Digilent 410-183P-KIT - Manual (Page 7)

Basys3™ FPGA Board Reference Manual
clocking resources that can be inserted into the user’s design. The Clocking Wizard can be accessed from within IP
Catalog, which can be found under the Project Manager section of the Flow Navigator in Vivado.
5 USB-UART Bridge (Serial Port)
The Basys3 includes an FTDI FT2232HQ USB-UART bridge (attached to connector J4) that allows you to use PC
applications to communicate with the board using standard Windows COM port commands. Free USB-COM port
drivers, available from www.ftdichip.com under the "Virtual Com Port" or VCP heading, convert USB packets to
UART/serial port data. Serial port data is exchanged with the FPGA using a two-wire serial port (TXD/RXD). After
the drivers are installed, I/O commands can be used from the PC directed to the COM port to produce serial data
traffic on the B18 and A18 FPGA pins.
Two on-board status LEDs provide visual feedback on traffic flowing through the port: the transmit LED (LD18) and
the receive LED (LD17). Signal names that imply direction are from the point-of-view of the DTE (Data Terminal
Equipment), in this case the PC.
The FT2232HQ is also used as the controller for the Digilent USB-JTAG circuitry, but the USB-UART and USB-JTAG
functions behave entirely independent of one another. Programmers interested in using the UART functionality of
the FT2232 within their design do not need to worry about the JTAG circuitry interfering with the UART data
transfers, and vice-versa. The combination of these two features into a single device allows the Basys3 to be
programmed, communicated with via UART, and powered from a computer attached with a single Micro USB
cable.
The connections between the FT2232HQ and the Artix-7 are shown in Fig. 6.
TXD B18
Micro-USB
(J4)
2
RXD
Artix-7 FT2232
JTAG
4
JTAG
A18
Figure 6. Basys3 FT2232HQ connections.
6 USB HID Host
The Auxiliary Function microcontroller (Microchip PIC24FJ128) provides the Basys3 with USB HID host capability.
After power-up, the microcontroller is in configuration mode, either downloading a bitstream to the FPGA or
waiting for it to be programmed from other sources. Once the FPGA is programmed, the microcontroller switches
to application mode, which in this case is USB HID Host mode. Firmware in the microcontroller can drive a mouse
or a keyboard attached to the type A USB connector at J2 labeled "USB.” Hub support is not currently available, so
only a single mouse or a single keyboard can be used. The PIC24 drives several signals into the FPGA – two are
used to implement a standard PS/2 interface for communication with a mouse or keyboard, and the others are
connected to the FPGA’s two-wire serial programming port, so the FPGA can be programmed from a file stored on
a USB pen drive.
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
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