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.

The schematic circuit is as follows:

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.

Following are the files for this project:

PIC Tutorials - Interface a Single 7seg Digit

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Basics       What will you need       Choosing the right PICThe 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 PICSection 1: Beginner's theoryMemory Organization       The Data Memory Organization       The Program Memory OrganizationThe instructions       General knowledge about instructions       Value Loading Instructions       Program Flow Instructions       Mathematic Instructions       Logic Function Instructions       Bit Orientated Instructions       Byte Orientated Instructions       Miscellaneous InstructionsThe Basic Special Function Registers       The Status Register       The Option_Reg Register       The TRIS and PORT registersBeginner'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 ButtonSection 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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