COMSATS
UNIVERSITY ISLAMABAD
MICROPROCESSOR SYSTEMS AND INTERFACING
LAB REPORT 5
SUBMITTED TO:
SIR KHIYAM
IFTIKHAR
SUBMITTED BY:
JUNAID AHMAD
Ibrar ahmad
Jarrar malik
REGISTRATION NO:
CIIT/FA19-BEE-089/ISB
Ciit/fa19-bee-083/isb
Ciit/fa19-bee-087/isb
DATE:
25-10-2021
LCD Interfacing
with AVR Microcontroller
Objectives:
•
Overview
of controller to controller communication
•
To
understand LCD interfacing with AVR microcontroller
Software
Tools:
•
Microchip Studio/
AVR Studio
•
Proteus ISIS
•
AVRDUDESS
Hardware Tools:
•
Microcontroller
•
Breadboard
•
16
x 2 LCD
•
Variable
Resistor
Ø 4.2 LCD Interfacing
·
LCD controller has two 8-bit registers:
·
Command Register allows the user to send commands such as clear
display, cursor at home etc.
·
Data register allows the user to send the data to be displayed
on LCD
·
·
Since same pins from D0 to D7 are used for both command and data,
RS pin is used to identify between the command and data.
·
Following steps are used to send command or data to LCD:
·
1. Initialize the LCD.
·
2. Send commands from Table 4.3 to LCD.
·
3. Send data to be displayed on LCD.
· 4.2.1 Initializing the LCD
To initialize the LCD for 5x7 matrix and 8-bit communication mode,
following commands should be send to LCD. See Table 5.3 for description of each
command.
·
Function Set: Select
LCD mode to 8-bit interface, 2 line, and character size to 5x7.
·
Display On/Off control: Display
On, turn on the cursor, No blinking.
·
Clear Display
·
Entry mode set: Increment
Cursor, No display shift
PRE-LAB TASK:
TASK 1:
Find
hexa-decimal codes for commands mentioned in LCD initializing heading using
Table 4.3.
|
CLEAR DISPLAY |
01 |
|
RETURN HOME |
02 |
|
ENTRY MODE |
06 |
IN-LAB TASKS:
TASK 1:
Consider the basic wiring shown between an ATmega328P chip
and an LCD in figure 4.2. Write and execute a C-program on Proteus that is able print your name on the first
row of the LCD and your roll-number on the second row of the LCD.
Figure 4.2: Wiring of Atmega328P
with LCD
CODE:
#define F_CPU 16000000
#include <avr/io.h>
#include <util/delay.h>
#include <string.h>
void LCD_init();
void cmdwrite(int command);
void LCD_display(char str[]);
void datawrite(char ch);
int main(void)
{
char str[]="its working yoo";
DDRD=0xFF;
DDRB|=(1<<PORTB0)|(1<<PORTB1)|(1<<PORTB2);
LCD_init();
LCD_display(str) ;
/* Replace with your
application code */
while (1)
{
}
}
void LCD_display(char str[]){
int i;
//char ch;
for (i=0; i<strlen(str);i++ ) {
datawrite(str[i]);
_delay_us(5000);
if(i==15) //i.e first line is filled
cmdwrite(0xC0); //Write address 0x40 which is starting address of next
line
_delay_us(1000);
}
}
void datawrite(char ch){
PORTB|=(1<<PORTB2); //RS=1 for Data
PORTB&=~(1<<PORTB1); //RW=0 for writing
PORTD= ch;
PORTB|=(1<<PORTB0); //EN=1
_delay_us(1); //High to low pulse (According to datasheet level 1 time is 450ns
PORTB&=~(1<<PORTB0); //EN=0
}
void LCD_init() {
_delay_ms(5000); //>15ms
cmdwrite(0x30);
_delay_ms(5); //4.1 ms
cmdwrite(0x30);
_delay_us(1000); //>100us
cmdwrite(0x30);
_delay_us(1000);
cmdwrite(0x38); // interface length 8 bits, 2 lines, 5x7 font
_delay_us(1000); //Check Busy bit or wait > 37us at
270kHz
cmdwrite(0x08); // Display Off
_delay_us(1000); //Check Busy bit or wait > 37us at
270kHz
cmdwrite(0x01); //Clear LCD (and also returns cursor to home)
_delay_ms(50); // Clear Display command takes longer time to execute
cmdwrite(0x06); //Cursor move Direction set to right
_delay_us(1000); //Check Busy bit or wait > 37us at
270kHz
cmdwrite(0x0E); // Display on, with Cursor, but no cursor blink
_delay_us(1000); //Check Busy bit or wait > 37us at
270kHz
}
void cmdwrite(int command) {
PORTB&=~(1<<PORTB2); //RS=0 for Command
PORTB&=~(1<<PORTB1); //RW=0 for writing
PORTD= command;
PORTB|=(1<<PORTB0); //EN=1
_delay_us(1); //High to low pulse (According to datasheet level 1 time is 450ns
PORTB&=~(1<<PORTB0); //EN=0
}
Proteous simulation:
Hardware simulation:
CRITICAL ANAYSIS:
In this lab we were introduced to LCD interfacing with atmega328p
microcontroller unit. LCD interfacing has many important details that need to
be taken care of. There can be 2 modes i.e. command mode and data mode and same
pins are used for both purposes but with different register bit configurations.
Tx and Rx modes should also be disabled. The LCD
have vast application in our daily life it is used to show the temperature. Also used
in calculators.
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