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Embedded System Development Notes 79: why should I get the IP address of the local network card

2022-07-01 04:02:00 【snmplink】

《 Integrated practice of embedded system 》 Series column Introduction

《 Integrated practice of embedded system 》 A series of columns will be published in 《 Integrated development of embedded system 》 Based on the column , The knowledge of embedded system development is systematically introduced in the form of actual combat 、 Skill 、 Skills and sublimated design ideas .

The author strives to make every small column under this series of columns self-contained , Complete a real project practice , Solve the actual needs of a real application . Topics involved in this column , It all comes from the author's years of project practice .

This column series covers the following body of knowledge ：Ubuntu、Python、STM32、C++、VSCode、CPLD、FPGA、Verilog HDL、 Altium Designer.

The knowledge system covered in this series of columns Schematic diagram will be provided for hardware , The software part will provide the source code , For readers' reference .

Welcome your valuable comments on this series of columns , I must accept it with an open mind , You are also welcome to ask questions about the contents of this column , I will answer it within my power .

Last , What I need to explain to you is this series of articles The schematic diagram and program source code provided by us are free （free） Use , No restrictions . But all the articles in this column belong to snmplink original , Please follow Creative Commons Copyright agreement , Without the permission of the blogger , Shall not be reproduced , Shall not be used for any commercial purpose （ Including but not limited to book publishing ）.

List of articles

《 Integrated practice of embedded system 》 Series column Introduction
Preface
One 、 Demonstration effect
Two 、 Basic knowledge required
3、 ... and 、 Why should I get the local network card IP Address
- 1、 How to get equipment IP Address ？
- 2、 How to get the local network card IP Address
Four 、 The content of this column

Preface

This article is 《 Get the local network card IP Address 》 The first of the column 1 An article , I will talk about in this article “ Why should I get the local network card IP Address ”, as well as “ Get the local network card IP Address ” The basic design idea of , On this basis, the specific knowledge arrangement of this column is given , After reading this column , Further systematic learning can be carried out according to the actual needs of individuals .

One 、 Demonstration effect

When the project is completed , The effect shown in the figure below can be achieved , After the application starts , Will prompt “ Please select the communication network card ” Dialog box , The user selects the corresponding network card to communicate with the device , After correct selection , Enter the main interface of the application .
Insert picture description here

Two 、 Basic knowledge required

The knowledge you need to master to read this column is as follows ：

Python

PyQt

Supplement to basic knowledge , May refer to Integrated development of embedded system special column

3、 ... and 、 Why should I get the local network card IP Address

1、 How to get equipment IP Address ？

The topic comes from the actual project needs , Under the LAN , How can we get the equipment quickly IP Address . for instance , You are an equipment maintenance personnel arriving at the equipment installation site , You need to use a laptop or mobile phone to set up your device , But you forgot the device at this time IP Address , How should you operate ？
In general , We can take 3 Methods , Get the device IP Address ：
1、 adopt USB、 A serial port 、485 Get by mouth, etc IP Address
This method does not require equipment IP Address can communicate with the device , But additional interfaces and wiring are needed , It's troublesome to use .
2、 Reset the device
This method first resets the device , Restore its default IP Address , Then apply the default IP Address , Set up the device . This seems simple , Just use the network cable , But after setting , Restore the original settings , Unless the original settings have been backed up , Otherwise, it can be used , Also extremely inconvenient .
3、 The equipment automatically submits IP Address
This method directly uses Ethernet to operate the device , There is no need to reset the device , And let the device make its own IP Submit the address , The main use is IPV4 Broadcast technology of . This is the easiest way , It is also the most widely used .

2、 How to get the local network card IP Address

As mentioned earlier , adopt IPV4 Broadcast technology of , Enables the device to automatically submit its own IP Address , But the first thing we need to do is broadcast on the LAN “ Upload IP Address ” command , If this computer has only one network device （ For example, network card ）, Then directly send the broadcast command to this device .
however , Many computers own multiple network devices , for example , My computer itself has many network devices , As shown in the figure below . therefore , How to confirm which network device sends the broadcast command is an urgent problem to be solved .
Insert picture description here
To solve this problem , We need to start the program , Search all network devices on this computer IP Address , And provide it to users , Let them choose , Confirm the network equipment connected to the equipment .

Four 、 The content of this column

This column will explain how to use Python Language search to all network devices on this computer , actually , Searching the core code of the local network device is very simple , However, this column will explain all the technical details of realizing this application in the form of a complete example , Including the following ：