1300 Henley Court
Pullman, WA 99163
509.334.6306
www.digilentinc.com
PmodR2R™ Reference Manual
Revised April 12, 2016
This manual applies to the PmodR2R rev. B
DOC#: 502-165
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 Digilent PmodR2R is an 8-bit Digital-to-Analog converter. It may not look as sleek and professional as some of
the other DACs that are out there, but on a fundamental level that is easy to see, this Pmod does exactly the same
thing as its counterparts.
1 Functional Description
The PmodR2R accepts 8 bits in parallel, either at a logic low or high voltage, which then go through a resistor
ladder to output a desired voltage. The “R2R” resistor ladder is one of the most popular ways that digital-to-analog
converters take a set of digital inputs and create a single analog output, requiring just two resistor values of R and
2*R. Because this Pmod only uses 10K Ω and 20K Ω resistors, very little current is drawn from the input pins.
2 Interfacing with the Pmod
The PmodR2R communicates with the host board via the GPIO protocol. Each of the 8 input pins are expected to
send out either a logic high or logic low voltage signal in such a way that represents the desired binary ratio of the
full analog output.
The PmodR2R.
Features include:
PmodR2R™ 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
Header J1
Pin Number (top row)
Description
Pin Number (bottom row)
Description
1
Data Bit 0
7
Data Bit 4
2
Data Bit 1
8
Data Bit 5
3
Data Bit 2
9
Data Bit 6
4
Data Bit 3
10
Data Bit 7
5
Ground
11
Ground
6
VCC
12
VCC
Table 1. Pinout description table.
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 0.8 inches long on the sides perpendicular to the pin header.