Data Sheet

Nexys Video™ FPGA Board Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 20 of 29
The Nexys Video features four Pmod ports of different "styles" with subtle differences between them.
Table 9 summarizes these differences.
Pmod
connector
Power
Analog/Digital
Routing
Series
protection
Recommended usage
JXADC
V
ADJ
Dual
Differential; Pairs:
1-7,2-8,3-8,4-10
100 ohm
Analog inputs; LVDS_25
input/output (V
ADJ
=2.5V)
JA
3.3 V
Digital-only
Single-ended
200 ohm
<10 MHz, LVCMOS33
JB, JC
3.3 V
Digital-only
Differential; Pairs:
1-2,3-4,7-8,9-10
0 ohm
>=10MHz; LVDS_25 input only,
or TMDS_33 input/output
Table 9. Pmod differences.
JXADC is a dual digital/analog Pmod wired to auxiliary analog FPGA input pins (see description below). JA, JB, and
JC are digital-only but routed in a different manner. JA signal traces are routed as single-ended signals with no
length matching or characteristic impedance guarantees. JB and JC connector signals, on the other hand, are
routed differentially in pairs at 100 ohm characteristic impedance. Inter-pair matching is +- 20mm. The series
resistor on these two Pmods are replaced by 0 ohm shunts, so care must be exercised not to use voltages higher
than 3.3V, or short FPGA-driven pins.
For slow, single-ended digital signals below 10 MHz, all Pmod ports are equivalent, assuming V
ADJ
is set to 3.3 V
(see the Regulatory Warning
Warning: This is a class A product. In a domestic environment this product may cause radio interference, in which
case the user may be required to take adequate measures.
1 Power Supplies section). For higher frequencies, the routing and series protection need to be taken into
account as well.
PMOD Pinouts
JA1: AB22
JB1: V9
JC1: Y6
JXADC1: J14
JA2: AB21
JB2: V8
JC2: AA6
JXADC2: H13
JA3: AB20
JB3: V7
JC3: AA8
JXADC3: G15
JA4: AB18
JB4: W7
JC4: AB8
JXADC4: J15
JA7: Y21
JB7: W9
JC7: R6
JXADC7: H14
JA8: AA21
JB8: Y9
JC8: T6
JXADC8: G13
JA9: AA20
JB9: Y8
JC9: AB7
JXADC9: G16
JA10: AA18
JB10: Y7
JC10: AB6
JXADC10: H15
Table 10. Nexys Video Pmod pin assignments.
Digilent produces a large collection of Pmod accessory boards that can attach to the Pmod expansion connectors
to add ready-made functions like A/Ds, D/As, motor drivers, sensors, and other functions. Visit Digilent's website
and check out the Pmod category for more information.
10.1 Dual Analog/Digital Pmod