• [n32g457] usb2can debugger based on RT thread and n32g457


    This article is the original release of RT thread user @ civil and military soldiers. It is used to participate in the n32g457 RT thread design competition jointly launched by RT thread and national technology. The original text:https://club.rt-thread.org/as… introduce A simple and convenient USB 2Can debugger can be used for CAN bus data debugging and […]

  • Memory delay difference test under NUMA architecture!


    Today’s server physical machine CPUs are generally multiple CPUs, and the number of cores is more than ten or even dozens of cores. There are dozens of GB or even hundreds of GB of memory. So let me think about how so many CPUs and memory are connected to each other? Does the same CPU […]

  • Challenge the maximum memory limit of redis single instance and “encounter” NUMA trap!


    Our company’s infrastructure department has a cloud redis platform, in which redis instances can freely choose the required memory size when applying. Then it triggered my thinking, how large is the maximum memory of redis single instance more appropriate? Assuming that the mother machine is a physical machine with 64GB memory, if the waste of […]

  • Meituan Interviewer: young man, talk about the principle of volatile keyword?


    preface Before talking about the volatile keyword, let’s talk about the CPU multi-core concurrent cache architecture, then to JMM, that is, the JAVA memory model, and finally to the volatile keyword. JMM (JAVA memory model) Introduction of multi-core concurrent cache architecture In order to solve the mismatch between the speed of CPU and main memory, […]

  • Understand the difference between SOA architecture and micro service architecture


    scene If we open the Alipay home page to see our balance, it will show your total assets, yesterday’s income and accumulated income. If the information displayed on this page comes from different systems / applications, we will display these data through various interfaces. If we want to display these data on the front page […]

  • STM32 (1): turn on the LED (upper)


    This article is taken from: https://blog.csdn.net/xiashiwendao/article/details/122291583 summary Today, we started the first stop of STM32 development: lighting up the LED. Today’s content contains a lot of basic knowledge and some means of persuading you to retreat. However, if you can withstand this wave of offensive, I think your high embedded aspect is really “rare and […]

  • Design mode – observer mode


    The previous article talked about the more traditional usage of the observer model. This article is going to share some popular ones. However, before starting new content, we might as well think about two scenarios: one is the newspaper subscribing to the newspaper, and the other is making an announcement on the blackboard. They are […]

  • [original] analysis of Linux PCI Driver Framework (I)


    background Read the fucking source code!–By Lu Xun A picture is worth a thousand words.–By Golgi explain: Kernel version: 4.14 Arm64 processor Tools used: source insight 3.5, Visio 1. General Starting from this article, we will focus on PCIe topics, including: PCI / PCIe bus hardware; Linux PCI Driver core framework; Linux PCI host controller […]

  • CentOS hard disk expansion and deletion


    All operations in this paper are carried out in the experimental environment. Do not test in the production environment 1. Add hard disk to virtual machineAdd according to your own needs image.png 2. Identify the hard diskadoptfdisk -lWe find that we can’t find the newly added SCSI hard disk. At this time, we need to […]

  • [original] analysis of Linux PCI Driver Framework (II)


    Background Read the fucking source code!–By Lu Xun A picture is worth a thousand words.–By Golgi explain: Kernel version: 4.14 Arm64 processor Tools used: source insight 3.5, Visio 1. General This paper will analyze the framework of Linux PCI subsystem, mainly focusing on the initialization and enumeration process of Linux PCI subsystem; If you lack […]

  • Raspberry pie 4b-spi read / write flash-fm25cl16b (also supports FM25CL64 and other series of flash)


    1. Introduction to raspberry pie SPI The pin of 4b is shown in the figure below: Pin19, 21 and 23 are spi0, and the interface definition is as follows: Clock (SPI, CLK, SCLK) Master output, slave input (MoSi) Master input and slave output (MISO) Before using SPI interface, you need to use GPIO command to […]

  • Pit filling – about IIC communication


    ​01. Overview In previous articles《Stm32iic details》The IIC protocol is explained in detail, and the use is the official Manual of NXP. The demo example uses IIC to read the RTC chip, which runs normally without any problems. And updated《IIC stepped pit》, describes the problems encountered when using IIC to read RTC chip, and solves them […]