Digilent System Board Capabilities Serial Port (RS-232) Parallel Port 1 Pushbutton Hint: Good for a reset button Connected to a clock input. See Digilent Inc.'s reference design for how use it 1 LED 50 Mhz Oscillator GCK0 (pin 80)

RS232 5 wire serial interface Rx,Tx RTS,CTS (hardware flow control) DSR Requires a UART Rx and Tx are the only lines needed RS-232 UARTS Opencores.org (several) Xilinx appnotes (several) 

RS232 UART Functions Parallel-serial conversion (transmit) Serial-parallel conversion (receive) Start bit, stop bit, parity bit(optional) Baud rate generation (not always) UART uses the start bit to syncronize its internal clock to the incoming data Stop bit indicates end of data Misread or missing stop bit indicates a framing error Parity Bit XOR operation Detects single bit errors

Parallel Port 8 bit data transfers No serial to parallel conversion needed Extra control lines required  Address Strobe, data strobe, interrupt, reset, write enable 2 Mbit/s capable EPP timing diagrams not given in users manual Specified in IEEE 1284 Standard

Digital I/O Board

Board-to-board Connectors

XC95108 CPLD Interfaces between Discrete devices and FPGA 7 segment displays LED's Switches Buttons Timing Diagrams Page 15 of dio2 users manual DIO2 board does not have a local oscillator 7-segment display uses BOCI input signal  256Hz – 1kHz input clock required

CPLD Interfacing LED and 7-segment are write only Must write to all devices at that address simultaneously Buttons and switches are read-only

Buttons & Switches Must poll CPLD to detect when a button or switch has changed The CPLD does NOT debounce the inputs 1ms debounce for pushbuttons needed 2ms debounce for switches needed The CPLD does NOT sychronize the asynchronous inputs Inputs will be asynchronous to the FPGA

DIO2 Self test Starting self Test SW1 => VDD SW8 => GND Press Button 7,E, & 0 to start self-test Press Button 0 to finish self-test Self-test Buttons control LED Switches control 7-segment displays

PS2 port Keyboard or Mouse input Interfacing with Keyboard or Mouse similar to RS- 232 protocol 1 start bit 1 stop bit 1 parity bit Separate clock line used to synchronize data More reliable than start bit No baud rate generation required (input clock gives the baud rate) Half-duplex 2-wire serial

LCD Samsung KS0066 Controller 208 preset characters 8 user defined 80 character RAM (Frame buffer)  Only 32 can be displayed at any time Informative LCD site Application notes Data sheets

VGA 8 bit color (3 green, 3 blue, 2 red) 60 Hz, 640 x 480 display Write every pixel to screen in 16.7 ms 307,200 pixels on a 640 x 480 display 2,457,600 bit frame buffer needed (300 Kbytes) 17.6 Mbytes/sec bandwidth from FPGA to Monitor  Easily done by FPGA  Getting data into FPGA is a problem 56 Kbits Block RAM available Could possibly hold a 80 x 80 frame buffer Use internal FPGA logic for a larger frame buffer