NFC-SIM chip design and analysis of contactless mobile payment solutions
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With the advent of the 3G era, the mobile terminal identification SIM card will develop in three aspects in the next two years: First: a high-security identity recognition platform; second: a contactless mobile payment platform; third: a large-capacity multi-application platform . In the era when the mobile Internet enters the content as the king, mobile payment has become an inevitable trend. The SIM card will inevitably develop in the direction of NFC contactless mobile payment and large-capacity with the requirements of these two trends, and will eventually be integrated and become a real Multi-application platform.
According to in-depth understanding, China Mobile demonstrated its “mobile ticket” service as early as 2006. Until the Shanghai World Expo, China Mobile has achieved large-scale commercial promotion of this service and has become the current three major domestic telecom operators. The first pioneer in this business. This will undoubtedly seize the opportunity for China Mobile to compete in this field in the future, and the electronic sales channel represented by “mobile phone tickets” will be a huge market for future telecom operators. Two other telecom operators, China Unicom and China Telecom, are also actively planning and launching pilot projects for contactless mobile payments.
The International NFC Organization was established in 2004. At present, almost all major international mobile phone, telecommunications, and smart card manufacturers are members. Shanghai Huahong formally joined the organization at the end of 2007. In the same year, Shanghai Huahong actively carried out NFC-SIM market research and conceptual product development. Pre-research work. In the process of industrialization of contactless mobile payment, Shanghai Huahong actively promoted and participated in the formulation of the following standards and the joint debugging of NFC-SIM chip practical application testing: In the second half of 2008, Shanghai Huahong participated in the drafting system of the Expo Mobile Ticket Standard Specification; 2009 In February, Shanghai Huahong took the lead in formulating mobile ticket test specifications and test scripts; from April to May 2009, Shanghai Huahong’s contactless mobile payment products participated in the joint debugging test and end-to-end business function test of China Mobile’s external systems.
At present, Shanghai Huahong has the design technology of high-end SIM card chips, as well as the research and development capabilities of related products. In mid-2008, it completed the mass production of the ARM SC100 32-bit CPU embedded 384KB high-reliability Flash 3G high-end SIM card product. In December of the same year, the product began to be supplied in batches. Based on the design and mass production of this high-end product, Shanghai Huahong conducted a large number of research and product definitions on the contactless mobile payment market and technology, and completed the domestic first by the end of 2008 Mass production of a high-end NFC-SIM chip. Figure 1 is a block diagram of the system structure of the high-end NFC-SIM designed by Shanghai Huahong.
Figure 1 NFC-SIM chip system architecture
The chip has the following characteristics:
1) The new single-wire protocol (SWP) IP is designed and implemented to support the latest NFC mobile payment architecture. The actual test SWP transmission rate of the chip is 1.33Mbps;
2) Abundant internal timers to support higher transmission rate of SWP LDPU;
3) High safety design;
4) Chip application support in NFC system power feeding mode (low-power design and chip architecture design support);
5) Low power consumption design;
6) The use of high-performance, high-reliability embedded Flash (384KB Flash) and a large amount of RAM simultaneously meet the resource and speed requirements of JAVA operation.
7) In order to speed up the processing response speed of the system, there are the following design innovations: change the ARM interrupt to vector interrupt to ensure the shortest interrupt response time; hardware supports multi-level interrupt priority nesting;
8) Rich IO interface design: SPI, GPIO, 7816, SWP;
9) Two-chip laminated package;
10) Complex software system support.
To realize mobile payment by mobile phone, the mobile phone SIM card needs to use a special NFC-SIM card, and the financial area is separated from the SIM card for bank financial applications. At the same time, mobile phones need to be modified to support NFC. After the cardholder obtains a mobile phone that supports NFC payment and an NFC-SIM card, he uses his mobile phone to remotely activate the financial area and download the application. After activation, the financial area in the SIM card has the function of a chip credit card. The NFC method of mobile phone payment is the same as the contactless payment with chip credit cards. For mobile remote payment, use the WAP mobile banking and SMS mobile banking modes provided by the bank.
Figure 2 Near-field communication chip-UICC physical connection
The user card supporting near field communication (NFC-SIM) is connected to the near field communication chip through the C6 pin to ensure the communication between the near field communication chip and the user card, see Figure 2. The hardware structure of the contactless mobile payment terminal (supporting NFC-SIM mobile phone) is shown in Figure 3. It consists of a near field communication module, a wireless communication module, a main controller, a SIM card module, output, input, storage, and external interfaces. The near field communication module in Taichung communicates with the SIM card through a single-wire communication protocol.
The SIM card stores the user key and various near field communication applications of the user. in:
1. Near-field communication module: realizes three working modes of near-field communication, and transmits application data to the SIM card or main controller;
2. Wireless communication module: complete the communication function of the mobile station and provide a data transmission channel;
3. Main controller: control various applications in the mobile station and control the conversion of the working mode of the near field communication module;
4. SIM card module: manage the SIM card;
5. Output: display text and video, and play sound;
6. Input: input of external information;
7. Storage: Store information during the operation of the mobile station and store user files;
8. External interface: the interaction channel between the terminal and the peripheral;
9. Power module: provide power;
10. Single-wire communication protocol: connect the near field communication chip in the mobile station and the SIM card, through this protocol, contactless applications in the SIM card can be realized; the SIM card needs to provide a pin support.
Joint debugging of SWP interface and mobile phone terminal compatibility
1) Technical risk: As the SWP communication protocol is also in the stage of modification and improvement of the protocol, the SWP7.6 version of the chip communication interface suitable for contactless mobile payment released by the International NFC Standardization Organization has just been released, so the SIM card and the mobile terminal are combined There are certain design risks in the debugging process. As the current manufacturer of the CLF master chip is only Inside, there are compatibility issues between the SIM card and the mobile phone and more design uncertainties.
2) Risk avoidance countermeasures: Shanghai Huahong is currently researching and familiar with the SWP communication protocol, and at the same time, it has passed the verification of the protocol function and compatibility on FPGA DEMO2.0. Shanghai Huahong has jointly verified the development of NFC mobile phones with the ZTE mobile phone division Cooperate with the communication function and compatibility test between contactless mobile payment chips. At the same time, the compatibility of the SWP module design has been tested on the SWP protocol analyzer TC3.
Fast response and processing of system interrupts
1) Technical risk: The design of the interrupt system in the chip directly affects the performance of the system. For the contactless mobile payment chip, the priority queuing of the interrupt, the response time of the interrupt, and the processing speed of the interrupt directly affect the operating speed and multitasking of the RTOS Processing performance. Judging from the current definition of contactless mobile payment products, it contains at least two communication interfaces. The ISO7816/SWP two interfaces work in parallel at the same time, and the CPU processes the two interface protocol stacks with interrupt priority and time slice management. If The system interruption is designed unreasonably, and the direct risk is that the system cannot meet the application requirements of contactless mobile payment chips.
2) Countermeasures to avoid risks: Shanghai Huahong Design 32-bit design platform adopts high-performance interrupt controllers, and at the same time, adopts high-performance architecture design schemes for system design, and undergoes detailed static calculation and analysis of system performance . Ensure that the interrupt priority definition meets the actual application requirements of the contactless mobile payment chip.
Summary of this article
The promotion of new products and services by mobile operators, such as mobile payment and contactless mobile payment, also depends on the maturity speed of the entire industry chain. For example, NFC terminal phones corresponding to mobile payments will be mass-produced as soon as the fourth quarter of this year, and there are still few mobile phones that support contactless mobile payments. All of these will affect the uptime of NFC-SIM and contactless mobile payment IC card. The development of the card is likely to be ahead of the terminal, but the replacement of the terminal takes time, which affects the batch issuance time of the card. The current countermeasure of mobile operators is to push new cards first, regardless of whether the phone has been upgraded. This is good news for us.
As mobile payment applications involve the integration of mobile operators and traditional financial industries, the negotiation process between the two parties is bound to be an iterative and long-term process. Mobile operators start trial operation with micropayments (applications such as public transportation and e-tickets) in order to accumulate operating experience, and do a good job of accumulating technology for subsequent large-scale mobile payments. As long as there is a payment business, regardless of scale, new cards with contactless mobile payment functions will be adopted. No doubt, this high-end NFC-SIM of Shanghai Huahong is currently the most suitable chip product for contactless mobile payment applications in China.
(Text/Song Changzhu, Chip Division, Shanghai Huahong Integrated Circuit Design Co., Ltd.)
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