Beginner Programming Workshop Simona Doboli Assistant Professor Computer Science Department Hosftra University November 17, 2007 Hauppauge High School SPBLI - FIRST Mark McLeod Advisor Hauppauge Team 358 Northrop Grumman Corp.

Agenda FIRST Control System FIRST Control System MPLAB Environment MPLAB Environment C Basics C Basics FRC Default Code FRC Default Code –Robot Driver Control Demonstration of Basic OI Controls Demonstration of Basic OI Controls –Robot Autonomous Control Demonstration of Dead Reckoning Demonstration of Dead Reckoning Hands-On Hands-On

FIRST Control System solenoidmotor

FIRST Control Elements Hardware Hardware –Robot Controller (RC) User Processor vs. Master Processor User Processor vs. Master Processor PWM, Relay, Digital I/O, Analog, Misc. PWM, Relay, Digital I/O, Analog, Misc. –Operator Interface (OI) –Tether cable / Programming cable –Laptop Programming Programming –C Language –MPLAB/mcc18 (write & compile your program) –IFI_Loader (download to robot controller) –Dashboard (optional) –FIRST Default Code

Robot Controller Architecture User Processor User Processor –What we download to –Runs our code –Reads the digital/analog I/O directly Master Processor Master Processor –Controls Disable/Autonomous/Driver modes –Disables OI inputs & most RC outputs –Must hear from User periodically or shuts it down –Master Code Software is updated each year

Robot Controller I/O Banner Sensor Touch Sensor Switch Gyroscope Camera Limit Switch Analog Rangefinder Encoder Potentiometer Pressure Sensor Servo SolenoidCompressor Analog Digital Motors Relays Team LEDs TTL

Getting Started Create/Open an MPLAB Project Create/Open an MPLAB Project Edit a File Edit a File Build/Compile Build/Compile Download Download

MPLAB IFI_Loader.hex file Robot Controller Operator Interface Dashboard (optional)

C Basics Structure (#include, functions) Structure (#include, functions) IF, THEN, ELSE IF, THEN, ELSE WHILE WHILE FOR FOR =, ! =, ! >=,, =,, <, != &&, || &&, || Operators Operators Prototype declarations Prototype declarations

C Basics – Structure Program #include // C header file – standard library function // prototypes #include “myHeader.h” // User header file – user function prototypes int globalVar = 10; // definition global variable – can be used anywhere // in this file // in this file void main(void) { // What your program does int result; // local variable – can be used only in main() function int result; // local variable – can be used only in main() function result = max(1, 10); // call function max: 1, 10 – actual parameters result = max(1, 10); // call function max: 1, 10 – actual parameters} int max(int i, int j) // int i, int j = formal parameters { // a function definition // a function definition}

C Basics – Data Types TypeSizeMinMax char 8 bits unsigned char 8 bits 0255 int 16 bits -32,76832,767 unsigned int 16 bits 0 65, 535 short long 24 bits -2^232^23-1 unsigned short long 24 bits 02^24-1 long 32 bits -2^312^31-1 unsigned long 32 bits 02^32-1

C Basics – A simple program #include #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 statement if (touch == 1 && light != 0 ) goStraight = 1; else goStraight = -1; !!! NOTE: if (touch =1) vs. if (touch == 1) ASSIGNMENT CONDITION ASSIGNMENT CONDITION AND Logic OR Logic (||)

C Basics – while loop while (touch == 0) while (touch == 0) { leftMotor = 5; rightMotor = 5; read(touch); // need to change touch inside // the loop // the loop } // use { } if more than one statement in a loop // use { } if more than one statement in a loop

C Basics - Exercise Write a program that computes the first n numbers in the Fibonnacci series: Write a program that computes the first n numbers in the Fibonnacci series: 0, 1, 1, 2, 3, 5, 8, 13. n is an integer number between 0 and 30. n is an integer number between 0 and 30.

C Basics - Algorithm int first = 0, second = 1, third; while (n > 0){ third = first + second; output third first = second; second = third; n --; }

FRC Default Code Flow Main() Main() –User_Initialization() –Do as long as we’re on New radio packet (slow loop) New radio packet (slow loop) –Process_Data_From_Master_uP() Default_Routine() Default_Routine() –As long as we’re in auto mode do this User_Autonomous_Code() User_Autonomous_Code() Fast loop stuff Fast loop stuff User Initialization Radio packet ? Driver Routine Auto Mode ? User Autonomous NO YES

FRC Default Code Files to change Files to change –user_routines.c (to add switches & change controls) Default_Routine() Default_Routine() User_Initialization() User_Initialization() –user_routines_fast.c User_Autonomous() (to add autonomous movement) User_Autonomous() (to add autonomous movement) –user_routines.h (to share variables between files)

Input / Output OI OI –Inputs Joysticks x & y (0-254) Joysticks x & y (0-254) Buttons (0 or 1) Buttons (0 or 1) Unused inputs Unused inputs –Outputs LEDs – lights or 3-digit readout LEDs – lights or 3-digit readout RC RC –Outputs 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) Don’t use PWM for motors (0=reverse, 127=stop, 254=forward) Don’t use Relay for on/off, e.g., pneumatics (forward, reverse, stop) Relay for on/off, e.g., pneumatics (forward, reverse, stop) –Inputs Analog for sensors, e.g., potentiometers (0 to 1023) Analog for sensors, e.g., potentiometers (0 to 1023) –Both TTL for devices, e.g., camera or LCD screen TTL for devices, e.g., camera or LCD screen

Sample OI Controls (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 Input/Output Changing the OI LED/digital display Changing 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 Input 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) 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 Input 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 movement int armpot; pwm01 = p3_y; armpot = Get_Analog_Value(rc_ana_in03); // value will be 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 Output Forward / Reverse / Neutral Forward / 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 Control Must be developed under identical environment as in competition Must be developed under identical environment as in competition Training the robot must be repeated over & over to get right Training the robot must be repeated over & over to get right Develop code using old robots or prototypes Develop code using old robots or prototypes Plan on multiple autonomous options Plan on multiple autonomous options Use as few distinct movements as possible Use as few distinct movements as possible

Sample 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 Issues Syntax and typos Syntax and typos Program & Data Space Program & Data Space Code Too Slow trying to do too much Code Too Slow trying to do too much Joystick trim Joystick trim Embedded math (variable overflow) Embedded math (variable overflow) Infinite or too large loops Infinite or too large loops Variables keep values until you change them Variables keep values until you change them Unfortunately, it does exactly what you tell it to do Unfortunately, it does exactly what you tell it to do

Hands-On Vex Robots Vex Robots Timed Autonomous Timed Autonomous Sensors for Advanced Students Sensors for Advanced Students 1.Vex w/encoder, turret, gyro 2.Vex w/camera 3.Vex w/pot controlled arm 4.Vex w/rangefinders (IR, sonic) 5.Vex w/swerve drive 6.Edu w/bumper sensor

References Programming Quick Start Programming Quick Start FIRST RC Reference Guide FIRST RC Reference Guide FIRST OI Reference Guide FIRST OI Reference Guide Programming forum Programming forum

Reference Books C For Dummies, Volume One C For Dummies, Volume One C For Dummies, Volume Two C For Dummies, Volume Two C Programming - A Modern Approach - K N King “The C Programming Language” - Kernighan & Ritchie “The C Programming Language” - Kernighan & Ritchie “The C Answer Book” - Kernighan & Ritchie “The C Answer Book” - Kernighan & Ritchie

Presentation slides at: Presentation slides at: orTeam358.org Questions/Help please us. Questions/Help please us.