Intro to Robotics

Moayad H. AlmohaishiLouisiana Tech MS computer science

President of Louisiana Tech Robotic Club

ROBOTIC 2010

Video Deleted to reduce the file size. I will add it soon to Youtube.

What you need to start

MPLAB Programming IDE (need windows OS)

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en019469&part=SW007002

MPLAB C compiler for PIC18 MCUs

http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en534868

PIC18F2520 Data Sheet

http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en010277

Programming tool

Parts

Prototype Board

Wires

PIC 18 Microprocessor

Capacitors

Resistors

Voltage regulator

LEDs

6-pins headers

Battery

Sensors

Parts

4Mhz Crystal

H-Bridge / Motor ControllerThe Base (Chassis)- Each group will bring its own robot base.Note1: When buying the base, put in your mind the maze size. and the way the base move.Note2: a sample of the maze is available in the second floor of Nethken Hall

Board connectivity

Note: All the pins inside the shaded areas are connected together.

Power Circuit

Voltage Voltage RegulatRegulat

oror

Main Main Power Power sourcesource

CapacitCapacitoror

ResistoResistorr

LEDLED

5 volt5 volt

GroundGround

Power CircuitNote: The same like the previous slide, just another perspective.

The Board

PIC 18 pins map

Port APort AAnalog InputAnalog Input

Port CPort CDigital I/ODigital I/O

Port CPort CDigital I/ODigital I/O

Port BPort BDigital I/ODigital I/O

Port APort A

Connecting PIC 18

ResistoResistor r

CapacitCapacitor or

Crystal Crystal CapacitCapacitors ors

Note: Sometimes you will need to add a resistor between the Pin 10 and the crystal. for more information look at the PIC18F2520 Data Sheet.

Start Reset

Note: You need the Start/Reset sercut to give the micro controller the signal to start/restart the program. You can add a push button if you want a restart button

The Board

The H-Bridge

Why do we need the H-bridge ?

The H-Bridge

Note: As and ENs are inputs from the Micro Controller and Ys are outputs to the motors.

H-Bridge Logic

1 1

1 1

0 0

+ +

- -

H-Bridge Logic

1 1

0 0

1 1

- -

+ +

0 0

1 1

0 0

Connecting The H-Bridge

Pin Pin C0 C0

Pin Pin C1 C1

Pin Pin C2 C2

Pin Pin C4 C4

Pin Pin C6 C6

Pin Pin C5 C5

LM LM + +

LM - LM -

RM RM + +

RM - RM -

Note: LM = Left Motor, RM = Right Motor

Complete Board

What You Learned

Robot requirements (Softwares and Hardwares)

How to make the power circuit

How to connect your PIC18 chip

How to connect the H-Bridge

MPLAB

Port APort A

Port APort A

Hello World - LED ON/** I N C L U D E S **************************************************/#include "p18f2520.h"

/** D E C L A R A T I O N S ******************************************/

void main (void){

TRISC = 0b01111111; // PORTC bit 7 to output (0); bits 6:0 are inputs (1)

LATCbits.LATC7 = 1; // Set LAT register bit 7 to turn on LED

while (1);

}

Note1: You need to include the specific library of the PIC18 you are using.Note2 : Use the register TRIS to define the output pins and the input pins in the Port.

Note3 : Use The function LAT to define the output value of a specific pin

Hello World - Blinking LED/** I N C L U D E S **************************************************/

#include "p18f2520.h"#include "delays.h"

/** D E C L A R A T I O N S ******************************************/

void main (void){

TRISC = 0b01111111; // PORTC bit 7 to output (0); bits 6:0 are inputs (1)

while (1){LATCbits.LATC7 = 1; // Set LAT register bit 7 to turn on LED

Delay1KTCYx(50); // Delay 50 x 1000 (1k) = 50,000 cycles; 50ms @ 4MHzLATCbits.LATC7 = 0; // Set LAT register bit 7 to turn on LED

Delay1KTCYx(20); // Delay 50 x 1000 (1k) = 50,000 cycles; 20ms @ 4MHz

};

}

K K

Note: To use the delay function, you have to include the delay libraryNote: Put your application inside the While(1) loop to make it run forever.

DirectionsC7 C7 C6 C6 C5 C5 C4 C4 C3 C3 C2 C2 C1 C1 C0C0PORTC = 00

RM RM + + RM - RM - RM E RM E 00 LM - LM - LM LM

+ + LM ELM E

DirectionsPORTC = 00

RM RM + + RM - RM - RM E RM E 00 LM - LM - LM LM

+ + LM ELM E

int moveForward = 00 11 0 0 11 00 00 11 11

int moveBackward = 00 0000 1 1 1 1 11 00 11110000 11

int turnLeft = 00 11 0 0 11 00 00 11 0000

int turnRight = 00 11 0 0 0000 00 00 11 11

Running The Robot/** I N C L U D E S **************************************************/#include "p18f2520.h"

/** D E C L A R A T I O N S ******************************************/

void main (void){ int moveForward = 0b01010011; int moveBack = 0b00110101; int turnLeft = 0b01010010; int turnRight = 0b01000011;

TRISC = 0b00000000; // All PORTC bits to output (0)PORTC = moveForward ; // set PORTC bits to 0b10100011

while (1);

}

Note : Use the register PORT to give or read a value from/to all the pins in the specified Port.

Note : PORTA, PORTB, PORTC

Timing/** I N C L U D E S **************************************************/#include "p18f45k20.h"#include "delays.h"

/** D E C L A R A T I O N S ******************************************/

void main (void){ int moveForward = 0b01010011; int moveBack = 0b00110101; int turnLeft = 0b01010010; int turnRight = 0b01000011;

TRISC = 0; // All PORTC bits to output (0) (using the dismal system )PORTC = moveForward ;

Delay1KTCYx(50); // Delay 50 x 1000 (1k) = 50,000 cycles; 50ms @ 4MHzPORTC = turnLeft ;

Delay1KTCYx(50); // Delay 50 x 1000 (1k) = 50,000 cycles; 50ms @ 4MHzPORTC = turnRight ;

Delay1KTCYx(50); // Delay 50 x 1000 (1k) = 50,000 cycles; 50ms @ 4MHzPORTC = moveBack ;

Delay1KTCYx(50); // Delay 50 x 1000 (1k) = 50,000 cycles; 50ms @ 4MHzwhile (1);

}Note: Think about how this robot will be moving

What You Learned

How to start your first project

How to define the Input and the output ports

How to Time Control your output

Problem

WallWall

Our RobotRobot with Touch SensorRobot with IR Sensor

IR Sensor

Operating Voltage 4.5v - 5.5v (red and black)

Distance 4cm - 30cm

Analog output (White Cable)

Note: The white cable will go to the Micro Controller. And the Red to the Regulated 5v we created. and the black to the ground.

Note2: The response time for this IR Sensor is 39ms. which is too slow for a moving robot.

IR Sensor

Note: if the distance is less than 4cm the Sensor gives back wrong measuring.

Note2: Because the response time for the IR sensor is too slow, you need to detect the distance as early as you can. and put a safe fail back technique

PIC 18 pins map

Port APort AAnalog InputAnalog Input

Port APort A

Connecting the IR Sensors

Center Sensor (AN0)Center Sensor (AN0)Left Sensor (AN1)Left Sensor (AN1)

Right Sensor (AN2)Right Sensor (AN2)

Using The AD Converter

void setSensor(sensorChannel){

switch (sensorChannel){

case 0:// channel AN0 for Central SensorADCON0 = 1;break;

case 1: // channel AN1 for Right SensorADCON0 = 5; //101break;

case 2: // channel AN2 for Left SensorADCON0 = 9; //1001break;

}}

Note2: We create the Function SetSensor to make it easer for us to debug and understand the code.

ADCON0

CHANNEL NUMBER BITS CHANNEL NUMBER BITS STATUS STATUS BIT BIT

ON/OFF ON/OFF BIT BIT

Note2: if you need to understand more about the Analog to Digital Converter’s registers read about it in the micro controller Data Sheet.

void setupAD(){

ADCON1 = 12; //This sets the chip so that AN0, AN1, AN2 are analog. Instructions for this can be found in the chip documentation. p 230

ADCON0 = 0; //Make sure ADC settings are 0ADCON2 = 164; //this sets Right justified. Bit 6 is NC (0), Bits 5-0 adjust time (Bits 5-0 are

100100)}

void enableAD() // You don’t need this function, we already set our ADON to 1 in the function SetSensor() I put it just to explain what you can do. {

ADCON0bits.ADON = 1; //Enables the A/D converter}

void listenToAD(){

ADCON0bits.GO_DONE = 1; //Like the start button for the converter. while(ADCON0bits.GO_DONE == 1) //Wait until the ADC is finished. GO_DONE will change to 0

and the loop will end{

//do nothing here}

}

Note: Enable the AD buy changing the pit ADON value to 1 and disable it by changing the value to 0;

How to use it in the main

int farRange = 70;int closeRange = 150; int centralSensor, rightSensor, leftSensor;

setSensor(0);listenToAD();

centralSensor = ADRES;if (centralSensor < farRange)PORTC = moveBack;if (centralSensor > farRange && SC < clsoeRange) PORTC = turnLeft;

if (centralSensor > closeRange) PORTC = moveBackward;

Note: The Values for FarRange and CloseRange is just for explaining. You will need to figure out the best values for your own robot.

Note: The values from the AD will be stored in the Register ADRES, if you need to compare the distance from the sensors you need to store the value to a variable or your ADRES will be overwritten.

What You learned

The Usage of Sensors

How to use Analog IR sensor

Making The right dictionNote: The Code I provided is not meant to be running 100%, it is explanatory code ONLY.

You will need to define your functions and variables correctly.

SPECIAL THANKS

Robotic Club Advisor

Dr. Ben Choi

Robotic Club Vise President

James Hurst

Our FaceBook Group : Louisiana Tech Robotic Club