Host machine: A computer capable of developing applications for other computer systems is called a host machine. The concept of a host originates from the biological world, where other organisms often reside within a host. Similarly, applications reside on other computer systems within a host machine. On a host machine, program code can be written for other computers, then cross-compiled to generate executable programs that can run on those other computer systems. Offline simulation and online debugging are also possible. In actual development, the PC typically plays the role of the host machine.
Target System: The embedded hardware device on which the software to be developed is called the target system. Due to limitations in hardware and software resources, the target system often lacks the ability to develop applications independently. Therefore, it must rely on a host machine to complete software development. However, the target system can utilize certain resident software to assist the host machine in software development, thereby significantly improving development efficiency.
Debugging Connections: Software developed for the target system must be cross-compiled on the host machine before it can be downloaded and run on the target system. Simultaneously, online simulation debugging must be completed before the software can be finally released. Therefore, various hardware connections are necessary during development to facilitate various data exchanges. Debugging connections typically include: serial cables, JTAG cables, and Ethernet cables. Serial cables are generally used for data exchange when the host machine issues control commands and displays the target system's running status; JTAG cables are generally used for online simulation or burning the bootloader; Ethernet cables are generally used for large-scale data exchange (downloading the kernel, root file system, user applications, etc.). Different types of debugging connections have different uses, and none can completely replace the other. Understanding the specific function of each type of connection is crucial.
Host development environment
Operating System Environment: The host machine typically uses Linux as the operating system, requiring developers to be proficient in and use Linux. Before deployment, it is essential to configure the Linux working environment, including file sharing with Windows, configuration of critical system services, text editing tools, etc. When installing the operating system, if you are unfamiliar with Linux, you can choose a full installation to effectively avoid some problems during use.
Cross-compilation environment: Applications developed on the host machine must be compiled into executable programs that can run on the target system, which requires cross-compilation. Cross-compilation requires a cross-compiler, and after installing the cross-compiler, the correct environment variables must be configured. During development, different versions of cross-compilers may often be used, so it is essential to stay alert and choose the appropriate version at all times.
Debugging environment: During the debugging process, serial ports will be used, so you must be proficient in using serial port debugging tools; JTAG hardware device drivers and JTAG programming tools must also be installed and configured correctly; during development, network tools such as NFS and TFTP will also be used, so configuring and starting network services on the host machine is also a very important task.
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