup window • Using Analog and Digital Sensors • Using them • The SensorValue[] command

26. Potentiometers • Variable Speed Program • Use the rotation of the potentiometer to control how fast the robots motors spin • Arm Control • Instead of using the limit switches, use the potentiometer to control how far the arm is allowed to swing up and down

27. Servo Motors • Very similar in appearance to the normal motor • Very different in operation • Rotates between 0 and 120 degrees • Where the motor is set to a “power value” the servo is set to a “position value” • -127 = 0 degrees, 0 = 60 degrees, 127 = 120 degrees, ect • Servo motors are programmed exactly the same way as normal motors in ROBOTC, so the programmer must know the hardware and intent

28. Pneumatics

29. Pneumatics • Solenoids operate as Digital Outputs • Are plugged into Analog/Digital Ports • Are set to open by setting them to 1 • Are set to close by setting them back to 0 • Demo in ROBOTC

30. End of Day Challenge • Minefield Level 2 • Incorporate an autonomous scoring behavior before your tele-operated code begins • One “mine” should always be in the same place, near the goal