Difference between revisions of "Arduino/C3/AVR-GCC-programming-through-Arduino/English"

Learning objectives

• Interface a seven segment display to Arduino board.
• Write an AVR-GCC program to display a digit on seven segment display and
• Display digits 0 to 9 on the seven segment display.

Pre-requisites

• Electronics
• C Programming and
• AVR-GCC

System Requirement

• Arduino UNO Board and
• Ubuntu Linux operating system version 14.04

AVR -GCC

• GCC stands for GNU Compiler Collection.
• It is a compiler which supports various programming languages.
• AVR-GCC is a part of GCC and supports compiling C programs for AVR microcontrollers.
• Since Arduino uses ATMEGA328P, this is a suitable compiler.

External Devices

• Seven-Segment Display
• 220 ohm Resistor
• Breadboard
• Arduino UNO Board
• Jumper Wires

Seven-segment display

Please refer to the basic level tutorials of this series to know more about Seven segment display.

The Dot pin of the Seven Segment Display is connected to the pin 13 of the Arduino.

Any one of the common pins is connected to the +5V through a resistor.

• We need to install AVR-GCC assembler and a AVR-LIBC library.

• AVR-GCC will generate a hex file and upload it to Arduino board.

• AVR-LIBC contains the required library files that can be used in the program.

> sudo apt-get install avr-libc gcc-avr

sudo space apt hyphen get space install space avr hyphen libc space gcc hyphen avr

And press Enter.

Press 'Y' wherever there is a prompt during installation to confirm the configuration.

Installation will take some time to complete depending upon the internet speed.

Let me clear the terminal.

ls space forwardslash dev forwardslash ttyACM asterisk

and press Enter.

Here ttyACM0 represents the port number of Arduino.

You may get a different port number. Make a note of your port number.

Make file for ATmega328P

Makefile enables us to create a dot hex file and upload it to Arduino.

Save the Makefile in the folder where you will be saving the C program.

// include library files

#include <avr/io.h>

#include <util/delay.h>

avr slash io dot h contains all the basic libraries required to perform the input and output operations.

util slash delay dot h contains the libraries for the delay function.

int main (void)

{

DDRB |= ((1 << DDB5));

while(1)

{

PORTB = ((0 << PB5));

_delay_ms (1000L);

PORTB = ((1 << PB5));

_delay_ms (1000L);

}

return 0;

}

Set PB5, that is pin 13 of Arduino as output.

Sending 0 to PB5 turns on the LED.

Sending 1 to PB5 turns off the LED.

These two steps will run in an infinite while loop making the LED blink.

You can download and use it.

> cd /home/spoken/Downloads

This command creates a dot hex file and uploads it to the Arduino.

The common pin is connected to +5Volts through resistor.

// Prints decimal number 2

#include <avr/io.h>

#include <util/delay.h> int main (void)

{

DDRD |= 0xFC;

DDRB |= ((1 << DDB0));

{

PORTB = ((0 << PB0));

PORTD = 0b10010000;

}

return 0;

}

Sending 0 will cause the LED to glow and sending 1 will turn it off.

Clear the terminal now.

Assignment 1

• Modify the above code to display any other digit from 0 to 9.

Open any text editor and type the following code.

// Prints decimal numbers from 0 to 9

#include <avr/io.h>

#include <util/delay.h>

void sevenseg(int);

int main (void)

{

DDRD |= 0xFC;

DDRB |= ((1 << DDB0));

while(1)

for(int i = 0; i < 10; i++)

{

sevenseg(i);

_delay_ms (1000L);

}

}

return 0;

}

Each time, the variable ‘ i ‘ is incremented by one and the value is passed to sevenseg function.

{

switch(dec)

{

case 0:

PORTB = ((1 << 0));

PORTD = 0b00000000;

break;

case 1:

PORTB = ((1 << 0));

PORTD = 0b11100100;

break; case 2:

PORTB = ((0 << 0));

PORTD = 0b10010000;

break;

case 3:

PORTB = ((0 << 0));

PORTD = 0b11000000;

break;

case 4:

PORTB = ((0 << 0));

PORTD = 0b01100100;

break;

case 5:

PORTB = ((0 << 0));

PORTD = 0b01001000;

break;

case 6:

PORTB = ((0 << 0));

PORTD = 0b00001000;

break;

case 7:

PORTB = ((1 << 0));

PORTD = 0b11100000;

break;

case 8:

PORTB = ((0 << 0));

PORTD = 0b00000000;

break;

case 9:

PORTB = ((0 << 0));

PORTD = 0b01000000;

break;

default:

PORTB = ((1 << 0));

PORTD = 0b00000000;

break;

}

}

Based on the input, the case structure is executed.

Thus displaying the digits from 0 to 9.

Summary

• Interface a Seven-segment display to Arduino board
• Write an AVR-GCC program to display a digit on seven-segment display and
• Display digits 0 to 9 on the Seven segment display.

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Forum for specific questions

Acknowledgement

More information on this mission is available at

this link.

This is Priya from IIT Bombay.

Thanks for joining.