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 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 0.2 C Good stability at high humidity 14-bit measurement resolution Internal resistive heating element 6-pin Pmod connector with IC interface Pass-through Pmod host port for daisy chaining The Pmod HYGRO. 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 3 5.5 V Serial Clock Frequency 10 400 kHz Copyright Digilent, Inc. All rights reserved. DOC : 510-347 Page 1 of 6 Other product and company names mentioned may be trademarks of their respective owners. Pmod HYGRO Reference Manual Parameter Value Units RH Accuracy 2 %RH RH Repeatability 0.1 %RH RH Hysteresis 1 %RH RH Response Time 15 sec Temperature Accuracy 0.2 C Sleep Mode Current Draw 100 nA 3 Interfacing with the Pmod The Pmod HYGRO communicates with the host board via the IC protocol. By first sending the 7-bit IC address of 1000000 (0x40) and then a read/write bit (high/low logic level, respectively), followed by the register address of interest at a maximum clock frequency of 400 kHz, users can both configure and read from the Pmod HYGRO. Header J2 on the Pmod HYGRO passes through all of the signals present on the main Header J1 to allow for the daisy chaining of multiple IC compatible modules. 3.1 Configuration Register The Configuration register (address 0x02) allows users to control the resolution of the temperature and humidity measurements, change the acquisition mode, enable the heater, and more. A table of the 16-bit register, recreated from Table 4 in the HDC1080 datasheet, is provided below. Bit Name Bit Number Bit Description Bit Values Functional Description 1 0 Normal Operation, this bit self clears RST 15 Software reset bit 1 Software Reset Reserved 14 Reserved 0 Reserved, must be 0 1 0 Heater Disabled HEAT 13 Heater 1 Heater Enabled Temperature or Humidity is acquired 0 depending on which register you choose to read MODE 12 Acquisition Mode Temperature and Humidity are 1 1 acquired in sequence, with the Temperature first Battery voltage (Vdd) > 2.8V (read 1 0 only) BTST 11 Battery Status Battery voltage (Vdd) < 2.8V (read 1 only) 1 Temperature 0 14 bit TRES 10 Measurement 1 11 bit Resolution 1 00 14 bit Humidity HRES 9:8 Measurement 01 11 bit Resolution 10 8 bit Reserved 7:0 Reserved 0 Reserved, must be 0 1 This is the default value on power-up or reset. Table 3. Configuration register description (Address 0x02). Copyright Digilent, Inc. All rights reserved. Page 2 of 6 Other product and company names mentioned may be trademarks of their respective owners.