With the advancement of science and technology, the living standards of human beings are gradually improving, and there is also a desire for intelligent home. The smart home will become more and more in the future market. The following describes an application scheme of a temperature and humidity acquisition system in a smart home. The program uses Si7001 temperature and humidity sensor, C8051F985 low-power MCU, CP2403LCD driver and display to build a home temperature and humidity acquisition system to detect indoor and outdoor temperature and humidity data.

How the temperature and humidity collection system works

Two two Si7001 temperature and humidity sensors are installed indoors and outdoors, and the raw data of temperature and humidity are periodically awakened, and AD conversion is performed inside the Si7001, and sent to the C8051F985 through the I2C bus. The C8051F985 can activate the data of which acquisition node to reduce energy consumption and control the CP2403LCD driver. The final data is displayed on the LCD display for easy reading.

Performance parameters of temperature and humidity acquisition system

First, the power consumption of each major node

1, Si7001

The current of the Si7001 during the temperature measurement period is 320 μA, the current during the humidity measurement period is 240 μA, and the sleep current is 0.2 μA. If the temperature and humidity are collected every minute, the average power consumption of the temperature and humidity sensor is about 1 micro. Ann.

2, C8051F985

Sleep current 10nA, working current 150uA/MHz

3, CP2403

The sleep current is 0.02 μA and the operating current is less than 3 μA.

If the measurement is performed every minute and the operating frequency is 4MHz, the average power consumption will be less than 15μA, so it can be powered by the battery and it is convenient to use.

Second, the scope of data collection

The Si7001 has a temperature range of -40 to 85 ° C and an accuracy of ± 0.5 ° C at 25 ° C. The humidity range is 5 to 90% RH and the accuracy is 2 to 3% RH at 20% to 80% RH. If the family uses it, it will fully meet the requirements.

During the specific implementation, it is recommended to arrange a collection point in the outdoor, two collection points in the indoor living room and bedroom, and the collected data is given to the control system to adjust the indoor temperature and humidity.

Third, scalability

In addition to the temperature and humidity sensor, the home data acquisition system can also add a smoke sensor, a fire alarm, a pyroelectric infrared sensor, etc., and then send it to a more powerful processor for data processing through the I2C bus technology. An extension of the functionality is possible. The power saving arrangement should be considered comprehensively in order to save costs.

to sum up

This paper briefly introduces a family temperature and humidity data acquisition system scheme. The SI7001 temperature and humidity sensor is used to collect temperature and humidity data, which is sent to the C8051F985 low-power MCU processor for processing. The final value is displayed on the LCD display. The program has the characteristics of strong practicability, low energy consumption, convenient arrangement, strong extensibility, etc., and is very suitable for applications such as homes and warehouses where temperature and humidity are required to be collected and controlled.

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