The detection terminal detects the state change of the seat sensor, detects whether someone is sitting down, packages the detection results, and sends them to the host for centralized processing through wireless signals at regular intervals. A seat detection terminal can detect the seating status of four seats.
It is widely used in statistics of passenger vehicle sitting rate.
Power supply: disposable lithium subbattery (replaceable);
Battery capacity: 3600mAh;
Timed sending: 4 seconds to send once
Battery life: more than 3 years;
Communication frequency band: 2.4G;
Communication distance: 40 meters (open);
Shell material: ABS material;
Wiring harness interface: 43020;
Wire harness length: 200mm;
Shell size: 84.7mm×73.3mm×24.4mm;
Working temperature: -20℃~70℃;
Installation method: fixed installation with cable ties.
1.Statistics on passenger car occupancy rates, to help passenger transport companies realize real-time monitoring of the seat status of operating passenger vehicles, and to help managers use big data analysis to make scientific and effective decisions.
2.Statistics on the attendance rate of movie theaters, intelligently identify and count the number of people seated in movie theaters through the Internet of Things technology, and provide technical support for big data analysis.
Wireless sensor air interface protocol specification
■ In order to realize the interconnection and data sharing between wireless sensor nodes and gateways or sensor collectors, this document has specially formulated wireless sensor air protocol specifications.
■ Hereinafter, wireless sensor nodes are referred to as nodes for short, and collectors or gateways are collectively referred to as collectors.
1.1 Features of the protocol specification
☆ Open: so that the nodes of various manufacturers can be interconnected with the collector.
☆ Flexible packaging: data structure can be freely organized according to application requirements, and manufacturers can customize privatized data.
1.2 Application scenarios
■ Different manufacturers can design and develop nodes and collectors in accordance with this specification, so that all nodes and collectors can be interconnected.
2. Air interface
■ All node devices and collectors communicate through the air interface, so the air interface is a unified standard that requires the communication parties to follow each other. This protocol standardizes the data organization structure of the air interface.
2.1.1 Physical layer
■ The physical layer can be selected according to the actual situation. The data format of the link layer is specified in this specification. The following is an example parameter of the physical layer.
■ Modulation method: GFSK/FSK；
■ Working frequency and channel： 2402MHz-2480MHz，Channel spacing 2MHz；
■ Working rate：1Mbps；
■ All types of data are transmitted in little-endian mode.
2.1.2 Link layer
Table 2.1 Link layer format
■ Preamble (1 byte)：The preamble before the access channel is used by the receiver to perform frequency synchronization, symbol time slot estimation and automatic gain control, so that subsequent data can be accurately received. It is automatically added on general hardware, and is fixed at 0xAA or 0x55.
■ Access address (4 bytes): channel address, fixed at 0x8e89bed6.
■ Data type (1 byte): indicates the type of data, fixed to 0x42 (normal data) or 0x43 (IO trigger data).
■ Length (1 byte): The length of the data frame, the value range [9,27], the manufacturer ID, the fixed data, and the sum of the length of the payload data.
■ Fixed data (3 bytes): The value is fixed to 02,01,06.
■ Vendor ID: Vendor, the upper 4 bits are encrypted identification, 0b0000 is not encrypted, other values are encrypted parameters, the specific meaning is defined by the vendor; the lower 12 bits are the vendor ID code.
■ Protocol data unit (0-18 bytes): load data, store user-defined data.
☆ Load data: The load data is organized by structure data. The structure data format is shown in Table 2.2.
☆ Data length: The byte sum of data ID and data content.
☆ Data ID：Reference《Generic Access Profile.pdf》、《CSS_v9.pdf》.
Table 2.2 Structure data format
● Check code (3 bytes)：Calculate the check value from the data between the access address and the check code (excluding the access address and check code fields).
2.2 Link layer frame example
Address：0xD6 0xBE 0x89 0x8E ：
Type of data：0x42；
Data length：0x11，Length 11 bytes;
The vendor ID is：Encryption identification 0x0, data is not encrypted, 0x0A2 manufacturer ID code;
Device ID：0x44332211(Little endian format);
Fixed data：0x02 0x01 0x06；
Load data：07 08 34 34 33 33 32 32，Length 0x07, data ID 0x08 (identifyingdevice name), data content 0x343433333232 (string is 443322)
Check code：0xB4 0x23 0x0C
Table 2.3 Examples of link layer data frames (data in hexadecimal format)