SIO2 Command Sequence

  Cmd     Reply
  42h     ID_lo
  ??h     ID_hi
  ??h     Buttons_lo
  ??h     Buttons_hi
  ---- transfer stops here if digital ----
  ??h     Analog right joystick, y-axis (00h = upmost, 80h = centered, FFh = downmost)
  ??h     Analog right joystick, x-axis (00h = leftmost, 80h = centered, FFh = rightmost)
  ??h     Analog left joystick, y-axis (see above)
  ??h     Analog right joystick, x-axis (see above)
  ---- transfer stops here if not DS2 ----
  ??h     D-pad right pressure (00h = no pressure, FFh = max pressure)
  ??h     D-pad left pressure
  ??h     D-pad up pressure
  ??h     D-pad down pressure
  ??h     Triangle pressure
  ??h     Circle pressure
  ??h     Cross pressure
  ??h     Square pressure
  ??h     L1 pressure
  ??h     R1 pressure
  ??h     L2 pressure
  ??h     R2 pressure