Several ARM debugging methods that embedded programmers need to know

　　According to different functions, the development tools of ARM application software include compiler software, assembler software, linker software, debugger software, embedded real-time operating system, function library, evaluation board, JTAG emulator, online emulator, etc. At present, there are more than 40 companies in the world that provide the above products of different categories. The following is a detailed introduction by Fuzhou Zhuoyue Education. 
Using the integrated development environment to develop ARM-based application software, including editing, compiling, assembling, linking, etc., all can be completed on the PC, and debugging work needs to be completed with other modules or products. At present, the common debugging methods of ARM training classes are as follows:
　　1. Instruction set simulator
　　Some integrated development environments provide instruction set simulators, which can facilitate users to complete some simple debugging work on PCs. However, since the instruction set simulator is very different from the real hardware environment, even if the user uses the instruction set simulator to debug the program, it may not be able to run in the real hardware environment. The user must eventually complete the development of the entire application on the hardware platform.
　　2. Resident monitoring software
　　Resident monitoring software (Resident Monitors) is a program running on the target board. The debugging software in the integrated development environment interacts with the resident monitoring software through communication ports such as Ethernet ports, parallel ports, and serial ports. The debugging software issues commands to notify the resident monitoring software to control the execution of the program, read and write memory, read and write registers, set breakpoints, etc. Resident monitoring software is a relatively cheap and effective debugging method that does not require any other hardware debugging and simulation equipment. ARM's Angel is such software, and most embedded real-time operating systems also use such software for debugging. The difference is that in embedded real-time operating systems, resident monitoring software exists as a task of the operating system.
　　3. JTAG emulator
　　JTAG emulator, also known as JTAG debugger, is a device for debugging through the JTAG boundary scan port of the ARM chip. JTAG emulators are relatively cheap and easy to connect. They communicate with the ARM CPU core through the existing JTAG boundary scan port. They are completely non-insertional (i.e., do not use on-chip resources) debugging. They do not require target memory and do not occupy any ports of the target system, which are required by resident monitoring software. In addition, since the target program of JTAG debugging is executed on the target board, the simulation is closer to the target hardware. Therefore, many interface problems, such as high-frequency operation restrictions, AC and DC parameter mismatches, and wire length restrictions, are minimized.
　　4. In-circuit emulators
　　In-circuit emulators use emulation headers to completely replace the CPU on the target board, which can fully simulate the behavior of ARM chips and provide more in-depth debugging functions. However, in order to be able to simulate processors with clock speeds higher than 100MHz at full speed, such emulators usually have to adopt extremely complex designs and processes, so their prices are relatively expensive. In-circuit emulators are usually used in ARM hardware development and are rarely used in software development. Their high price is also a factor that makes in-circuit emulators difficult to popularize.