RxUsb is a high level reactive facade. Read more about RxUsb here.

RxUsb for Android brings two kinds of implementations: using LibUsb and Native Android USB.

The default system configuration on most Android devices will not allow access to USB. There are several options for changing this.

Modify the ueventd.rc used in the image to change the permissions on /dev/bus/usb/*/*. If using this approach then it is advisable to create a new Android permission to protect access to these files. It is not advisable to give all applications read and write permissions to these files.

The following example will give all applications read and write permissions for all USB devices.

# vi /ueventd.rc

find line starting with /dev/bus/usb/* and edit it to have 0666 in second column:

/dev/bus/usb/*            0666   root       usb

In most cases it is still possible to obtain permission with android.hardware.usb.UsbManager.

The difficulties in this method is that there is no guarantee that it will continue to work in the future Android versions, it requires invoking Java APIs and running code to match each android.hardware.usb.UsbDevice to a libusb_device.