Introduction A microcontroller, also known as a microcontroller unit (MCU), integrates a complete computer system, including the CPU, RAM, ROM, timers/counters, and various I/O interfaces, onto a single chip. Due to its numerous advantages and characteristics, the applications of microcontrollers are extremely wide-ranging. A microcontroller system consists of both hardware and software systems, which involves the issue of program writing. There are many programming languages for microcontrollers, generally divided into three categories: machine language, assembly language, and high-level languages. Machine language is cumbersome and prone to errors, and is generally no longer used by ordinary users. Below, we will analyze assembly language and the most commonly used high-level languages. Assembly Language for Microcontrollers Assembly language is a symbolic language that uses mnemonic symbols to represent machine instructions, making it the closest language to machine code. Its main advantages are low resource usage and high program execution efficiency. Since each instruction corresponds to a machine code, the execution actions are clear, and it is easy to control program size and stack calls, making debugging relatively convenient. However, different types of microcontrollers may have slight differences in their assembly languages, making them less portable due to differences in their instruction sets. However, understanding assembly language can help comprehend the special rules that affect the efficiency of any language. For example, knowing assembly language instructions enables the use of on-chip RAM as variables, since external variables require several instructions to set up the accumulator and data pointer for access. Similarly, when floating-point numbers and functions are required, only those with assembly programming experience can avoid generating large, inefficient programs. This aspect of programming cannot be achieved without assembly language. C Language for Microcontrollers The C language for microcontrollers is a compiled programming language that combines features from various high-level languages while retaining the capabilities of assembly language. C language has a rich set of library functions, fast computation speed, high compilation efficiency, and good portability, allowing direct control over system hardware. Additionally, C language programs have a complete modular structure, providing strong support for modular programming methods in software development. Compared to assembly language, it has the following advantages: it does not require an understanding of the instruction set of the microcontroller, only a basic understanding of the memory structure of the 8051, while details such as register allocation, addressing of different memory types, and data types are managed by the compiler. Programs have a standardized structure that can be divided into different functions. This approach allows for structured programming, combining variable selections with special operations, thereby improving program readability. Programming and debugging time are significantly reduced, thus enhancing efficiency. The provided libraries include many standard subprograms with strong data processing capabilities, allowing already written programs to be easily integrated into new programs due to convenient modular programming techniques. C language for microcontrollers has gained widespread support as a very convenient language, and C language programs themselves do not depend on the machine hardware system, allowing for quick adaptation to different microcontrollers with minimal modifications. Programming with C language for microcontrollers has become a mainstream in microcontroller software development, and it is best for developers involved in large-scale software system development to master basic C programming. Other High-Level Languages For microcontroller programming, there are also BASIC and PL/M languages. BASIC has always been considered an entry-level programming language, easy to learn, while PL/M language is known for its good readability and high reliability, but it does not support complex arithmetic operations, floating-point variables, and lacks rich library function support. Conclusion Assembly language is closely related to the processor. Each processor has its own instruction set, and corresponding assembly languages differ. Therefore, assembly language programs have poor universality and portability. In contrast, high-level languages are not tied to specific computers; high-level language programs can be compiled and executed on various computers. Assembly language has limited functionality and involves hardware details such as registers and main memory units, making programming cumbersome and debugging difficult. High-level languages offer powerful features with syntax similar to natural language, making them easier to learn and apply, without needing to worry about trivial issues like flags and stacks. Assembly language is essentially machine language, allowing for direct and effective control over computer hardware, resulting in high-efficiency target programs with fast execution speed and short instruction sequences. High-level languages, however, do not easily control various operations of the computer, and the target programs generated by compilers are often large and difficult to optimize, leading to slower execution speeds. In summary, each programming language for microcontrollers has its own advantages and disadvantages. As a beginner in microcontrollers, it is advisable to first learn assembly language, as assembly language programs possess advantages such as simplicity, agility, and low ROM resource usage, while also being closely linked to the underlying hardware, helping beginners to better understand the various resources of the microcontroller hardware system and familiarize themselves with the functions of different modules, thus laying a solid foundation for writing more efficient programs. Programs written in assembly language for microcontrollers are highly efficient, but they are relatively difficult to learn. Moreover, for large projects, programming entirely in assembly language can be cumbersome, especially when dealing with algorithm-related issues, where assembly language may not suffice. Furthermore, as the main frequency of microcontrollers continues to increase, we no longer require such highly efficient code; additionally, the ROM and RAM space of microcontrollers is also constantly increasing, which is sufficient to accommodate any program code written in C language. There is ample and easily accessible information related to microcontroller C language, and its portability is excellent; for example, changing an I/O port for a temperature sensor program can be used on any microcontroller. Programming with C language for microcontrollers has become a mainstream in microcontroller software development, and it is best for technical personnel to master basic C programming. Of course, sometimes using C language for microcontrollers cannot achieve all required functionalities, such as when writing a precise timing program, where using assembly language is still more convenient. Therefore, to become an excellent microcontroller programming technician, it is best to understand mixed programming using both C language and assembly language. This is because assembly language programs occupy very little storage space, allow flexible hardware control, and have fast response times, but they are poorly readable and difficult to debug and maintain. C language is easy to update and maintain, with strong portability, but practical experience has shown that developing microcontroller programs solely with C language has many shortcomings, such as large storage space usage and inflexible hardware control. Therefore, it is not ideal to develop microcontroller programs using any single language. To write high-speed, high-efficiency, and highly portable microcontroller programs, it is essential to combine the advantages of both C language and assembly language, creating what is known as mixed programming with C and assembly language. During the programming process, C language is typically used to construct the program framework, while assembly language is used for subprograms to handle special applications that require real-time performance.
