Interfacing a libUSB device powered by V-USB library for AVR

问题

I've wrote a simple program (based on the following tutorial) that send data from an AVR chip (Attiny 2313) to the computer via a USB port, since this device doesn't have a built-in USB port, I've used the V-USB library to emulate such a port via software.

The device works as expected, and I had no problem to interface the it with C using the libusb library, However I want to access it with Java, so I looked up for a java implementation of libusb.The only library that I've managed to set up, and it has successfully found the usb on the bus was "libusb-win32 wrapper".

The only problem is that the device throws an exception when I try to open it

ch.ntb.usb.USBException: No USB endpoints found. Check the device configuration
at ch.ntb.usb.Device.updateMaxPacketSize(Device.java:82)
at ch.ntb.usb.Device.initDevice(Device.java:114)

How can it be fixed? is there another way to do it? any recommendation?

Here is the code that throws the exception

Device dev = USB.getDevice((short) 0x16c0, (short) 0x05dc);
dev.open(1, 0, -1);

here is data I got about the device viw USBview

Device Descriptor:
bcdUSB:             0x0110
bDeviceClass:         0xFF
bDeviceSubClass:      0x00
bDeviceProtocol:      0x00
bMaxPacketSize0:      0x08 (8)
idVendor:           0x16C0
idProduct:          0x05DC
bcdDevice:          0x0100
iManufacturer:        0x01
0x0409: "mymail@gmail.com"
iProduct:             0x02
iSerialNumber:        0x00
bNumConfigurations:   0x01

ConnectionStatus: DeviceConnected
Current Config Value: 0x01
Device Bus Speed:     Low
Device Address:       0x03
Open Pipes:              0

Configuration Descriptor:
wTotalLength:       0x0012
bNumInterfaces:       0x01
bConfigurationValue:  0x01
iConfiguration:       0x00
bmAttributes:         0x80 (Bus Powered )
MaxPower:             0x32 (100 Ma)

Interface Descriptor:
bInterfaceNumber:     0x00
bAlternateSetting:    0x00
bNumEndpoints:        0x00
bInterfaceClass:      0x00
bInterfaceSubClass:   0x00
bInterfaceProtocol:   0x00
iInterface:           0x00

related question the answer, but I couldn't understand what to change, and if its related to the device, how can it be done with a VUSB?

回答1:

The following library doesn't support a device with no endpoint, and doesn't count the control endpoint as an endpoint.I solve that by enabling another endpoint which I won't use anyway.

To enable another endpoint open the following file usbconfig.h within the V-usb folder and look up for the following line and change it to 1.

#define USB_CFG_HAVE_INTRIN_ENDPOINT    1 //default 0

Now, you can use the control endpoint for low speed communication with the controlMsg() function.

here you can see (via USBview) that the device now has an interruption endpoint

Endpoint Descriptor:
bEndpointAddress:     0x81  IN
Transfer Type:   Interrupt
wMaxPacketSize:     0x0008 (8)
bInterval:            0x0A

来源：https://stackoverflow.com/questions/14129112/interfacing-a-libusb-device-powered-by-v-usb-library-for-avr

标签

java

usb

libusb