Empty data from device

[Mikołaj Sochacki]

Hi, I'm trying to read data from device. Code seems work, but I receive a empty data filled with 0. Its no mater if I use hight level API or low. In low level I get ByteBuffer with 0. What am I doing wrong? I'm using Ubuntu Linux 64-bit, and I gave in udev proper rights for user.

My simple code for high level API:

import javax.usb.UsbConfiguration;
import javax.usb.UsbDevice;
import javax.usb.UsbDeviceDescriptor;
import javax.usb.UsbEndpoint;
import javax.usb.UsbHostManager;
import javax.usb.UsbHub;
import javax.usb.UsbInterface;
import javax.usb.UsbInterfacePolicy;
import javax.usb.UsbPipe;
import javax.usb.UsbServices;

import org.usb4java.Device;
import org.usb4java.DeviceHandle;
import org.usb4java.LibUsb;

import java.util.List;

public class Main {
    public static void main(String[] args) throws Exception {
        System.setProperty("javax.usb.services", "org.usb4java.javax.Services");
        UsbServices services = UsbHostManager.getUsbServices();
        UsbHub rootHub = services.getRootUsbHub();
        UsbDevice device = findDevice( rootHub, (short) 0x10c4, (short)  0xea60);
        System.out.println(device.getUsbDeviceDescriptor().toString());
        UsbConfiguration configuration = device.getActiveUsbConfiguration();
        UsbInterface iface = configuration.getUsbInterface((byte) 0);
        System.out.println("iface active " + iface.isActive());
        iface.claim(new UsbInterfacePolicy()
        {           
            @Override
            public boolean forceClaim(UsbInterface usbInterface)
            {
                return true;
            }
        });
        try
        {
//            UsbEndpoint endpoint = iface.getUsbEndpoint((byte) 0x02);
//            UsbPipe pipe = endpoint.getUsbPipe();
//            pipe.open();
//            try
//            {
//                int sent = pipe.syncSubmit(new byte[] { 65, 66, 67, 68, 69, 70, 71, 72 });
//                System.out.println(sent + " bytes sent");
//            }
//            finally
//            {
//                pipe.close();
//            }
            UsbEndpoint endpoint = iface.getUsbEndpoint((byte) 0x01);
            UsbPipe pipe = endpoint.getUsbPipe();
            pipe.open();
            try
            {
                byte[] data = new byte[8];
                int received = pipe.syncSubmit(data);
                System.out.println(received + " bytes received " + new String(data));
            }
            finally
            {
                pipe.close();
            }
       
        }
        finally       
        {
            iface.release();
        }
      
    }
    public static UsbDevice findDevice(UsbHub hub, short vendorId, short productId)
    {
        for (UsbDevice device : (List<UsbDevice>) hub.getAttachedUsbDevices())
        {
            UsbDeviceDescriptor desc = device.getUsbDeviceDescriptor();
            if (desc.idVendor() == vendorId && desc.idProduct() == productId) return device;
            if (device.isUsbHub())
            {
                device = findDevice((UsbHub) device, vendorId, productId);
                if (device != null) return device;
            }
        }
        return null;
    }

}

Thank you for advance,

Nikolas.

[Mikołaj Sochacki]

The problem was causing  by drivers on Linux. I didn't find proper driver for device. Module cp210x not works with some devices by USB to UART bridge.