Getting Started Guide for LX9 and Nexys3 User Manual

Analog Essentials Getting Started Guide
9
For LX9 and Nexys-3
3. Setting Up the PC for Communication
Before loading the executable software file, the serial communications program should be opened so that the
PC is ready to communicate with the FPGA board once the software begins executing. The example/demo
software running on the host board communicates with the PC via a USB port set up to emulate a serial port
(UART). To establish this communication link, the PC must be configured with the appropriate Windows drivers.
While the drivers for both the LX9 and Nexys-3 are functionally equivalent, the boards use different USB-UART
bridge ICs. Therefore, the boards use different drivers. Also, a suitable communications program such as
HyperTerminal should be invoked.
a. The Nexys-3 utilizes the FTDI USB UART, so you need to install FTDI’s virtual COM port drivers. These
may be obtained from the FTDI
website. (www.ftdichip.com/Drivers/VCP.h) Note: the Windows®
operating system generally performs this step automatically the first time the USB on the host is
connected to the PC’s USB port, so the driver might already be installed.
The LX9 also utilizes a USB UART in a similar fashion. However, the USB UART IC used on the LX9 is the
CP2102 from Silicon Labs. Follow the same instructions as above but install the driver from the Silicon
Labs
website. (http://www.silabs.com/products/mcu/pages/usbtouartbridgevcpdrivers.aspx)
Once installed, Windows will assign a previously unused COM port. Use Control Panel | System | Device
Manager to determine the COM port number. (It will be named USB Serial Port). Make a note of which
COM port this is. That information is needed in the next step.
b. Next, a terminal emulation program needs to be installed and launched. For Windows XP® and earlier
systems, the Hyperterminal program is the usual choice. However, since Hyperterminal was eliminated
from Windows 7, it may be necessary to locate an alternative. Several are available, one of which is
called “PuTTY” (
www.putty.org). Whatever program you choose, the communication should be set up as
follows: bits per second: 115,200
; data bits: 8; parity: none; stop bits: 1; and flow control: none.