Xser is PIC18F2553-based serial to USB adapter with a small LCD display. When connected to a computer, the LCD shows the COM port number assigned to the device. This device helps you to find correct COM port for the USB adapter device without need to check it in your control panel.
The firmware on the microcontroller implements a composite USB device which has two “heads”. One “head” implements the CDC protocol to create virtual COM port in computer. The other “head” is uses a proprietary control protocol to set the number shown on the LCD. The last part is host application which detect and finds the device type in hardware list based on their PID and VID numbers. It then determines what is the COM port number assigned to each of them and sends a command to show the number on the LCD screen. Download: Xser Source code