1. Initialization process Initialize clock Set the multiplexed IO port of GPIO Set the electrical properties of GPIO Initialize GPIO 2. Understanding volatile initialization registers in C language #define CCM_CCGR0 *((volatile unsigned int *)0x020C4068) Understanding of volatile The volatile keyword has the following uses: (1) Used for synchronization, because the same thing may have multiple […]
Tag: stan
Echart polar coordinates, azimuth and distance diagram, icon symbol rotation and size, color gradient
Background: Participating in an interactive chart project, the customer had a need for polar coordinate comparison to display different types of indicator data in different directions and distances. Specifically, the attribute fields are: Source, distance, orientation, ID, rotation angle, size Let’s look at the renderings first: Technical points: Legend description: The distance is the radial […]
nginx four-layer tcp load balancing and active and standby, four-layer udp load balancing and active and standby, 7-layer http load balancing and active and standby configuration (wndows system active and standby, load balancing)
Preparation Prepare two centos7 computers, virtual machines can also be used Use vmware17 to build centos7 mini version server on windows-CSDN Blog Set up a static IP address (because the network load balancing manager on the Windows server does not support dhcp servers) Modify the network card IP address in ky10, centos7 and other linux […]
How to understand and select optimistic locks and pessimistic locks during back-end development?
The author was asked this practical question when participating in a soft opening interview at a bank, so I came here to learn and summarize it. To get straight to the point, when choosing between pessimistic locks and optimistic locks, you need to consider the specific application scenarios: Pessimistic locking is suitable for scenarios where […]
Understanding Crontab in Linux With Examples
The crontab is used to automate all types of tasks on Linux systems. This is an especially important skill for aspiring system administrators to learn. It can be somewhat challenging to get started if you’re a beginner. The syntax is different than most other commands. For this reason, this lesson will include a little more […]
One Demo handles the front-end and back-end multi-part uploading of large files, resumed uploading at breakpoints, and instantaneous uploading.
1Foreword File uploading is very common in project development. Most projects will involve the uploading of pictures, audios, videos, and files. Usually a simple Form can upload small files, but when encountering large files, such as more than 1GB, or When the user’s network is relatively slow, simple file upload is not applicable. The user […]
LC-1334. The city with the fewest neighbors within the threshold distance (Floyd algorithm, memorized search ==> dynamic programming (0x3f))
1334. The city with the fewest neighbors within the threshold distance medium There are n cities, numbered from 0 to n-1. Give you an edge array edges, where edges[i] = [fromi, toi, weighti] represents fromi and toi code> A bidirectional weighted edge between two cities, the distance threshold is an integer distanceThreshold. Returns the city […]
Linux file operations – standard c library for file operations
The difference between Linux and standard c library in file operations 1. Source From the perspective of source, the two can be distinguished very well, and this is also the most obvious difference between the two: open is a UNIX system call function (including LINUX, etc.). It returns a file descriptor (File Descriptor), which is […]
Instances of all methods in the list type (except sort) and explanations (called through help (list))
1. Overview After using help (list) and running it, you can see the following methods: append, clear, copy, count, extend, index, insert, pop, remove, reverse, a total of ten methods. Next, I will give examples one by one. explain. 2. Examples and explanations 1.append: Append object to the end of the list. (Append object to […]
Synchronization Quest: Understanding the differences and applications of System V and POSIX semaphores
Directory title 1. Introduction 1.1 Overview of the importance of semaphores 1.2 Purpose of this article: Compare System V and POSIX semaphores 2. Basics of Semaphores 2.1 Definition and Function of Semaphores 2.2 The role of semaphores in process synchronization (Role in Process Synchronization) Synchronization and Mutual Exclusion The similarity between the psychology of semaphores […]