Design of customizable human-computer interaction interface based on P89C51RD2

introduction

With the development of social needs and science and technology, product competition is becoming more and more fierce, and the update cycle is getting shorter and shorter, so designers are required to design new products quickly; in the overall design of the product, the design of the human-computer interaction interface often occupies a large part of the work, which not only greatly increases the development cost of the product but also prolongs the product's listing cycle. The human-computer interaction interface based on P89C51RD2 discussed in this article is a universal human-computer interaction interface with customizable interface, compact structure, low price, simple and easy to use, and excellent performance, which can solve the above problems well.

1 System Working Principle

1.1 Working Principle

According to the needs of the control system in actual applications and the agreement between the control system and the human-machine interface, the entire interface information can be customized through the visual human-machine interface customization software on the PC, and then the customized interface information can be downloaded to the human-machine interface system, so that the human-machine interface can be easily customized. In the application, the human-machine interface interacts with the control system through the serial interface, sends information such as keystrokes to the control system, and receives the required variable information to complete the human-machine interaction.

Now, we take the human-machine interface of the air compressor controller as an example to illustrate the relevant concepts. The interface system diagram is shown in Figure 1. The relevant concepts are explained as follows:

① The screen, i.e. the LCD display area, consists of one or more screen items;

②Screen items, which are the whole units in the screen divided according to the nature of the displayed content, such as text screen items;

③ Classification of screen items: According to the nature of the displayed content, they can be divided into text, integer, floating point, enumeration, graphics, etc.

The entire human-machine interface system is composed of linked screens, and each screen is composed of one or more screen items. Each screen item has its own attributes, and there are also certain mutual links (for example, a screen item is linked to another screen). In this way, a linked list network is formed by the reasonable organization of each screen item, and the operation of the human-machine interface, that is, the display operation of the screen, is realized by operating this linked list network.

1.2 System working process

The software part of the system consists of a user boot program and an application program. After the system is running, the user boot program decides whether to perform an interface information update or normal operation. If the interface information is updated, the system receives the interface customization information from the host computer through the serial interface, saves the received information through the in-application programming (IAP) function, and then reads the new interface customization information locally to establish a linked list network; if it runs normally, the old interface customization information is directly read from the local computer to establish a linked list network. The functions implemented by the application program include key input, interface display, and communication with the control system.

2 System Hardware Design and Circuit Schematic Diagram

This system uses the powerful and resource-rich P89C51RD2 microcontroller from Philips as the microcontroller, and forms a human-computer interaction interface by expanding the LCD module and key module. The hardware circuit principle of the system is shown in Figure 2.

2.1 Introduction to P89C51RD2 MCU

P89C51RD2 is a derivative product of Philips based on the 8-bit 80C51 microcontroller. It has been strengthened, expanded and innovated in many aspects while fully retaining the 80C51 instruction system and hardware structure. P89C51RD2 has 64 KB parallel programmable non-volatile Flash program memory, and can realize serial in-system programming and in-application programming of the device.

2.2 LCD Module

This system uses OCM12864 graphic dot matrix LCD module. OCM12864 LCD module is a 128×64 dot matrix LCD module that can display various characters and graphics and can be directly connected to the CPU; it has an 8-bit standard data bus, 6 control lines and a power line.

2.3 Key input module

According to the needs of the system, the system needs to set at least the following 6 screen operation buttons: left, right, up, down, screen change, and confirm buttons. Among them, the left and right buttons are used to switch screen items; the up and down buttons are used to modify variable screen items; the confirm button is used to generate the function action corresponding to the selected screen item; the screen change button is used to enter the link screen of the selected item. If there is no selected item on the current screen, it enters the screen of the first link. Of course, the number buttons and function buttons can be expanded as needed.

This system uses a common matrix key structure, also known as a "row-type keyboard structure". The system is designed with 4 rows and 4 columns, a total of 16 keys, which only occupy 8 I/O port lines. The number of keys is large while the number of I/O port lines is small. In addition to the above 6 screen operation keys, the remaining 10 keys can be customized by the user according to their needs, such as numeric keys or function keys.

3 System Software Design

Since the function of the system is not particularly complex, the traditional control program design method based on the front and back ends is adopted. The program flow of the system is shown in Figure 3.