Product Name: | Digital temperature and humidity module |
Product model: | MHTCI |
Version: | V1.0 |
Formulator: | He Genwen |
Reviewer: | Yuan Chao |
1. Product Description:
This product is a sensor with temperature and humidity integrated with calibrated digital signal output. It uses imported sensing elements and digital signal output. It has long-term stability, high reliability, high accuracy, low power consumption and other characteristics. It is not affected by interference such as power supply noise and voltage fluctuations. It is widely used in HVAC automatic control and thermostats. /Thermostat, computer room monitoring, white goods, indoor weather stations, automobile climate control, medical and other fields;
2. Performance indicators:
■ | Power supply voltage | DC 5V |
■ | Measurement accuracy | temperature: ±0.4℃ humidity: ± 3%RH |
■ | Measurement range | Humidity 0%-100% RH Temperature --40 ℃ －85℃ |
■ | Power consumption | Work:<1mA Standby: 150 uA(3V) |
■ | Data interface | standard I2C |
■ | Resolution | Temperature 0.1 ℃ Humidity: 0.1% RH |
three, I2C Interface definition
3.1 Sensor Pin Allocation Table 1: Pin Allocation
Pin | name | describe |
1 | GND | land |
2 | VCC | power supply DC5V |
3 | SCL | Clock signal |
4 | SDA | Serial data, bidirectional port |
3.2 Power pins (VCC GND)
The power supply voltage of this product is DC5V
3.3 Serial clock (SCL)
Figure 1: Pin assignment
SCL Used for communication synchronization between the microprocessor and the sensor.
3.4 Serial data (SDA)
SDA The pin is a three-state structure, used to read and write sensor data.When sending commands to the sensor, SDA exist SCL The rising edge is valid and SCL It must remain stable at high levels. SDA exist SCL Change after falling edge.When reading data from the sensor, SDA exist SCL It will be effective after it becomes low and will be maintained until the next one SCL The falling edge
Figure 2 Host write command 
Sensor output data
Table 2 I/O Signal Characteristic Table
4. Sensor communication instructions 4.1 I2C Signal description
1) 7 Bit address address
Startup timing S
Stop timing P
I2C Bus interface timing diagram
Each transmission sequence Start The status starts.when SCL When it is high, SDA Convert from high to low
Level
Each transmission sequence Stop Status ends.when SCL is high, SDA Convert from low level to high power
flat
4.2 Timing description
Use parameters as follows
I2C Command address byte
I2C Command table
Ask the register description below program
Humidity calculation
Temperature calculation
5. Basic connection diagram
Since there are 10 added inside the sensor K The pull-up resistor can be directly connected and used when the communication distance is not very far.If the communication distance is too far, a pull-up resistor must be added externally to ensure normal and reliable communication.
VI. Specifications and Sizes
7. Application information
7.1 Working and storage conditions
The relative humidity of the environment is greatly affected by the temperature. During installation, the sensor should be kept away from electronic components with large operating temperature rises as much as possible, while maintaining good ventilation.
7.2 Exposed to chemicals
This product is similar to a capacitive humidity sensor and is more sensitive to chemical steam.The diffusion of chemicals in the induction layer will lead to inaccurate measurement data and a decrease in reaction sensitivity.
