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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 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. Features include: 8-bit digital-to-analog conversion Convert data at up to 25MHz Easy attachment of oscilloscopes to illustrate the data conversion process Small PCB size for flexible designs 1.0 0.8 (2.54 cm 2.0 cm) 26-pin Pmod port with GPIO interface Follows Digilent Interface Specification Type 1 The PmodR2R. 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 and 20K 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. Copyright Digilent, Inc. All rights reserved. DOC : 502-165 Page 1 of 2 Other product and company names mentioned may be trademarks of their respective owners. PmodR2R Reference Manual 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. Copyright Digilent, Inc. All rights reserved. Page 2 of 2 Other product and company names mentioned may be trademarks of their respective owners.