Si4432 RF chip scheme typical application of data transmission of wireless communication module of Internet of things

Si4432 yes Silicon labs The company's RF chip , It is a highly integrated 、 low power consumption 、 Multi band EZRadioPRO Series wireless transceiver chip . Its working voltage is 1．9～3．6V, Can work in 315／433／868／915MHz Four bands ; Internal integrated diversity antenna 、 power amplifier 、 Wake up timer 、 Digital modem 、64 Byte sending and receiving data FIFO And configurable GPIO etc. .

Si4432 The chip requires very few external components in use , Only required 1 individual 30MHz The crystal of 、 Several capacitors and inductors can form a highly reliable transceiver system , Design simple , And the cost is low .Si4432 The receiving sensitivity reaches -117dB, It can provide excellent link quality , Minimize power consumption while expanding transmission range ; The minimum filter bandwidth is 8kHz, Excellent channel selectivity ; stay 240～960MHz In the frequency band , The maximum output power without power amplifier can reach +20dBm, When the design is good, the farthest distance between transmitter and receiver can reach 2km.

Si4432 Make it Wireless communication module Widely applied , It can be applied to wireless data communication 、 Wireless remote control system 、 Small wireless networks 、 Small wireless data terminal 、 Wireless meter reading 、 Access control system 、 Wireless remote sensing monitoring 、 Hydrometeorological monitoring 、 Robot control 、 wireless RS485／RS232 Data communication and many other fields .

At present, most intelligent access control systems are based on wired communication . as everyone knows , Wired communication has security 、 Good stability 、 Easy to implement, etc ; But at the same time, the wired communication mode has high initial installation cost 、 Construction time is long 、 Cannot move 、 Little room for change 、 Maintenance costs are high 、 Small coverage 、 Expansion difficulties and other defects . With the development of communication technology , Wireless communication network has entered a new world . Strong function 、 Easy to install 、 Flexible networking 、 Plug and play network connection 、 Strong mobility and other advantages , The wireless network provides unlimited applications . Therefore, the radio frequency access control system can not only improve the security and reliability , And compared with the traditional fitting mechanism , The radio frequency access control system has less wear and consumption , Long service life , It can effectively reduce the replacement of access control equipment , Of ebat E27-433M20S The module is small , Low power consumption , Under the current trend of advocating environmental protection and energy conservation , Undoubtedly of great significance .

The hardware of wireless access control system mainly includes main control equipment 、 Electric lock 、 Power Supply 、 Speech compression / Control platform 、 Wireless transmission platform , Other peripheral equipment consists of several parts , The overall architecture of the system is shown in the figure .
　　 When the authorized user swipes the card to open the door , The card reader sends a certain frequency RF signal through the transmitting antenna , When the RF card enters the working area of the transmitting antenna, an induced current is generated , The RF card gets energy and is activated , The RF card sends its own coding and other information through the card's built-in transmission antenna , The system receiving antenna receives the modulated signal sent from the RF card , It is transmitted to the card reader through the antenna regulator , The card reader demodulates and decodes the received signal, and then sends it to the main control equipment for related processing ; The main control system judges the legitimacy of the card according to the logic operation , Make corresponding processing and control according to different settings , Send command signal to control the action of actuator , If the authorized user forgets to bring the card , You can also enter the password through the external keyboard of the system to open the door .

For authorized users, access control can be opened by swiping card or entering password , Unauthorized users can send entry requests to residents through the wireless voice system , You can enter the building with permission , When the system is invaded illegally , Be able to actively send an emergency alarm to the security center .

The system has the following advantages ：

（1） Security , The system can prevent all unauthorized objects from entering , Ensure the safety of property and life .

（2） reliability , The system can work stably , It can better resist external interference , Ensure the accuracy of actions .

（3） The real time , The system can respond to user objects in real time .

（4） flexibility , The system can be easily extended , Easy to add new users .

（5） confidentiality , The system has strong anti - deciphering ability , Strong protection of user passwords .