This resource is chapter xi of the e-technology university's teacher lai xiao hong course on micro-engineering principles. The theme focuses on software system design based on arm microprocessors, which includes, inter alia, embedded software system architecture and workflow, induction and loading of embedded software systems, embedded linux operating systems and examples of driver design under linux. Embedded system software designs can be divided into two categories based on functional needs: simple embedded applications and complex embedded applications. In simple applications, such as 8051 chips for toy, home electricity or car control, software usually does not rely on operating systems, is developed directly based on nud machines, directly executes the main function, initializes and enters the work cycle once the system is powered. In complex applications, such as arm-based mobile phones or pdas, embedded operating systems, such as linux, are often used to improve development efficiency and system reliability, owing to the need for more complex functions, such as graphical user interfaces, network management, etc. The structure of complex embedded systems software typically includes a hardware abstract layer (hal), a bottom envelope and some of the services provided by the operating system. When the system is activated, there will be a guided loader (botload) to load the operating system. In the case of s3c2440, the microprocessor can be activated by a hardware jumper, e. G. From nand flash or nor flash. When you choose to start from nand flash, the s3c2440 nandflash controller automatically moves u-boot data from the first 4kb to a low-end internal sram. This part of the sram is referred to as “boot ram” and is used for the temporary storage guide loading program, after which u-bot will continue, complete the initialization of the system, equipment testing, memory testing, and loading of the operating system image into memory and eventually jump to the operational system entry point to start running. The embedded linux operating system plays a key role in such a system, providing a wealth of api and kernel services that enable developers to construct complex applications and drivers. The preparation of drivers under linux usually involves bottom codes that interact with hardware and may include functions such as initialization hardware, registration equipment, processing interruptions and data transmission. The arm-based embedded system design involves hardware, operating systems, drivers and applications at multiple levels and requires an in-depth understanding of the microprocessor system structure, the workflow of embedded software and the characteristics of specific operating systems in order to effectively develop efficient software systems that meet demand。
