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 device tree, and assemble a USB Micro-AB receptacle at J23 on the bottom of the VAR-6ULCustomBoard.
For example:
Follow either the "Build the Linux kernel from source code" or "Customizing the Linux kernel" Wiki pages and edit the following device tree file:
arch/arm/boot/dts/imx6ul-imx6ull-var-dart-common.dtsi
(in very old kernel releases where this file is not available, you should edit arch/arm/boot/dts/imx6ul-var-dart.dtsi instead)
&usbotg1 {
- dr_mode = "host";
+ dr_mode = "peripheral";
disable-over-current;
status = "okay";
};
If you build the kernel manually from source code, you should build only the device trees and copy them to your SD card.
Using the USB1 port under Linux
As host (default)
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.