' =========================================================================
'   File....... SW21-EX04-Runway_LEDs.SXB
'   Purpose.... Advanced LED Flasher
'   Author..... (C) 2000 - 2005, Parallax, Inc.
'   E-mail..... support@parallax.com
'   Started.... 01 SEP 2005
'   Updated.... 23 MAR 2007 by TSaavik for SX28
' =========================================================================
' -----[ Program Description ]---------------------------------------------
'
' Strobe one of eight LEDs to behave like airport runway landing lights.
' This program will work, unmodified, on any BS2-family module.
'------{ Device Settings ]-------------------------------------------------

DEVICE 		SX28,TURBO,BANKS8,OSCHS3,SYNC,OPTIONX
FREQ            50_000_000
ID		"EX03"

' -----[ I/O Definitions ]-------------------------------------------------

LEDs            VAR     RB			' LEDs on RB.0 - RB.7

' -----[ Constants ]-------------------------------------------------------

'DelayTm         CON     100                     ' delay time for LEDs
DelayTm         CON     1			' delay time for LEDs in SXSIM


' -----[ Initialization ]-------------------------------------------------
PROGRAM Start

' -----[ Program Code ]----------------------------------------------------

Start:
  LEDS = %00000001                              ' start with right LED on
  Tris_B = %00000000                          ' make LEDs outputs
Main:
  LEDs = %00000001                              ' start with right LED on
  DO
    PAUSE DelayTm                               ' on-time for lit LED
    LEDs = LEDs << 1                            ' shift LED left
  LOOP UNTIL LEDs = %10000000                 ' test for last LED
  GOTO Main