Dream Cheeky USB Missile Launcher

missile_launcher.rb

# REFERENCES
# https://github.com/codedance/Retaliation/blob/master/retaliation.py
# http://www.rkblog.rk.edu.pl/w/p/controlling-usb-missile-launchers-python/
# http://matthias.vallentin.net/blog/2007/04/writing-a-linux-kernel-driver-for-an-unknown-usb-device/

require 'libusb'

class Launcher
  ID_PRODUCT = 0x0701
  ID_VENDOR = 0x0a81

  SETUP_PACKET = {
    bmRequestType: 0x21,
    bRequest: 0x09,
    wValue: 0x02,
    wIndex: 0x0
  }

  MOVES = {
    down:  "\x01\x00", # 1
    up:    "\x02\x00", # 2
    left:  "\x04\x00", # 4
    right: "\b\x00", # 8
  }.freeze

  FIRE = "\x10\x00".freeze # 16
  STOP = "\x20\x00".freeze # 32

  def initialize
    device = connect_device!
    @handle = device.open
  end

  def fire
    send(FIRE)
    sleep(5) # recoil for 1 missile
    stop_fire
  end

  def move_left
    timed_move(:left)
  end

  def move_right
    timed_move(:right)
  end

  def move_up
    timed_move(:up)
  end

  def move_down
    timed_move(:down)
  end

  private

  attr_reader :handle

  # STOP bytes are not stoping the fire command.
  # Sending a command to move somewhere and then STOP, works. ¯\_(ツ)_/¯
  def stop_fire
    send(MOVES[:up])
    stop
  end

  def stop
    send(STOP)
  end

  def timed_move(move, timeout: 0.5)
    send(MOVES[move])
    sleep(timeout)
    stop
  end

  def connect_device!
    usb = LIBUSB::Context.new
    device = usb.devices(idVendor: ID_VENDOR, idProduct: ID_PRODUCT).first
    raise('device not found') unless device
    device
  end

  def send(data)
    handle.control_transfer(**SETUP_PACKET, dataOut: data)
  end
end

launcher = Launcher.new
launcher.fire