iST HYT 221 Evaluation Kit for Digital Humidity Modules User Guide
- June 4, 2024
- iST
Table of Contents
iST HYT 221 Evaluation Kit for Digital Humidity Modules
Description
The purpose of this evaluation board is to facilitate the evaluation of HYT
sensor modules for humidity and temperature. The evaluation board enables to
connect a HYT module and if required convert its digital I2C signal into an
analog voltage signal to test the module under the environmental conditions of
the intended application. The output signals are proportional to the two
parameters measured: relative humidity and temperature. The transmitter can
also be connected directly to a PC via a USB cable for signal read-out and
logging. The transmitter communication protocol is compatible with standard
Arduino IDE software.
If additional mechanical protection during evaluation tests is required, the
transmitter can be placed in a housing. It is compatible e.g. with the
following housing type: RND 455-01083
Schematics
Compatibility
The evaluation board is compatible with all IST AG humidity modules of the HYT family.
HYT271 Material no. 153349
HYT939 Material no. 103923
HYT 221Material no.103922
The material numbers refer to our standard versions, which are available in the IST AG webs hop. For custom calibration or housing solutions please contact our customer service.
Input
For the communication between transmitter and HYT humidity module the digital
I2C protocol is applied. The transmitter is pre-programmed to recognize a HYT
module with the default I2C address 0x28. For information on how to change the
I2C address of a HYT module, please refer to the HYT application note
available from the IST AG website. Please note that no more than one HYT
humidity module is to be connected to the transmitter at any given time.
Refer to Schematics (1.1) for position of the following ports:
The recommended maximum length of the extension cable is 30 cm. The quality of signal transmittance depends on operational conditions and the cable material.
The following images show the correct orientation of the HYT modules in the socket along with the corresponding pin alignment of the modules.
Modules HYT271 and HYT221
Input socket 1
Module HYT939
Input socket 2 and HYT939 pin assignment
All modules via extension cable
Input connector J2
Please see pin assignment above. The recommended maximum length of the extension cable is 30 cm.
Power supply and outputs
The transmitter can be powered via USB cable from a PC or from a DC power
source. Please refer to Schematics (1.1) for the position of the corresponding
connectors.
Power supply requirements:
Signal transmission
Analog output
The analog voltage signals transmitted are directly proportional to the measured parameters. The following measuring and signal ranges represent the default HYT calibration:
The effectively measured values can be calculated according to the following formula:
Digital outputs
The measured values are transmitted via USB.
A terminal software such as PuTTY can be applied to read out and log data.
Start-up:
- Connect a HYT humidity module to the correct port on the evaluation board. Refer to the corresponding pin assignments for the orientation (match SDA/ VCC/ GND/ SCL).
- Connect the evaluation board to a PC using a USB cable.
- Determine the COM Port number assigned (e.g. look for Arduino Micro in the Ports section of the Windows device manager)
- Start the terminal software PuTTY.
- Select Serial and enter the COM port number. Set Speed to 9600.
- Click Open to connect the board.
- In the empty window that appears, press the key “m” for measure. Measured values for relative humidity and temperature are displayed.
Functions:
- m Single point measurement
- l nnn Start automatic measurement with set interval nnnn = interval in mSec. (e.g. l 1000 shall log a measurement every 1000 mSec, i.e. 1 second)
To stop an automatic interval measurement, press ,,m” again
Measurement data can be logged and exported in form of a log file from the
PuTTY terminal.
Arduino IDE Connection
The Arduino IDE software allows to:
- Read out data
- Update or modify firmware
The Evaluation is supplied with the latest firmware version for direct use. No updates are required or recommended. Therefore, please avoid flashing the firmware of the board. Do NOT press the Upload button. Please note that IST AG does not warranty any functionality of the evaluation board after any firmware modification performed by our customers.
To establish a connection with Arduino IDE, please apply following settings:
-
Go to Tools and select Board: Arduino Micro
-
Select the Port marked with Arduino Micro
-
Go to Serial Monitor (icon in the top right corner) to open a new window
-
Check that the baudrate is set to 9600
-
Enter m in the command line to start a single point measurement
Order information
Resources and download links
Visit www.ist-ag.com and go to the Download section for the following documents:
- Datasheets for individual humidity modules HYT271, HYT221, HYT939
- Application note with handling instructions for HYT modules
- Software to change the I2C address of a HYT module
- Firmware for the evaluation board (published on www.ist-ag.com/download) Terminal Software PuTTY: www.putty.org
For the latest Version of Arduino IDE please visit https://www.arduino.cc/ and follow the installation instructions. Please note that additional libraries are required to compile custom firmware.
Disclaimer
The HYT evaluation board is designed solely for preliminary evaluation purposes and tests with IST AG`s humidity modules from the HYT family under laboratory conditions. It is not suitable as an electronic component for any type of product. It remains an engineering board, and the electronic layout is subject to changes without prior notice.
Contact
Please contact IST AG for individually designed sensor solutions, including
signal evaluation and housing. We will be happy to support you with the
development and manufacturing of an OEM humidity module to fit your specific
requirements.
Please visit our website and get in touch with IST AG for personal support:
https://www.ist-ag.com/en/contact
We look forward advising you on the perfect sensor solution for your
application!
Your IST AG Team
Innovative Sensor Technology IST AG
Stegrütistrasse 14
9642 Ebnat-Kappel Switzerland
[email protected]
+41 71 992 01 00
Innovative Sensor Technology IST AG, Stegrütistrasse 14, 9642 Ebnat-Kappel,
Switzerland
Phone: +41 71 992 01 00
Fax: +41 71 992 01 99
Email: [email protected] | www.ist-ag.com
All mechanical dimensions are valid at 25 °C ambient temperature, if not differently indicated
- All data except the mechanical dimensions only have information purposes and are not to be understood as assured characteristics
- Technical changes without previous announcement as well as mistakes reserved
- Load with extreme values during a longer period can affect the reliability
- The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner · Product specifications are subject to change without notice
- All rights reserved
References
- IST AG | Innovative Sensor Technology
- Download | IST AG
- Download PuTTY - a free SSH and telnet client for Windows
- Arduino - Home
- Get in touch with our team of experts & distributors | IST AG