gistfile1.rb

  class Ledpwmbutton < ArduinoSketch
    
    #Turn on LED when the button is pressed and keep it on after is is
    #released, if the button is held brightness changes
    
    #page 61 of getting started with arduino
    
      output_pin 9, :as => :led #pin for led
      input_pin 7, :as => :button_one, :device => :button #input pin of pushbutton
      
      @val = 0 #state of input pin
      @old_val = 0 #stores previous value of @val
      @state = 0 # 0 = LED off while 1 = LED on
      
      @brightness = 128 #stores brightness value
      @startTime = 0 #when did we begin pressing

      def loop
        @val = digitalRead button_one #read input and store it
        
        #check if there was a transition
        if @val == 1 && @old_val == 0 then #this is the line causing problems
          
         @state = 1 - @state #changes state from off to on and vice versa
          
         @startTime = millis #millis is the arduino clock returns number of milliseconds since board was reset
                            #remembers when button was last pressed
         delay 10
        end
        
        if @val == 1 && @old_val == 1 then
          if @state ==1 && (millis - @startTime) > 500 then
            @brightness +=1 #increment brightness by 1
            delay 10
            if @brightness > 255 then
              @brightness = 0 #if we go over 255 lets go back to 0
            end
          end
        end
        
        @old_val = @val #val is now old lets store it
        
        if @state == 1 then
          analogWrite led, @brightness #turn led on at the current brightness level
        else
          analogWrite led, 0 #turn led off
        end
      end
      
  end