Digilent 410-044-10P-KIT Manual de usuario descargar pdf (Pagina 27)

Spartan-3 Starter Kit Board User Guide www.xilinx.com 27

UG130 (v1.1) May 13, 2005 1-800-255-7778

Chapter 6

PS/2 Mouse/Keyboard Port

The Spartan-3 Starter Kit board includes a PS/2 mouse/keyboard port and the standard 6-

pin mini-DIN connector, labeled J3 on the board and indicated as in Figure 1-2.

Figure 6-1 shows the PS/2 connector, and Table 6-1 shows the signals on the connector.

Only pins 1 and 5 of the connector attach to the FPGA. A detailed schematic appears in

Figure A-7.

Both a PC mouse and keyboard use the two-wire PS/2 serial bus to communicate with a

host device, the Spartan-3 FPGA in this case. The PS/2 bus includes both clock and data.

Both a mouse and keyboard drive the bus with identical signal timings and both use 11-bit

words that include a start, stop and odd parity bit. However, the data packets are

organized differently for a mouse and keyboard. Furthermore, the keyboard interface

allows bidirectional data transfers so the host device can illuminate state LEDs on the

keyboard.

The PS/2 bus timing appears Table 6-2 and Figure 6-2. The clock and data signals are only

driven when data transfers occur, and otherwise they are held in the idle state at logic

High. The timings define signal requirements for mouse-to-host communications and

Figure 6-1:

PS/2 DIN Connector

Table 6-1:

PS/2 Connections to the Spartan-3 FPGA

PS/2 DIN Pin Signal FPGA Pin

1 DATA (PS2D) M15

2 Reserved —

3 GND GND

4 Voltage Supply —

5 CLK (PS2C) M16

6 Reserved —

UG130_c6_01_042404

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 63 64

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Digilent 410-044-10P-KIT Manual de usuario Pagina 27