USB Device Printer Function Driver Events 

These events are specific to the USB Device Printer Function Driver instance. Each event description contains details about the parameters passed with event. The contents of pData depends on the generated event.

typedef enum {
  USB_DEVICE_PRINTER_GET_PORT_STATUS,
  USB_DEVICE_PRINTER_EVENT_WRITE_COMPLETE,
  USB_DEVICE_PRINTER_EVENT_READ_COMPLETE
} USB_DEVICE_PRINTER_EVENT;

The USB Device Printer control transfer related events allow the application to defer responses. This allows the application some time to obtain the response data rather than having to respond to the event immediately. Note that a USB host will typically wait for event response for a finite time duration before timing out and canceling the event and associated transactions. Even when deferring response, the application must respond promptly if such time outs have to be avoided.