Below I post a popular explanation of the embedded system I saw on the Internet, the source of which can't be found ..... (I'm not a computer major, but I only learned about it because of my internship in a recording and broadcasting company) (put an advertisement of my company: Beijing Hantang Ziyuan Technology Co., Ltd., if you are interested, you can learn about it);
What is embedded technology?
Simply put, it is the technology to realize embedded system.
What is an embedded system?
The definition of online or book flooding is that embedded system is a computer system with strict requirements on volume, power consumption and cost, and its software and hardware can be tailored for a certain application.
It looks complicated and abstract, but there are actually two points:
First of all, the embedded system is a computer system.
Second, the embedded system is aimed at an application, which is usually called "dedicated".
In other words, an embedded system, to put it bluntly, is an applied computer system!
Others: this pile of modifiers is flexible in software and hardware, and strict in volume, power consumption and cost. , is a factor to be considered in an embedded system. Doing well is two different things. Of course, if you really want to do an embedded system well, it is far from enough to consider these. There are many other things to consider.
Everyone knows that PC, or notebook computer, PC or notebook computer is a computer system, just a general computer system. Almighty means that you can do anything without a specific purpose. For example, you can surf the internet, listen to songs, watch movies, look at photos, even develop programs, be a server, etc ... Anyway, you can do whatever you want, and there is no mandatory specific purpose. Therefore, it is universal, but the embedded system is special.
How to understand this special?
Dedicated for a specific purpose. Example: Didn't you just say that you can watch photos on your PC? Take out the photo-viewing application and make it into a computer, which is an application computer. What is the name of this computer after it is built? It's called digital photo frame, and the computer city is piled up. According to the definition just mentioned, it is not difficult to see that the digital photo frame is an embedded system!
Deduct the application of listening to songs and make it into a computer. What's the name of this computer? It's called mp3 player. Mp3 player is aimed at computers that listen to music, so mp3 player is also an embedded system!
Take out the movie-watching application and make it into a computer. What's the name of this computer? It's called mp4 player. Mp4 player is aimed at computers watching movies, so mp4 player is also an embedded system! ......
From here, we can see a general difference between PC and embedded system, and we should also have a general impression of embedded system.
But doesn't it mean that embedded systems can only be based on PC applications? No, if so, there is no need for embedded systems to exist. In addition to applications from PC, more N applications of embedded system should be from all walks of life except PC! We have been shouting for many years about the information society, the information society, what is the information society? I don't think the information society refers to the information society with access to the Internet, but refers to the information society in which everything is digitized and informationized. This should be where embedded systems come into play!
Let's talk about what everyone has seen first, so it's easy to understand! Everyone should have seen the POS machine, which is the thing that goes to the checkout counter of X Fu and Wo X Ma when shopping in the supermarket. What is a POS machine? Typical embedded system: First of all, the POS machine is really a computer with a motherboard, a CPU, an operating system and software. It has the core characteristics of a computer, so it is a computer. Secondly, it is aimed at a special application computer, and this special application is checkout cashier! According to our previous definition of embedded system, it is not difficult to understand that POS machines are embedded systems!
Let's first compare this POS machine (the original big-headed POS machine) with PC. Everyone is familiar with PC, so compare it with PC as a reference and benchmark!
We compared hardware and software:
Let's talk about hardware first: What hardware is there on the PC? There are CPU, memory, graphics card, sound card, hard disk, network card, keyboard, mouse and other things. What should we do if we want to make a POS machine with reference to PC?
See what the POS machine needs: CPU and memory are necessary, network card, video card and keyboard should be necessary, and sound card and mouse should not be needed. Therefore, if you want to make a PC-based pos machine, you must remove the sound card and mouse, and add a display screen (POS machine has two screens) and a printer. Remove some hardware and add some hardware, which is hardware reducible. In order to work, hardware needs software support, at least driver support. Therefore, if you remove some hardware and add some hardware, you must remove and add some software, which means you can cut the software. Together, it is the sentence in the definition of embedded system: embedded system is aimed at a certain application, and both software and hardware can be cut, xxxxxx computer system. Do you understand the meaning of cuttability?
Above: xxxxx definition: volume, power consumption and cost. In fact, the size and power consumption are not obvious in POS machines, because this kind of large-head POS machine is not sensitive to the size, the space is too small (of course, it cannot be too large), and it is not sensitive to the power consumption. Ac power supply, and it's not too hot to turn it off every day. These two points are very sensitive in embedded products of handheld devices such as mobile phones. If your mobile phone is made as big as a brick, it is estimated that you don't want to buy it either (unless it is for female compatriots' self-defense). If the power consumption is high, it only takes 1 hour to fully charge, and you won't buy it anyway. So in the definition of embedded system, it is said that there are strict requirements on volume and power consumption. That's what it means, right?
In addition, the cost is very sensitive. Take a simple example to understand: if you are the boss of Apple and sell100000 iphones a year, if one part of the iPhone can save100000 yuan, selling100000 units will save100000 yuan, and the money saved is equivalent to the money earned. Therefore, if you really don't want to, embedded devices are very sensitive to cost!
Based on the sensitivity to cost, you have to understand: we do embedded products, not which CPU is the best, but we should combine various factors to choose. If arm9 can handle it, we don't need arm 1 1, a8 or a9. Don't choose expensive ones, just choose the right ones, and more!