Blinking LED using PIC Microcontroller – MikroC

Ligo George

12 years ago

Contents

Welcome to the world of PIC Microcontrollers. You are in the right place if you are a beginner in the filed of microcontrollers. MikroC is the best compiler for beginners as it contains built in functions for most of the commonly used tasks. But MikroC is less efficient and the hex file generated will be large size compared to other compilers. So I suggest you to use Hi-Tech C compiler by Microchip after you get familiar with microcontrollers. Note that, Hi-Tech C is a bit difficult compared to MikroC as there is no built in functions. You can follow our Hi-Tech C Tutorials.

Getting Started with MikroC Pro

You can buy mikroC form mikroElectronika or download a trial version here. Trial Version is limited to 2k of program words and is sufficient for most of our applications.

Download and Install MikroC Pro
Create a Folder for this project in any of your drives
Open microC Pro For PIC

Click on Project >> New Project

Click Next

Enter Project name, path (created folder path), clock frequency, microcontroller and click Next. Clock Frequency is the frequency of oscillator used with microcontroller. Here we use PIC 16F877A microcontroller with 8MHz crystal.

Add Files to Project – New Project Wizard

Here you can add your subprogram files or user defined header files in large projects. Hence we are dealing with simple LED Blinking in this tutorial, ignore it and click Next.

Here you can add MikroC’s built in libraries such as UART, PWM, LCD etc… You may include All Libraries or include None. If you select None, then you can selectively include required libraries later. Then click Next.

Click Finish, to complete the New Project Wizard.
Then you will see the editor, where you can enter the MikroC Code.

MikroC Programming

Before going to the programming you should understand the following things.

Output pins of a PIC Microcontroller is divided in to different PORTS containing a group of GPIO (General Purpose Input Output Pins) pins.
In 16F PIC Microcontrollers, there are two registers associated with a port, TRIS and PORT. eg: TRISB, PORTB, TRISC, PORTC
TRIS stands for Tri-State, which determines the direction of each GPIO pin. Logic 1 at a particular bit of TRIS register makes the corresponding pin Input and Logic 0 at a particular bit of TRIS register makes the corresponding pin Output. An Input pin of PIC Microcontroller have very high input impedance, thus it may said to be in Hi-Impedance state.
PORT register is used to read data from or write data to GPIO pins. Logic 1 at a particular bit of PORT register makes the corresponding pin at Logic High (VDD) and Logic 0 at a particular bit of PORT register makes the corresponding pin at Logic Low (VSS) if that pin is an Output pin (TRIS bit is 0).
PORT register can be used to read digital data from an Input pin. Logic 1 indicates the pin is at Logic High and Logic 0 indicates that the pin is at Logic Low.

You can write to PORT and TRIS register entirely or bit by bit.

Writing Bit by Bit :

TRISC.F0 = 1; //Makes 0^th bit of PORTC Input
TRISC.F5 = 0; //Makes 5^th bit of PORTC Output
PORTB.F3 = 1; //Makes 3^ed bit of PORTB at Logic High
PORTB.F7 = 0; //Makes 7^th bit of PORTB at Logic Low

Writing Entire Register

You should be familiar with following C Programming concepts.

A number with a prefix ‘0b’ indicates a binary number.
A number with a prefix ‘0’ indicates an octal number.
A number with a prefix ‘0x’ indicates a hexadecimal number.
A number without prefix is a decimal number.

Let’s see some examples…

Decimal	Binary	Octal	Hexadecimal
0	0b00000000	00	0x00
1	0b00000001	01	0x01
128	0b10000000	0200	0x80
255	0b11111111	0377	0xFF

PORTB = 0xFF; //Makes all pins of PORTB Logic High
TRISC = 0x00; //Makes all pins of TRISC Output
PORTD = 128; //Makes 7^th bit of PORTD Logic High

MikroC Code – Blinking an LED

The following program blinks an LED with a delay of 1 second.

void main()
{
  TRISB.F0 = 0; //Makes PORTB0 or RB0 Output Pin

  while(1) //Infinite Loop
  {
    PORTB.F0 = 1; //LED ON
    Delay_ms(1000); //1 Second Delay
    PORTB.F0 = 0; //LED OFF
    Delay_ms(1000); //1 Second Delay
  }
}

Note : Delay_ms(const unsigned long a) is a built in function of MikroC Pro which provides a delay of ‘a’ milliseconds. The variable ‘a’ must be a constant of type unsigned long integer.

Enter the above MikroC code

Save it
Then Compile it. Click Build >> Build (or Ctrl+F9)

A hex file will be generated in your Project Folder. You need to write this file to microcontroller using a programmer.

Circuit Diagram

VDD and VSS of PIC Microcontroller is connected to +5V and GND respectively to provide necessary power for the operation of the microcontroller. 8MHz crystal is used to provide necessary clock for the microcontroller. 22pF capacitors stabilizes the oscillations of the crystal. LED is connected to the 0^th bit of PORTB and a 470Ω resistor is connected in series to limit the current through the LED.

You can simulate the working in Proteus. If you haven’t yet started with Proteus, please try this tutorial. Also see the following video.

Don’t forget to set the clock frequency and to add the hex file in your project folder by editing the properties of PIC Microcontroller as shown below.

Hardware Implementation

You can wire this circuit in breadboard after writing the hex file to PIC 16F877A using a programmer and verify the output. I am using the Microchip’s PICKit2 for programming the microcontroller. You may buy PICKit2 or try to make one.

Programming

Connect the PIC 16F877A microcontroller to PICKit2 in the following manner.

Connect VPP of PICKit2 to MCLR (1^st pin) of PIC 16F877A
Connect VDD of PICKit2 to VDD (11 and/or 32 pins) of PIC 16F877A
Connect VSS of PICKit2 to VSS (12 and/or 31 pins) of PIC 16F877A
Connect PGD of PICKit2 to PGD (40^th pin) of PIC 16F877A
Connect PGC of PICKit2 to PGC (39^th pin) of PIC 16F877A

Then connect the programmer to PC and open the PICKit2 Software.

After Opening the PICKit2 Programmer Tool

Erase the data in the Microcontroller, click Erase

Import Hex file from your Project Folder, File >> Import

Select the Hex file from your Project Folder

Importing Hex File – PICKit2 Programmer Tool

Click Open

To write the program to PIC, click Write

Then you may verify the program in the PIC Microcontroller with the Hex file. This can used to check whether the program in the microcontroller is corrupted or not. For that, import the hex file if it is not already imported and click Verfiy.