Brad Miller Associate Director WPI Robotics Resource Center Programming the 2009 FRC Control System

Agenda  How’s C programming different from last year  C++ and Object Oriented Programming  Writing a simple program  How to download, debug and deploy  Conventions used in the library  C Programming  Using the WPILib source code  Updates and more information

What’s Different - Processor 2009Previous 800 MIPs (400MHz) 32-bit Power PC10 MIPs (40MHz) 8-bit PIC Hardware floating point (double precision) Software floating point 128MB solid state disk128KB flash memory 64MB RAM4KB RAM 2M gate FPGAAll software device support

What’s Different - Tools 2009Previous years Wind River WorkbenchMicrochip MPLab Full C, C++, LabVIEWReduced C Full debugging (break, watchpoints)printf statements Wireless debugging / downloadingAll operations tethered Complete WPILib implementations in C, C++ and LabVIEW Sample code or sample framework

What’s Different – I/O 2009Previous Years 2 x (500kS/s, 12-bit, +/- 10V, 8 channels)75kS/s, 10-bit, 5V, 16 channels Hardware Timed SamplingSoftware Timed Sampling 28 Digital I/O, 6.525us18 Digital I/O, ?? us 20 PWM, 5ms16 PWM, 26.2ms 16 Spike 8 SolenoidN/A I2C x 2N/A Ethernet x 2N/A RS232RS232 x 2

Object Oriented Programming  C++ = C + Objects + other features –C++ programs that don’t use the extensions look are C programs  C++ objects are similar to Java objects –Java taught in many high schools –Java used on programming AP exams

Quick Tour of Objects  Objects are a good way of representing real-world “things” –Motors, sensors, driver station, robot drive train, robot subsystems, your whole robot –Have data associated with the “thing” and code that operates on the data (member data and methods) –Some objects are more specific versions of other objects (subclasses)

Objects (Classes) Quadrature Encoder Object What can it do? GetCount() GetPeriod() Reset() What does it know? Port numbers Reversed or not Methods RobotDrive Object What can it do? Drive() ArcadeDrive() TankDrive() What does it know? Port numbers Speed controller type Member Variables

Special Class Methods  Constructors (method with class-name) –Called automatically when the class is created –Used to initialize resources Happens when declared or when explicitly creating a new instance  Destructors (method with ~class-name) –Called automatically when the class is deleted –Frees class resources Happens when the object goes out of scope or when explicitly deleted

Subclass of a class SimpleRobot class Autonomous() { print message “Autonomous” } OperatorControl() { print message “Operator control” } Very boring! Autonomous() { Drive around the field and score point } OperatorControl() { Drive our robot using tank steering} Now very cool! IsAutonomous() { return the current field state } IsEnabled() { return robot state } Team190Robot class

Making Your First Program  Start with a template –SimpleTemplate –IterativeDemo  There are a bunch of samples, more coming…

Objects in sample program RobotDrive Object Joystick Object Methods: RobotDrive(leftmotor, rightmotor); Drive(speed, curve); Arcade(joystick); Methods: Joystick(port); GetX(); Gety(); GetTwist(); … stick myRobot

Robot Definition class RobotDemo : public SimpleRobot { RobotDrive myRobot; Joystick stick; // constructor, Autonomous, and Operator Control go here }; START_ROBOT_CLASS(RobotDemo);

Initialization (constructor) RobotDemo(void) : myRobot(1, 2), stick(1); { GetWatchdog().SetExpiration(100); } Initialize the RobotDrive and Joystick Set the Watchdog timer expiration

Autonomous part of program void Autonomous(void) { GetWatchdog().SetEnabled(false); myRobot.Drive(0.5, 0.0); Wait(2000); myRobot.Drive(0.0, 0.0); } Use the RobotBase object Drive method to go 0.5 speed (forward, half speed) with no turn Then stop. Key to the example: myRobot.Drive(speed, curve) speed: a value from -1.0 to 1.0 where 0.0 is stopped curve: a value from -1.0 to 1.0 where 0.0 is no turn Watchdog disabled because of the Wait – will fix this soon

TeleOp part of program void OperatorControl(void) { GetWatchdog().SetEnabled(true); while (1) { GetWatchdog().Feed(); myRobot.ArcadeDrive(stick); } Use the RobotBase object ArcadeDrive method to do arcade driving using our Joystick object Re-enable the watchdog since we aren’t waiting any more

How this is Really Done  Header file with the class declaration (class-name.h) –Include the header file in every module that uses the class  Implementation file (class-name.cpp) with the methods –Methods are prefixed with class-name::  Look at WPILib source code for examples

Using Workbench  What you have to do: –Write and compile program –Create a remote system connection –Create a run/debug configuration –Debug the program –Rinse and repeat  Then deploy the working program

Compiling the program  Build project and Build all  Structure of built program –Targets –Output file (.out)  Auto-build on save option  Errors –Build Console and Problems Window

Connecting to the cRIO  Create a remote system connection to the cRIO  Once connected –You can see tasks running –Get access to consoles –Reboot –And more…  Kernel image must be correct! –Located in c:\windriver\wpilib

Debug/Run Configurations  Run / debug configurations tie the program to a connection –Place to put run / debug options –Easy launch from the toolbar –Loads directly into cRIO memory – does not deploy program –Must check the debug “all tasks” box

Program debugging  Download program to cRIO  Debugger has professional tools –Breakpoints –Watchpoints –Examination of variables  … all done wirelessly

Seeing output on screen Connection methodProCon Connect a serial cable between the computer and robot controller (console switch turned on) with null modem cable. Works over reboots, all output works Robot must be tethered Network Target Console. To get that, right-click on the remote system, then "Target Tools", then "Target Console". This will create a console window over the network Gets everything without tether cable Goes away on reboot. cout may not work Allocate a console. In the Debug Configuration (debug icon in toolbar), select the run or debug configuration. Then look at the "Common" tab. There check the "Allocate Console" checkbox. Works over network cout doesn’t work

Deploying Robot Programs  Set up downloader – common mistake  Deploy / undeploy programs –Can only have one program at a time –Be careful not to mix debugging with deployed programs

Everything is C++  What if I can’t or don’t want to write C++ code? –Put.cpp at the end of file names –Write C code, except when referencing WPILib objects Use C++ object construction and referencing rather than the C method Create one class for your robot program Everything else looks like C  C Interfaces exist for most functions

Sample C Program #include "WPILib.h" #include "SimpleCRobot.h" #include "CRobotDrive.h" static const UINT32 LEFT_MOTOR_PORT = 1; static const UINT32 RIGHT_MOTOR_PORT = 2; static const UINT32 JOYSTICK_PORT = 1; void Initialize(void) { CreateRobotDrive(LEFT_MOTOR_PORT, RIGHT_MOTOR_PORT); SetWatchdogExpiration(100); }

Sample C Program void Autonomous(void) { SetWatchdogEnabled(false); Drive(0.5, 0.0); Wait(2000); Drive(0.0, 0.0); } void OperatorControl(void) { SetWatchdogEnabled(true); while (IsOperatorControl() { WatchdogFeed(); ArcadeDrive(JOYSTICK_PORT); } START_ROBOT_CLASS(SimpleCRobot);

Programming Paradigm  Subclass one of the robot classes –SimpleRobot – like easyC/WPILib –IterativeRobot – more like raw IFI code  Lots of sensors –All supported sensors are built-in objects and all supported through the FPGA –Lots of support code to make other stuff work  Full multi-tasking operating system at your disposal –VxWorks has tasks, syncronization, I/O, etc. everything you expect and all built in!

Using WPILib Source Code  Source code will soon be available on a SourceForge server at WPI –Will have code in a SVN repository –Readable by all  WPILib normally is referenced inside the WindRiver directory tree  Teams need to change –The include path to use the new library –The library (wpilib.a) location

Program Structure  Subclass SimpleRobot or IterativeRobot classes –Fill in constructor (things that run when the robot is turned on) –Fill in methods (Autonomous, OperatorControl)

Program Develop/Debug/Deploy  Programs are developed in WorkBench –Environment based on eclipse with additions –Full debugger available with breakpoints, watchpoints, variable examining, etc. –CVS/SVN plug-ins for tracking source code  Download your code for debugging  Deploy working code so that starts at power-up –Programs are loaded onto internal SSD, and load on reboot –Tools in Workbench will help you get your code there

What kinds of objects are there?  About 48 objects currently: –Robot definition –Motors and servos –Driver station –Sensors –Utility classes

Defining the Robot  RobotBase defines the robot control RobotBase –SimpleRobot has methods for Autonomous and Operator Control –IterativeRobot has methods for state transitions on the field  RobotDrive handles easy autonomous and operator controlled driving RobotDrive –You tell it about motors –Call methods to Drive, TankDrive, ArcadeDrive, HolonomicDrive

RobotDrive class RobotDrive { RobotDrive(unsigned frontLeftMotorChannel, unsigned rearLeftMotorChannel); void Drive(float speed, float curve); void TankDrive(float leftValue, float rightValue); void ArcadeDrive(float moveValue, float rotateValue); void HolonomicDrive(float magnitude, float direction, float rotation); void SetLeftRightMotorSpeeds(float leftSpeed, float rightSpeed); void TankDrive(GenericHID *leftStick, GenericHID *rightStick); void ArcadeDrive(GenericHID *stick); void SetInvertedMotor(MotorType motor, bool isInverted); };

Motors and Servos  Motors are created as Victor or Jaguar objects –Have float values ranging from -1.0 to +1.0, 0 is stopped –Can be shut off completely –Works with the RobotDrive object  Servos are created as Servo objects –Values from 0.0 to 1.0 –Never automatically set to 0

Driver Station  Allows access to all DriverStation I/O –Joysticks, digital input/output, and analog inputs –Packet numbers tell when values have changed –Build custom interfaces and retrieve values

Sensors  As many sensors as we could get to integrate –All FIRST kit of parts sensors –Popular hobby sensors –Many Lego/HiTechnic I2C sensors  Specify channel and (optional) module –Channels generally are 1-based –Module (slot) is always 1-based  Additional general purpose code like interrupts, timing, etc. to handle those that we haven’t implemented

Compressor  One stop shopping for compressor control –You specify the relay port and the digital input port –Compressor automatically starts and stops using a task –You can turn off the compressor when not in use

Ultrasonic Rangefinder  Interface for Vex or Daventech SRF04 Ultrasonic Rangefinder –Individual operation for fire sensor –Automatic mode to round-robin sensors –Results returned in inches or millimeters

Utility Classes  PID Class  Safety - Watchdog timer  Timing –Timer class –Clock support  Interrupts  Communications –Serial port –I2C

Timers  Timing various processes in your programs –Start, Stop, Get, Reset functions –Millisecond granularity  System clock with uSec granularity for synchronizing all events  VxWorks timing is also available

Interrupts  Interrupts will notify your program of changes in a device or timer –Digital I/O –Notification queue  Can either wait or be notified of an interrupt  Task priorities allow you to tune the system

Camera – Setting up Colors SimpleTracker(void) { // start the CameraTask if (frcStartCameraTask() == -1) { printf( "Failed to spawn camera task; Error code %i“, frcGetErrorText(frcGetLastError()) ); } Wait(500); // tell the camera server to start acquiring images frcStartImageAcquisition(); Wait(500); // color values under greenish fluorescent lights greenHue.minValue = 65; greenHue.maxValue = 80; greenSat.minValue = 100; greenSat.maxValue = 255; greenLum.minValue = 100; greenLum.maxValue = 255; }

Camera – tracking an object void Autonomous(void) { GetWatchdog().Feed(); FrcParticleAnalysisReport par; while (IsAutonomous()) { if (frcFindColor(IMAQ_HSL, &greenHue, &greenSat, &greenLum, &par) && par.particleToImagePercent < MAX_PARTICLE_TO_IMAGE_PERCENT && par.particleToImagePercent > MIN_PARTICLE_TO_IMAGE_PERCENT) myRobot->Drive(1.0, (float) par.center_mass_x_normalized); else myRobot->Drive(0.0, 0.0); Wait(50); } myRobot->Drive(0.0, 0.0); }

Conventions in WPILib  Constructors associate objects and channels –Module/channel, channel only (shorthand for first module), or another object  Methods are overloaded, i.e. can take various types for arguments when it makes sense) –ArcadeDrive(moveValue, rotateValue) or ArcadeDrive(Joystick)  Object arguments can either be references or pointers  Default constructors are private

Getting Help  Documentation  Online resources

WPILib Documentation  Documentation comes in two forms: –Doxygen output compiled from the source code comments A C and a C++ Reference Manual –C/C++ Programming Users Guide  Both documents are stored in: c:\WindRiver\docs\extensions\FRC  Vision system spec

Support  FIRST forums  NI Community Forums –  WPI / FIRST NSF Community site (ThinkTank)  All monitored by: –WPI –NI –FIRST –Beta teams  All source code available for team-team assistance  Phone support through NI – (1PM-7PM CST, M-F)

Software Updates  Imaging tool to completely reimage cRIO –All shared libraries on cRIO and FPGA image  Updates often require reimaging the cRIO –Imaging utility installs with LabVIEW –Best practice is always apply updates and always update image

Future  Update mid-January  Community involvement –Looking for contributions back to the libraries Bug fixes Improvements –Run as an open source project Community projects SourceForge site coming soon

Questions?

Examples and Templates  Sample programs will be included –Use the samples as templates for your own code –Additional samples to show how other aspects of the system work

Analog I/O and Triggers  Analog I/O features: –User defined sample rates/module –Averaging of multiple values –Oversampling –DMA for synchronous measurements and user averaging  Triggers –Range of analog values –Routed to a counter to count values in/out of range –Can interrupt program on transitions

Using Robot Objects  Objects are created as: –Local/global variables or allocated with C++ new operator Encoder leftWheelEncoder(3, 4); Encoder *leftWheelEncoder = new Encoder(3, 4);  Used by calling methods (functions) –encoder.Get() –speedController.Set() –rangefinder.Start() –Stop(), etc.

Common Problems  Running two programs concurrently  Opening output windows  Problems downloading code –Modules already loaded, tasks loaded  None of the libraries available –cRIO FPGA image doesn’t match –Loading program before FPGA loads  Motors don’t move –Watchdog timer  Kernel image compatibility

Common Problems  Joystick support – Linux HID devices –Might have to play with the device to see what’s there  Installation –Must be online for validating key –Virus scanners have caused problems –HP Single Signon features breaks installation  Driver Station connections have no pullup or pulldown resistors

How Updates Work  Updates are self extracting zip files –Extracts into a temp directory –Deletes old files –Copies in new files  Everything happens in the WindRiver directories  Updates are standalone non-cumulative  Getting updates from FIRST website:

The Hardware  Overview Video Overview Video  Some specs: –400 mhz PPC –64 mb RAM –128 mb Flash (solid state disk) –2m gate FPGA –2 Ethernet ports –Serial port

More Hardware  2 Digital modules – 32 GPIO lines each translates to: –10 PWMs –14 Digital I/O –8 Relay –I2C  2 Analog modules – 8 lines –500 khz aggregate sample rate / module –12 bits (sort of) –Oversampling, averaging, and integration  1 Solenoid module for pneumatics –8 lines  Ethernet Webcam

The Software  Your choice of language! –National Instruments LabVIEW 8.5 with WPI Robotics Library, LabVIEW version –WindRiver Workbench 3.0 with WPI Robotics Library, C/C++ version  Assorted examples, documentation, utilities like imaging, etc.

Introduction  Introduction to the hardware  Writing C++ programs  Demos  What’s going on inside  Debugging

A Little about Architecture  All heavy lifting to sensors and motors is through an FPGA –Field Programmable Gate Array Fancy name for custom logic that makes the sensors work –All time sensitive hardware interactions are done through the FPGA –If we did our job, you should never have to deal with it.

FPGA in WPI Robotics Library  All modules are connected to the PPC through the FPGA  Programming with the FPGA –Create instance of object with the port number or port object the device is physically connected to Most objects are “overloaded” to take either unsigned port numbers or port objects –Start and/or use the device

Architecture PowerPC FPGA Analog Module (2) Gyro and accelerometer Potentiometers Digital Module (2) Encoders, gear tooth sensors, switches, GPIO Speed controls, servos, other PWM devices I2CSpike Relays Solenoid Module (1) Pneumatics Network

Accelerometer and Gyro  Gyro returns heading in degrees using the FPGA Analog Input accumulator –Relies on the oversampling and averaging engine built into the FPGA  Accelerometer converts value to mGs

Counters and Sources  Counters count Digital Sources and Analog Triggers –Digital sources are digital inputs where you can specify modes (standard, geartooth, and semi-period) and edges –Analog Triggers can be counted  Subclasses include: –Quadrature encoders –Geartooth sensors (with direction) –Simple counters

Digital I/O  Simple Digital Input and Output –Can route to a counter or used along with a counter –Pulse generation for small signals –Can interrupt on edges

Relays and Solenoids  Relays are designed for spikes –On, Off, Forward, and Reverse output  Solenoids use the 9472 module –Controls pneumatics directly

Watchdog Timer  Stops all motors in event of failure  System watchdog –Can’t be modified by users –Based on the e-stop/enable flag and reliable communications  User Watchdog –Default enabled –You are responsible for care and feeding the watchdog

DMA (Direct Memory Access)  Feature to record complete state of sensors periodically –Use for logging –Data smoothing and averaging