The best article for beginners on ARM

I am learning arm7 myself, and I accidentally saw this article on the Internet. The content is as the title says. I feel that it is well written, so I post it here for novices to refer to, and experts don’t need to read it. The author of the article is unknown, and I just reprint it here without any modification: 1. Grasp the 51 to develop ARM. In the past few months, I have been crawling on the problem of 51. I am a little bit laughing at myself. It took me 4 months to consolidate the principles and procedures of 51. Fortunately, I have come through it. I am stupid, and the talented students around me don’t think highly of the principles of 51. They are all "good" and say that 51 is outdated. Why do you ask that? ? ? I am quite depressed! Is it outdated? I have a little doubt? They don’t want to say that they have their own reasons. No one forces them. Just rely on yourself.

My personal opinion: 51 is a foundation, and it is also very important. This is what I feel after watching ARM. It can speed up your ARM learning speed, really! If you don't believe it, just give it a try. 

Whenever you require speed and efficiency, don't do useless work and seize every minute around you. People are alive, things (knowledge, books) are dead, so what you want to do will be simple. 

2. I saw a very good ARM article on the Internet, and I pasted it here for those who are like me, who are self-studying ARM with little help. "How to get started with ARM". I am not an expert, I am still a novice. But thinking back to my confusion at that time, I wrote this article specially, as a help to my brothers and sisters like me. Most of the people who ask this question are not engineers who have already worked, but students like me, so this note will be regarded as a novice like me, experts please don't blame me. First of all, I declare: I haven't found a job yet. In fact, I have just graduated from graduate school and have not started looking for a job. 44B0 is just an interest, to kill time. All opinions are completely my own feelings and do not represent anyone else. Please help me correct the wrong opinions. Another addition: Many friends read the above words and asked me why I didn't find a job after graduating from graduate school:) It's said to kill time, but in fact it was because I took a project when I was a graduate student. After applying for early graduation, the project still had a tail, and I promised my supervisor to finish the project before leaving:) It's that simple. Men always have to take some responsibilities, hehe. The following questions are often asked, so I'll talk about whatever I think of. 

First of all, the development of ARM can be described as a great success. Opening the websites of various companies, most of the engineer positions in the recruitment are in the embedded field. Broadly speaking, there are only a few types of embedded systems: the traditional 51, AVR, and PIC are called embedded microcontrollers; ARM is an embedded microprocessor; DSP; FPGA. Objectively speaking, the demand for DSP is greater than that for ARM, while ARM and FPGA are similar. DSP is popular because of the unprecedented development in the field of digital processing and communication. It has a wide range of applications, from MP3 cameras to controllers in our military products. FPGA's brother is generally ANSIC (special chip design, it seems to be translated like this). ARM is not much better than a single-chip microcomputer, but its uniqueness lies in its ever-decreasing price and improved performance. This is entirely due to the strategy of ARM, which is amazing! ! I admire their strategic vision! ! It is worth noting that when looking for a job, companies (famous ones, not small ones) do not pay more attention to pure ARM hardware development engineers than single-chip microcomputers. Few large companies write "employed in ARM development is preferred" in their positions. What are the ones that are written more? I believe everyone can see that "Embedded LINUX" requires software in hardware. 

Second, it is difficult to say whether ARM is hardware or software. ARM is hardware and LINUX is software. ARM's hardware is mostly modularized. Modifying the board like this as I did is considered a lot of changes. This is also the strategy of ARM. I admire it again. The actual development work of LINUX is more and more time-consuming. From this perspective, ARM should be considered software. This is even more true when looking for a job. For example, the closest thing to ARM in Lenovo is "BIOS engineer", which is software, and the closest thing to ARM in MOTO is embedded LINUX engineer, which is software. Many other companies classify embedded product development as hardware. So, don't discuss this. The key is to play with your own board well. If you are really unhappy, just call yourself an "embedded development engineer" 

Third, whether to buy a development board and which company to buy. My answer is "it depends on your personal learning method", but if you need to look at the level of the cheating notes, I personally recommend buying a ready-made one. 

1 Buying a board can help you focus on software development. Software development (especially drivers) does not need to worry about hardware problems. I write drivers and programs while debugging. Every time before writing a driver, I have to confirm that there is no problem with the hardware. In addition, buying a board saves money and time. The board I made myself took more than 2 weeks to make the schematic PCB! It took another 15 days to make the plate. After I came back, I soldered 44B0 160 pins! That's a hassle~~How much did it cost? A 2-layer board costs 300 yuan for plate making! Of course, I externalized all the interfaces and made a 20X18 LCD backplane. The board is relatively large. In general, components + LCD screen + PCB = 11XX yuan! Enough for 2410. Another thing is that the information you buy is relatively complete, but don't expect technical support! They are all scammers. They will ignore you after selling you. 

2 Doing it yourself can help you understand the underlying hardware better, and you can add things according to your own requirements. For example, I added a GPS module, a GPRS module, and an SD card module, expanded an IIC keyboard with 35 keys, and modified the LCD interface according to the LCD I bought, so that it can be directly connected with an FPC line. It was very fun to do. Have a try. Of course, you can do it strategically, such as keeping the RAM, ROM, and network the same as a ready-made board like I did, so that you can use their data directly and leave yourself a way out. Other things such as SD can be done by yourself. All of them have been achieved~~ It's just that it costs money and time. In addition, I would like to give a few suggestions to friends who do it: try to get a ready-made board, try to collect a full set of data for other boards, and be sure to get a schematic diagram without any problems. Most of the schematic diagrams circulating on the Internet were drawn by Gong Jun in 2003. Here I would like to express my respect to Gong Jun! ! Awesome! But there is a small bug in that diagram. I mean the 2003 version. There is no such problem in later ones. There are problems with the address lines and addresses of 8019. Some people imitated the SCH of his PDF drawing, which is full of loopholes! Condemn! By the way, condemn the person who stole and sold Gong Jun's board. 

3. Which one to buy? I personally think it can be divided into three categories. 

1) First of all, ZLG has very complete information. It feels like they really want to teach you how to develop ARM, instead of making a board and selling it for money like some companies that haven't even finished their own technology. But the biggest disadvantage is that the price is too expensive! And it's mainly PHILIP, and it's more difficult to source it~~ Some people may say that the 21XX series is not expensive, but that's because the bus is not expanded, and it can only run UCOS, not UCLINUX. But to be honest, the 21XX series is the price-performance combination of ARM7. ARM7 is most suitable for industrial control. How did ARM become popular and sell well? It's all from ARM7, and 44B0 is a typical commercial film. However, if you are looking at preparing for work here, you should still choose the one that can run UCLINUX. But it's still the first recommendation, because in the rookie period, the right information is too important! ! I was touched by ZLG's pragmatic spirit here! Look at the code they wrote. 

2) I feel that Liyutai's 44B0 is good. There is nothing special about the hardware, but the information is relatively complete. Unlike some companies, the schematic diagram is directly copied from others, and it is still wrong~~

3) Find the cheapest one. The cheapest one seems to be sold for 350, right? There is nothing else to do, just saving money and time to collect information. As for whether the information is complete or not, don't worry about it~~ the hardware must be good.

4. Do you need to have the basics of 51 AVR and other single-chip microcomputers? It is better to have them, but it does not matter if you do not have them. Two months ago, I just watched others do it and learned from them. I studied single-chip microcomputers in my undergraduate studies, but I have never done it. The main technical backbone of our company is AVR and 51, and I have adjusted C language programs with them. You can see it? I am an absolute novice, right? But before doing this, I specially found two books by ZLG and read the examples and schematics in them. This is very important. There are assembly and C in the routines. It is OK if you understand them all, and you don’t have to write them yourself. 

What software do you need to learn for the five developments? In summary, the most important ones are the following. 

1 ADS debugging is ADS+AXD to be exact. ADS contains AXD. Originally, SDT was used, but ARM stopped supporting SDT and changed to support ADS. So it is better to use ADS. Some people still release SDT versions of their programs, but basically you can find the corresponding ADS. Newbies should not be confused here. ADS is the compiler, and AXD is the debugger. After converting to AXF, debug in ARM's RAM.