I'm trying to use V-Usb to control a display, among other things. To send text to the display I thought I would use control messages, using usbFunctionWrite() to get the string data.
I've got the communication up and running: there are valid calls to usbFunctionSetup(), but usbFunctionWrite() is never called. Thus I never get any data.
I've created a very basic program based on libusb running on Ubuntu. When I call usb_control_msg() to send the string data i get error -75 returned ("Value too large for defined data type"). I need some help to decode that!
My call to usb_control_msg() looks like this:
Code: Select all
char *buf = "Hello World";
usb_control_msg (handle, USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_ENDPOINT_OUT, 123, 0, 0, buf, strlen (buf), 5000);