' =========================================================================
'   File....... SW21-EX02-Flash_LED-Cntr.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 ]---------------------------------------------
' Flashes an LED connected to RB.4, controlled by the value of a bit that's
' part of another variable.  This program will work, unmodified, on
' the SX28
' -------------------------------------------------------------------------

'------{ Device Settings ]-------------------------------------------------

DEVICE 		SX28,TURBO,BANKS8,OSCHS3,SYNC,OPTIONX
FREQ            50_000_000
ID		"EX02.1"

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

Strobe		PIN     RB.4                    ' LED on RB.4

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

IsOn            CON     1                       ' on for active-high LED
IsOff           CON     0                       ' off for active-high LED

FlashOn         CON     50                     ' on for 50 ms
FlashOff        CON     950                    ' off for 950 ms

'for sxsim
'FlashOn         CON     1                     	' on for 1 ms
'FlashOff        CON     2                    	' off for 2 ms

' -----[ Variables ]-------------------------------------------------------

cntr            VAR     Byte                     ' simple counter, 0 - 15

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

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

Start:
  OUTPUT Strobe                                 ' enable pin to drive LED
  Strobe = IsOff

Main:
  DO
    Strobe = cntr.0
    PAUSE 500
    cntr = cntr + 1
  LOOP