I've started a project on Andorid, but I don't know NDK very much. I want to send custom data as per receiving message on usb port. I saw some applications that can send/recieve custom data on usb port if the phone is in recovery. I've programmed usb connection in windows before. But I haven't any clue where should I start in android. Is there any documentation for usb programming for android? If NDK isn't suitable to implement this, which options do I have? It is not important if the application is device specific.
The issues are more of system architecture and permission, an area where the NDK offers little in excess of the SDK.
Android does not really support (direct) custom use of the USB port, at least when the device is connected to a computer (there are some recent options when the device is hosting a USB peripheral). What is possible in recovery mode is essentially irrelevant, unless you want to make substantial modifications to the installation of Android running on your device.
Generally, the only practical way to do application-level communication between the device and a hosting PC is to use the IP networking paradigm over the USB cable. You do this either by enabling USB debugging on the device and installing much of the android SDK on the PC, or by enabling some forms of tethering which may create a general network as a side effect.
For the SDK method, read up on adb port forwards, including the limitation that the PC side must initiate the connection.
It may also be possible to create custom drivers which get a PC to pretend to be an android accessory kit (ADK) circuit and use the apis related to that.
Unfortunately, pretty much all of these ideas are more suitable for developers/power users, than for general consumer application. For consumer apps, most developers ignore the USB cable and do IP networking over WIFI, requiring the user to put the device and the PC on the same network, or proxy through an Internet server visible to both the PC and the device's mobile network.
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I have a USB device and want to build a nice graphical interface for it. Is it possible to connect the USB device to Android, have Android be the host, and communicate with it and build a UI? If so, which libraries would allow me to do this? And if not, what alternative workarounds are there? I would prefer a wired connection for reliability.
It's possible. I have personally used an USBc to USB cable to hook up everything from a keyboard and mouse to an external monitor. Some phones/devices may not have a data port on the external USB port or the chips needed for external monitors but android itself has USB drivers built in.
I think this question remained unanswered for so long because it's so easy to google the android developer page that should answer your question in specifics here. It's the developer guide for using android as a USB host.
Does anyone know how to configure an Android device (tablet) to appear as a USB HID device when connected to a PC?
Is there any other way of getting data from the tablet to the PC (via USB) other than writing it to a file, and have the PC retrieve the (updated) file from the tablet which is acting as a 'mass storage device' for the PC?
Can USB carry a TCP/IP end-end connection?
Using a tablet as a high-end intelligent 'keyboard' or 'mouse' or similar device would be immensely powerful, and open up lots of possibilities. Controlling a model railway layout is the end I have in mind.
Thanks
It's possible to do this using the linux gadget framework http://www.linux-usb.org/gadget/ using a custom composite USB device. The gadget framework is part of the Android kernel source tree by inheritance from Linux.
Unfortunately, Android has its own customizations that restrict the ability to dynamically register new USB gadgets so you will need to patch the kernel source tree for your particular device and add your HID gadget (otherwise you could create a module and load it that way) to the supported Android list.
I have done this before and will update this answer to contain more detail if there is interest. Unfortunately I lost the code so I will have to start from scratch.
If I set up a web server on my phone and enable usb tethering, I can access that server from my PC. If that's not enough for you, this might help: https://market.android.com/details?id=usbwebcam.application&hl=en
I'm running cyanogenmod on a Desire CDMA (BravoC)
Let me know what you find out; it would be pretty handy to use my phone as a USB keyboard in the field. An android server with a PC client is gonna be easiest though.
Have a look at Android Open Accessory Protocol 2.0. This could help you out.
Is it possible to access the USB port on Android phones? (Droid X for example)
Here is my usage case:
Have a USB device attached to the Android phone. The phone listens for data on this USB device. (The USB device is connected to a USB->RS-232 converter that has I/O attached to it)
This would be slick if possible. Does anyone know if this is possible?
Would be slick, yup. Not possible though. There's a feature request for it: http://code.google.com/p/android/issues/detail?id=738
Actually it is possible on a lot of the phones if you are able to install a new kernel with a USB host driver and rig up a custom cabling scheme to provide usb bus power to the device as the phone won't. A few phones even shipped with this capability already live.
I don't know if the Droid X specifically ships with this already, can have it added (if you are able to flash kernels), could have it added but no one has written the host driver yet, or is missing the hardware capability.
You also would need to enable the appropriate usb serial converter device driver (identified by experimenting with the device on a desktop linux box), but that's probably already in the kernel sources and just needs to be selected in the config. You may also need to create a device file for the /dev/ttyUSB0 or whatever and give it permissions appropriate to the application that wants to access it. (This requires root, but if you can reflash the kernel, you can get root)
If you want to pursue this, search the android kernel google group for posts about USB host mode.
One serious downside to putting the USB into host mode is that you loose the adb interface into the phone, which makes working on your projects hard. You'll probably need to either build an adapter for the low voltage debug serial port if there is one (as on G1, mytouch, etc) so you can get a console shell (or just use that instead of USB to talk to your peripheral) or at a minimum set up an ssh and sftp server on the wifi.
Since you want serial anyway, another option people have used is to get a bluetooth-to-serial module from an outfit such as sparkfun.
A bluetooth to serial adapter might solv your problems.
You can find one at https://www.sparkfun.com/products/582. Boards from other companies are also available for example on ebay.
I've been able to find a few posts on StackOverflow about how to control USB devices using an Android phone -- which I understand is impossible (The Android being a USB device and all.)
However, I would be perfectly happy to set up my application to communicate with the other computer (a Linux host) as a USB device. (Like a really expensive mouse...)
Does anybody have information about how to set up an Android app/phone to use the USB connection and exchange data with a host computer. Obviously, it already works at some level -- it's how Eclipse and Android SDK/debugger do what they do, but I'm still looking for some way to do this in an application.
(My current phone, BTW, is a Droid Incredible.)
Thanks,
R.
Basically you'd need to install the USB device driver and the ADB toolsuite from the SDK, either that or reverse engineer their functionality and build it into something else.
Then you enable USB debugging on the phone.
And then you can do something like an adb port forward to allow an application on the pc to connect to a network socket listener on the phone. Note that connections cannot be made in the other direction, but once a connection is made it is bidirectional.
If your version of android supports tethering over USB, you could also leverage that to implicitly create a network between the PC and the phone, at which point you can make connections in either direction. Just make sure nothing starts accidentally pumping lots of data through the phone's mobile network!
(Many android phones actually can experimentally function as USB hosts, but you have to compile new drivers into the kernel, install the new version, and make up a cable to provide USB power to the device as the phone cannot. Also you lose the ADB over USB channel which makes debugging a pain)
We have made a device which can act as an USB host or slave and processes the data it receives. I want to use the Android phones to send the data to it via USB.
My research leads me to conclude that we cannot use Android devices in USB Host mode without modifying the hardware or OS. Doing so is not an option as this is going to be a commercially deployed device.
However, I couldn't find any information on using the Android phone as a slave. This is already technically possible because it can connect to the PC in a similar configuration. Can we do the same via an application? If so, any information on how to achieve this will be greatly appreciated. I have full access to our device's embedded system, so custom code there should not be a problem.
This is already technically possible
because it can connect to the PC in a
similar configuration.
Only for things baked into the firmware. Your SDK application cannot invent new Linux device drivers, nor does it have any access to the Android device side of the adb connection.
Can we do the same via an application?
Since you have not said what you are trying to do, this is impossible to answer in a definitive fashion.
Say, for example, the "device which can act as an USB host or slave and processes the data it receives" wants screenshots off of the Android device. That is eminently possible via adb, because adb has a protocol for that built in. All you would need to do is have your device connect to the Android device via the adb protocol and request screenshots, no different than does DDMS or hierarchyviewer.
So, I would look at the problem from a different perspective: if you can accomplish it via DDMS, you can do it via your custom device. If you can accomplish it via adb shell commands, you can do it via your custom device. If you cannot accomplish your goals via existing interfaces, though, since you have no way to invent new ones over USB, you will be stuck.
Conceivably, you could plug your custom device into a Bluetooth or WiFi dongle, then use those on Android for communication.