Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
2002-01-31
2004-09-14
Nguyen, Hiep T. (Department: 2187)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S115000
Reexamination Certificate
active
06792501
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a flash memory device, and more particularly, to a universal serial bus flash memory integrated circuit that is connectable via a universal serial bus.
2. Description of Related Art
Flash memory has become an important means for storing data for the advantage of high mobility and non-erasable. This is an extremely useful way of storing data for portable devices such as handheld devices. The convenience that flash memory provides gives it numerous advantages over traditional mass storage devices such as hard disks. Besides portability, flash memory further offers advantages such as low power consumption, reliability, small size and high speed.
Flash memory is non-volatile which means that it retains its stored data even after power is turned off. This is an improvement over standard random access memory (RAM), which is volatile and therefore looses stored data when power is turned off.
Universal serial transmission interface is the standard of PC/NB/IA products. PC/NB/IA products are bootable by storage medium of serial transmission interface, thereby increasing the possibility of substituting serial transmission interface storage medium for hard diskdrive. Due to external attachment arrangement, existing serial transmission interface storage media cause certain inconveniences.
In order to fit different function requirements, current small-sized IA products, such as PDA, industrial computer, digital camera, and the like are commonly provided with an operation system, for example, Win CE/Linux. The hardware architecture requires a CPU and a NOR type flash memory for storing program code. If it is necessary to store data, SRAM or built-in NAND flash memory, or external memory card is needed. The aforesaid three measures are not of standard interface to Win CE/Linux. The designer needs to modify the driving program or application program of these operation systems. Therefore, it requires much effort and money on these interfaces when developing a new product.
As the number of mobile, portable, or handheld devices grows, the popularity of flash memory increases. The most common type of flash memory is in the form of a removable memory card. This card allows the contents of the flash memory to be transferred easily between devices or computers.
However, when moving the flash memory card between devices, an additional host or adapter is required in order for the host to communicate with the flash card. Many devices may not have the built-in ability to connect to a flash card, therefore a special adapter or card must be installed in the host device. In addition, the bus architecture can limit the speed of data transfer between the host and flash memory device.
Therefore, there is a need for a flash memory device that can be directly connected to a host device without the need for special cables or adapters.
SUMMARY OF THE INVENTION
To achieve these and other advantages and in order to overcome the disadvantages of a conventional flash memory card in accordance with the purpose of the invention as embodied and broadly described herein, the present invention provides a flash memory integrated circuit device that is connectable to a host via a universal serial bus.
The universal serial bus (USB) has become a standard serial interface, which allows data to be stored in and read from an external memory device at high speed. Therefore, it is advantageous to combine the benefits of a flash memory device with the speed of the universal serial bus. In addition, by designing the flash memory device with a USB interface, the flash memory device appears as a standard USB storage device, which permits the host and flash memory device to connect and interact with ease.
The main board of the flash memory integrated circuit device comprises a controller and at least one flash memory chip. A USB connector connects the flash memory integrated circuit device with a USB host. The flash memory on the main board comprises at least one flash memory chip but as described below, the memory capacity of the flash memory device can be easily expanded.
In an embodiment of the present invention, the memory storage device further comprises an extension stack connector that allows for extending the number of flash memories on slave boards. The extension stack connector connects the pins needed by the flash memory chip on the slave board with the controller on the main board. In this way, the memory capacity of the flash memory device can be conveniently expanded as required.
The controller is a major component of the device. The controller controls commands and data between the USB host and manages data in the flash memory array or module. It is preferred that the controller is of a single chip design that does not need external ROM or RAM.
A regulator regulates the voltage for the memory storage device. Typically, flash memory requires 3.3 volts or 5.0 volts. Some flash memory devices utilize means of switching between 3.3 volts and 5.0 volts as required by the flash memory. However, an advantage of the flash memory device of the present invention is that the flash memory device only needs 3.3 volts. Therefore, regardless if 5.0 volts or 3.3 volts is received from the host, the regulator will ensure that 3.3 volts is available for the USB transceiver without the need for detecting and converting the voltage.
A clock generator, for example a crystal, generates a clock signal for the controller of the flash memory device.
The flash memory integrated circuit device of an embodiment of the present invention further comprises an indicator, for example an LED indicator, which indicates the status of the memory storage device such as whether it is busy or in standby.
The main board of the flash memory device can also have a stack connector for connecting a slave board to the main board for extending the memory size with flash memory arrays. The slave board comprises at least one additional flash memory module or array. Multiple slave boards can be connected in order to provide unlimited memory expansion.
A write protection switch provides write protection from the USB host. The switch has at least two positions; a position for allowing the host to read and write normally, and another position for write protection. When the switch is in the write protect position, the host can read data but cannot write or erase data.
The controller of the flash memory device of the present invention performs numerous functions. Among these functions is controlling the USB interface. The controller follows the USB specification for physical and logical protocol. The controller further comprises a FIFO controller buffer. The controller receives command and parameter packets from the USB host, which are then stored in a special register defined by the controller. The controller is also responsible for controlling the transfer of data to and from the USB host. In addition, the controller also provides status data to the USB host.
When the host sends a write command, an interrupt is generated and sent to the controller microprocessor to inform the microprocessor of the command and the command location. The microprocessor, for example an 8 or 16-bit microprocessor, is a major component of the controller. The microprocessor reads the USB commands and parameters from the register. The microprocessor also executes the commands with parameters. The microprocessor manages and maps the USB FIFO address to the controller buffer while receiving or transferring data to and from the USB host. Also, the microprocessor manages commands such as erase, program, or read for the flash memory array. In addition, the microprocessor executes the addressing method according to the algorithm of the controller.
Microprocessor ROM stores the program code of the controller and is built into the controller. Microprocessor RAM is a system RAM used by the controller when executing USB commands or the flash algorithm. By eliminating the requirement for off-chip memory, the system cost is r
Chen Chien-An
Pua Khein-Seng
Nguyen Hiep T.
Phision Electronic Corp
LandOfFree
Universal serial bus flash memory integrated circuit device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Universal serial bus flash memory integrated circuit device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Universal serial bus flash memory integrated circuit device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3264735