Interfacing of led with PIC16F877A microcontroller

A LED is a p-n junction semiconductor device which emits light when biased in forward direction. i.e, the positive terminal is to be connected to the anode & negative terminal of supply is to be connected to cathode of Led.

Led have two terminals 1^st are longer which tends to anode of Led and 2^nd is shorter which tends to cathode terminal.

As we already know that Led will work on forward biasing means +ve to anode & -ve to cathode of Led, similar way in digital electronics +5V means HIGH or Logic 1(one) & -Ve means LOW or Logic 0(zero).

So its means when Logic 1 or HIGH applied across to anode & LOW or Logic 0 to cathode then Led will Glow. So to glow the Led , toggle & control the Led according to customization of program. We are using one 8-bit PIC16F877A microcontroller of microchip technology PIC family controller.

LEDs have dropped a voltage of 1.3 V to 2.2 V and require 7 to 10 mA to glow Led at full intensity.

R=(Vcontroller – Vled)/I

If we want to allow 10mA current through the LED then resistor value will be as below:-

R = (Vcc-led voltage)/current.

R = (5-1.7)/10mA.

R= 330 Ohms

The following picture describes “how to glow a led”.

Now it’s time for interfacing of Single Led with microcontroller. We are using 8-bit  PIC16F887A Microchip 40 pin microcontroller, it has all 33 input/output port, CPU, and peripheral in a single chip. Reason for using a PIC microcontroller is that it uses low power, and is application specific and PIC16F877based on HIGH Performance RISC (Reduced Instruction Set Computer) machine. It has 14.3KB flash memory & 368 bytes SRAM with UART & SPI , I2C communication protocol support in a single chip IC.

Proteus Design for interfacing of led with PIC16F877A microcontroller.

For connection of Led with PIC16F877A , we take PORTB as output direction and connect the RB0 pin to +ve terminal of Led and – ve terminal of Led connected Ground as you can see from below figure.

C programming for interfacing of Led with PIC16F877A microcontroller using MicroC compiler.

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This program is developed by EMBEDDINATOR DEVELOPERS.
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void delay(int a)

{

int b,c;

for(b=0;b<a;b++)< p=””>

{

for(c=0;c<500;c++)

{}}}

void main() {

TRISB=0b0000000;

while(1)

{

PORTB=0b00000001;        //on the led (led get 1)

delay(100);                //delay of 100 msec.

PORTB=0b00000000;        //off the led (led get 0)

delay(100);

}}

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End program

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