' -------------------------------------------------------------------------
' Program Description
' -------------------------------------------------------------------------
'
' Uses FREQOUT to modulate an IR LED for object detection.  When object
' is detected, a tone is generated from the pieze element.


' -------------------------------------------------------------------------
' Device Settings
' -------------------------------------------------------------------------

DEVICE          SX28, OSCXT2, TURBO, STACKX, OPTIONX
FREQ            4_000_000
ID              "FREQOUT"  

' -------------------------------------------------------------------------
' IO Pins
' -------------------------------------------------------------------------

IrLED           VAR     RB.0                    ' output to IR LED
Detect          VAR     RB.1                    ' input from IR detector
Spkr            VAR     RB.2                    ' output to piezo

' -------------------------------------------------------------------------
' Constants
' -------------------------------------------------------------------------

IrMod           CON     38000                   ' modulation freq = 38 kHz

Yes             CON     0                       ' for active-low output
No              CON     1

' =========================================================================
  PROGRAM Start
' =========================================================================

' -------------------------------------------------------------------------
' Program Code
' -------------------------------------------------------------------------

Start:
  DO
    FREQOUT IrLED, 1, IrMod                     ' modulate IR diode
    IF Detect = Yes THEN                        ' check detector
      SOUND Spkr, 100, 2                        ' buzz if object detected
    ENDIF
  LOOP