Application of AT91RM9200 in Embedded Tax Control POS System

1 Introduction

According to CCID Consulting, there will be 3 to 5 million units of total installed capacity in the market and market demand for related tax interface hardware and software, supporting equipment, services and training, which will form a huge market of at least 30 to 40 billion yuan. However, there are still many problems that need to be solved in the entire tax control cash register market.

Although the concept of tax-controlled POS has been proposed in my country for several years, the overall technical content of the existing solutions is relatively low, and the products of various merchants are now basically homogenized. This phenomenon is very unfavorable to the development of the industry and has weakened people's expectations for the development of the industry. The reasons for this are the lack of independent innovation capabilities of the enterprises themselves, the lack of cooperation from upstream and downstream manufacturers in the industrial chain, and even the relatively backward and imperfect laws and regulations of relevant industries in my country. All these problems have seriously affected the development of my country's tax-controlled POS industry.

2 Solution Requirements Analysis

When selecting a solution for a target system application, many issues should be considered, such as safety performance, intellectual property rights, product diversification, and service specialization. However, the main considerations are as follows:

First of all, whether from the perspective of hardware or software implementation, the tax control POS system is a very complex system. Different from ordinary POS terminals, the tax control POS system must not only meet the various requirements of today's social informatization, but also meet the strict requirements of tax source monitoring in my country at this stage.

Secondly, the unique advantages of embedded ARM processors in terms of integration and relatively low price are also important reasons why we choose to use it to implement the tax control POS system.

Furthermore, the embedded tax control POS system is an intelligent and complex tax control system, which is difficult to implement with a single-function processor like a single-chip microcomputer. Even if it can be done with a single-chip microcomputer, the cost of system implementation and the complexity of system design will far exceed the model implemented with a 32-bit embedded processor. This article adopts a new design concept, that is, a highly secure, 32-bit embedded processor as the core, combined with an embedded Linux operating system. The following will give a detailed introduction to the implementation of the AT91RM9200, a typical and high-performance embedded processor in the ARM processor series, in the tax control POS system.

3. Solution design and implementation

3.1 System design architecture and performance parameters

AT91RM9200 is the most representative embedded processor based on ARM920T core, and its bus architecture interface mode is shown in Figure 1. AT91RM9200 not only has excellent performance and relatively low price, but also is an industrial-grade microcontroller; its integration is also very high, almost covering all mainstream interfaces in the field of embedded applications. Another important reference factor is the application positioning of the solution. At the beginning of the design of this tax control POs solution, the typicality and universality of the solution positioning were fully considered, and there was no blind pursuit of high-end. At the same time, the characteristics of embedded system design also tell us that application system design should not blindly pursue high performance. As an application system design in the embedded field, we should fully consider the specific needs of the system application, make full use of the various resources of the software and hardware itself, and reasonably position the system selection. In this way, we can better play the advantages of embedded systems in design flexibility and so on.

Table 1 shows the performance parameters of the system.

3.2 System hardware and software composition and implementation

(1) Hardware configuration

In terms of hardware design, based on the core processor AT91RM9200, dedicated chips for various interfaces are expanded, as shown in Figure 2. [page]

Its main implementation interfaces are as follows:

① Tax control dedicated interface: The dedicated channel of the tax controller is designed and reserved for the tax department to effectively control the source of tax revenue; its flexible modular design greatly facilitates the functional upgrade and maintenance of the tax controller.

② Network interface: 10/100MHz adaptive high-speed Ethernet port design with intelligent error correction function ensures efficient and real-time data transmission.

③ Standard serial interface: provides three 2-wire serial ports, one 4-wire serial port and one 8-wire serial port to support a variety of peripherals, such as IC card, magnetic stripe scanner, serial thermal printer and GPRS/CDMA wireless communication module.

④Memory card interface: A variety of memory card interfaces, including USB Host, USB Device, CF card and IDE hard disk, can realize large-capacity data storage.

(2) Software composition

It uses a standard embedded Linux system - ARM-Linux, which includes three main parts: Uboot (Boodoader), zImage (Kernel) and Ramdisk (Filesystem). Among them:

①Bootloader: A piece of code that is executed immediately when the system starts up; it is similar to the BIOS system on a PC in terms of function. The application system mainly relies on it to complete tasks such as system installation and debugging; in the entire system design process, BootLoader is the part that is most closely integrated with the specific hardware, and its implementation is mainly in assembly language.

②Kernel: The core of the entire application system, which is responsible for unified scheduling and management of all resources on the system; during the system startup process, it further initializes peripherals and system configurations after the boot code.

③Filesystem: An important component of the ARM-Linux system, which can be simply understood as the organic organization structure of various files under the system; generally includes the system and various library files and resource files required for the running of applications on it.

The organic combination of the above three parts constitutes a complete ARM-Linux operating system. In actual application, it must be solidified on a FLASH chip through a burner.

3.3 Value and characteristics of the solution

① High security: First, the solution is system-level in application, and the entire system design is implemented by incorporating upper-level applications into the system level; secondly, the operating system is implemented using the Linux system, which is famous for its security, and combined with the use of various data protection mechanisms of the ARM processor, it effectively ensures the high security of the tax control POS in the process of data collection, processing, storage and transmission.

② Stability and robustness: The most mainstream ARM9 processor AT91RM9200 is adopted, with a main frequency of 200MHz, high performance, low power consumption, rich built-in resources, and simple peripheral circuit design, which ensures convenient and stable production. The processor with QFP package replaces BGA package, which greatly reduces the welding cost of the whole board and improves the success rate of the first commissioning of the whole machine.

③Expansion flexibility: The two built-in USB Host interfaces provide high expandability for subsequent product upgrades, such as USB wireless network cards and LISB keyboards, mice and other input devices.

④Multiple storage methods: Provides extended FLASH storage and supports storage cards such as IDE hard disk, electronic disk, CF card and USB disk.

⑤Multiple communication modes: Provide 100MFIz Ethernet, with a throughput of more than 60Mbps. Support common Modem dial-up, GPRS/CDMA dial-up and ADSL dial-up Internet access.

⑥ Universal applicability: supports a variety of LCD screens and VGA displays, including black and white screens and TFT true color screens; the resolution can support 640×480 and above, and supports touch screens (800×600), meeting the application requirements of various POS machines.

⑦ Customizable interface: Provides rich software resources based on embedded Linux operating system, such as various GUIAPIs for customers to customize their own u1 interface; even the product shell can be designed to be very small and exquisite.

⑧Easy and convenient operation: supports PS2, USB standard keyboard, mouse, custom keypad and touch screen, etc.

4 Development Trend of Tax Control POS

Various embedded tax control POS are constantly being innovated, and handheld POS with wireless functions have also begun to be used. With the rise of online tax payment in my country, it will not be long before tax control POS products embedded with more powerful online tax management systems will develop. By then, the entire tax control POS system will no longer be a single POS terminal, but a set of networked, systematized, and intelligent tax control POS equipment. This type of POS terminal is likely to appear first in some high-end restaurants, entertainment and other places, and then gradually become popular. Therefore, in the next few years, the development of tax control POS should be more advanced in the direction of higher informatization, networking and intelligence.

5 Conclusion

At present, this solution has passed the strict testing and certification of relevant national departments and has been put into mass production. Facts have proved that the embedded tax control POS solution based on the ARM architecture system has obvious advantages and is also very successful. For this, we should thank ARM and its partners for providing us with such excellent microcontrollers/microprocessors; what is more exciting is that ARM and its partners have been rapidly and steadily launching ARM architecture cores and microcontrollers/microprocessors suitable for various occasions. We have reason to believe that the popularization and promotion of ARM architecture processors in the Chinese market will surely drive the rapid development of my country's tax control POS and other electronic industries.