Necessary steps for ARM learning for beginners of embedded development

　　1. Make a minimum system board: If you have never done ARM embedded development , it is recommended that you do not try to do all the applications well at the beginning, because the startup method of ARM is different from that of DSP or MCU, and you will often encounter various problems. Therefore, it is recommended to first build a small system board with only Flash, SRAM or SDRAM, CPU, JTAG, and reset signal, leaving an expansion interface. If the minimum system can run normally, your task is half done. Fortunately, the peripheral interfaces of ARM are basically standard interfaces. If you have experience in wiring these hardware, it is a very easy thing for you.

　　2. Write the startup code. According to the hardware address, write a small code that can be started, including the following parts:

Initialize the port, shield the interrupt, copy the program to SRAM; complete the code remapping; configure the interrupt handle and connect it to the C language entry. You may see that the bootloader has a lot of things in some sample programs given to you, but don't be bothered by these complicated programs, because you are not making a development board, your task is to make a small program to make your application run.

　　3. Carefully study the information of the chip you are using. Although ARM is compatible in terms of core, each chip has its own characteristics, and these issues must be considered when writing programs. Especially for girls, don't be dependent here. You always want to modify other people's sample programs, but the more you modify them, the more messy they become.

　　4. Read more operating system programs. There are many open source programs in ARM embedded development. If you want to improve yourself, you should read more programs of others. Linux, uc/os-II, etc. These are all very good original codes.

　　5. If you are working on hardware, each manufacturer basically has a DEMO board schematic for the chip. Digest the schematic first. This way, when you design in the future, you will have a clear idea of ​​how to allocate resources. You must digest the device's DATSHEET.

　　6. If you are doing software, it is best to have some understanding of the operating system mechanism. Of course, this is a piece of cake for software engineers. But if you are a hardware engineer who wants to do ARM embedded development, it will be a bit difficult.