▷ Generate pseudo-random numbers - PIC/Microcode

In this post, we will see how to generate pseudo-random numbers and print them on a 16x2 LCD using the PIC 16F628A microcontroller.

WHAT IS A PSEUDO-RANDOM NUMBER?

A pseudo-random number is a number generated in a process that seems to produce random numbers, but does not actually do so. Pseudo-random number sequences do not show any apparent pattern or regularity from a statistical point of view, despite being generated by a completely deterministic algorithm, where the same initial conditions always produce the same result.

MATERIALS:

The materials used for this project are as follows:

• PIC 16F628A
• LCD 16*2

WIRING DIAGRAM:

OPERATION:

When powering the microcontroller, random numbers will appear on the LCD; in this case, the numbers that will appear will range from 0 to 50. If we want to obtain values greater than 50, we must modify the following values.

X = (((7*X)+5) Mod 99)
N = X Mod 51

Example:

If we want to generate random numbers with values ranging from 0 to 100, we modify:

X = (((7*X)+5) Mod 199)
N = X Mod 101

For the generation of pseudo-random numbers, we base ourselves on the following algorithm:Linear congruential generator

CODE:

'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : Esteban Carrillo - www.edeptec.com                *
'*  Notice  : Copyright (c) 2022                                *    
'*          : All Rights Reserved                               *
'*  Date    : 18/03/2021                                        *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
DEFINE LCD_DREG PORTB 
DEFINE LCD_DBIT 0 
DEFINE LCD_RSREG PORTB 
DEFINE LCD_RSBIT 4 
DEFINE LCD_EREG PORTB 
DEFINE LCD_EBIT 5

x VAR BYTE
y VAR BYTE
n VAR BYTE

y = 5
CICLO: 
    x = (((7*x)+5) Mod 99)
    n = x Mod 50

    LCDOUT $fe, 1
    LCDOUT $fe, $80 + y, "Num:" ,DEC n
    PAUSE 500
GOTO CICLO