Temperature is the measure of warmth or coldness in reference to a set standard, often expressed in terms of degrees Fahrenheit or Celsius. Humidity refers to the amount of water vapor, or moisture, in the air.
There are generally two types of humidity ie. absolute and relative. The former tells the humidity present in a parcel of air without taking temperature into consideration whereas the latter tells the humidity present in the air concerning the temperature of the air.
If temperature increases it will lead to a decrease in relative humidity, thus the air will become drier whereas when temperature decreases, the air will become wet means the relative humidity will increase.
Temperature and humidity sensor are devices that can convert temperature and humidity into electrical signals that can easily measure temperature and humidity. Temperature humidity transmitters available on the markets, generally measure the amount of temperature and relative humidity in the air, and convert it into electrical signals or other signal forms according to certain rules and output the signal to the instrument or software to meet the environmental monitoring needs of users.
An overview of the HTU20D sensor
HTU20D sensors are digital humidity sensors that have low energy consumption and are designed for high volume and cost sensitive applications with tight space constraints. it is embedded in a Dual Flat No leads (DFN) packag. This sensor provides calibrated, linearized signals in digital, I²C format. The resolution of these digital humidity sensor can be changed by command (8/12bit up to 12/14bit for RH/T).
Specification
Applications
- Output type: Digital-I2C
- Humidity rangege: 0 to 100 %RH
- Temperature range: -40°C to +125°C
For more specifications, please refer to datasheet
- Home Appliance
- Medical
- Printers
- Humidifier
- Multimedia: Smartphone, Tablet, …
HTU20D module Key Features
- User-selectable module power supply voltage between 1V8 and 3V3
- ON/OFF LED indicator
- Pin Compatible with GEBRABUS
- It can be used as a daughter board of Gebrabit MCU Modules
- Featuring Castellated pad (Assembled as SMD Part)
- Separatable screw parts to reduce the size of the board
- Package: GebraBit small (36.29mm x 32.72mm)
GebraBit HTU20D module
GebraBit HTU20D is a digital humidity and temperature measurement module.
GebraBit HTU20D Communicate with I2C protocol and operates with 1V8 and 3V3 Supply Voltages which users can easily select with a Considered onboard jumper selector; This feature helps to use a wide range of microcontrollers for interfacing with this module.
Considering that it is difficult to access the sensor pins, the user needs a starter circuit and driver for the hardware development and of course the software development of the HTU20D sensor. GebraBit implements the HTU20D sensor circuit and provides access for the convenience of users.
It is enough to put the GebraBit HTU20D module in the BreadBoard, then by applying the proper voltage set up the GebraBit HTU20D module with any of Arduino, Raspberry Pi, Discovery board, and especially we recommend using GebraBit microcontroller development modules (GebraBit STM32F303 or GebraBit ATMEGA32 module) then receive the data.
The reason for our recommendation when setting up the GebraBit HTU20D module with GebraBit microcontroller development modules (such as GebraBit STM32F303 or GebraBit ATMEGA32), is the presence of an internal 3V3 regulator on these modules and the compatibility of the pin order of all GebraBit modules together (GEBRABUS standard), it’s enough to Put the HTU20D in the corresponding socket as shown in the above picture and develop the desired sensor module without the need for wiring.
Introduction of module sections
HTU20D sensor
HTU20D sensor is the Digital Relative Humidity sensor of this module which its circuit is designed and Its temperature output is available to the user.
VCC SEL
According to the state of 0R resistance of this jumper, the main voltage of the sensor power supply is selected between “1V8” and “3V3”.
Power supply LED
According to the state of the VCC SEL jumper and applying voltage to the module by the corresponding pin, the LED of the module will be lit.
GebraBit HTU20D Module pins
Supply pins
- 3V3 and 1V8: These pins can supply the sensor main power supply according to the state of the VCCSEL selector jumper.
- GND: This is the common ground pin for power and logic level of the sensor.
I2C pins
- SDA: This pin is the I2C communication data pin, which is connected to the corresponding data pin in the microcontroller (processor). According to the state of the VCCSEL jumper, you can use the logic level with a voltage of 1V8 or 3V3.
- SCL: This pin is the I2C communication clock pin, which is connected to the corresponding clock pin in the microcontroller (processor). Depending on the state of the VCCSEL jumper, you can use the logic level with a voltage of 1V8 or 3V3.
Connect to the processor
I2C connection with GebraBit STM32F303
for i2c communication of GebraBit HTU20D and GebraBit STM32F303 microcontroller module, after defining SDA and SCL on pins PB9 and PB8 (for convenience in STMCUBEMX), follow the below steps:
- Connect the 3V3 pin of the HTU20D module to the 3V3 output pin of the microcontroller module. (red wire)
- Connect the GND pin of the HTU20D module to the GND pin of the microcontroller module (black wire).
- Connect the SCL pin of the HTU20D module to the PB8 pin of the microcontroller (SCL) module (blue wire).
- Connect the SDA pin of the HTU20D module to the PB9 pin of the microcontroller (SDA) module. (yellow wire)
Note: Considering that the PA14 pin of the GebraBit STM32F303 microcontroller module is used to program the microcontroller, I2C setting on the PA14 and PA15 pins is impossible in this version, so in this version for I2C connection with the GebraBit STM32F303 microcontroller module, GebraBit HTU20D module cannot be placed as Pin to Pin on it.
I2C connection with GebraBit ATMEGA32A
for i2c communication of GebraBit HTU20D and GebraBit STM32F303 microcontroller module, after defining SDA and SCL on pins PB9 and PB8 (for convenience in STMCUBEMX), follow the below steps:
- Connect the 3V3 pin of the HTU20D module to the 3V3 output pin of the microcontroller module. (red wire)
- Connect the GND pin of the HTU20D module to the GND pin of the microcontroller module (black wire).
- Connect the SCL pin of the HTU20D module to the PB8 pin of the microcontroller (SCL) module (blue wire).
- Connect the SDA pin of the HTU20D module to the PB9 pin of the microcontroller (SDA) module. (yellow wire)
Note: If you are using GebraBit microcontroller modules, note that the power selector jumper of the GebraBit HTU20D is set to 3V3 so that you can easily power-on the GebraBit HTU20D module by getting the 3V3 voltage from the microcontroller module.
I2C Connection with ARDUINO UNO
follow the below steps to connect the GebraBit HTU20D module to the ARDUINO UNO via I2C:
- Since the VCC SEL jumper is set to 3V3, connect the “3V3” pin of the HTU20D module to the “3V3” output pin of the ARDUINO UNO board. (Red wire)
- Connect the SCL pin of the HTU20D module to the A5 pin of the ARDUINO UNO board (SCL). (blue wire)
- Connect the SDA pin of the HTU20D module to the A4 pin of the ARDUINO UNO board (SDA). (orange wire)
How to connect the above mentioned steps, can be seen in this picture: