Connect USB device to Android Emulator?

Question

We've been looking into Android 3.1+ and its ability to read/write to USB devices connected to the OTG/Host port.

I've found some code examples that allow me to detect and read/write to a USB HID device, but at the moment, I simply don't have a physical 3.1+ compatible device to deploy and remotely debug on.

Does anyone know how I can attach my HID device to the emulator, via the PC/Eclipse so the app can detect and read/write to/from the device?

I've tried listing the currently connected USB Devices but it shows none, as you'd no doubt guess.

Any ideas?

Cheers

Answer 1

The Android emulator is based on QEMU. Even if the emulator version is so ancient, there appears to be support for passing USB devices from the host. It does not seem to be available for ARM devices though, the emulated ARM machine does not have a USB controller. (I have already tried enabling all USB host controllers for the goldfish_armv7 kernel based on Linux 3.4, without luck. The default emulator goldfish_armv7 kernel does not even have Host USB enabled.)

If you are not limited to ARM and can use x86, then I suggest to check out http://www.android-x86.org/, its images can be used with a standard QEMU i386 (or x86_64) machine. This also yields better performance by using the KVM extension on Linux.

To passthrough a USB device with of vendor ID 1234 and device ID abcd, you can run the emulator command:

emulator -avd x86-machine -qemu -usb -usbdevice host:1234:abcd 

Or, when using QEMU:

qemu-system-i386 -m 1G -cdrom android-x86.iso -usb -usbdevice host:1234:abcd 

You will need read/write permissions for /dev/bus/usb/XXX/YYY, for that you can create a udev rule such as:

SUBSYSTEM!="usb", GOTO="end_skip_usb" ATTRS{idVendor}=="1234", ATTRS{idProduct}=="abcd", TAG+="uaccess" LABEL="end_skip_usb" 

Now, upon insertion of the USB device, your emulator should recognize a USB device. This is tested for a Linux installation with a Android x86 4.3 image.