piano.lua added to repository

examples/piano.lua

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+-- "Piano" in eLua, showing yet another use for the PWM module :)
+-- [TODO] platform/module check
+
+local oct, pause = 4, 0
+local pwmid, tmrid = 1, 0
+
+-- Mapping between keys and note offsets
+local offsets = { a = 0, w = 1, s = 2, d = 3, r = 4, f = 5, t = 6, g = 7, h = 8,
+  u = 9, j = 10, i = 11, k = 12, o = 13, l = 14, [";"] = 15, ["["] = 16, ["'"] = 17,
+  ["]"] = 18, ["\\"] = 19 }
+  
+-- Write the curent octave
+function show_octave()
+  term.putstrxy( 2, 4, "Oct: " .. tostring( oct ) .. "(+/-)" )
+  term.gotoxy( 2, 19 )  
+end
+
+-- Write the current pause between notes
+function show_pause()
+  term.gotoxy( 2, 5 )
+  term.clreol()
+  term.putstrxy( 2, 5, "Pause between notes: " .. tostring( pause ) .. "ms (</>)" )
+  term.gotoxy( 2, 19 )  
+end
+
+-- Show the main interface
+function show_all()
+  term.putstrxy( 2, 2, "eLua piano demo" )  
+  show_octave()
+  show_pause()
+  term.putstrxy( 4,  7, " w   r  t   u  i  o   [  ]  " )
+  term.putstrxy( 4,  8, " |   |  |   |  |  |   |  |  " )
+  term.putstrxy( 4,  9, " A#  C# D#  F# G# A#  C# D# " )
+  term.putstrxy( 4, 10, "A  BC  D  EF  G  A  BC  D  E" )
+  term.putstrxy( 4, 11, "|  ||  |  ||  |  |  ||  |  |" )
+  term.putstrxy( 4, 12, "a  sd  f  gh  j  k  l;  '  \\" )  
+  term.putstrxy( 2, 14, "Use above keys to play notes." )
+  term.putstrxy( 2, 15, "+/- to change octave." )
+  term.putstrxy( 2, 16, "</> to change pause between notes." )
+  term.putstrxy( 2, 17, "Space to stop playing." ) 
+  term.putstrxy( 2, 18, "ESC to exit." ) 
+  term.gotoxy( 2, 19 )
+end
+
+-- Conversion of note to frequency
+function note_to_freq( index )
+  return 55 * 2 ^ ( ( index + ( oct - 1 ) * 12 ) / 12 )
+end
+
+-- Entry point
+term.clrscr()
+pwm.setclock( pwmid, 1000000 )
+show_all()
+while true do
+  local key = term.getch( term.WAIT )
+  if key == term.KC_ESC then break end
+  local res, strkey = pcall( string.char, key )
+  if res then     
+    if offsets[ strkey ] ~= nil then
+      local freq = note_to_freq( offsets[ strkey ] )
+      pwm.stop( pwmid )
+      if pause > 0 then
+        tmr.delay( tmrid, pause * 1000 )
+      end
+      pwm.setup( pwmid, freq, 50 )
+      pwm.start( pwmid )
+    elseif strkey == ">" then
+      pause = pause < 1000 and pause + 10 or pause
+      show_pause()
+    elseif strkey == "<" then
+      pause = pause > 0 and pause - 10 or pause
+      show_pause() 
+    elseif strkey == "+" then
+      oct = oct < 7 and oct + 1 or oct
+      show_octave()
+    elseif strkey == "-" then
+      oct = oct > 1 and oct - 1 or oct
+      show_octave()
+    elseif strkey == " " then
+      pwm.stop( pwmid )
+    end
+  end  
+end
+
+term.clrscr()
+term.gotoxy( 1, 1 )
+