A Complete Guide to the SHT10 Temperature and Humidity Sensor

08 May 2024 279


Ⅰ. What is SHT10?

Ⅱ. Operating conditions of SHT10

Ⅲ. Features of SHT10

Ⅳ. Electrical characteristics of SHT10 sensor

Ⅴ. Pin description of SHT10

Ⅵ. How does SHT10 work?

Ⅶ. How does SHT10 communicate with the microcontroller?



Ⅰ. What is SHT10?


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SHT10 is a temperature and humidity composite sensor with calibrated digital signal output developed by Sensirion, the world's leading sensor manufacturer. The sensor uses CMOSense technology to ensure that the product has extremely high reliability and excellent long-term stability. It consists of a band gap temperature measurement element and a capacitive polymer moisture measurement element, and is seamlessly combined with a 2-wire digital interface and a 14-bit A/D converter in a single chip, which makes this product has the advantages of fast response, low power consumption, and strong anti-interference ability, and is widely used in medical equipment, industrial production, environmental testing and other fields.


Alternatives and equivalents:

SHT11

SHT15



Ⅱ. Operating conditions of SHT10


The sensor operates stably within the recommended normal range - see graph below. Prolonged exposure to conditions outside the normal range, especially humidity >80 percent RH, may temporarily cancel out the RH signal (+3 percent RH after 60 hours). After returning to the normal range, it will slowly return to calibration on its own. Prolonged exposure to extreme conditions may accelerate aging.


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Ⅲ. Features of SHT10


1. Ultra-small size (surface mount)

2. Ultra-low power consumption, automatic sleep

3. Excellent long-term stability

4. Simple interface (2-wire), fast response

5. All calibrated, digital output

6. Relative humidity and temperature measurement with dew point output

7. Humidity measurement accuracy is ±4.5 percent RH, temperature measurement accuracy is ±0.5°C (25°C)



Ⅳ. Electrical characteristics of SHT10 sensor


The electrical characteristics of the sensor (such as high level, low level, input voltage, output voltage, etc.) are affected by the supply voltage. The parameters listed below, unless otherwise specified, default to the parameters under 5V power supply conditions.


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Note: RP stands for pull up resistor, while IOL is low level output current.



Ⅴ. Pin description of SHT10


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1. Power pins (VDD, GND)


The supply voltage range of SHT10 is 2.4V to 5.5V. When the sensor is powered on, it needs to wait approximately 11 milliseconds to resume from the "sleep" state. During this period, no instructions should be sent. For decoupling filtering, we can add a 100nF capacitor between the power pins (VDD and GND).


2. Serial interface


The SHT10's bidirectional 2-wire is optimized in terms of sensor signal reading and power consumption. Its bus is similar to the I²C bus, but it is not actually compatible with the I²C bus standard.

(1) DATA: The DATA pin is a three-state gate used for data transmission between the MCU and SHT10. The state of DATA changes after the falling edge of the serial clock SCK and is valid on the rising edge of SCK. During data transfer, the DATA data line must remain stable when SCK is high.

(2) SCK: The SCK pin is the synchronous clock for communication between the MCU and SHTIO. Since the interface contains fully static logic, there is no minimum clock frequency.

To avoid data conflicts, the MCU should drive the DATA pin to maintain a low level, and an external pull-up resistor should be connected to pull the signal up to a high level.



Ⅵ. How does SHT10 work?


The principle of SHT10 sensor is mainly divided into two parts: humidity measurement and temperature measurement.


1. Principle of humidity measurement


Its humidity measurement principle can be mainly divided into the following steps:

(1) Chemical adsorption humidity sensor: The humidity sensor inside the SHT10 sensor uses a chemical adsorption humidity sensor, which can sense humidity changes in the environment with high sensitivity.

(2) Sampling environmental humidity: The humidity sensor inside the SHT10 sensor senses the humidity in the environment through chemical adsorption, and converts the sensed humidity into a corresponding electrical signal.

(3) Conversion to digital signal: The analog-to-digital conversion circuit inside the sensor converts the analog signal of humidity conversion into a digital signal to facilitate subsequent processing and communication.

(4) Digital output: The SHT10 sensor outputs the measured humidity data through a digital interface, which can be read and processed by microcontrollers and other devices.


2. Principle of temperature measurement


The SHT10 sensor integrates a high-precision thermistor to measure the temperature in the environment. Its temperature measurement principle can be mainly divided into the following steps:

(1)Surface MEMS technology: The thermistor inside the SHT10 sensor is made into a tiny sensitive element through surface micro-electromechanical system technology, which can reflect changes in ambient temperature with high sensitivity.

(2) Sampling ambient temperature: The SHT10 sensor senses the temperature in the environment through the thermistor and converts the sensed temperature into a corresponding electrical signal.

(3) Conversion to digital signal: The analog-to-digital conversion circuit inside the sensor converts the analog signal of temperature conversion into a digital signal to facilitate subsequent processing and communication.

(4) Digital output: The SHT10 sensor outputs the measured temperature data through a digital interface, which can be read and processed by microcontrollers and other devices.



Ⅶ. How does SHT10 communicate with the microcontroller?


Following are the basic steps for SHT10 to communicate with a microcontroller. First, the microcontroller needs to initialize its I²C interface. This usually involves setting the pins of the I²C data line (SDA) and clock line (SCL), and configuring the associated registers to set communication parameters such as baud rate (but note that I²C communication does not use baud rate; rather is the clock frequency), slave device address, etc. Next, the microcontroller sends an I²C enable signal by pulling the SDA line low while holding the SCL line high. This indicates the SHT10 sensor to be ready to start communicating. Next, the microcontroller sends the SHT10's device address and a write command. The device address is used to identify the SHT10 sensor, and the write command tells the sensor what data it will receive next. Then, the microcontroller sends a measurement command to SHT10. This tells the sensor to start measuring temperature and humidity. SHT10 will start measuring after receiving the measurement command. This process may take some time (depending on the specific measurement mode and sensor specifications). During this time, the microcontroller may need to wait or continue performing other tasks. When the measurement is complete, the SHT10 stores the digital data of temperature and humidity in its internal registers. The microcontroller requests this data by sending a read command. The microcontroller then reads this data via the I²C interface. After reading the data, the microcontroller sends an I²C stop signal to end the communication.




Frequently Asked Questions


1. Where is temperature and humidity sensor used?


A humidity sensor is also found as part of home heating, ventilating and air conditioning systems (HVAC systems). These are also used in offices, cars, humidors, museums, industrial spaces and greenhouses and are also used in meteorology stations to report and predict the weather.


2. What is the response time of the SHT10 sensor?


The response time of the SHT10 sensor is typically less than 8 seconds for humidity measurement and less than 5 seconds for temperature measurement.


3. What is a SHT10 soil temperature and humidity sensor?


SHT10 Soil Temperature and Humidity Sensor Module is one of the surface mountable relative humidity and temperature sensors. It contains a temperature-humidity sensor module housed in a sintered metal mesh.




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