Wiznet makers

With the development of society, parents pay more and more attention to the growth and development of their children in infants and young children, and they need to invest more time and energy in babysitting. They often feel powerless under the pressure of fast-paced life and work in modern society. In real life, there are too many unforeseen factors that affect the healthy growth of infants and young children. The child's body shape is in the developmental stage, and 70% of the time is spent in bed. In order to reduce the burden of parents during childcare and improve the quality of childcare, ordinary cribs have single functions, simple performance, and almost no functions such as intelligent detection and control. Therefore, a new type of movable crib is designed, suitable for indoor and outdoor play, with real-time intelligent monitoring and a system for detecting danger, which can provide parents with information such as the living environment and activity status of the baby at any time.

　　1 System functional architecture

　　The baby real-time monitoring system mainly realizes 4 functions, which are data collection, analysis and control of various sensors , wireless network transmission, terminal reception and monitoring, and anti-fall and collision prevention. The realization of wireless network transmission is the key to this system. . Figure 1 shows the overall structure of the baby real-time monitoring system. The latest socket program library is used to improve the stability and reliability of system data transmission over the network. The Internet of Things is an important part of the new generation of information technology, which has been applied and developed in smart home systems, industry, agriculture and other industries. The basic architecture of the Internet of Things includes three aspects: perception layer, network layer, and application layer. Using hardware TCPIP protocol network controller W5500, WiFi wireless router and n RF 2 4L 01 wireless technology as the communication of the network layer of the system, to realize the collection and transmission of each sensor data, with strong stability, wide transmission range, power consumption inferior advantages.

　　2 System Modular Design

　　2.1 Data acquisition module

　　2.1.1 Temperature and humidity acquisition circuit

　　The design of this circuit is mainly responsible for the monitoring of the baby's real-time body temperature and the monitoring of bed-wetting by the temperature sensor and the humidity sensor . Figure 2 shows the temperature and humidity acquisition circuit. Body temperature data is digitally transmitted using a high-precision DS18B20 temperature sensor commonly used in temperature control, industrial systems, or thermal sensing systems. The high-speed scratchpad RAM included in the DS18B20 temperature sensor contains a two-byte temperature register . These two registers can store the output data. A weak pull-up resistor is connected to the control line . By programming the registers TH and TL, the increase The accuracy and resolution of the measurement can realize the conversion of the temperature value within 93.75 ms and 750 ms and the output accuracy is as high as 9 to 12 bits.

　　Detect whether the baby wets the bed through the HS1100 humidity sensor. HS1100 is a capacitive sensor that measures humidity according to the change in the electrical constant of its polymer material after absorbing moisture . Through A/D analog-to-digital conversion, the output of the capacitance value is converted into a voltage signal data that is inversely proportional to it, and the data is received by the main controller.

　　2.1.2 Cry recognition circuit

　　The cry recognition circuit adopts the LN567 general-purpose phase- locked loop circuit tone decoder. The design of this circuit is shown in Figure 3. The MIC is used to collect the baby's cry audio signal. The analog signal is amplified to a strong signal. Babies cry at different frequencies in different situations. The crying frequency is around 15 kHz, indicating that the baby is hungry, and when the frequency is around 6 kHz, the baby wants to sleep. The capacitive filter circuit is used to filter the sound to reduce the interference of environmental noise. The filtered sound signal is shaped by a diode to obtain a low-frequency signal. Finally, the analog signal is converted into a digital signal of sound duration through a comparator, and a pulse signal is output from the OUTPUT port of the LN567 chip to the main controller chip.

　　2.2 Wireless network module

　　2.2.1 WiFi transmission module

　　The wireless network module is designed to be the main core part of the system. Data transmission between sensors is carried out through the wireless network, so that the communication wiring of each sensor in the wireless network is less , and the efficiency and coordination of communication are improved. The WiFi wireless network in the system mainly realizes the transmission of video images and the drive of the crib motor . By flashing a highly modular and highly automated OpenWRT system based on an embedded Linux system to the WiFi control board. The camera is connected to the WiFi control board through USB , and the picked-up video image is modulated and converted and transmitted to the host computer wirelessly, so as to realize real-time monitoring of the baby. The WiFi control board communicates with the main controller through the serial-day interface , and drives the shaker motor, toy motor, and travel motor by sending commands from the host computer.

　　2.2.2 W5500 Ethernet Module

　　W5500 is an embedded Ethernet controller launched by wiznet company. It realizes Internet network connection through SPI interface and supports TCP/IP protocol processing. The architecture is divided into 10/100M Ethernet data link layer (MAC), network layer

　　(NWK), application layer (APL), data link layer and physical layer comply with all the specifications defined by the IEE 802.3 standard. Specific functions and related services are completed between layers and network connections are realized through interfaces. As shown in Figure 4, W5500 communicates with the main controller chip through the SPI serial external interface, and at the same time communicates with the host computer through the network cable , and sends the data received by the nRF24L01 from the temperature sensor to the W5500 through the wireless network. Ethernet sends the data to the machtalk server of the host computer for real-time display and recording.

　　2. 2.3 nRF24L01 wireless transceiver module

The system realizes short-range wireless communication 　　based on the enhanced 2.4 GHz wireless transceiver nRF24L01 based on 8051 produced by NORDIC Company , which can sense and collect sensor signals in real time, and use radio waves as a carrier to achieve

　　2.3 System main controller module

The STM32 series microcontrollers with 　　embedded ARM core have the advantages of high performance, resources, and rich instructions. The main control module of the baby real-time monitoring system adopts the 32-bit STM32F103 ZET6 processing chip based on the Cortex-M3 core introduced by STMicroelectronics , which is integrated on-chip. 64 KB of SRAM and 512 KB of FLASH, with CAN and USB bus, 5 USART serial communication interfaces, 3 SPI bus interfaces and other circuit interfaces, to meet a variety of simultaneous communication functions, fast processing speed, powerful functions, external interface It is rich and has a large internal data storage space, which can well realize the functional design requirements of the system. The overall design structure frame of the system is shown in Figure 6.

　　3 System software design

　　3.1 W5500 network initialization

　　Since the access to machtalk is accessed through the domain name, it is necessary to include the DNS service program in the program. DNS resolution requires a timer to regularly call the domain name resolution related functions, and also needs to configure the network IP address, MAC address, gateway, DNS server, etc. .

　　3.2 Initialization of nRF24L01

　　The nRF24L01 is configured as PTX working mode to realize the transmission and reception of data between the master and the slave. If the slave receives data from the sensor, it starts to send data, and the master starts the receive mode.

　　4 System testing and data analysis

　　The system test takes temperature acquisition as an example to conduct multiple real-time acquisition tests. The data test is shown in Figure 7. The collected temperature is sent to the main control chip through nRF24L01 and sent to the server on the PC side by W5500 through Ethernet communication for storage and display. From the data analysis of the system test, it is concluded that the real-time monitoring system for infants has good real-time performance and high stability, and achieves the expected design goals.

　　5 Conclusion

　　According to the fact that the current ordinary crib does not have functions such as intelligent detection and control, the design of the baby real-time monitoring system is carried out, and the new Internet of Things technology and wireless network communication technology that are widely used in various fields are used to add real-time baby monitoring to the crib. And increase the security and control system, refer to the latest socket program library to optimize the wireless network in the system, which greatly improves the security and effectiveness of the data. The direct purpose of designing this system is to ensure that the baby can be monitored in real time when the baby is in the crib, effectively monitor and prevent the baby's physical condition or the occurrence of safety problems, and notify the parents in time, so as to facilitate the parents to take care of their children. can also work. In addition, the baby real-time monitoring system has high transplantability and can be applied in other fields, such as the treatment and monitoring management center for babies in hospitals, and the monitoring management for the elderly in nursing homes. Therefore, the research and development of this system has higher practical significance and expansibility.