1. Overview:
Application layer, network layer/transport layer, physical layer/data link layer, device layer.
Access protocols are generally responsible for networking and communication between devices in the subnet.
2. Near-field communication protocol:
2.1. RFID
1. Introduction to
RFID The air interface communication protocol specification of RFID basically determines the working type of RFID. The communication rules between RFID readers and corresponding types of RFID tags include: frequency, modulation, Bit coding and command set. ISO/IEC has formulated air interface protocols for five frequency bands.
[1] ISO/IEC 18000-1
[2] ISO/IEC 18000-2
[3] ISO/IEC 18000-3
[4] ISO/IEC 18000-4
[5] ISO/IEC 18000-6
[6] ISO/ The
other three RFID protocols of IEC 18000-7 :
[7] ISO/IEC 14443: identification card, contactless integrated circuit card, proximity card
[8] ISO 14443 TypeA: access control card, bus card and small-value stored-value consumer card
[ 9] ISO 14443 TypeB: ID card, passport, UnionPay card
2.2. NFC
1. Introduction to
NFC Near Field Communication NFC is the abbreviation of Near Field Communication, which is short-range wireless communication technology. It is a short-range high-frequency wireless communication technology that allows non-contact point-to-point data transmission between electronic devices ( Within 10 cm) exchange data.
2. Principle of NFC technology
[1] In the passive mode, the device that initiates NFC communication, also known as the NFC initiating device (master device), provides a radio frequency field during the entire communication process. It can select a transmission speed of 106kbps, 212kbps or 424kbps to send data to another device. The other device is called the NFC target device (slave device). It does not need to generate a radio frequency field, but uses load modulation technology, which can transmit data back to the initiator device at the same speed. Mobile devices mainly operate in passive mode, which can greatly reduce power consumption and extend battery life. A device with a low battery level can be required to act as a target device in passive mode instead of an initiating device.
[2] In the active mode, each device must generate its own radio frequency field when sending data to another device. This is the standard mode of peer-to-peer network communication, and you can get very fast connection settings.
3. NFC application
[1] Touch and Go: access control, tickets and tickets, etc.
[2] Touch and Confirm: mobile payment
[3] Touch and Connect: download music, transfer pictures, and exchange communication simultaneously Book, etc.
[4] Touch and Explore: By browsing an NFC device, you can learn what functions and services are provided.
2.3. Bluetooth
1. Specifications and characteristics of
Bluetooth technology Bluetooth technology is an open global specification for wireless data and voice communication. It works in the global 2.4GHz ISM (industrial, scientific, and medical) frequency band. The standard is IEEE802.15 , Working in the 2.4GHz frequency band with a bandwidth of 1Mb/s.
2. Bluetooth version
[1] Currently, Bluetooth has developed to Bluetooth 5.0. The versions are as follows:
Version 1.1, Version 1.2, Version 2.0, Version 2.1, Version 3.0+HS, Version 4.0, Version 4.1, Version 4.2, Version 5.0
[2] Bluetooth 4.0 is the upgrade standard of Bluetooth 3.0. The most important feature of Bluetooth 4.0 is power saving. The extremely low operating and standby power consumption can make a button battery work continuously for several years. In addition, low cost and cross-vendor interoperability, 3 milliseconds low latency, AES-128 encryption and many other features can be used in many fields such as pedometers, heart rate monitors, smart meters, sensor IoT, etc., greatly expanding the Bluetooth technology Application scope.
[3] The key word for Bluetooth 4.1 should be IOT (Full Internet), which means connecting all devices to the Internet. In order to achieve this, the improvement of the communication function is one of the most important improvements of Bluetooth 4.1. The features of Bluetooth 4.1 are as follows:
"1" The transmission speed of batch data
"2" Connect to the network via IPV6
"3" Simplify device connection
"4" Peaceful coexistence with 4G
"5" Enhanced functions: make wireless headsets more suitable for the government , Medical and banking applications where safety is paramount.
[4] Bluetooth 4.2:
On December 4, 2014, the Bluetooth 4.2 standard was promulgated, which improved the data transmission speed and the degree of privacy protection, and can directly access the Internet through IPv6 and 6LoWPAN. Under the new standard, the Bluetooth signal wants to connect or track the user equipment must be approved by the user, otherwise the Bluetooth signal will not be able to connect and track the user equipment.
[5] Bluetooth 5.0:
Version 5.0 was officially released in London on June 16, 2016, US time, and is the most advanced Bluetooth protocol standard at this stage. Bluetooth 5.0 has the following features:
"1" Faster transmission speed
"2" Longer effective distance
"3" Navigation function
"4" Internet of Things function
"5" Upgrade hardware
"6" More transmission functions
"7" More Low power consumption
"8" truly supports lossless transmission
[6] Bluetooth matching rules
Before two Bluetooth devices communicate, they must be matched together to ensure that the data information sent by one of the devices will only be accepted by the other device that is allowed. Bluetooth technology divides devices into two types: master device and slave device.
[7] Precautions The
master device and the master device, between the master device and the slave device, can be matched with each other; the slave device and the slave device cannot be matched. For example: Bluetooth PC and Bluetooth mobile phone can be matched together; Bluetooth PC can also be matched with UD pen; and UD pen and UD pen cannot be matched. At the same time, only point-to-point communication between Bluetooth devices is supported.
3. Bluetooth application
Bluetooth technology can be applied to all aspects of daily life. For example, the introduction of Bluetooth technology can remove the annoying connection cable between the mobile phone and the laptop and establish communication wirelessly.
Printers, PDAs, desktop computers, fax machines, keyboards, game joysticks, and all other digital devices can be part of the Bluetooth system.
3. Long-distance cellular communication protocol:
1. Introduction The
long-distance cellular communication protocol is mainly the standard and protocol adopted by various telecom operators under technologies such as 2/3/4/5G and NB-IoT. Telecom operators and major equipment vendors waved their flags.
4. Long-distance non-cellular communication protocol:
4.1. ZigBee technology
1. Introduction to
ZigBee The name ZigBee comes from the communication method of bee colony: bees exchange messages by dancing in the shape of Zigzag, so as to share the direction, location and direction of food source. Distance and other information. This means that Zigbee is the name of a new generation of wireless communication technology.
2. ZigBee technical characteristics
ZigBee is a wireless connection that can work in 2.4GHz (globally popular), 868MHz (popular in Europe) and 915 MHz (popular in the United States) 3 frequency bands, with the highest 250kbit/s, 20kbit/s and The transmission rate of 40kbit/s, its transmission distance is in the range of 10-75m, but it can continue to increase.
As a wireless communication technology, ZigBee has the following characteristics: low power consumption, low cost, short delay, large network capacity, reliability, and safety
3. ZigBee protocol stack The
ZigBee protocol stack structure is based on the standard OSI seven-layer model, including: high-level application specifications, application convergence layer, network layer, media access layer and physical layer. IEEE 802.15.4 defines two physical layer standards, namely the 2.4GHz physical layer and the 868/915MHz physical layer. Both are based on direct sequence spread spectrum (DSSS) technology.
4. ZigBee application
[1] Automated control of homes and buildings: remote control of lighting, air conditioning, curtains and other furniture equipment;
[2] consumer electronic equipment: remote control of TVs, DVDs, CD players and other electrical appliances.
【3】PC peripherals: wireless keyboard, mouse, game joystick, etc.;
【4】Industrial control: make the automatic collection, analysis and processing of data easier;
【5】Medical equipment control: medical sensors, patient emergency Call buttons, etc.;
[6] Interactive toys.
4.2. LoRa technology
LoRa™ (Long Range) is a modulation technology that provides a longer communication distance compared with similar technologies. Since LoRa modulation is the physical layer (PHY), it can also be used for different protocols and different network architectures (such as Mesh, Star, point-to-point) and so on. LoRa can be summarized as the following several protocols:
[1] LoRaWAN protocol
LoRaWAN protocol is a low-power wide area network protocol promoted by the LoRa Alliance, optimized for low-cost, battery-powered sensors, including different types of nodes, optimization It reduces network latency and battery life. The LoRa Alliance has standardized LoRaWAN to ensure that LoRa networks in different countries are interoperable.
[2] CLAA Network Protocol
"China Lora Application Alliance (CLAA) is a technology alliance supported by the LoRa Alliance, initiated by ZTE, and extensively participated in and jointly established by various industry IoT application innovation entities. To jointly establish China's LoRa application cooperation ecosystem, promote the application and development of the LoRa industry chain in China, and build a multi-service sharing, low-cost, wide-coverage, and operable LoRa Internet of Things. ZTE serves as the board of directors of the LoRa Alliance (LoRa Alliance) Members, together with the members of the LoRa Alliance, promote the development of LoRa technology in the global low-power wide area network (LPWAN) construction and industry chain."
[3] LoRa private network protocol
In applications that face a small number of nodes in a small area, the cost of deploying a network using a LoRaWAN gateway becomes high. Use one or several SX127x to make a small "gateway" or "concentrator", wirelessly connect hundreds of SX127x to form a small star network, through its own LoRa private communication protocol, you can achieve a simple LoRa private Network, this is also a more flexible way
[4] LoRa data transparent transmission
At present, LoRa chips on the market are basically derived from the SX127x series of SEMTECH in the United States. LoRa is used as a transparent transmission module, which only performs simple transmission and reception, and realizes point-to-point data transmission. The application is relatively simple.
6. Wired communication protocol:
6.1. USB protocol
1. Previous version of
USB protocol : USB protocol specification 1.1-support USB low-speed and full-speed specification (12Mbps)
USB protocol specification 2.0-support USB high-speed protocol specification (480Mbps)
USB protocol specification 3.0——Support USB Super Speed Protocol Specification (5Gbps)
6.2. RS232 protocol
1. Introduction to RS232 protocol:
RS232 is an asynchronous transmission standard interface protocol. Generally, the RS-232 interface appears in the form of 9 pins (DB-9) or 25 pins (DB-25). The most commonly used connection for RS232 is three wires: a sending wire, a receiving wire and a ground wire. Level signal: logic 1 (MARK)=-3V～-15V, logic 0 (SPACE)=+3～+15V
6.3. RS485 protocol
1. Introduction to RS232 protocol:
RS485 is an upgraded version of RS232 serial port protocol, generally two-wire transmission: A and B two transmission lines. Level signal: -2V～-6V means "0", +2V～+6V means "1", and the voltage is AB voltage.
6.4. M-Bus protocol
1. Introduction to M-Bus protocol:
M-Bus was born for data collection of remote meter reading systems.