7 segment Display Interfacing
7 segment display is commonly uses
where we want to display any data like temperature display, stop watch,
industrial meters etc. We can found different colors & different sizes 7seg
displays. Inside the 7seg display seven lightemitting diodes are arranged so
that all ten digits (0 - 9) can roughly be displayed. Seven-segment displays are used for decimal
numeric displays.
Now we will discuss about 0.5”, 5vdc,
common anode (all of the led digits anode pins connect together and share a common
pin) 7seg display and will use PIC18f2520 microcontroller to display data on
7seg. We will use BC547 (NPN Epitaxial Silicon Transistor) for digit driving.
7seg display pinout and digit numbers.
We can display any of the number
and character that can be possible to combination of segments. But in this
example we will display 0-900 decimal value in a sequence. See the given blow
char, how to 7-seg display appears decimal value with pin combination.
Circuit
Diagam
In the circuit diagram three 7seg
display ABCDEFG pins connected to same pins each other and connect to
microcontroller port. Common anode pins connected to BC547 transistors. With
this circuit, every beginner confused that how to display on indusial 7-segment
a specific decimal value. Now i clear this, for example we want to display 123,
fist we will turn on first digit’s transistor (Q3) and turn on specific pins of
controller port. Turn off Q3 and clear port pins, next turn on Q2 and turn on
specific pins of controller port that will display 2. Now turn off Q2 and clear
the controller port pins. Next turn on Q1 and turn on specific pins. It will
done very fast and human eyes can not see turn off digits. Timer-0 used to
adjustment digits on/off interval. So all decimal value can be display crisply.
Codes
// 3 transistor for switching 7_seg digits.
// 20Mhz Oscillator.
// All configuration bits set in IDE.
#include <p18f2520.h>
//-------------------------------------------------------------------------
void Digit_Show(void);
#pragma interrupt chk_isr // Timer-0 interrupt vector
void chk_isr(void)
{
if(INTCONbits.TMR0IF==1)
Digit_Show();
}
#pragma code isr = 0x08 // store the below code at address 0x08
void isr(void)
{
_asm
GOTO
chk_isr
_endasm
}
#pragma code
void Break_val( int val);
char dig_val[3];
char dig_no;
unsigned int a, counter = 0;
void main()
{
dig_no = 0;
TRISC = 0x00;
TRISB = 0x00;
PORTB = 0x00;
PORTC = 0x00;
T0CON = 0x06; //
Set timer-0 for display digits switching time
arrangement.
TMR0H = 0xF0; // Using
timer-0 interrupt.
TMR0L = 0xC0;
INTCONbits.TMR0IF = 0;
INTCONbits.TMR0IE = 1;
INTCONbits.GIE = 1;
INTCONbits.PEIE = 1;
T0CONbits.TMR0ON = 1;
while(1)
{
Break_val(counter);
counter++;
for(a=0;a<0xFFFF;a++);
for(a=0;a<0xFFFF;a++);
if(counter>900)
counter = 0;
}
}
void Break_val( int val) // Display 0 to 999 decimal value.
{
INTCONbits.TMR0IF = 0;
dig_val[0] = val % 10;
dig_val[1] = (val %
100) / 10;
dig_val[2] = val /
100;
}
void Digit_Show()
{
INTCONbits.TMR0IF = 0;
TMR0H = 0xFF;
TMR0L = 0xC0;
switch (dig_no){
case 0
: PORTBbits.RB1 = 0; //
Switch on right digit.
PORTBbits.RB2 = 0;
PORTBbits.RB0 = 1;
break;
case 1
: PORTBbits.RB0 = 0; //
Switch on middle digit.
PORTBbits.RB2 = 0;
PORTBbits.RB1 = 1;
break;
case 2
: PORTBbits.RB0 = 0; //
Switch on left digit.
PORTBbits.RB1 = 0;
PORTBbits.RB2 = 1;
break;
default :
;
}
switch
(dig_val[dig_no]){
case
0 : PORTC = 0x3F; // Print 0 on 7_seg.
break;
case
1 : PORTC = 0x06; // Print 1 on 7_seg.
break;
case
2 : PORTC = 0x5B; // Print 2 on 7_seg.
break;
case
3 : PORTC = 0x4F; // Print 3 on 7_seg.
break;
case
4 : PORTC = 0x66; // Print 4 on 7_seg.
break;
case
5 : PORTC = 0x6D; // Print 5 on 7_seg.
break;
case
6 : PORTC = 0x7D; // Print 6 on 7_seg.
break;
case
7 : PORTC = 0x07; // Print 7 on 7_seg.
break;
case
8 : PORTC = 0x7F; // Print 8 on 7_seg.
break;
case
9 : PORTC = 0x6F; // Print 9 on 7_seg.
break;
default
: ;
}
dig_no++;
if(dig_no>2) dig_no
= 0;
}
Download
Project file :- https://drive.google.com/file/d/0B886Kbl42IVuRld2Z2JCY0xEdmc/view?usp=sharing
If you have any question, ask feel free. I will totally devoted for your help.
Posts
No comments:
Post a Comment