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PmodSSD™ Reference Manual
Revised May 24, 2016
This manual applies to the PmodSSD rev. A
DOC#: 502-126
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 1 of 2
Overview
The PmodSSD is a two-digit seven-segment display. Users can toggle through GPIO signals which digit is currently
on at a rate of 50Hz or greater to achieve persistence-of-vision to give the effect of both digits being lit up
simultaneously.
1 Functional Description
The PmodSSD utilizes a common cathode configuration to display a variety of LED segment combinations. The ten
segment combinations corresponding to digits 0 - 9 are generally the most useful, although other custom
combinations can also be created.
2 Interfacing with the Pmod
The PmodSSD communicates with the host board via the GPIO protocol. A logic level high signal on a particular
anode will light up that respective segment on whichever digit is currently enabled. Users are able to select a
particular digit by driving the Digit Selection pin (C) to a logic high or low voltage.
The PmodSSD.
Features include:
PmodSSD™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 2 of 2
Because only one digit can be lit at a particular time, users that want to use both digits to display a particular value
will need to alternately light up the two digits at least every 20 milliseconds (50 Hz). This will correlate to each digit
being lit up for 10 milliseconds each before the other segment needs to be “turned on”. Higher refresh rates can
be achieved by alternating which digit is currently powered at shorter time intervals.
Header J1
Header J2
Pin
Signal
Description
Pin
Signal
Description
1
AA
Segment A
1
AE
Segment E
2
AB
Segment B
2
AF
Segment F
3
AC
Segment C
3
AG
Segment G
4
AD
Segment D
4
C
Digit Selection pin
5
GND
Power Supply Ground
5
GND
Power Supply Ground
6
VCC
Positive Power Supply
6
VCC
Positive Power Supply
Table 1. Pinout description table.
J1 Connector
P1
P2
P3
P4 AA1
AB1
AC1
AD1
AE1
AF1
AG1
C1
AA2
AB2
AC2
AD2
AE2
AF2
AG2
C2
GND
Vcc
AE
AF
AG
C
GND
Vcc
560
AA
AB
AC
AD
J2 Connector
P1
P2
P3
P4
GND
Vcc
Figure 1. Seven-segment display connection diagram.
Any external power applied to the PmodSSD must be within 2.7V and 5.25V; however, it is recommended that
Pmod is operated at 3.3V.
3 Physical Dimensions
The pins on the pin header are spaced 100 mil apart. The PCB is 1 inch long on the sides parallel to the pins on the
pin header and 1.7 inches long on the sides perpendicular to the pin header.