Beginner Programming Beginner Programming Workshop Workshop

Simona DoboliSimona DoboliAssistant ProfessorAssistant Professor

Computer Science DepartmentComputer Science DepartmentHosftra UniversityHosftra University

Email: Email: Simona.Doboli@hofstra.eduSimona.Doboli@hofstra.edu

November 17, 2007Hauppauge High School

SPBLI - FIRST

Mark McLeodMark McLeodAdvisorAdvisor

Hauppauge Team 358Hauppauge Team 358Northrop Grumman Corp.Northrop Grumman Corp.Mark.McLeod@ngc.comMark.McLeod@ngc.com

AgendaAgenda

FIRST Control SystemFIRST Control System MPLAB EnvironmentMPLAB Environment C BasicsC Basics FRC Default Code FRC Default Code

– Robot Driver ControlRobot Driver Control Demonstration of Basic OI Controls Demonstration of Basic OI Controls

– Robot Autonomous ControlRobot Autonomous Control Demonstration of Dead ReckoningDemonstration of Dead Reckoning

Hands-OnHands-On

FIRST Control SystemFIRST Control System

solenoid motor

FIRST Control ElementsFIRST Control Elements

HardwareHardware– Robot Controller (RC)Robot Controller (RC)

User Processor vs. Master ProcessorUser Processor vs. Master Processor PWM, Relay, Digital I/O, Analog, Misc.PWM, Relay, Digital I/O, Analog, Misc.

– Operator Interface (OI)Operator Interface (OI)– Tether cable / Programming cableTether cable / Programming cable– LaptopLaptop

ProgrammingProgramming– C LanguageC Language– MPLAB/mcc18 (write & compile your program)MPLAB/mcc18 (write & compile your program)– IFI_Loader (download to robot controller)IFI_Loader (download to robot controller)– Dashboard (optional)Dashboard (optional)– FIRST Default CodeFIRST Default Code

Robot Controller Robot Controller ArchitectureArchitecture User ProcessorUser Processor

– What we download toWhat we download to– Runs our codeRuns our code– Reads the digital/analog I/O directlyReads the digital/analog I/O directly

Master ProcessorMaster Processor– Controls Disable/Autonomous/Driver modesControls Disable/Autonomous/Driver modes– Disables OI inputs & most RC outputsDisables OI inputs & most RC outputs– Must hear from User periodically or shuts it downMust hear from User periodically or shuts it down– Master Code Software is updated each yearMaster Code Software is updated each year

Robot Controller I/ORobot Controller I/O

Banner Sensor

Touch Sensor

Switch

Gyroscope

CameraLimit Switch

Analog Rangefinder

Encoder

Potentiometer

Pressure Sensor

Servo

Solenoid Compressor

Analog

Digital

Motors

Relays

TeamLEDs

TTL

Getting StartedGetting Started

Create/Open an MPLAB ProjectCreate/Open an MPLAB Project Edit a FileEdit a File Build/CompileBuild/Compile Download Download

MPLAB

IFI_Loader

.hex file

Robot Controller

Operator Interface

Dashboard (optional)

C BasicsC Basics

Structure (#include, functions)Structure (#include, functions) IF, THEN, ELSEIF, THEN, ELSE WHILEWHILE FORFOR =, !=, ! >=, <=, ==, >, <, !=>=, <=, ==, >, <, != &&, ||&&, || OperatorsOperators Prototype declarationsPrototype declarations

C Basics – Structure C Basics – Structure ProgramProgram

#include <stdio.h> #include <stdio.h> // C header file – standard library function // C header file – standard library function // prototypes// prototypes

#include “myHeader.h” #include “myHeader.h” // User header file – user function prototypes// User header file – user function prototypes

int globalVar = 10; // definition global variable – can be used int globalVar = 10; // definition global variable – can be used anywhereanywhere

// in this file// in this filevoid main(void)void main(void){{

// What your program does// What your program does int result; // local variable – can be used only in main() int result; // local variable – can be used only in main()

functionfunction result = max(1, 10); // call function max: 1, 10 – actual parametersresult = max(1, 10); // call function max: 1, 10 – actual parameters}}

int max(int i, int j) // int i, int j = formal parametersint max(int i, int j) // int i, int j = formal parameters{{ // a function definition// a function definition}}

C Basics – Data TypesC Basics – Data Types

TypeType SizeSize MinMin MaxMax

charchar 8 bits8 bits -128-128 127127

unsigned charunsigned char 8 bits8 bits 00 255255

intint 16 16 bitsbits

-32,768-32,768 32,76732,767

unsigned intunsigned int 16 16 bitsbits

00 65, 53565, 535

short longshort long 24 24 bitsbits

-2^23-2^23 2^23-12^23-1

unsigned short unsigned short longlong

24 24 bitsbits

00 2^24-12^24-1

longlong 32 32 bitsbits

-2^31-2^31 2^31-12^31-1

unsigned longunsigned long 32 32 bitsbits

00 2^32-12^32-1

C Basics – A simple C Basics – A simple programprogram

#include <stdio.h>

#pragma config WDT = OFF

int max(int i, int j); // function declaration

void main(void){ int m, n, bigger; m = 10; n = 20; bigger = max(m,n); printf("m= %d, n = %d, bigger = %d”, m, n, bigger); while(1);}

//###############// Function definition//###############

int max(int i, int j){ int result; if (j > i)

result = i; else

result = j; return result;}

C Basics – if statementC Basics – if statement

if (touch == 1 if (touch == 1 &&&& light != 0 ) light != 0 )

goStraight = 1;goStraight = 1;

elseelse

goStraight = -1;goStraight = -1;

!!! NOTE: if (touch =1) vs. if (touch == !!! NOTE: if (touch =1) vs. if (touch == 1)1)

ASSIGNMENT CONDITIONASSIGNMENT CONDITION

AND Logic

OR Logic (||)

C Basics – while loopC Basics – while loop

while (touch == 0) while (touch == 0) { {

leftMotor = 5;leftMotor = 5;rightMotor = 5;rightMotor = 5;read(touch); // need to change touch read(touch); // need to change touch

insideinside // the loop// the loop

}}

// use { } if more than one statement in a // use { } if more than one statement in a looploop

C Basics - Exercise C Basics - Exercise

Write a program that computes the Write a program that computes the first n numbers in the Fibonnacci first n numbers in the Fibonnacci series: series:

0, 1, 1, 2, 3, 5, 8, 13. 0, 1, 1, 2, 3, 5, 8, 13.

n is an integer number between 0 and n is an integer number between 0 and 30.30.

C Basics - Algorithm C Basics - Algorithm

int first = 0, second = 1, third;int first = 0, second = 1, third;while (n > 0){while (n > 0){

third = first + second;third = first + second;output thirdoutput thirdfirst = second;first = second;second = third;second = third;n --;n --;

}}

FRC Default Code FlowFRC Default Code Flow

Main()Main()– User_Initialization()User_Initialization()– Do as long as we’re onDo as long as we’re on

New radio packet (slow loop)New radio packet (slow loop)– Process_Data_From_Master_uP(Process_Data_From_Master_uP(

)) Default_Routine()Default_Routine()

– As long as we’re in auto mode As long as we’re in auto mode do thisdo this

User_Autonomous_Code()User_Autonomous_Code() Fast loop stuffFast loop stuff

User Initialization

Radiopacket

?

Driver Routine

AutoMode

?

User Autonomous

NO

NO

YES

YES

FRC Default CodeFRC Default Code

Files to changeFiles to change– user_routines.c user_routines.c (to add switches & change (to add switches & change

controls)controls) Default_Routine()Default_Routine() User_Initialization()User_Initialization()

– user_routines_fast.cuser_routines_fast.c User_Autonomous()User_Autonomous() (to add autonomous (to add autonomous

movement)movement)

– user_routines.huser_routines.h (to share variables between files) (to share variables between files)

Input / OutputInput / Output

OI OI – InputsInputs

Joysticks x & y (0-254)Joysticks x & y (0-254) Buttons (0 or 1)Buttons (0 or 1) Unused inputsUnused inputs

– OutputsOutputs LEDs – lights or 3-digit readoutLEDs – lights or 3-digit readout

RC RC – OutputsOutputs

Digital I/O for sensors and devices (0 or 1)Digital I/O for sensors and devices (0 or 1) PWM for motors (0=reverse, 127=stop, 254=forward) PWM for motors (0=reverse, 127=stop, 254=forward) Don’t Don’t

use 13-16use 13-16 Relay for on/off, e.g., pneumatics (forward, reverse, stop)Relay for on/off, e.g., pneumatics (forward, reverse, stop)

– InputsInputs Analog for sensors, e.g., potentiometers (0 to 1023)Analog for sensors, e.g., potentiometers (0 to 1023)

– BothBoth TTL for devices, e.g., camera or LCD screenTTL for devices, e.g., camera or LCD screen

Sample OI ControlsSample OI Controls

(note: OI switches =0 when off and =1 when on)(note: OI switches =0 when off and =1 when on)

Sample uses:• Drive

• Control arm• Control turret

// motor controlled by switch

pwm03 = 127;if (p1_sw_trig == 1){ pwm03 = 254;}

// arm joystick

pwm03 = p3_y;

// 2-Joystick drive

pwm01 = p1_y;pwm02 = 255-p2_y;

// 1-Joystick drive

pwm01 = Limit_Mix(p1_y + p1_x - 127); pwm02 = Limit_Mix(p1_y - p1_x + 127);// Limit_Mix keeps pwm between 0 & 254

Sample OI Sample OI Input/OutputInput/Output Changing the OI LED/digital displayChanging the OI LED/digital display

// LED display on the OI

if (user_display_mode == 0) // OI lights are in use (select switch on OI){ Pwm1_green = 1; Pwm1_red = 1;}else // OI digital display is in use{ User_Mode_byte = 123;}

Sample uses:• Trim joysticks

• Display auto selected• Display backup battery voltage

Sample RC Digital Sample RC Digital InputInput Switches on the Robot Controller (RC Digital Inputs)Switches on the Robot Controller (RC Digital Inputs)(note: RC switches =1 when off and =0 when on)(note: RC switches =1 when off and =0 when on)

Sample uses:• Limit switches

• Autonomous selection• Field starting position

• Pressure sensor

// Autonomous selection

if (rc_dig_in01 == 1){ Autonomous_1();}else{ Autonomous_2();}

// Limit Switch on arm

pwm03 = p3_y;if ((rc_dig_in01 == 1) && (pwm03 > 127)){ pwm03 = 127;}

Sample RC Analog Sample RC Analog InputInput Analog Inputs on the RC (e.g., a potentiometer)Analog Inputs on the RC (e.g., a potentiometer)

// Use of arm position sensor (potentiometer) to limit arm movementint armpot;

pwm01 = p3_y;armpot = Get_Analog_Value(rc_ana_in03); // value will be 0-1023

if ( (armpot > 900) && (pwm01 > 127) ){ pwm01 = 127; // Neutral}else if (armpot < 100) && (pwm01 < 127) ){ pwm01 = 127; // Neutral}

Sample uses:• Position sensors

• Gyroscope• Analog rangefinder

Sample RC Relay Sample RC Relay OutputOutput Forward / Reverse / NeutralForward / Reverse / Neutral

relay8_fwd = 1;relay8_rev = 0;

relay8_fwd = 0;relay8_rev = 1;

relay8_fwd = 0;relay8_rev = 0;

// Single pneumatic solenoid (valve) relay8_fwd = p1_sw_trig; relay8_rev = 0;

// Double pneumatic solenoid (valve) relay8_fwd = p1_sw_trig; relay8_rev = !p1_sw_trig;

// Turn on Compressor when Pressure Switch on digital input 18 says so relay8_fwd = !rc_dig_in18; relay8_rev = 0;

Sample uses:• Pneumatic valves

• Compressor on/off• On/off motors

Robot Autonomous Robot Autonomous ControlControl Must be developed under identical Must be developed under identical

environment as in competitionenvironment as in competition Training the robot must be repeated over Training the robot must be repeated over

& over to get right& over to get right Develop code using old robots or Develop code using old robots or

prototypesprototypes Plan on multiple autonomous optionsPlan on multiple autonomous options Use as few distinct movements as possibleUse as few distinct movements as possible

Sample AutonomousSample Autonomous

// Drive forward and stop

Sample_Auto_1(){ static int counter=0;

if (counter<100) {

counter++;pwm01 = 200;pwm02 = 54; //motor is reversed

} else // Make sure it always stops {

pwm01 = 127;pwm02 = 127;

}}

May need function prototype:void Sample_Auto_1(void);

Common IssuesCommon Issues

Syntax and typosSyntax and typos Program & Data SpaceProgram & Data Space Code Too Slow trying to do too muchCode Too Slow trying to do too much Joystick trimJoystick trim Embedded math (variable overflow)Embedded math (variable overflow) Infinite or too large loopsInfinite or too large loops Variables keep values until you change Variables keep values until you change

themthem Unfortunately, it does exactly what Unfortunately, it does exactly what

you tell it to doyou tell it to do

Hands-OnHands-On

Vex RobotsVex Robots Timed AutonomousTimed Autonomous Sensors for Advanced StudentsSensors for Advanced Students

1.1. Vex w/encoder, turret, gyroVex w/encoder, turret, gyro2.2. Vex w/cameraVex w/camera3.3. Vex w/pot controlled armVex w/pot controlled arm4.4. Vex w/rangefinders (IR, sonic)Vex w/rangefinders (IR, sonic)5.5. Vex w/swerve driveVex w/swerve drive6.6. Edu w/bumper sensorEdu w/bumper sensor

ReferencesReferences

Programming Quick StartProgramming Quick Start FIRST RC Reference GuideFIRST RC Reference Guide FIRST OI Reference GuideFIRST OI Reference Guide www.chiefdelphi.com/forums www.chiefdelphi.com/forums

Programming forumProgramming forum

Reference BooksReference Books

C For Dummies, Volume OneC For Dummies, Volume One C For Dummies, Volume TwoC For Dummies, Volume Two C Programming - A Modern

Approach - K N King ““The C Programming Language” -The C Programming Language” -

Kernighan & RitchieKernighan & Ritchie ““The C Answer Book” - Kernighan & The C Answer Book” - Kernighan &

RitchieRitchie

Presentation slides at: Presentation slides at:

www.cs.hofstra.edu/~sdoboliwww.cs.hofstra.edu/~sdoboli

oror

Team358.orgTeam358.org

Questions/Help please email us. Questions/Help please email us.

Simona.Doboli@hofstra.eduSimona.Doboli@hofstra.edu

Mark.McLeod@ngc.comMark.McLeod@ngc.com