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PmodSSD Reference Manual
Revised May 24, 2016
This manual applies to the PmodSSD rev. A
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.
Features include:
Two-digit high brightness seven-segment
display
Easily view a counter or timer
Common Cathode configuration
Small PCB size for flexible designs 1.0
1.7 (2.5 cm 4.3 cm)
Two 6-pin Pmod connectors
with GPIO interfaces
Follows Digilent Pmod Interface
Specification Type 1
The PmodSSD.
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.
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PmodSSD Reference Manual
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.
560
AA
P1
AB
P2
AC
P3
AD
P4
AA1 AA2
GND AB1 AB2
AC1 AC2
Vcc
AD1 AD2
AE1 AE2
AF1 AF2
AE AG1 AG2
P1
AF
P2 C1
C2
AG
P3
C
P4
GND
GND
Vcc
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.
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Page 2 of 2
Other product and company names mentioned may be trademarks of their respective owners.
J2 Connector J1 Connector