Operation

Software

Note

Make sure you have installed the control software as described in Software Commissioning.

Using multiple USB-SD-Muxes on a single host is considered a common use case. Thus, it is a good practice to access a USB-SD-Mux via the /dev/usb-sd-mux/id* symlinks created by the provided udev-rule. The following examples are based on a USB-SD-Mux FAST with the ID 00002.

The USB-SD-Mux FAST uses serial numbers that look something like 00034.00002, while the USB-SD-Mux Classic uses serial numbers that look like 000000000002.

If you have set up the udev rule to grant access to the USB-SD-Mux control interface to your current user, you should be able to use it as shown below. Otherwise you may need to use the sudo command.

  • To multiplex the Micro-SD-Card to the DUT

    $ usbsdmux /dev/usb-sd-mux/id-00034.00002 dut

Important

The DUT may have a mechanical switch in the SD card slot, that drives the card detect signal on the SD card controller and triggers a re-enumeration of the SD card.

This signal will not be toggled by the USB-SD-Mux. This means the controller may not detect the newly connected card.

In this case you may need to manually trigger a re-enumeration or simply power-cycle the DUT.

  • To multiplex the Micro-SD-Card to the host:

    $ usbsdmux /dev/usb-sd-mux/id-00034.00002 host

  • To disconnect the micro SD card from DUT and Host:

    $ usbsdmux /dev/usb-sd-mux/id-00034.00002 off

  • To get the current status of the USB-SD-Mux:

    $ usbsdmux /dev/usb-sd-mux/id-00034.00002 get
off

Note

On power-up the USB-SD-Mux Classic starts in the off state, while the USB-SD-Mux FAST starts in the dut state.

The block device of an USB-SD-Mux is symbolically linked by udev to:

/dev/disk/by-id/usb-LinuxAut_sdmux_HS-SD_MMC_*-0:0

Tool Integration

The labgrid project has support for the USB-SD-Mux. See labgrid's documentation for more details.