DART-6UL USB OTG

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Revision as of 08:40, 16 February 2017 by Eran (talk | contribs)
DART-6UL - USB "OTG"

Configuring the USB1 port under Linux

By default, the USB1 port is configured as host in the device tree, and a USB type-A receptacle is assembled on the VAR-6ULCustomBoard.
To use it as peripheral (OTG is not supported in the VAR-6ULCustomBoard) you need to change the value of the dr_mode property, under the usbotg1 node, in the imx6ul-var-dart.dtsi device tree, and assemble a USB Micro-AB receptacle at J23 on the bottom of the VAR-6ULCustomBoard.

For example:

  • Get the toolchain and the Linux source code by following the Build Linux from source code guide.
  • Edit arch/arm/boot/dts/imx6ul-var-dart.dtsi:
 &usbotg1 {
-       dr_mode = "host";
+       dr_mode = "peripheral";
	disable-over-current;
        status = "okay";
 };

Using the USB1 port under Linux

As host (default)

USB host

As peripheral

In order to use the board as a peripheral, an appropriate module needs to be loaded.
For example, there is an Ethernet gadget module called g_ether, a mass storage gadget called g_mass_storage, a serial gadget called g_serial, etc.

Example using the g_mass_storage module to expose the BOOT partition on our recovery SD card to a PC:
Connect a micro-B plug to Standard-A plug cable between the board and a PC, and run the following on the board:

# umount /dev/mmcblk0p1
# modprobe g_mass_storage file=/dev/mmcblk0p1

The partition should be loaded on the PC as a mass storage device.