ex19 - theremin.bs2

proteus得一些经典例子

' {$STAMP BS2}
' ==============================================================================
'
' File...... Ex19 - Theremin.BS2
' Purpose... Simple Digital Theremin
' Author.... Parallax
' E-mail.... [e-mail]
' Started...
' Updated... 01 MAY 2002
'
'
' ==============================================================================
' ------------------------------------------------------------------------------
' Program Description
' ------------------------------------------------------------------------------
' This program uses RCTIME with a photocell to create a light-controlled
' theremin.
' ------------------------------------------------------------------------------
' I/O Definitions
' ------------------------------------------------------------------------------
Speaker CON 0 ' piezo speaker output
PitchCtrl CON 1 ' pitch control (RCTIME) input
' ------------------------------------------------------------------------------
' Constants
' ------------------------------------------------------------------------------
Scale CON $0100 ' divider for BS2/BS2e
'Scale CON $0066 ' divider for BS2sx
'Scale CON $0073 ' divider for BS2p
Threshold CON 200 ' cutoff frequency to play
' ------------------------------------------------------------------------------
' Variables
' ------------------------------------------------------------------------------
tone VAR Word ' frequency output
' ------------------------------------------------------------------------------
' Program Code
' ------------------------------------------------------------------------------
Main:
HIGH PitchCtrl ' discharge cap
PAUSE 1 ' for 1 ms
RCTIME PitchCtrl, 1, tone ' read the light sensor
tone = tone */ Scale ' scale input
IF (tone < Threshold) THEN Main ' skip for ambient light
FREQOUT Speaker, 25, tone ' output the tone
GOTO Main
END