This disclosure relates to a method and apparatus for connecting different types of data storage interfaces. In particular, the disclosure relates to emulating data transfer protocols of a disk drive over a flash memory interface.
Flash memory is a non-volatile memory that enables data programming and deleting in a system after the system is deployed in the field. Due to the compact size of flash memory, it is commonly used in many consumer devices, such as digital camera, cellular phone, personal digital assistant (PDA), MP3 player, audio recorder, laptop computer, television set-top box, etc. Many such consumer devices are designed to accept flash memory devices and so have a specific flash memory interface, such as a flash memory connector or slot, in which flash memory devices may be inserted. This interface controls the data flow between the host device and the flash memory.
However, the amount of data that can be stored through the flash memory interface is limited to the capacity of the flash memory device. A currently available flash memory may be able to store up to about one gigabyte (1 GB) of data, which is significantly lower than a currently available disk drive that may be able to store a few hundred gigabytes of data. Therefore, there is a need for an apparatus and method to couple a disk drive to a host device having a flash memory interface.
In accordance with this disclosure, an interface controller is provided that allows connection of such a disk drive to a host slot or interface that is intended to accept flash memory. In one embodiment, an interface controller for coupling a disk drive to a host includes a flash memory interface having interface signal lines in communication with the interface controller and the host, a buffer memory to store data received from the host and from the disk drive, a flash controller to emulate data transfer protocols of the disk drive using the interface signal lines over the flash memory interface, and a memory wrapper in communication with the interface controller and a buffer manager where the memory wrapper controls the buffering memory according to data transfer rates of the host and the disk drive.
Conversions between the disk drive data and command formats and the host flash memory interface data and commands are performed by the interface. Thereby the disk drive appears to the host to be a flash memory and can be addressed and accessed as if it were a flash memory. The host system is typically of the type described above, such as digital cameras, portable music systems such as MP3 players, personal digital assistance, cellular telephones, laptop computers, personal digital assistance, etc. Hence the disclosed interface controller allows transmission of data stored to/from the disk drive via one or more standard industry input/output interfaces to the host system which typically includes a flash memory type interface.
The disclosed interface controller may be compatible on the host side with one or more of a variety of industry standard flash memory interfaces such as SD/MMC, SD, MMC, HS-MMC, SD/HS-MMC, and Memory Stick, but this is not limiting. On the disk drive side, the controller or interface may be compatible with one or more industry standard disk drive interfaces such as ATA, CE-ATA, and IDE and others as desired. The disclosed interface controller supports data transfers to and from the disk drive, whether the host is operating at a faster or slower data transfer rate than the disk drive. Therefore typically a buffer (storage) is included in or associated with the disclosed interface controller. The disclosed interface controller supports both random (single logical block) read or write operations as well as sequential (multiple logical block) read or write operations. Moreover, the sequential read or write operation may be open-ended in terms of the number of logical blocks transferred. Control features are provided in the disclosed interface controller for the disk drive such as servo control, disk formatting, error correction and read channel processing as part of a disk drive controller. The buffer referred to above may be on a separate integrated circuit or may be incorporated on the same integrated circuit as the interface. There also may be provided a connection from the disclosed interface controller to a separate flash memory for additional storage.
Also contemplated is a method of coupling a host to a disk drive (such as a hard disk drive or optical disk drive) via a flash memory interface so that the disk drive, in combination with the interface, appears to the host as being a flash memory. In one embodiment, a method for coupling a disk drive to a host includes coupling interface signals from an interface controller to the host via a flash memory interface and coupling the interface controller to a buffer memory for storing data received from the host and from the disk drive. The method further includes emulating data transfer protocols of the disk drive using the interface signals over the flash memory interface, and controlling the buffering memory according to data transfer rates of the host and the disk drive.
Also contemplated is a system including the host, a disk drive such as an optical or magnetic (hard) disk drive, and means for connecting the two, where the means for connecting couples to a flash memory interface provided by the host. In one embodiment, a system for coupling a disk drive to a host includes means for interfacing to the host via a flash memory interface, means for storing data received from the host and from the disk drive, means for emulating data transfer protocols of the disk drive using the interface signals over the flash memory interface, and means for controlling the buffering memory according to data transfer rates of the host and the disk drive.
Hence, the means for coupling a disk drive to a host includes an interface controller which presents to the host as being a flash memory. The interface controller includes logic for emulating data transfer protocols of the disk drive using the interface signals over the flash memory interface and storing data and/or commands so as to present same in a form suitable for standard disk drive interfaces to the disk drive.
Also contemplated are systems, including the host, the disclosed interface controller, and the disk drive, all incorporated in a single electronic device such as digital camera, cellular phone, personal digital assistant (PDA), MP3 player, audio recorder, laptop computer, television set-top box, etc. The interface controller in certain embodiments may be implemented as an integrated circuit separated from the host and from the disk drive circuitry. In other embodiments, it may be combined with either the host or the disk drive circuitry. Yet in other embodiments, the disclosed interface controller may be implemented as a separate integrated circuit which is on a card adapted to connect to a standard flash memory interface slot on the host system.
The aforementioned features and advantages of the invention as well as additional features and advantages thereof will be more clearly understandable after reading detailed descriptions of embodiments of the invention in conjunction with the following drawings.
The following descriptions are presented to enable any person skilled in the art to make and use the invention. Descriptions of specific embodiments and applications are provided only as examples. Various modifications and combinations of the examples described herein will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other examples and applications without departing from the spirit and scope of the invention. Thus, the present invention is not intended to be limited to the examples described and shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.
Some portions of the detailed description which follows are presented in terms of procedures, steps, logic blocks, processing, and other symbolic representations of operations on data bits that can be performed on computer memory. A procedure, computer executed step, logic block, process, etc., are here conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those utilizing physical manipulations of physical quantities. These quantities can take the form of electrical, magnetic, or radio signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system. These signals may be referred to at times as bits, values, elements, symbols, characters, terms, numbers, or the like. Each step may be performed by hardware, software, firmware, or combinations thereof.
A typical application is a portable computer or consumer electronic device such as MP3 music player or cellular telephone handset that has one application processor that connects to an embedded flash memory through a NAND flash memory interface. In accordance with this disclosure, rather than a flash memory, a hard disk drive or other type of disk drive is provided replacing the flash memory and using its interface signals. The disclosed method provides a flash memory-like interface for a disk drive, which makes it easier to incorporate a disk drive in such a host system which normally only accepts flash memory. One advantage of a disk drive over flash memory as a storage device is far greater storage capacity for a particular cost.
In
In certain embodiments the disk drive 104 may be referred to by an industry as a small form factor (SFF) hard disk drive, which typically has a physical size of 650×15×70 mm. A typical data transfer rate of such SSF hard disk drive is 25 megabytes per second.
The functions of the disk drive controller 100 of
The buffer manager 112 is also connected to a processor Interface/Servo and ID-Less/Defect Manager (MPIF/SAIL/DM) circuit 122, which performs the functions of track format generation and defect management. The MPIF/SAIL/DM circuit 122 in turn connects to the Advanced High Performance Bus (AHB) 126. Connected to the AHB bus 126 is a line cache 128, and a processor 130; a Tightly Coupled Memory (TCM) 134 is associated with the processor 130. The processor 130 may be implemented by an embedded processor or by an external microprocessor. The purpose of the line cache 128 is to reduce code execution latency. It may be coupled to an external flash memory 106.
The remaining blocks in the disk drive controller 100 perform functions to support a disk drive and include the servo controller 140, the disk formatter and error correction circuit 142, and the read channel circuitry 144, which connects to the pre-amplification circuit in the disk drive 104.
The signals used between the host 102 and the interface controller 110 are shown in
The flash register block 152 is used for register access. It stores commands programmed by the processor 130 and the host 102. A flash state machine (not shown) in the flash controller 150 decodes the incoming command from the host 102 and provides the controls for the disk drive controller 100. The flash FIFO wrapper 154 includes a FIFO, which may be implemented by a 32×32 bi-directional asynchronous FIFO. It generates data and control signals for transferring data to and receiving data from the buffer manager 112 via the buffer manager interface (BM IF). The transfer direction of the FIFO may be controlled by the commands stored in the flash register 152. The flash system synchronization block 156 synchronizes control signals between the interface controller and the buffer manager interface. It also generates a counter clear pulse (clk2_clr) for the flash FIFO wrapper 154.
The disk drive controller 100 of
These commands map to task file registers used in the ATA commands for the ATA industry standard disk drive specification. In the case of the disclosed interface controller, the sector count used in the ATA task file registers is not present or needed. The Logical Block Address (LBA) Low command in ATA maps to, in the present case, LBA0.
The ATA LBA Mid command maps to, in this case, LBA1. The ATA LBA High command maps to LBA2. The LBA Low Ext command maps to LBA3. The Command Register in ATA maps to the first cycle command code (e.g., 25h). The ATA Status Register maps to I/O 0 that is returned by the device immediately following the second cycle command code of 70h.
Note that in one embodiment of the present invention, the logical block address is 32 bits long, which allows addressing of up to 2 terabytes of storage capacity in the disk drive. In addition, the command structure consumes less of the system bandwidth than in the ATA interfaces, and there is no performance degradation if the host is faster in terms of data transfer rate than the disk drive.
The disk drive may communicate with a host device 523 such as a computer, mobile computing devices such as personal digital assistants, cellular phones, media or MP3 players and the like, and/or other devices via one or more wired or wireless communication links. The disk drive may be connected to memory 529 such as random access memory (RAM), low latency nonvolatile memory such as flash memory, read only memory (ROM) and/or other suitable electronic data storage. Moreover, the signal processing and/or control circuits 521 may be implemented as a system-on-chip (SOC), and the memory 529 may be disposed on or off such SOC. The disk drive 500 may comprise a motor controller 526 that controls a spindle motor 540 and an actuator arm controller 552 that controls movement of an actuator arm 534. The actuator arm 534 may include a read/write (R/W) head 532 that writes/reads data to/from the storage medium 533. A preamp 531 may output write data to the R/W head 532. The preamp 531 may also output data read by the R/W head 532 to the signal processing and/or control circuitry 521.
More particularly, the cellular phone 650 may communicate with mass data storage 664 that stores data in a nonvolatile manner such as optical and/or magnetic storage devices for example hard disk drives (HDD) and/or DVDs. At least one HDD may have the configuration shown in
Signal processing and/or control circuits 704 communicate with a WLAN interface 716 and/or mass data storage 710 and/or memory 714 of the media player 700. The mass data storage 710 includes the disclosed interface controller circuitry (not shown).
The DVD drive 800 may communicate with an output device (not shown) such as a computer, television or other device via one or more wired or wireless communication links 817. The DVD 800 may communicate with mass data storage 818 that stores data in a nonvolatile manner. The mass data storage 818 may include a hard disk drive (HDD). The HDD may have the configuration shown in
The HDTV 900 may communicate with mass data storage 927 that stores data in a nonvolatile manner such as optical and/or magnetic storage devices. At least one HDD may have the configuration shown in
Other control systems 1040 of the vehicle 1000 may likewise receive signals from input sensors 1042 and/or output control signals to one or more output devices 1044. In some implementations, the control system 1040 may be part of an anti-lock braking system (ABS), a navigation system, a telematics system, a vehicle telematics system, a lane departure system, an adaptive cruise control system, a vehicle entertainment system such as a stereo, DVD, compact disc and the like. Still other implementations are contemplated.
The powertrain control system 1032 may communicate with mass data storage 1046 that stores data in a nonvolatile manner. The mass data storage 1046 may include optical and/or magnetic storage devices for example hard disk drives HDD and/or DVDs. At least one HDD may have the configuration shown in
The set top box 1100 may communicate with mass data storage 1190 that stores data in a nonvolatile manner. The mass data storage 1190 may include optical and/or magnetic storage devices for example hard disk drives HDD and/or DVDs. At least one HDD may have the configuration shown in
One skilled in the relevant art will recognize that many possible modifications and combinations of the disclosed embodiments may be used, while still employing the same basic underlying mechanisms and methodologies. The foregoing description, for purposes of explanation, has been written with references to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described to explain the principles of the invention and their practical applications, and to enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.
This application claims the benefit of the following applications: application No. 60/678,249, entitled “nDrive HDD Interface,” filed May 5, 2005; and application No. 60/748,421 entitled “Flash Memory/Disk Drive Interface and Method for Same,” filed Dec. 7, 2005; which are incorporated herein in their entirety by reference.
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