Intended Use
############

.. note::
  Do not use the USB-SD-Mux for any other use cases than the ones listed
  below:

* The USB-SD-Mux is intended to be used during the development of embedded
  devices with a micro SD card slot.

* The USB-SD-Mux is intended to switch a micro SD card between a host computer
  and an embedded device.

* The USB-SD-Mux must be handled in an :term:`ESD` -safe environment to
  prevent damage to the device, the embedded target and the host computer.

.. warning:: The USB-SD-Mux may be damaged if it is not handled in an
  :term:`ESD` -safe environment.

* The USB-SD-Mux is intended to work with Micro SD-Cards with a speed up to
  50 MHz.

* The USB-SD-Mux is intended to work with Micro SD-Cards with a voltage of
  3.3 V and 1.8 V.

.. warning::
  The voltage on the SD card slot must not be higher than 3.3V,
  otherwise the product may be damaged.

  Make sure your prototypes respect these limits, especially when the
  voltage has not been checked finally or can be set by software.

* The USB-SD-Mux is intended to be used with a Micro USB-Cable not longer than
  1.8 m.

.. note::
  In most environments the USB-SD-Mux creates an additional ground loop in
  the electrical environment.
  This can lead do unpredictable results.
  Use an USB-isolator to power the USB-SD-Mux in such cases.

* The USB-SD-Mux is intended to be directly inserted into the SD card slot of
  a :term:`DUT`.

.. Important::
  Do not use Micro-SD extension cables.
  Those may lead to unpredictable system behavior and
  may result in problems with :term:`EMI`.

* The USB-SD-Mux is intended to be controlled by a host computer running Linux.
  The ``usbsdmux`` control software uses low-level Linux APIs that are not
  available on other operating Systems.