Digilent Digilab 2 User Manual

Page 4

Digilent Digilab 2 Reference Manual

Digilent, Inc.

www.digilentinc.com

page 4 of 10

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GND

Data 2 (PD2)

Data 1 (PD1)

Data 0 (PD0)

Data 3 (PD3)

Data 4 (PD4)

Data 5 (PD5)

Data 6 (PD6)

Data 7 (PD7)

Write Enable (PWE)

Interrupt (PINT)

Data Strobe (PDS)

Reset (PRST)

Address Strobe (PAS)

Wait (PWT)

CCLK

DONE

DATA IN

INIT

VDD SENSE
CABLE DET1
CABLE DET2

Decouping
three-state
buffer

GND

Vdd

DB25

connector

Program enable
switch (SW1)

JTAG

PORT

Enable

TMS

TCLK
TDI

TDO

Pull-up resistors are used on all parallel
port signals. They are not shown here.

Xilinx
Spartan 2E
PQ208

P206
P205
P15

P14
P203
P10
P204
P9

P207
P159

P157

SPROM

Pull-ups on INIT and
DONE not shown

8-DIP

P107
P155
P153
P104

M0
M1
M2

Jumper
block

Figure 2. Parallel port and programming circuit schematic

Serial Port

The D2 serial port uses a Maxim MAX3386E RS-232 voltage converter to generate the required RS-
232 voltages. Five signals are connected through the RS-232 converter, allowing for partial hardware
handshaking. The serial port pin definitions and circuit are shown in Figure 3. The serial port is
provided, in part, to support the Xilinx MicroBlaze embedded RSIC processor core available from the
Xilinx website.

The two devices connected to either end of a serial cable are designated as the Data Terminal
Equipment (DTE) and the Data Communications Equipment (DCE). The DCE was originally
conceived to be a modem, but now many devices connect to a computer as a DCE. A DTE device uses
a male DB-9 connector, and a DCE device uses a female DB-9 connector. The DTE is considered the