# File lib/rad/arduino_sketch.rb, line 210
  def input_pin(num, opts={})
    raise ArgumentError, "can only define pin from Fixnum, got #{num.class}" unless num.is_a?(Fixnum)
    @pin_modes[:input] << num
    if opts[:as]
      @declarations << "int _#{opts[ :as ]} = #{num};"

      accessor = []
      accessor << "int #{opts[ :as ]}() {"
      accessor << "\treturn _#{opts[ :as ]};"
      accessor << "}"
      @accessors << accessor.join( "\n" )
      
      @signatures << "int #{opts[ :as ]}();"
    end
    @pullups << num if opts[:as]
  end