Why do microcontrollers use C language?

The transplantation of C to MCU (commonly known as single-chip microcomputer) 8051 began in the mid-to-late 1980s. Objectively speaking, there are many difficulties in transplanting C to 8051 MCU. For example:

The non-von Neumann architecture of the 8051 (separate program and data memory spaces), plus the addition of bit-addressable memory space on-chip;

The on-chip data and program memory space is too small and there is a possibility of expanding them off-chip;

On-chip integrated peripherals are registered (i.e. SFR) rather than using the conventional I/O address space;

There are many derivatives of the 8051 chip (more than a hundred), and the C language must be able to operate on each of their hardware resources without exception.

These are all features that the C language based on MPU did not have in the past. After unremitting efforts by Keil/Franklin, Archmeades, IAR, BSO/Tasking and other companies, it finally matured in the 1990s and became a professional MCU high-level language. The shortcomings that have long troubled people in the past, such as "the code generated by high-level languages ​​is too long and the running speed is too slow, so it is not suitable for single-chip microcomputers", have been largely overcome. At present, the code length of C language on 8051 has reached 1.2~1.5 times that of assembly level. Above 4K bytes, the advantages of C language can be more fully utilized. As for the issue of execution speed, as long as there is a good simulator to help find the key code and further optimize it manually, it can be very simple to achieve a very satisfactory level. If we talk about development speed, software quality, rigorous structure, and program robustness, the perfection of C language is by no means comparable to assembly language programming. Today, it is indeed time for MCU developers to pick up the weapon of C language.

The following introduces the advantages of the single-chip C language in combination with 8051:

Even if you don't know the instruction set of the microcontroller, you can still write a perfect microcontroller program;

·You can compile professional programs that conform to the actual hardware without having to understand the specific hardware of the microcontroller;

Data of different functions are overwritten to effectively utilize the limited RAM space on the chip;

·The program is robust: Data corruption is an important factor that causes program abnormality. C language performs many professional data processing to avoid non-asynchronous corruption during operation;

C language provides complex data types (arrays, structures, unions, enumerations, pointers, etc.), which greatly enhances program processing capabilities and flexibility;

Provide storage types such as auto, static, const, and storage types such as data, idata, pdata, xdata, code, etc. specifically for 8051 microcontrollers, and automatically allocate addresses for variables reasonably;

Provide small, compact, large and other compilation modes to adapt to the size of on-chip memory;

The scene protection and recovery of the interrupt service program and the filling of the interrupt vector table are directly related to the microcontroller and are handled by the C compiler;

Provide commonly used standard function libraries for users to use directly;

The header file defines macros, describes complex data types and function prototypes, which is conducive to the transplantation of programs and the development of serialized products supporting single-chip microcomputers;

There is strict syntax checking, and errors are rare, which can be easily and quickly eliminated at the high-level language level;

It can easily accept the services of various utilities: for example, the initialization of on-chip resources is automatically generated by special utilities; for another example, there is a real-time multitasking operating system that can schedule multiple tasks, simplify user programming, and improve operation security, etc.