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PIC Tutorials - Interface a Single 7seg Digit
Before reading this tutorial, make sure you have read the How to use our PIC Tutorials page!



The circuit on a breadboard

The most common and easiest way of number (and in some case letters) visualization is to use the classic 7-seg LED displays. Those displays have 7 different LEDs in their package. Combining the LEDs (segments) that will light, numbers and letters can be visualized. This circuit will visualize the numbers from 0 to 9.


In Action



The Circuit

The schematic circuit is as follows:






The Code

The code is shown bellow:

; Main Program ------------------------------------------------------------
Start
				bank1				;Go to bank 1
				movlw b'11111111'		;
				movwf TRISA			;Set the port pin types of the RA
				movlw b'00000000'		;
				movwf TRISB			;Set the port pin types of the RB
				bank0				;Go to bank 0
MainLoop
				movlw b'00111111'		;Number 0
				movwf PORTB
				call Wait500mSec

				movlw b'00000110'		;Number 1
				movwf PORTB
				call Wait500mSec

				movlw b'01011011'		;Number 2
				movwf PORTB
				call Wait500mSec

				movlw b'01001111'		;Number 3
				movwf PORTB
				call Wait500mSec

				movlw b'01100110'		;Number 4
				movwf PORTB
				call Wait500mSec

				movlw b'01101101'		;Number 5
				movwf PORTB
				call Wait500mSec

				movlw b'01111101'		;Number 6
				movwf PORTB
				call Wait500mSec

				movlw b'00000111'		;Number 7
				movwf PORTB
				call Wait500mSec

				movlw b'01111111'		;Number 8
				movwf PORTB
				call Wait500mSec

				movlw b'01101111'		;Number 9
				movwf PORTB
				call Wait500mSec

				goto MainLoop

As always, we set the pin types first. All RB pins are outputs, as they are connected on the 7-seg. Then, a series of binary bytes are sent to the PORTB. Each binary byte will correspond to a number. For example let's take a look at number '0'. For visualizing number '0' on the 7-seg, the segments a,b,c,d,e and f should light. From the schematic diagram it can be seen that segment 'a' is conencted to RB0, segment 'b' to RB1, segment 'c' to RB2 and so on. Now it makes sense. To visualize number '0',we send the binary number b'00111111'. For number '1', we send the binary number b'00000110' and so on.

Between each number, a 'call Wait500mSec' instruction is executed. This instruction will call a subroutine that will make a 500 mSec delay. So the numbers will change with half a second delay. This subroutine is inside the header file 'mSecDelays4MHz.inc'. As always, all files needed for the project can be found at the bottom of the page.




The project Files

Following are the files for this project:

 PIC Tutorials - Interface a Single 7seg Digit











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  • At 18 February 2016, 21:44:51 user flames wrote:   [reply @ flames]
    • you work is great, pls can you write the code in c-language? i'll greatly appreciate that..


  • At 5 September 2010, 18:40:11 user bit wrote:   [reply @ bit]
    • great
     






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  • Disclaimer
  • Book Contents
  • Discussion forum

  • Basics
  • What will you need
  • Choosing the right PIC
  • The MPLAB
  • Getting familiar with the MPLAB environment
  • Creating a new project
  • Open and close projects
  • Creating new files and including them in the project
  • Your very first assembly program
  • Compile a program and transfer to the PIC
  • Section 1: Beginner's theory
  • Memory Organization
  • The Data Memory Organization
  • The Program Memory Organization
  • The instructions
  • General knowledge about instructions
  • Value Loading Instructions
  • Program Flow Instructions
  • Mathematic Instructions
  • Logic Function Instructions
  • Bit Orientated Instructions
  • Byte Orientated Instructions
  • Miscellaneous Instructions
  • The Basic Special Function Registers
  • The Status Register
  • The Option_Reg Register
  • The TRIS and PORT registers
  • Beginner's PIC Tutorials
  • How to use our PIC Tutorials
  • A Pushbutton turning an LED on and off
  • A Simple LED Flasher
  • Interfacing Multiple Switches - The internal Pull-Up resistors
  • An LED Sequencer
  • Interface a Single 7seg Digit
  • Interface Multiple 7seg Digits
  • A 3-digits Decimal Counter
  • A Clever Button
  • Section 2: Intermediate theory
  • Instruction Cycle Duration and Calculated Delays
  • The Timer Modules - Timer0
  • The Timer Modules - Timer1
  • The Timer Modules-Timer2



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