Some integrated development environments provide instruction set simulators, which can facilitate users to complete some simple debugging work on PC. However, because the instruction set simulator is very different from the real hardware environment, even the program debugged by the user using the instruction set simulator may not run in the real hardware environment, and the user must finally complete the whole application development on the hardware platform.

2. Resident monitoring software

A resident monitor is a program that runs on the target board. The debugging software in the integrated development environment interacts with the resident monitor through communication ports such as Ethernet port, parallel port and serial port, and the debugging software sends commands to inform the resident monitor to control program execution, read and write memory, read and write registers, set breakpoints, etc.

Resident monitoring software is a relatively low-cost and effective debugging method without any other hardware debugging and simulation equipment. Angel of arm is such software, and most embedded real-time operating systems are debugged with such software. The difference is that in the embedded real-time operating system, resident monitoring software exists as the task of the operating system.

The inconvenience of resident monitoring software is that it requires high hardware equipment, and the application software can only be developed after the hardware is stable. At the same time, it takes up some resources on the target board, so it can't completely simulate the program running at full speed, which is not suitable for some demanding occasions.

3.JTAG emulator

JTAG emulator, also known as JTAG debugger, is a device that debugs through JTAG boundary scan port of ARM chip. JTAG emulator is relatively cheap and easy to connect. It communicates with the armCPU kernel through the existing JTAG boundary scan port, which is completely non-invasive (that is, it does not use on-chip resources) debugging. It does not need the target memory, nor does it occupy any ports of the target system, which are necessary for the resident monitoring software. In addition, because the target program of JTAG debugging is executed on the target board, the simulation is closer to the target hardware, so many interface problems, such as the limitation of high-frequency operation, the mismatch of AC and DC parameters, and the limitation of line length, are minimized. At present, using integrated development environment and JTAG simulator for development is the most widely used debugging method.

4. Online simulator

The on-line simulator completely replaces the CPU on the target board with an analog head, which can completely simulate the behavior of the ARM chip and provide more in-depth debugging function. However, to simulate the processor with clock speed higher than 100MHz at full speed, this kind of simulator usually adopts extremely complicated design and technology, so its price is relatively expensive. Java course/thinks that online simulators are usually used in hardware development of arm, but rarely used in software development, and its high price is also a factor that makes online simulators difficult to popularize.