What is the working mode of the Wifi module? What are the main functions of the Wifi module? This article mainly introduces the basic knowledge of the Wifi module, namely the working mode, main functions and application fields of the Wifi module.
To illustrate the topology of the wireless network, we must first understand two basic concepts
1): AP, which is the wireless access point, is the creator of a wireless network and is the central node of the network. The average home or office using a wireless router on an AP.
2): STA stations, each connected to the wireless network terminal (such as laptops, PDAs and other networked user equipment) can be called a site.
Wifi module work
1、passive serial device networking:
Passive serial device networking means that all devices in the system are always in the passive waiting connection state, only the background server initiates the connection with the device and requests or downloads the data. Typical applications, such as some wireless sensor networks, where each sensor terminal is always collecting data in real time, but the data collected are not immediately uploaded, but Harvatek is temporarily stored in the device. The background server is periodically periodically connected to the device and request upload or download data.
In this case, the backend server actually acts as the TCP client and the device as the TCP Server-side feature 2.4GHz, IEEE 802.11b / g internal PCB antenna with optional external antenna Support for AP-based / peer-to-peer networks Adhoc (IBSS) / Virtual AP mode, IPHONE / IPAD / Android devices can also be connected directly without an AP / router Supports 802.11i Encryption: WEP-64/128, TKIP and WPA2- PSK) MCU Built-in TCP / IP protocol stack 3 UART Serial Interfaces (1 of which supports DMA mode, full-function serial port, baud rate up to 921.6Kbps) SPI interface, I2S / PCM interface Digital Video port Up to 24 GPIO ports (Some GPIOs will be multiplexed with the above interface) Full-featured TCP / IP protocol stack with TCP / IP transmission bandwidth up to 10Mbps Supports three WiFi modes with timed auto-wake-up function Single 3.3V power supply Operating temperature range: 0 ° C ~ + 70 ° C Dimensions: 25 mm x 45 mm (internal PCB antenna) / 25 mm x 39 mm (external antenna).
2, active serial device networking:
Active serial device networking refers to the device initiated by the initiative to connect and interact with the background server data (upload or download) way. Typical active devices, such as wireless POS machines, connect to the backend server each time a credit card transaction is completed and upload transaction data. PUSH serial device network topology as shown on the right. Among them, the background server as the TCP Server side, the device access to the network through the wireless AP / router, and as a TCP Client side.
Wifi module's main function
2、 Adhoc: also known as ad hoc network, which consists of only two or more STAs themselves. There is no AP in the network. This type of network is a loose structure , All the STAs in the network can communicate directly.
3、Security mechanism: This module supports a variety of wireless network encryption, can fully guarantee the safe transmission of user data, including: WEP64 / WEP128 / TKIP / CCMP (AES) WEP / WPA-PSK / WPA2-PSK.
4、Fast Networking: This module supports fast networking by specifying the channel number. In normal wireless networking, all current channels are automatically scanned first to search for the created (or Adhoc) network of the destination AP to be connected. This module provides the parameters for setting the working channel. Under the condition of knowing the channel where the destination network is located, the working channel of the module can be directly specified so as to speed up the networking speed.
5、the address binding: This module supports the process of binding the destination network BSSID address function. According to the 802.11 protocol, different wireless networks may have the same network name (ie, SSID / ESSID), but must correspond to a unique BSSID address. An intruder can establish a wireless network with the same SSID / ESSID so that STAs in the network can connect to illegal APs, thereby causing network leakage. By BSSID address binding, STA can prevent access to the illegal network, thereby enhancing the security of the wireless network.
6、wireless roaming: This module supports wireless roaming based on 802.11 protocol. Wireless roaming refers to extending the coverage of a wireless network. A plurality of APs jointly create a wireless network with the same SSID / ESSID. Each AP is used to cover different areas. The STA accessing the network can determine, according to Different locations choose one of the most recent (ie, the strongest signals) AP to access, and with the STA's mobile automatically switches between different APs.
7、Flexible parameter configuration: 1. Based on the serial port connection, using the configuration management program 2. Based on the serial port connection, using the HyperTerminal program under Windows 3. Based on the network connection, using the IE browser program 4. Based on the wireless connection, the use of configuration management program.
Wifi module applications
1、serial port (RS232 / RS485) to WiFi, TTL to WiFi;
2、WiFi remote control / monitoring, TCP / IP and Wi-Fi coprocessor;
3、WiFi remote control aircraft, cars and other toys;
4、WiFi Internet radio, camera, digital photo frame;
5、medical equipment, data acquisition, handheld devices;
6、WiFi fat, smart card terminal; intelligent home;
7、instrumentation, equipment parameters monitoring, wireless POS machines;
8、modern agriculture, military fields and other wireless related secondary development and application.
Uart-Wifi is an embedded module based on the Uart interface that conforms to the wifi wireless network standard. The built-in wireless network protocol IEEE802.11 protocol stack and the TCP / IP protocol stack enable the conversion of user serial port or TTL level data to the wireless network . This article mainly introduces the basic knowledge of the Wifi module namely: Wifi module work, the main function and application areas.
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