PSI Science Lamp Random Number Generator Source Code

'*********************************************************************************
'* Name : ESP.BAS *
'* Author : John Iovine *
'* Notice : Copyright (c) 2010 Images Scientific Instruments Inc. *
'* : All Rights Reserved *
'* Date : 7/8/2010 *
'* Version : 1.0 *
'* Notes :ESP Lamp RNG *
'*********************************************************************************

'*

DEFINE OSC 16	'Set oscillator to 16 MHz
b0 var byte	'counting variable
x var byte	'general variable
w2 var word	'random number variable
TRISB = 1	'initialize ports
b0 = 0	'counting variable
PORTB = 2	'LED runover on startup
Pause 550
PORTB = 4
Pause 550
PORTB = 8
Pause 550
PORTB = 16
Pause 550
PORTB = 0
Loop:	'main counting loop
if intcon.1 = 1 then display	'interrupt polling, if positive edge, jump to display routine
b0 = b0 + 1
GoTo Loop
display:	'main display routine - interrupt subroutine
x = b0 / 4	'divide by four to find out integer quotient
x = x // 2	'quotient modulo 2 to find out whether its odd or even
b0 = b0 // 4	'modulo 4 on original counting variable to get random number from range 0 - 3
if x = 1 then b0 = 3 - b0	'reverse modulo in case of odd quotient
w2 = b0 + 1	'range shift from 0 - 3 to 1 - 4
SerOut PORTB.5,6, [w2.byte0, w2.byte1]	'serial out random number
PORTB = 0	'turn off any LED to let user see new number generated
Pause 150	'add pause to allow user to see new random number generated, if new and old 'number are same, user will see LED blink.
IF w2 = 1 Then PORTB = 2	'Light LED corresponding to new random number
IF w2 = 2 Then PORTB = 4
IF w2 = 3 Then PORTB = 8
IF w2 = 4 Then PORTB = 16
b0 = 0	'reset counting variable
INTCON.1 = 0	'reset interrupt flag
goto loop	'back to counting loop