Detailed analysis of the 7 major steps to write a microcontroller application

1. Find out the functions and plan.

After receiving a MCU project design file, it is not a matter of writing the program immediately. Instead, it carefully studies the technical requirements or technical descriptions put forward by the user. According to these technical requirements and technical descriptions, that is, the customer requirements, the main functions that the program should have are written. Clear, write carefully, this is the most critical job. If you are not sure, you should ask the customer and the user clearly. Otherwise, after the design is completed, some functions will be found to be troublesome because they have not been considered beforehand. It may be easy to add some functions that need to be re-added, and some may be due to It cannot be realized without prior consideration.

2. Prepare the general flow chart and the flow chart of each functional module

According to the program function to be completed, the total flow chart is written. According to the general flow chart, the whole program is divided into several main function modules. Each function module must write the basic flow chart, which is mainly for the later program writing. A guiding role. Of course, there will be some changes in the actual programming process, and a basic process will guide you in the process of writing the program without much deviation. For example, write a keyboard scan and distinguish whether it is a function key or a numeric key subroutine. If it is a function key, it will switch to the corresponding function processing program; if it is a numeric key, it will be displayed on the corresponding digital tube; you can write its flowchart.

Software level division. Generally divided into application layer, functional layer, hardware isolation layer, hardware driver layer.

3, prepare programming materials

These materials are mainly books, magazines, etc. in programming languages. Because some information about the programming language can not be remembered clearly by any programmer, such as the meaning of each instruction, the hardware circuit involved in the operation of each instruction. If the information is prepared adequately, you can put it on the side of the case and, if necessary, check it out.

4, man-machine interface programming

The human-machine interface of the project realized by the single-chip microcomputer is relatively simple. If it is LED display, it should be based on the number of LEDs to select a simple, clear, user-looking prompt; the number of data displayed should fully consider the technical requirements of the user.

5, analysis of programming difficulties and technical solutions

Even a skilled programmer will encounter some difficulties during the programming process. In order to complete the program design smoothly, the framework of the whole program should be analyzed according to the functions and program flow completed by the program, and the difficulties of the whole program should be located according to the skills mastered by the program, and then the best algorithm can be found. For example, for a slightly larger project, the programming of the keyboard scan and display should be a difficult point in microcontroller programming.

(1) Whether it is the keyboard scanning or the display process and the hardware part are closely related to the chip selection signal to select the keyboard, it is necessary to find out whether the single-chip chip is a high-level strobe or a low-level strobe; after strobing the keyboard, it is also necessary to read back the keyboard. status. Anti-shake processing is also performed on the read-back keyboard state; if the keyboard is jittery, the read-back data is discarded, and the keyboard state is re-read; if it is determined that the keyboard is pressed, the key value can be processed; the processed key value is sent to display or Used as other. It can be seen that each of the above processes deals with the hardware circuit.

(2) The algorithm involved in keyboard scanning and display is more complicated because the process of scanning the keyboard is to traverse each button, identify the jitter, and recognize whether the button is released or not; in addition, delay the appropriate time to read again. Key value. The display process also traverses each digital tube or liquid crystal character; in the process of looking up the table, the display process uses a more complicated loop traversal algorithm.

(3) The difference between the numeric key and the function key is that the numeric key is sent to display, and the function key is transferred to the corresponding function subroutine, and the combination of the two constitutes a relatively complicated transposition program. The MCS51 MCU has a ready-made loose rotor program for reference. The PIC can be applied with reference to the MCS51's loose rotor program.

The above three points are the difficult part of MCU programming, and should be found out carefully before programming. Through analysis, all the possible difficulties are found out and the corresponding algorithms are found out, which is correspondingly smooth in the process of writing later.

6, start coding

After the above preparations are completed, you can start writing the program. Because there is a clear program flow, with sufficient information, the difficulties that may be encountered basically find a solution; thus, the preparation is sufficient in advance, even if it is difficult to solve in the later process of writing, it is easier to solve . This saves a lot of time, so that you can calm down and carefully write programs according to the program and process. In addition, generally write a function program to debug, after writing another function code, this can prevent the mutual influence of debugging after all the code is written, so that you can figure out which part of the program has problem.

7, program debugging

The debugging process of the program is a relatively complicated process, and some require a high degree of skill and certain methods. General programming software provides basic methods such as single-step, single-step crossing, breakpoint, and running to the cursor. Generally, mastering these basic methods can solve most problems. After a long period of debugging practice, you can naturally master certain debugging skills, that is, practice makes perfect.