android - 传输数据 USB

Question

我正在尝试通过 USB 发送和接收数据，我的设备，Acer Iconia A500 拥有连接到设备所需的一切，一切都很好并且工作正常，但是当我尝试发送和接收数据时，它的行为不像预期的。这是我的代码

for( ; ; ) { //this is the main loop for transferring   
    String get = "$getPos";
    byte[] getBytes = get.getBytes();
    conn.bulkTransfer( epOUT, getBytes, getBytes.length, 500 );

    try {
        Thread.sleep( 500 );
        byte[] buffer = new byte[4096];
        conn.bulkTransfer( epIN, buffer, 4096, 500 );
        StringBuilder byStr = new StringBuilder();

        for( int i = 0; i < buffer.length; i++ ) {
            if( buffer[i] != 0 ) {
                byStr.append( buffer[i] + ", " );
            }
        }

        l( byStr );
    }
    catch( InterruptedException e ) {
        e.printStackTrace();
    }

    if( mStop ) {
        mStopped = true;
        return;
    }

    l( "sent " + counter );
    counter++;
    counter = (byte)( counter % 16 );
}

它的意思是返回一个大约 80 个字符长的字节数组，但它只返回两个字节，即 1 和 96，如果 USB 设备端出现错误，它仍然会返回几个多于两个。我的代码甚至接近正确吗？我基于 serverbox 的 USB 转串口文章。

Answer 1

我试图以错误的波特率发送数据。

这是有效的代码。为所有使用 FTDI 设备并需要帮助的人发布它。

private Runnable mLoop = new Runnable() {

        @Override
        public void run() {
            UsbDevice dev = sDevice;
            if (dev == null)
                return;
            UsbManager usbm = (UsbManager) getSystemService(USB_SERVICE);
            UsbDeviceConnection conn = usbm.openDevice(dev);
            l("Interface Count: " + dev.getInterfaceCount());
            l("Using "
                    + String.format("%04X:%04X", sDevice.getVendorId(),
                            sDevice.getProductId()));

            if (!conn.claimInterface(dev.getInterface(0), true))
                return;

            conn.controlTransfer(0x40, 0, 0, 0, null, 0, 0);// reset
                                                            // mConnection.controlTransfer(0×40,
                                                            // 0, 1, 0, null, 0,
                                                            // 0);//clear Rx
            conn.controlTransfer(0x40, 0, 2, 0, null, 0, 0);// clear Tx
            conn.controlTransfer(0x40, 0x02, 0x0000, 0, null, 0, 0);// flow
                                                                    // control
                                                                    // none
            conn.controlTransfer(0x40, 0x03, 0x0034, 0, null, 0, 0);// baudrate
                                                                    // 57600
            conn.controlTransfer(0x40, 0x04, 0x0008, 0, null, 0, 0);// data bit
                                                                    // 8, parity
                                                                    // none,
                                                                    // stop bit
                                                                    // 1, tx off

            UsbEndpoint epIN = null;
            UsbEndpoint epOUT = null;

            byte counter = 0;

            UsbInterface usbIf = dev.getInterface(0);
            for (int i = 0; i < usbIf.getEndpointCount(); i++) {
                l("EP: "
                        + String.format("0x%02X", usbIf.getEndpoint(i)
                                .getAddress()));
                if (usbIf.getEndpoint(i).getType() == UsbConstants.USB_ENDPOINT_XFER_BULK) {
                    l("Bulk Endpoint");
                    if (usbIf.getEndpoint(i).getDirection() == UsbConstants.USB_DIR_IN)
                        epIN = usbIf.getEndpoint(i);
                    else
                        epOUT = usbIf.getEndpoint(i);
                } else {
                    l("Not Bulk");
                }
            }

            for (;;) {// this is the main loop for transferring
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                String get = "$fDump G" + "\n";
                l("Sending: " + get);

                byte[] by = get.getBytes();

                // This is where it sends
                l("out " + conn.bulkTransfer(epOUT, by, by.length, 500));

                // This is where it is meant to receive
                byte[] buffer = new byte[4096];

                StringBuilder str = new StringBuilder();

                if (conn.bulkTransfer(epIN, buffer, 4096, 500) >= 0) {
                    for (int i = 2; i < 4096; i++) {
                        if (buffer[i] != 0) {
                            str.append((char) buffer[i]);
                        } else {
                            l(str);
                            break;
                        }
                    }

                }
                // this shows the complete string
                l(str);

                if (mStop) {
                    mStopped = true;
                    return;
                }
                l("sent " + counter);
                counter++;
                counter = (byte) (counter % 16);
            }
        }
    };