Beginner Programming Workshop

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Beginner Programming Workshop
November 17th, 2007 Hauppauge High School SPBLI
- FIRST

• Simona Doboli
• Associate Professor
• Computer Science Department
• Hosftra University
• Email Simona.Doboli_at_hofstra.edu

Mark McLeod Advisor Hauppauge Team 358 Northrop
Grumman Corp. Mark.McLeod_at_ngc.com
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Agenda

• FIRST Control System
• MPLAB Environment
• C Basics
• FRC Default Code
• Robot Driver Control
• Demonstration of Basic OI Controls
• Robot Autonomous Control
• Demonstration of Dead Reckoning
• Wrap-up
• Playtime

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FIRST Control Elements

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

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FIRST Control System
solenoid
motor
5
Robot Controller
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Robot Controller
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Architecture

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

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

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

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

• Structure (include, functions)
• IF, THEN, ELSE
• WHILE
• FOR
• , !
• gt, lt, , gt, lt, !
• ,
• Operators
• Prototype declarations

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C Basics Structure Program

• include ltstdio.hgt // 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
• void main(void)
• // What your program does
• int result // local variable
  can be used only in main() function
• 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

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C Basics Data Types
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C Basics A simple program
include ltstdio.hgt 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 gt i) result i else result j
return result
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C Basics if statement

• if (touch 1 light ! 0 )
• goStraight 1
• else
• goStraight -1
• !!! NOTE if (touch 1) vs. if (touch 1)
• ASSIGNMENT CONDITION

AND Logic
OR Logic ()
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C Basics while loop

• while (touch 0)
• leftMotor 5
• rightMotor 5
• read(touch) // need to change touch inside
• // the loop
• // use if more than one statement in a loop

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C Basics - Exercise

• 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.

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C Basics - Algorithm

• int first 0, second 1, third
• while (n gt 0)
• third first second
• output third
• first second
• second third
• n --

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Competition Modes

• Three Competition Modes
• Disabled
• Receive all inputs
• No outputs get out
• Autonomous
• Receive RC inputs
• Do not receive OI inputs
• Outputs all working
• Driver
• Receive all inputs
• Outputs working

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FRC Default Code Flow
User Initialization

• Main()
• User_Initialization()
• Do as long as were on
• New radio packet (slow loop)
• Process_Data_From_Master_uP()
• Default_Routine()
• As long as were in auto mode do this
• User_Autonomous_Code()
• Fast loop stuff

Radio packet ?
NO
YES
Driver Routine
Auto Mode ?
NO
YES
User Autonomous
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Miscellaneous Points

• Slow loop vs. Fast loop
• Slow loop
• Can be used for rough timing
• Cant update motors etc. any faster than this
• Fast loop
• Irregular duration so cant be used for timing
• Used for sampling fast sensors, e.g., gyroscope
• Getdata() - Putdata()
• If Master processor doesnt see Putdata regularly
  it will shutdown the User processor.
• Finding Bugs
• IFI_Loader terminal window
• printf() - include ltstdio.hgt
• Does not print long or float directly

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FRC Default Code

• Files to change
• user_routines.c (to add switches change
  controls)
• Default_Routine()
• User_Initialization()
• user_routines_fast.c
• User_Autonomous() (to add autonomous movement)
• user_routines.h (to share variables between files)

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Input / Output

• OI
• Joysticks
• Stick x y
• Buttons
• Unused inputs
• Switches
• LEDs lights or digital readout
• RC
• Digital I/O for sensors and devices (0 or 1)
• Analog for sensors, e.g., potentiometers (0 to
  1023)
• Relay for on/off, e.g., pneumatics (forward,
  reverse, stop)
• PWM for motors (0reverse, 127stop, 254forward)
• Dont use PWMs 13,14,15,16
• TTL for devices, e.g., camera or LCD screen

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Robot Driver Control

• What do OI joysticks do
• 1 or 2 joystick driving
• Operate arm
• Add OI buttons/switches
• Open/close grippers
• Choose autonomous variations
• Add RC switches/sensors
• Choose autonomous variations
• Limit mechanism movement, e.g. an arm
• Add/modify code in Default_Routine() in
  user_routines.c

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Sample OI Controls

• (note OI switches 0 when off and 1 when on)

• Sample uses
• Drive
• Control arm
• Control turret

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Sample OI Input/Output

• 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

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Sample Digital Code

• 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

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Sample Analog Code

• 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 0-1023 if ( (armpot gt 900)
(pwm01 gt 127) ) pwm01 127 //
Neutral else if (armpot lt 100) (pwm01 lt 127)
) pwm01 127 // Neutral

• Sample uses
• Position sensors
• Gyroscope
• Analog rangefinder

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Sample Relay Code

• Forward / Reverse / Neutral

relay8_fwd 1 relay8_rev 0
relay8_fwd 0 relay8_rev 1
relay8_fwd 0 relay8_rev 0

• Sample uses
• Pneumatic valves
• Compressor on/off
• On/off motors

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Robot Autonomous Control

• Must be developed under identical environment as
  in competition
• Training the robot must be repeated over over
  to get right
• Do the best you can developing on old robots
• Plan on multiple autonomous options
• Use as few distinct movements as possible
• Add code to User_Autonomous() in
  user_routines_fast.c

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Sample Autonomous
// Drive forward and stop Sample_Auto_1()
static int counter0 if (counterlt100)
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)
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Common Issues

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

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Wrap Up

• Projects for Next Time
• References
• FIRST control System
• C
• Playtime

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Projects

• Autonomous program to
• Drive 2 ft.
• Turn 180o
• Return to start
• Add a start delay so you have time to set the
  robot down
• Convert to use seconds
• Driver controls to
• Add a spin in place button
• Reverse the controls so the robot front is now
  the back
• Add Debug printfs to tell you when you press a
  button

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References

• Programming Quick Start
• FIRST RC Reference Guide
• FIRST OI Reference Guide
• www.chiefdelphi.com/forums Programming forum

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Reference Books

• C For Dummies, Volume One
• C For Dummies, Volume Two
• C Programming - A Modern Approach - K N King
• The C Programming Language -Kernighan Ritchie
• The C Answer Book - Kernighan Ritchie

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• Presentation slides at
• www.cs.hofstra.edu/sdoboli
• or
• Team358.org
• Questions/Help please email us.
• Simona.Doboli_at_hofstra.edu
• Mark.McLeod_at_ngc.com