Patent Application
20060047982
1. Field of the Invention
This invention is related to a dual interface auto-switch circuit. In particularly, this invention is related to a device which implanted in a flash memory device which includes the USB/SD interfaces. Through detecting a voltage signal, this dual interface auto-switch circuit can determine either the first interface or the second interface to be connected to the external device.
2. Description of the Prior Art
Nowadays, a variety of portable memory devices and peripherals are developed and widely used. For example, the portable memory device can be USB Flash Disk, Compact Flash Card (CF card), Memory Stick (MS card), Secure Digital (SD card), Multi-Media Card (MMC), xD Card, Micro Hard Disk which have either CF or USB interface, and a hard disk located at the external portable box which have USB or PCMCIA interface, etc. These portable memory devices enhance the convenience of user.
The conventional portable memory device includes a non-volatile memory array, a memory controller, and an I/O interface. The non-volatile memory array is used for storing the data and preserves the data without an external power supply. Therefore, the non-volatile memory array is usually made by a flash memory. Of course, the designer can replace the hard disk with the non-volatile memory array. The memory controller includes a circuit, a communication interface and a driving mechanism for driving and accessing the non-volatile memory array. The driving mechanism can be implemented by a hardware (command sequencer circuit) which executes corresponding micro-code or by micro-controller/micro-processor which executes corresponding firmware stored in the controller portable memory device. The communication interface of the portable memory device used a corresponding protocol to communicate with an external device.
Please refer to
In order for improving the convenience, a type of Flash Memory Card which combines the USB and the memory card interface is developed. For example, U.S. Pat. Nos. 6,658,516 and 6,385,677 disclose a dual interface memory card which has both the USB and the SPI interfaces. However, because the connectors of the USB interface and the memory card interface are different, a converting module is needed when this dual interface memory card connects to the USB connector of a computer.
In additions, U.S. Pat. Nos. 6,676,420 and 6,567,273 disclose a dual interface memory in which the USB interface and the memory card interface are developed. Because these two interfaces are implanted directly on the memory card, no converting module is needed while connecting this memory card to the computer.
However, the commercial available dual interface memory cards such as those disclosed in U.S. Pat. Nos. 6,658,516, 6,385,677, 6,676,420, and 6,567,273 use the protocol signal or clock signal input from the external device to determine which, USB or memory card, interface should be used. Because the electrical characteristic of the USB interface is very different from that of the memory card interface, it is hard to detect and compare the protocol signal and/or clock signal. Therefore, the detecting circuit of the conventional dual interface memory card is complicate and the cost is relatively high.
In additions, because two sets of interface circuits are set in the dual interface memory card, both sets of circuits will be activated during the operation of the dual interface memory card and the dual interface memory card will be high power consumption. Therefore, there is room for improvement.
It is therefore one of the objectives of the claimed invention to provide a dual-interface auto-switch circuit located at a memory device. The dual-interface auto-switch circuit is used for detecting a power voltage from an external device to determine one of the dual-interface to be used to communicate with the external device. This invention can simplify the design of the circuit and reduce the cost.
It is therefore one of the objectives of the claimed invention to provide a dual-interface auto-switch circuit located at a memory device. At the same moment, only one interface is activated, whereas the other interface is inactive. Since the inactive interface does not consume power, the total power consumption can be reduced.
It is therefore one of the objectives of the claimed invention to provide a method for auto-switching the interface of the dual-interface memory device. By detecting a power voltage from an external device, which interface should be used for communicating can be determined. In additions, only one interface circuit is activated and the other interface circuit is inactive such that the total power consumption can be reduced.
These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
The details of the present invention will be more readily understood from a detailed description of the preferred embodiments taken in conjunction with the following figures.
Please refer to
As shown in
The size of the body 21 fits the size of the flash memory card. In this embodiment, the memory device 20 is a Secure Digital Card (SD). The connection pins 22 are also fit the size of the SD. The memory device 20 of this invention can also be, but not limit to, the Multimedia Card (MMC), Compact Flash (CF), Memory Stick (MS), xD Card, etc.
The connection pins 22 are located on the frontal margin of the body 21 and are exposed externally. Through the connection pins 22, the memory device 20 of this invention can electronically connect to and communicate with an external device 90. The external device 90 can be a card reader, a digital camera, a PDA, a printer, or a computer with the connector of the memory card this invention. The connection pins 22 comprise a supply voltage pin 221 (VBUS/INSS), a plurality of the shared pins 222, and a plurality of the non-shared pins 222. The supply voltage pin 221 (VBUS/IVSS) is for receiving the power supply signal. The plurality of the shared pins 222 are for both interfaces. The plurality of the non-shared pins 222 are for only one interface.
The memory unit 23 is implanted in the body 21. The memory unit 23 is composed of a non-volatile memory array for storing data. For example, in the embodiment, the memory unit 23 comprises at least one flash memory. It can also be a read only memory (ROM) or other type of memories.
The control unit 24 is implanted in the body 21 and connected to the memory unit 23. The control unit 24 can drive the memory unit 23, read the data from the memory unit 23, write data into the memory unit 23, and communicate with the external device 90 through the connection pins 22. In this embodiment, the control unit 24 also comprises a controller 241, a control logic circuit 242, a cache memory 243, and a memory interface 244. The controller 241 and the corresponding firmware control the data transporting and processing. The control logic circuit 242 connects between the controller 421 and the interface switch circuit 32. The data from the interface switch circuit 32 is processed by the control logic circuit 242 and, then, is stored in the memory unit 23 through the memory interface 244. The data stored in the memory unit 23 can also be processed by the controller 241 and, then, transported to the pins 22 through the interface switch circuit 32. The cache memory 243 can speed up the data processing.
The power detecting and supplying module 31 connects to the supply voltage pin 221 of connection pins 22. The power detecting and supplying module 31 can receive and detect a voltage comes from the supply voltage pin 221 and generate an electrical signal in corresponding to the received voltage from the supply voltage pin 221. In this embodiment, the power detecting and supplying module 31 can compare the received voltage with a predetermined value and transfer the received voltage signal into either a first power signal A or a second power signal B according to the result of the comparison. The electrical signal mentioned previously is either the first power signal A or the second power signal B.
Generally speaking, the supply voltage of the USB interface is 5.0 voltage, whereas the supply voltage of the memory card such as SD and MMC is 3.3 voltage or lower. This invention sets a value between 3.3 and 5.0 as the predetermined value for the power detecting and supplying module 31. For example, the predetermined value is set as 4.2 or as other value between 3.3 and 5.0. Thus, by comparing the supply voltage comes from the supply voltage pin 221 with the predetermined value, which is 4.2 in this case, whether the external device 90 uses the USB interface or other memory card interface can be detected. In other words, if the supply voltage form the supply voltage pin 221 is greater than the predetermined value, the external device 90 is connected to the USB interface.
The interface switch circuit 32 connects to the power detecting and supplying module 31, and serially connects between the control unit 24 and the connection pins 22. The interface switch circuit 32 can receive the first power signal A and the second power signal B, which are also known as the electrical signal, and switch to connect either the first communication interface or the second communication interface to the control unit 24 and to communicate with the control unit 24 through the connection pins 22. In this embodiment, the first communication interface is the computer interface, such as a USB interface, whereas the second communication interface is the memory card interface, such as the interface of SD, MMC, CF, MS, xD, etc.
As shown in
In this embodiment, the first power signal A also supplies the power to the first communication interface circuit 323. The second power signal B also supplies the power to the second communication interface circuit 324. Therefore, at any moment, only one of the first communication interface circuit 323 or the second communication interface circuit 324 is supplied the power and is driven. At this moment, the other communication interface circuit is grounded. In other words, the power detecting and supplying module 31 not only provides the control signal to control the operation of the first switch 325 and the second switch 326 , but also provides the power to drive only one of the first communication interface circuit 323 and the second communication interface circuit 324. The communication interface circuit which is not driven is grounded. Thus, the power consumption of the memory device 20 can be reduced.
As shown in
Step 61 is the initializing step. In this step, the memory device 20 of the invention which contains the dual interface auto-switch circuit is connecting with, or plugging in, an external device 90 and receiving an input voltage (VBUS/VDD) from the external device 90.
In step 62, the received input voltage is checked to determine if it is greater than a predetermined value. If it is greater than the predetermined value, the step 63 is then executed. If it is not greater than the predetermined value, the step 67 is then executed.
In step 63, the USB is selected and the power is supplied to the USB interface. In other words, the first switch 325 is turned on and power is supplied to the first communication interface circuit 323.
In step 64, the USB is ready.
In step 65, it is checking if there is any USB control signal inputted. If it is, the step 66 is then executed. If it is not, the step 64 is then executed.
In step 66, the USB control signal is processed and the operation the memory device 20 of the invention responds to the USB control signal.
In step 67, the SD bus is selected and the power is supplied to the SD interface. In other words, the second switch 326 is turned on and power is supplied to the second communication interface circuit 324.
In step 68, the SD bus is ready.
In step 69, it is checking if there is any SD control signal inputted. If it is, the step 70 is then executed. If it is not, the step 68 is then executed.
In step 71, the SD control signal is processed and the operation the memory device 20 of the invention responds to the SD control signal.
In the following embodiments, most of the components and steps are the same as or similar to the embodiments described previously. Therefore, the same or similar components or steps will be named the same and the detail descriptions will not be repeated.
Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, that above disclosure should be construed as limited only by the metes and bounds of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 093125704 | Aug 2004 | TW | national |
