Using Android USB Host API to read my USB game con

Question

I am trying to use Android USB Host API to read my USB game controller data, once I get this to work, I will connect other device to test. My game controller is connected to my Android phone using OTG cable. I am now able to get device, endpoints information, but I don't know how to read the raw data and display it.

Can someone please help me? Some example codes will be appreciated.

TextView countDisplay;
    ArrayList<String> listItems = new ArrayList<String>();
    ArrayAdapter<String> adapter;
    String values = "";
    UsbManager mManager;
    UsbDevice device = null;
    private byte[] bytes;
    private static int TIMEOUT = 0;
    private boolean forceClaim = true;
    static PendingIntent mPermissionIntent;
    UsbDeviceConnection connection = null;
    UsbEndpoint InputEndpoint = null;
    UsbEndpoint OutputEndpoint = null;
    private Handler mHandler = new Handler();


@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mManager = (UsbManager) getSystemService(Context.USB_SERVICE);
    mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(
            "com.android.example.USB_PERMISSION"), 0);
    IntentFilter filter = new IntentFilter();
    filter.addAction(UsbManager.ACTION_USB_DEVICE_ATTACHED);
    filter.addAction(UsbManager.ACTION_USB_DEVICE_DETACHED);
    registerReceiver(mUsbReceiver, filter);

    HashMap<String, UsbDevice> deviceList = mManager.getDeviceList();
    values = values + "deviceListSize:" + deviceList.size() + ",tostring:"
            + deviceList.toString();
    Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
    while (deviceIterator.hasNext()) {
        device = deviceIterator.next();
        values = values + ",device id:" + device.getDeviceId()
                + ",device name:" + device.getDeviceName();
        values = values + ",Protocol:" + device.getDeviceProtocol()
                + ",ProductId:" + device.getProductId();
        values = values + ",DeviceClass:" + device.getDeviceClass()
                + ",VendorId:" + device.getVendorId();
    }
    if (device != null) {
        values = values + ",getInterfaceCount:"
                + device.getInterfaceCount();
        UsbInterface intf = device.getInterface(0);
        values = values + ",intf.getEndpointCount():"
                + intf.getEndpointCount();
        UsbEndpoint endpoint1 = intf.getEndpoint(0);
        UsbEndpoint endpoint2 = intf.getEndpoint(1);

        mManager.requestPermission(device, mPermissionIntent);
        if (mManager.hasPermission(device)) {
            values = values + ",has permission over device!";
            connection = mManager.openDevice(device);
            if (connection == null) {
                values = values + ",connection null";
            } else {
                values = values + ",getFileDescriptor:"
                        + connection.getFileDescriptor();
                if (endpoint1.getDirection() == UsbConstants.USB_DIR_IN) {
                    InputEndpoint = endpoint1;
                } else {
                    OutputEndpoint = endpoint1;
                }
                if (endpoint2.getDirection() == UsbConstants.USB_DIR_IN) {
                    InputEndpoint = endpoint2;
                } else {
                    OutputEndpoint = endpoint2;
                }
            }
            if (InputEndpoint == null) {
                countDisplay.setText(values + ",InputEndpoint is null");
            }
            if (OutputEndpoint == null) {
                countDisplay.setText(values + ",OutputEndPoint is null");
            }
            connection.claimInterface(intf, forceClaim);
            mHandler.postDelayed(runnable, 1);
        } else {
            values = values + ",Do not have permission over device!";
        }

    }

    setContentView(R.layout.activity_main);
    LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);

    View v = inflater.inflate(R.layout.activity_main, null);
    LinearLayout ll = new LinearLayout(this);
    ll.setOrientation(LinearLayout.VERTICAL);
    int counter = 1;
    countDisplay = new TextView(this);
    ll.addView(countDisplay);

    countDisplay.setText(values + ",counter here");
    final Button button = new Button(this);
    button.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            if (device != null && mManager.hasPermission(device)) {
                values = values + ",device id:" + device.getDeviceId()
                        + ",device name:" + device.getDeviceName();
                values = values + ",Protocol:" + device.getDeviceProtocol()
                        + ",ProductId:" + device.getProductId();
                values = values + ",DeviceClass:" + device.getDeviceClass()
                        + ",VendorId:" + device.getVendorId();

                countDisplay.setText(values + ",okok");

            } else {
                if (device != null)
                    mManager.requestPermission(device, mPermissionIntent);
            }
        }

    });
    ll.addView(button);
    setContentView(ll);
}

And Runnable:

private Runnable runnable = new Runnable() {
    public void run() {
        if (connection != null) {
            int count = connection.bulkTransfer(InputEndpoint, bytes,
                    bytes.length, TIMEOUT);
            countDisplay.setText(values + ",bultTransferNo:" + count);
            countDisplay.setText(values + "bulkValue:" + bytes);
        } else {
            countDisplay.setText(values + ",connection is null");
        }
    }
};

Answer 1

This program serves as an example of the following USB host features:

• Matching devices based on interface class, subclass and protocol (see device_filter.xml)

• Asynchronous IO on bulk endpoints

All code Copyright:

    /*
     * Copyright (C) 2011 The Android Open Source Project
     *
     * Licensed under the Apache License, Version 2.0 (the "License");
     * you may not use this file except in compliance with the License.
     * You may obtain a copy of the License at
     *
     *      http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */

AdbDevice

    package com.android.adb;

    import android.hardware.usb.UsbConstants;
    import android.hardware.usb.UsbDeviceConnection;
    import android.hardware.usb.UsbEndpoint;
    import android.hardware.usb.UsbInterface;
    import android.hardware.usb.UsbRequest;
    import android.util.SparseArray;

    import java.util.LinkedList;

    /* This class represents a USB device that supports the adb protocol. */
    public class AdbDevice {

        private final AdbTestActivity mActivity;
        private final UsbDeviceConnection mDeviceConnection;
        private final UsbEndpoint mEndpointOut;
        private final UsbEndpoint mEndpointIn;

        private String mSerial;

        // pool of requests for the OUT endpoint
        private final LinkedList<UsbRequest> mOutRequestPool = new LinkedList<UsbRequest>();
        // pool of requests for the IN endpoint
        private final LinkedList<UsbRequest> mInRequestPool = new LinkedList<UsbRequest>();
        // list of currently opened sockets
        private final SparseArray<AdbSocket> mSockets = new SparseArray<AdbSocket>();
        private int mNextSocketId = 1;

        private final WaiterThread mWaiterThread = new WaiterThread();

        public AdbDevice(AdbTestActivity activity, UsbDeviceConnection connection,
                UsbInterface intf) {
            mActivity = activity;
            mDeviceConnection = connection;
            mSerial = connection.getSerial();

            UsbEndpoint epOut = null;
            UsbEndpoint epIn = null;
            // look for our bulk endpoints
            for (int i = 0; i < intf.getEndpointCount(); i++) {
                UsbEndpoint ep = intf.getEndpoint(i);
                if (ep.getType() == UsbConstants.USB_ENDPOINT_XFER_BULK) {
                    if (ep.getDirection() == UsbConstants.USB_DIR_OUT) {
                        epOut = ep;
                    } else {
                        epIn = ep;
                    }
                }
            }
            if (epOut == null || epIn == null) {
                throw new IllegalArgumentException("not all endpoints found");
            }
            mEndpointOut = epOut;
            mEndpointIn = epIn;
        }

        // return device serial number
        public String getSerial() {
            return mSerial;
        }

        // get an OUT request from our pool
        public UsbRequest getOutRequest() {
            synchronized(mOutRequestPool) {
                if (mOutRequestPool.isEmpty()) {
                    UsbRequest request = new UsbRequest();
                    request.initialize(mDeviceConnection, mEndpointOut);
                    return request;
                } else {
                    return mOutRequestPool.removeFirst();
                }
            }
        }

        // return an OUT request to the pool
        public void releaseOutRequest(UsbRequest request) {
            synchronized (mOutRequestPool) {
                mOutRequestPool.add(request);
            }
        }

        // get an IN request from the pool
        public UsbRequest getInRequest() {
            synchronized(mInRequestPool) {
                if (mInRequestPool.isEmpty()) {
                    UsbRequest request = new UsbRequest();
                    request.initialize(mDeviceConnection, mEndpointIn);
                    return request;
                } else {
                    return mInRequestPool.removeFirst();
                }
            }
        }

        public void start() {
            mWaiterThread.start();
            connect();
        }

        public AdbSocket openSocket(String destination) {
            AdbSocket socket;
            synchronized (mSockets) {
                int id = mNextSocketId++;
                socket = new AdbSocket(this, id);
                mSockets.put(id, socket);
            }
            if (socket.open(destination)) {
                return socket;
            } else {
                return null;
            }
        }

        private AdbSocket getSocket(int id) {
            synchronized (mSockets) {
                return mSockets.get(id);
            }
        }

        public void socketClosed(AdbSocket socket) {
            synchronized (mSockets) {
                mSockets.remove(socket.getId());
            }
        }

        // send a connect command
        private void connect() {
            AdbMessage message = new AdbMessage();
            message.set(AdbMessage.A_CNXN, AdbMessage.A_VERSION, AdbMessage.MAX_PAYLOAD, "host::\0");
            message.write(this);
        }

        // handle connect response
        private void handleConnect(AdbMessage message) {
            if (message.getDataString().startsWith("device:")) {
                log("connected");
                mActivity.deviceOnline(this);
            }
        }

        public void stop() {
            synchronized (mWaiterThread) {
                mWaiterThread.mStop = true;
            }
        }

        // dispatch a message from the device
        void dispatchMessage(AdbMessage message) {
            int command = message.getCommand();
            switch (command) {
                case AdbMessage.A_SYNC:
                    log("got A_SYNC");
                    break;
                case AdbMessage.A_CNXN:
                    handleConnect(message);
                    break;
                case AdbMessage.A_OPEN:
                case AdbMessage.A_OKAY:
                case AdbMessage.A_CLSE:
                case AdbMessage.A_WRTE:
                    AdbSocket socket = getSocket(message.getArg1());
                    if (socket == null) {
                        log("ERROR socket not found");
                    } else {
                        socket.handleMessage(message);
                    }
                    break;
            }
        }

        void log(String s) {
            mActivity.log(s);
        }


        private class WaiterThread extends Thread {
            public boolean mStop;

            public void run() {
                // start out with a command read
                AdbMessage currentCommand = new AdbMessage();
                AdbMessage currentData = null;
                // FIXME error checking
                currentCommand.readCommand(getInRequest());

                while (true) {
                    synchronized (this) {
                        if (mStop) {
                            return;
                        }
                    }
                    UsbRequest request = mDeviceConnection.requestWait();
                    if (request == null) {
                        break;
                    }

                    AdbMessage message = (AdbMessage)request.getClientData();
                    request.setClientData(null);
                    AdbMessage messageToDispatch = null;

                    if (message == currentCommand) {
                        int dataLength = message.getDataLength();
                        // read data if length > 0
                        if (dataLength > 0) {
                            message.readData(getInRequest(), dataLength);
                            currentData = message;
                        } else {
                            messageToDispatch = message;
                        }
                        currentCommand = null;
                    } else if (message == currentData) {
                        messageToDispatch = message;
                        currentData = null;
                    }

                    if (messageToDispatch != null) {
                        // queue another read first
                        currentCommand = new AdbMessage();
                        currentCommand.readCommand(getInRequest());

                        // then dispatch the current message
                        dispatchMessage(messageToDispatch);
                    }

                    // put request back into the appropriate pool
                    if (request.getEndpoint() == mEndpointOut) {
                        releaseOutRequest(request);
                    } else {
                        synchronized (mInRequestPool) {
                            mInRequestPool.add(request);
                        }
                    }
                }
            }
        }
    }

AdbMessage

    package com.android.adb;

    import android.hardware.usb.UsbRequest;

    import java.nio.ByteBuffer;
    import java.nio.ByteOrder;

    /* This class encapsulates and adb command packet */
    public class AdbMessage {

        // command names
        public static final int A_SYNC = 0x434e5953;
        public static final int A_CNXN = 0x4e584e43;
        public static final int A_OPEN = 0x4e45504f;
        public static final int A_OKAY = 0x59414b4f;
        public static final int A_CLSE = 0x45534c43;
        public static final int A_WRTE = 0x45545257;

        // ADB protocol version
        public static final int A_VERSION = 0x01000000;

        public static final int MAX_PAYLOAD = 4096;

        private final ByteBuffer mMessageBuffer;
        private final ByteBuffer mDataBuffer;

        public AdbMessage() {
            mMessageBuffer = ByteBuffer.allocate(24);
            mDataBuffer = ByteBuffer.allocate(MAX_PAYLOAD);
            mMessageBuffer.order(ByteOrder.LITTLE_ENDIAN);
            mDataBuffer.order(ByteOrder.LITTLE_ENDIAN);
        }

        // sets the fields in the command header
        public void set(int command, int arg0, int arg1, byte[] data) {
            mMessageBuffer.putInt(0, command);
            mMessageBuffer.putInt(4, arg0);
            mMessageBuffer.putInt(8, arg1);
            mMessageBuffer.putInt(12, (data == null ? 0 : data.length));
            mMessageBuffer.putInt(16, (data == null ? 0 : checksum(data)));
            mMessageBuffer.putInt(20, command ^ 0xFFFFFFFF);
            if (data != null) {
                mDataBuffer.put(data, 0, data.length);
            }
        }

        public void set(int command, int arg0, int arg1) {
            set(command, arg0, arg1, (byte[])null);
        }
        public void set(int command, int arg0, int arg1, String data) {
            // add trailing zero
            data += "\0";
            set(command, arg0, arg1, data.getBytes());
        }

        // returns the command's message ID
        public int getCommand() {
            return mMessageBuffer.getInt(0);
        }

        // returns command's first argument
        public int getArg0() {
            return mMessageBuffer.getInt(4);
        }

        // returns command's second argument
        public int getArg1() {
            return mMessageBuffer.getInt(8);
        }

        // returns command's data buffer
        public ByteBuffer getData() {
            return mDataBuffer;
        }

        // returns command's data length
        public int getDataLength() {
            return mMessageBuffer.getInt(12);
        }

        // returns command's data as a string
        public String getDataString() {
            int length = getDataLength();
            if (length == 0) return null;
            // trim trailing zero
            return new String(mDataBuffer.array(), 0, length - 1);
        }


        public boolean write(AdbDevice device) {
            synchronized (device) {
                UsbRequest request = device.getOutRequest();
                request.setClientData(this);
                if (request.queue(mMessageBuffer, 24)) {
                    int length = getDataLength();
                    if (length > 0) {
                        request = device.getOutRequest();
                        request.setClientData(this);
                        if (request.queue(mDataBuffer, length)) {
                            return true;
                        } else {
                            device.releaseOutRequest(request);
                            return false;
                        }
                    }
                    return true;
                } else {
                    device.releaseOutRequest(request);
                    return false;
                }
            }
        }

        public boolean readCommand(UsbRequest request) {
            request.setClientData(this);
            return request.queue(mMessageBuffer, 24);
        }

        public boolean readData(UsbRequest request, int length) {
            request.setClientData(this);
            return request.queue(mDataBuffer, length);
        }

        private static String extractString(ByteBuffer buffer, int offset, int length) {
            byte[] bytes = new byte[length];
            for (int i = 0; i < length; i++) {
                bytes[i] = buffer.get(offset++);
            }
            return new String(bytes);
        }

        @Override
        public String toString() {
            String commandName = extractString(mMessageBuffer, 0, 4);
            int dataLength = getDataLength();
            String result = "Adb Message: " + commandName + " arg0: " + getArg0() +
                 " arg1: " + getArg1() + " dataLength: " + dataLength;
            if (dataLength > 0) {
                result += (" data: \"" + getDataString() + "\"");
            }
            return result;
        }

        private static int checksum(byte[] data) {
            int result = 0;
            for (int i = 0; i < data.length; i++) {
                int x = data[i];
                // dang, no unsigned ints in java
                if (x < 0) x += 256;
                result += x;
            }
            return result;
        }
    }

AdbSocket

    package com.android.adb;

    /* This class represents an adb socket.  adb supports multiple independent
     * socket connections to a single device.  Typically a socket is created
     * for each adb command that is executed.
     */
    public class AdbSocket {

        private final AdbDevice mDevice;
        private final int mId;
        private int mPeerId;

        public AdbSocket(AdbDevice device, int id) {
            mDevice = device;
            mId = id;
        }

        public int getId() {
            return mId;
        }

        public boolean open(String destination) {
            AdbMessage message = new AdbMessage();
            message.set(AdbMessage.A_OPEN, mId, 0, destination);
            if (! message.write(mDevice)) {
                return false;
            }

            synchronized (this) {
                try {
                    wait();
                } catch (InterruptedException e) {
                    return false;
                }
            }
            return true;
        }

        public void handleMessage(AdbMessage message) {
            switch (message.getCommand()) {
                case AdbMessage.A_OKAY:
                    mPeerId = message.getArg0();
                    synchronized (this) {
                        notify();
                    }
                    break;
                case AdbMessage.A_WRTE:
                    mDevice.log(message.getDataString());
                    sendReady();
                    break;
            }
        }

        private void sendReady() {
            AdbMessage message = new AdbMessage();
            message.set(AdbMessage.A_OKAY, mId, mPeerId);
            message.write(mDevice);
        }
    }

Answer 2

For additional information on usb and connecting you might find the following article helpfull.

http://android.serverbox.ch/?p=549

The last paragraph explains some of the issue you might face. The example they provide may also show you how to go about reading the data and how you will have to format the messages.

It looks like you face two issue. One setting up your code to read message, which Puspendu's answer aludes to, and the second issue which is "how" to communicate, what messages you will need to send to establish a connection, handshake, and determine the good stuff, i.e. the data you want.

Puspendu has shown one example of reading and writing to a device. However i would imagine that depending on the device you connect, the handshake and message structure will change, hence you'll have to look those parts up (afraid i dont know of any other examples).