The Design And Implementation Of Security SD Card SoC Chip SPI Interface

The SPI(Serial peripheral interface) put forward by Motorola is a high-speed and efficient serial interface technology, support full-duplex, synchronous, serial communication. SD card (Secure Digital Memory Card) which is a new memory equipment based on semiconductor storage memory is widely applied in portable device. SD card has enough storage, fast data transfer rate, high flexibility and security. It is integrated solid medium without any motion part, so that the damage of the mechanical movement needn't to be worried. The structure of SD card not only ensure the security of the digital document transaction, but also make the anew of the format easier. As SD card supports SPI transfer mode, its SPI controller's design becomes very important.To the users, the advantage of SPI controller is the compatibility for many devices. The Motorola puts forward a facial standard without unified protocol. While most companies designed SPI controller by consulting Motorola's standard, some difference will appear between different companies in SPI technical aspect. Therefore, designing a widely applied SPI controller needs many detail questions to be noticed. To the users, the advantage of SPI controller is the compatibility for many devices. If someone wants to achieve application widely, the first need is to meet multiple transmission formats. Although one device's transmission format is fixed, different devices usually have different transmission formats.If you want to ensure the SPI interface controller to communicate with the SD card, requirements the the interface controller must support Slave mode of operation. In this mode, the transmission clock and chip select signals are provided by the master device, this time involving not only the technical aspects of cross-clock domain, but also the diversity of problems encountered in transmission timing. In the design process synchronous transfer control signal design programs to address the problem of cross-clock domains, multi-mode transmission using support programs to address the transmission sequence diversity. Have shown that the design of various verification the accuracy and reliability.In addition to ensuring communication with the SD card, the interface module can also communicate with SPI FLASH, LCD displays, then the interface module in Master mode, in which the work mode leaves the clock selection signals and transmission by modules within. When the interface module in Master mode, the same sequence diversity encountered transmission problems, SPI protocol supports a master more from work, in order to achieve a main module and two modules without the need for hardware reset from the premise alternately work in the original basis of a chip select signal added on a chip select signal line, making the operation becomes easy.After careful designing, this SPI controller can support four transmission forms and choose whether the data is transferred the most significant bit first or the least significant bit first. Because there is a FIFO when the SPI sends data, the speed of data transmission is also improved.In the process of chip's design in modern times, verification becomes the most important part. There will be no eligible products without strict verification. Therefore, in the process of the designing of the SPI controller, every step is going with strict verification, especially the massive platform verification of the RTL level code.After massive platform verification, simulation and FPGA verification to the SPI controller IP core, the SPI controller is applied in a SoC chip successfully. At current time, the chip has been taped out successfully, the finishing test result indicates the IP's function and performance all achieve the design target, all kinds of tests results proves the design is highly reliable and flexible.