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PIC16F877A LED blink

The Microchip PIC16F877A has 40 pins 33 of them can be input or output. In this simple project I am going to configure this microcontroller to blink a 33...

Circuit diagram
Tags: #blink#led#pic16f877a
Ibrar Ayyub By Ibrar Ayyub
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At a glance

CategoryLED Projects
PIC modelPIC16F877A
IncludesCircuit diagram
Reading time~2 min

Summary of PIC16F877A LED blink

This project configures a PIC16F877A microcontroller to blink 33 LEDs by using each available digital I/O pin. All analog channels are set to digital; ports A–E are configured as outputs and toggled continuously. RA4 requires a pull-up resistor because it is open-drain. The code is written in MikroC PRO for PIC and inverts each port every 500 ms to blink the LEDs.

Parts used in the PIC16F877A 33 LED Blink Project:

  • PIC16F877A microcontroller (40-pin)
  • 33 LEDs
  • Current-limiting resistors for each LED
  • Pull-up resistor for RA4
  • Power supply (Vdd and Vss connections)
  • Decoupling capacitor(s)
  • Programming connector or ICSP for PIC
  • Prototyping board or PCB and wiring
The Microchip PIC16F877A has 40 pins 33 of them can be input or output. In this simple project I am going to configure this microcontroller to blink a 33 LED each LED is connected to one I/O pin.
PIC16F877A LED blink
The PIC16F877A has 8 analog channels, so we have to configure all these channels as digital output.
The pin RA4 is an open drain output we must add a pull up resistor to turn it on and off.
The circuit schematic is shown by the following picture:
The code is written using MikroC PRO for PIC compiler:
 PIC16F877A LED blink Schematic
void main(){  ADCON1 = 0x07;          // Configure all analoge pins as digital  PORTA = 0; TRISA = 0;   // Configure PORTA as output  PORTB = 0; TRISB = 0;   // Configure PORTB as output  PORTC = 0; TRISC = 0;   // Configure PORTC as output  PORTD = 0; TRISD = 0;   // Configure PORTD as output
  PORTE = 0; TRISE = 0;   // Configure PORTE as output  while (1) {  PORTA = ~ PORTA;       // Invert PORTA status   PORTB = ~ PORTB;       // Invert PORTB status   PORTC = ~ PORTC;       // Invert PORTC status   PORTD = ~ PORTD;       // Invert PORTD status   PORTE = ~ PORTE;       // Invert PORTE status   delay_ms(500);   } }

For more detail: PIC16F877A LED blink

  • How are the analog pins configured for digital output?
    The code sets ADCON1 = 0x07 to configure all analog pins as digital.
  • How do you configure the microcontroller ports as outputs?
    The code clears each PORT register and sets TRISx = 0 for TRISA, TRISB, TRISC, TRISD, and TRISE to configure them as outputs.
  • How is RA4 handled differently from other pins?
    RA4 is an open-drain output and requires a pull-up resistor to turn it on and off.
  • How many LEDs does this project blink and how are they connected?
    The project blinks 33 LEDs, each connected to one I/O pin of the PIC16F877A.
  • What compiler is used for the provided code?
    The code is written using MikroC PRO for PIC compiler.
  • How often do the LEDs toggle state in the example code?
    The code inverts all ports and then delays for 500 ms, causing the LEDs to toggle every 500 ms.
  • Which ports are toggled in the main loop?
    PORTA, PORTB, PORTC, PORTD, and PORTE are inverted in the main loop.
  • What operation is used to invert the port outputs?
    The code uses bitwise NOT (~) on each PORT register to invert the outputs.
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Ibrar Ayyub

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough...