Application Note Humidity Module HYT
Application Note Humidity Module Content 1. HYT 271 3 2. HYT 221 7 3. HYT 939 9 4. I2C Protocol Description 11 5. I2C Address Change 15 6. HYT Labkit 18 7. LCD Module for HYT 271 22 8. Additional documents: 23 AHHYTM_E2.2.
Application Note Humidity Module HYT 1. HYT 271 Mechanically robust, chemical resistant and dew formation resistant, the digital humidity sensor with only 10.2 mm x 5.1 mm x 1.8 mm size offers the widest application window and an optimal price performance ratio. Precisely calibrated, the HYT 271 delivers an accuracy of ±1.8 % RH and ±0.2 °C - ideal for sophisticated mass applications, industrial handheld devices and precise humidity transmitters.
Application Note Humidity Module HYT Mechanical Dimensions Pin Assignment 1 2 3 4 SDA GND VDD SCL 1.1 Packaging The digital humidity sensor HYT 271 is packaged in a plastic blister. Be careful when opening the plastic blister to avoid damaging the sensor. To avoid damages handle as follows: 1. Digital humidity sensors delivered in plastic blister 2. Open the plastic blister carefully 3. Take the sensors from the blister with plastic tweezers 4.
Application Note Humidity Module HYT 1.2 Storage Temperature The digital humidity sensor HYT 271 has to be stored in the original plastic blister only. Storage temperature (limited by the plastic tube): -20 °C to +50 °C 1.3 Active Sensor Area 1.4 Sensor Handling Hold the sensor with plastic tweezers or with gloves on the wires only Sensor held with plastic tweezers on the wires only Sensor held with gloves on the wires only Examples of prohibited handling: Sensor picked on the active area AHHYTM_E2.
Application Note Humidity Module HYT Sensor picked on the active area with metal tweezers ▪▪ ▪▪ ▪▪ ▪▪ ▪▪ ▪▪ Sensor held with fingers without gloves Do not touch the active area of the sensor Do not use metal tweezers to handle the sensors Never handle the sensor by hand without gloves Avoid mechanical stress to the sensor, e.g. bending or touching the sensor with sharp objects Hold the sensor with plastic tweezers on the wires and side edges only Do not touch or scratch the active area of the sensors.
Application Note Humidity Module HYT 2. HYT 221 The round stainless steel casing can easily be fitted into housing openings and can be sealed against the wall with the use of an O-ring. Combined with the waterproof metal filter, it results into an assembly that is splash water proof and enables a sealed housing construction while providing a high dynamic responsiveness. Precisely calibrated, the HYT 221 delivers an accuracy of ±1.8 % RH and ±0.2 °C.
Application Note Humidity Module HYT Mechanical Dimensions Pin Assignment 1 2 3 4 SDA GND VCC SCL AHHYTM_E2.2.
Application Note Humidity Module HYT 3. HYT 939 Precisely calibrated, the HYT 939 delivers an accuracy of ±1.8 % RH and ±0.2 °C. Further features are the integrated signal processing for measuring the physical parameters of relative humidity and temperature, the I2C compatible interface, easy interchangeability without adjustment as well as mechanical robustness, chemical resistance, dew formation resistance and long-term stability.
Application Note Humidity Module HYT Mechanical Dimensions Pin Assignment bottom view 1 2 3 4 SCL VCC GND SDA 3.1 Mounting Instructions The media compatibility of the sensor, housing and sealing materials are to be checked and kept suitable as per the application. The housing and the assembly must be so constructed that it can withstand the application pressure multiplied by the factor of safety.
Application Note Humidity Module HYT Version 1 Version 2 Legal Notice: The recommendations for construction are unbinding; alterations are possible in the recommendations at any time without prior notice. Any liability on our part for damages of any kind is excluded. 4. I2C Protocol Description 4.1 I2C Interface and Timing For integration with a micro-controller, the humidity module has an I2C-compatible interface which supports both 100 kHz and 400 kHz bit rates.
Application Note Humidity Module HYT Parameter Symbol Min Max Unit SCL clock frequency fSCL 100 400 kHz Start condition hold time relative to SCL edge tHDSTA 0.1 µs Minimum SCL clock low width 1 tLOW 0.6 µs Minimum SCL clock high width 1 tHIGH 0.6 µs Start condition setup time relative to SCL edge tSUSTA 0.1 µs Data hold time on SDA relative to SCL edge tHDDAT 0 µs Data setup time on SDA relative to SCL edge tSUDAT 0.1 µs Stop condition setup time on SCL tSUSTO 0.
Application Note Humidity Module HYT I2C MR - Measurement Request: Slave starts a measurement cycle S 6 5 4 3 2 1 0 W A S Device Slave Address [6:0] Wait for Slave ACK S Start Condition S Stop Condition A Acknowledge (ACK) 2 Slave Address Bit (Example: Bit 2) W Read/Write bit (Example:Write = 0) 4.3 DF (Data Fetch) The data fetch command serves to finish reading the output register.
Application Note Humidity Module HYT 4.4 Scaling of Measurement Values Traw and RHraw are the digital 16 bit values submitted by the sensor. Humidity signal (2 bytes): The first top bits are status bits with following relevance: Bit 15: CMode Bit, if 1 – element is in command mode Bit 14: Stale bit, if 1 – no new value has been created since the last reading. To mask the 2 top status bits in a 16 bit value, it will be linked logically with 3FFF and AND. The remaining 14 bit represents the measured value.
Application Note Humidity Module HYT 4.5 I2C pull up resistor 5. I2C Address Change To change the I2C-address of the sensor module, the module must be switched into the Command-Mode. The switching is performed by sending the start-command-mode message over I2C-bus no later than 10 ms after PowerOn reset. Each command-mode message is 4 byte long, like shown in table 1.
Application Note Humidity Module HYT At writing access both command data bytes contains the data, at reading access both data bytes must be set to 0x00. The response to the command-mode message can be read out by a Data-Fetch. The response time of the command-mode messages are 100 µs. Table 2 shows the response to the start of the command-mode.
Application Note Humidity Module HYT S 0x50 A 0x80 A 0x00 A 0x00 N P Start normaler mode or alternatively Power – Off The following table shows the I2C timing.
Application Note Humidity Module HYT 6. HYT Labkit The labkit was developed as a Plug&Play tool for a fast evaluation of the HYT digital humidity sensors. The ready-touse system consists of a PC-adapter with an USB connecting wire, a connection adapter with plugs for all product variants, a connection cable and an easy to operate, userfriendly WINDOWS software CD-ROM. The recording of the measured values and the graphic presentation is carried out with the help of a PC.
Application Note Humidity Module HYT Data recording: First activate the checkbox of all the measurement channels that are to be recorded. In ‚Text 1‘ and ‚Text 2‘, a description can be entered, which will appear on the header of the file. The data is recorded in the file, which is declared as a path under the settings. The recording begins with the ‚Start‘ button. EXCEL™: The stored file is compatible with CSVformating.
Application Note Humidity Module HYT Applicable for HYT 939: <- orientation mark Place the sensor as described into the adapter board and then connect it with the help of the connection leads provided with the PC adapter. Then connect the PC adapter through the USB cable to the PC or your notebook. Sensor adapter Connecting cable PC adapter USB cable PC/notebook CD-ROM 6.
Application Note Humidity Module HYT 6.5.2 Installation of Software PCLOG The software PCLOG is included in the labkit. Open and start the file “setup.exe“ in the path ...\Software\PCLog\ deu‘ on the enclosed CD. Please follow the installation instruction. The software is installed automatically. Start the software PCLOG and open the option „Extras“ in the menu and click on „Activation“.
Application Note Humidity Module HYT 7. LCD Module for HYT 271 The Hygrochip LCD module is an easy to use demonstration and evaluation kit for HYT sensors. The measured values of the connected sensor can be displayed on the display. If an external power supply is used the measured values are also available on the analog outputs. 7.1 Pin Designation Top Bottom AHHYTM_E2.2.
Application Note Humidity Module HYT 7.2 Description of Operation After power on, the module shows the following information for 2 seconds: HYT 271 – Module www.ist – ag.com After that it changes to the measurement mode and shows the values of relative humidity and temperature. Humidity 54,3 % Temperat 23,7 °C The following configuration options are available in addition to the measured values: 1. CONFIGURATION Address 0xHH (0x00 – 0x7F) 2. CONFIGURATION Corr-Temp. 0.
