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1300 Henley Court

Pullman, WA 99163

509.334.6306

www.digilent.com

Pmod HYGRO Reference Manual

Revised February 22, 2017

This manual applies to the Pmod HYGRO rev. A

DOC#: 510-347

Other product and company names mentioned may be trademarks of their respective owners.

Page 1 of 6

Overview

The Digilent Pmod HYGRO (Revision A) is small relative humidity and temperature sensor. With the TI HDC1080,

you can determine the relative humidity of the environment with up to 14 bits of resolution.

1 Functional Description

The Pmod HYGRO is designed to digitally report the relative humidity and ambient temperature upon request by

the host board. Up to 14-bits of resolution for each sensor may be collected by allowing for longer conversion

times. A resistive heating element can be enabled to drive off condensation that accumulates on the sensor after

being exposed at high humidity conditions.

2 Specifications

Parameter

Min

Typical

Max

Units

Power Supply Voltage

2.7

5.5

Serial Clock Frequency

400

kHz

The Pmod HYGRO.

 Relative humidity accuracy ±2%

 Temperature sensor accuracy 0.2 °C

 Good stability at high humidity

 14-bit measurement resolution

 Internal resistive heating element

 6-pin Pmod connector with I²C interface

 Pass-through Pmod host port for daisy chaining

Features:

Summary of content (6 pages)

PAGE 1
300 Henley Court Pullman, WA 99163 509.334.6306 www.digilent.com Pmod HYGRO Reference Manual Revised February 22, 2017 This manual applies to the Pmod HYGRO rev. A Overview The Digilent Pmod HYGRO (Revision A) is small relative humidity and temperature sensor. With the TI HDC1080, you can determine the relative humidity of the environment with up to 14 bits of resolution. Features:        Relative humidity accuracy ±2% Temperature sensor accuracy 0.
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Pmod HYGRO Reference Manual Parameter RH Accuracy RH Repeatability RH Hysteresis RH Response Time Temperature Accuracy Sleep Mode Current Draw 3 Value ±2 ±0.1 ±1 15 ±0.2 100 Units %RH %RH %RH sec ̊C nA Interfacing with the Pmod The Pmod HYGRO communicates with the host board via the I²C protocol.
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Pmod HYGRO Reference Manual 3.2 Temperature and Humidity Registers The temperature register (address 0x00) and the humidity register (address 0x01) are both 16-bit read only registers with the 14 MSBs corresponding to the 14-bit maximum resolution for both sensors. The two LSBs (bits D1 and D0) are always 0 for both registers. As the measurement resolution increases, the corresponding conversion time for each sensor also increases. A table of typical conversion times from Section 7.
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Pmod HYGRO Reference Manual I2CReadMultiple(4); //read four bytes, sending an ACK to the slave after each byte received and a NACK after the last byte 8. Convert the readings into usable data. Note that the two LSBs (D1 and D0) will always be set to a value of 0. Only the upper 14-bits in each register contains the relevant data 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 (℃) = 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 [15: 00] ∗ 165℃ − 40℃ 216 𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝐻𝑢𝑚𝑖𝑑𝑖𝑡𝑦 (%𝑅𝐻) = 9. 3.
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Pmod HYGRO Reference Manual Figure 1. Example write to the Pmod HYGRO (from the HDC1080 datasheet). Figure 2. Example reading from the Pmod HYGRO (from the HDC1080 datasheet). 4 Physical Dimensions The pins on the pin header are spaced 100 mil apart. The PCB is 1.25 inches 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. 5 Additional Information The schematics of the Pmod HYGRO are available here.
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Pmod HYGRO Reference Manual If you have any questions or comments about the Pmod HYGRO, feel free to post them under the appropriate section (“Add-on Boards”) of the Digilent Forum. Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.