CN105868082A - Non-contact CPU card communication monitor - Google Patents

A non-contact CPU card communication monitor relates to the communication monitoring technology of the non-contact CPU card. The non-contact CPU card communication monitor solves the problems that an existing non-contact CPU card communication monitor is serious in data loss and low in precision due to poor real-time performance. The decoding module of the invention is embedded with a filtering unit and a decoding unit; the filtering unit is used for judging whether the amplitude of the carrier signal changes within n continuous ETU time, and if so, the carrier signal is sent to the decoding unit for decoding; the decoding unit sends the decoded data to an internal memory of the MCU through an SSC interface of the MCU; the MCU restores the data in the memory into command-response pairs, stores the command-response pairs in the cache unit and uploads the command-response pairs to the PC in the non-interactive time slot. The invention filters useless signals, uses DMA transmission and develops large-capacity cache in the MCU, so that the monitor precision can reach more than 95 percent, and the invention is suitable for the development of non-contact CPU card reader-writer.

非接触式CPU卡通讯监测器Non-contact CPU card communication monitor

技术领域 technical field

本发明涉及非接触式CPU卡的通讯监测技术。 The invention relates to the communication monitoring technology of a non-contact CPU card.

背景技术 Background technique

非接触式CPU卡读写器在开发过程中，需要采用非接触式CPU卡通讯监测器检测ISO14443通讯信道中的原始信号，还原读写器与卡片间的命令-响应对，为读写器或卡片设计开发及测试人员在产品调试和测试过程中提供数据参考。目前市场上常见的非接触式CPU卡通讯监测器，其内部的MCU边还原命令-响应对边通过USB上传数据，这种处理机制由于实时性差导致数据丢失严重，监测器的精度仅能达到80%~85%。 In the development process of the non-contact CPU card reader, it is necessary to use the non-contact CPU card communication monitor to detect the original signal in the ISO14443 communication channel, restore the command-response pair between the reader and the card, and provide the reader or Card design, development and testing personnel provide data reference during product debugging and testing. At present, the common non-contact CPU card communication monitor on the market, its internal MCU restores the command-response and uploads data through USB. Due to the poor real-time performance of this processing mechanism, the data loss is serious, and the accuracy of the monitor can only reach 80. %~85%.

发明内容 Contents of the invention

本发明的目的是为了解决现有的非接触式CPU卡通讯监测器由于实时性差导致数据丢失严重，进而降低精度的问题，提供一种高精度的非接触式CPU卡通讯监测器。 The purpose of the present invention is to provide a high-precision non-contact CPU card communication monitor in order to solve the problem that the existing non-contact CPU card communication monitor has serious data loss due to poor real-time performance and further reduces precision.

本发明所述的非接触式CPU卡通讯监测器，包括接收电路、解码模块和MCU； The non-contact CPU card communication monitor of the present invention includes a receiving circuit, a decoding module and an MCU;

解码模块内嵌入解码单元，解码单元用于将接收电路接收到的载波信号进行解码； A decoding unit is embedded in the decoding module, and the decoding unit is used to decode the carrier signal received by the receiving circuit;

MCU内嵌入命令－响应对还原单元，用于对解码单元发来的数据还原为命令－响应对； An embedded command-response pair restoration unit in the MCU is used to restore the data sent by the decoding unit to a command-response pair;

解码单元将解码后的数据通过MCU的SSC接口发送给MCU内部的存储单元，即MCU的内存； The decoding unit sends the decoded data to the storage unit inside the MCU through the SSC interface of the MCU, that is, the memory of the MCU;

MCU内部嵌入有缓存单元，命令－响应对还原单元将内存中存储的数据还原为命令－响应对，并将所述命令－响应对存储在缓存单元中，在非交互时隙内将缓存单元中存储的命令－响应对上传至PC。 A cache unit is embedded inside the MCU. The command-response pair restoration unit restores the data stored in the memory into a command-response pair, and stores the command-response pair in the cache unit. Stored command-response pairs are uploaded to the PC.

本发明所述的非接触式CPU卡通讯监测器，其硬件结构与常规的非接触式CPU卡通讯监测器相同，本发明主要通过两个途径解决数据丢失的问题： The non-contact CPU card communication monitor of the present invention, its hardware structure is identical with conventional non-contact CPU card communication monitor, the present invention mainly solves the problem of data loss by two approaches:

1、使用DMA传输，提高实时性。MCU的SSC接口具备DMA传输功能，所谓DMA传输，即为：信号通过接收端口后直接存储到内存。这个过程不需要MCU介入，节省了MCU的处理周期，使MCU具有更多的时间来将FPGA发来的数据还原成命令-响应对。 1. Use DMA transmission to improve real-time performance. The SSC interface of the MCU has a DMA transmission function. The so-called DMA transmission means that the signal is directly stored in the memory after passing through the receiving port. This process does not require the intervention of the MCU, which saves the processing cycle of the MCU and enables the MCU to have more time to restore the data sent by the FPGA into command-response pairs.

2、大缓存存储处理完的数据。由于USB传输数据实时性差，MCU边还原命令-响应对边上传的处理机制将会导致一定的数据丢失，所以本发明采用的应对措施是在MCU中开辟大容量的缓存，用来存储命令-响应对，在非交互时隙内再将命令-响应对上送给PC。经多次反复验证，这种处理机制十分稳定，且基本无数据丢失。 2. The large cache stores the processed data. Due to the poor real-time performance of USB transmission data, the processing mechanism of MCU restoring command-response to side upload will cause certain data loss. Yes, send the command-response pair up to the PC in the non-interactive time slot. After many repeated verifications, this processing mechanism is very stable, and there is basically no data loss.

附图说明 Description of drawings

图1为实施方式一所述的非接触式CPU卡通讯监测器的原理框图。 FIG. 1 is a functional block diagram of the non-contact CPU card communication monitor described in the first embodiment.

具体实施方式 detailed description

具体实施方式一：结合图1说明本实施方式，本实施方式所述的非接触式CPU卡通讯监测器，包括接收电路、解码模块和MCU。解码模块通常采用FPGA或DSP实现，本实施方式采用FPGA实现。 Specific Embodiment 1: This embodiment is described with reference to FIG. 1 . The non-contact CPU card communication monitor described in this embodiment includes a receiving circuit, a decoding module and an MCU. The decoding module is usually realized by FPGA or DSP, and this embodiment adopts FPGA.

解码模块内嵌入过滤单元和解码单元； A filtering unit and a decoding unit are embedded in the decoding module;

过滤单元用于判断解码模块接收到的载波信号幅度在连续n个ETU时间内是否发生变化，并在判断结果为是时，将所述载波信号发送给解码单元进行解码，在判断结果为否时重新启动过滤单元，n为大于1的整数； The filter unit is used to judge whether the amplitude of the carrier signal received by the decoding module changes within the continuous n ETU time, and when the judgment result is yes, the carrier signal is sent to the decoding unit for decoding, and when the judgment result is no Restart the filter unit, n is an integer greater than 1;

解码单元用于将接收电路接收到的载波信号进行解码； The decoding unit is used to decode the carrier signal received by the receiving circuit;

解码单元将解码后的ISO14443二进制编码数据通过MCU的SSC接口发送给MCU内部的存储单元，即MCU的内存； The decoding unit sends the decoded ISO14443 binary coded data to the internal storage unit of the MCU through the SSC interface of the MCU, that is, the memory of the MCU;

MCU内嵌入命令－响应对还原单元，用于将内存中存储的数据还原为命令－响应对，并将所述命令-响应对存储在缓存单元中，在非交互时隙内将缓存单元中存储的命令-响应对上传至PC。 An embedded command-response pair restoration unit in the MCU is used to restore the data stored in the memory to a command-response pair, and store the command-response pair in the cache unit, and store the command-response pair in the cache unit during the non-interactive time slot. The command-response pairs are uploaded to the PC.

FPGA的解码速度远高于MCU，能够进一步保证数据传输的实时性。 The decoding speed of FPGA is much higher than that of MCU, which can further ensure the real-time performance of data transmission.

过滤单元能够过滤掉接收电路抓取到的无用信号，提高信号纯度。交易过程中，非接触式读写器的载波信号（磁场）一直贯穿整个交易周期，但是非接触式读写器与IC卡间的数据交互并不是时时刻刻都在进行。当交互产生时，载波信号的幅度是不断变化的，而非交互时，载波信号幅度则不会变化，也就是所谓的无用信号。由于接收电路无法智能滤除该信号，最后这种无用信号流入解码模块。无用信号和有用信号的区别是，无用信号在持续若干个ETU的时间内（通常在2个以上ETU时间内），载波信号幅度无变化。基于该特点，在解码模块内嵌入过滤单元，很容易区分出无用信号，从而只对有用信号进行ISO14443解码，使得解码模块向MCU发送的数据为纯度后的数据，进一步提高了监测器的精度。 The filtering unit can filter out useless signals captured by the receiving circuit and improve signal purity. During the transaction, the carrier signal (magnetic field) of the non-contact reader-writer runs through the entire transaction cycle, but the data interaction between the non-contact reader-writer and the IC card is not carried out all the time. When interaction occurs, the amplitude of the carrier signal is constantly changing, but when it is not interactive, the amplitude of the carrier signal does not change, which is the so-called useless signal. Since the receiving circuit cannot intelligently filter out this signal, this useless signal finally flows into the decoding module. The difference between the unwanted signal and the useful signal is that the amplitude of the carrier signal does not change when the unwanted signal lasts for several ETUs (usually more than 2 ETUs). Based on this feature, the filter unit is embedded in the decoding module to easily distinguish useless signals, so that only useful signals are decoded to ISO14443, so that the data sent by the decoding module to the MCU is pure data, which further improves the accuracy of the monitor.

采用过滤无用信号、使用DMA传输以及在MCU内开辟大容量缓存三个措施，本实施方式所述的监测器精度能够达到95%以上，理想情况（指符合ISO14443规范的标准读写器及IC卡）下可达到100% 。 With the three measures of filtering useless signals, using DMA transmission and opening up a large-capacity cache in the MCU, the accuracy of the monitor described in this embodiment can reach more than 95%. ) can reach 100%.