CN1198196C - Versatile compact memory card interface compatible with USB interface - Google Patents

Abstract

A multifunctional small memory card is used for storing digital information function and supporting other IO functions, and comprises a memory card I/O function module for storing digital information; a memory for storing digital information, and a main controller connected between the memory card I/O function module and the memory; the multifunctional small-sized memory card has the design of 4-pin position and 8-pin position at the same time; the 4-pin design is used for a basic USB interface; the 8-pin design is called SFMI interface, and is composed of 4-bit bidirectional instruction/data/state bus, clock synchronous signal, system interface and memory card insertion detection signal, and power supply and grounding, wherein the power supply and grounding are the same as the power supply and grounding pin in USB interface.

Description

Versatile compact memory card interface compatible with USB interface

technical field

The invention relates to a memory card interface device, in particular to a multifunctional small memory card interface capable of receiving a multifunctional small memory card interface and a USB interface.

Background technique

The Small-Form-Factor Memory Card (Small-Form-Factor Memory Card) uses a rewritable silicon chip with a large storage space as the storage medium, and has a built-in microcontroller to control the read and write operations of the silicon chip. It is also connected to an interface of an electronic application device using a small memory card, and accepts its instructions to perform corresponding read and write operations.

Small memory cards using silicon chips as storage media are widely used in the digitized information industry and home appliance industry for storing and exchanging digital information due to their advantages of small size, light weight, fast reading and writing speed, and power saving. Common small memory cards in the market can be divided into CompactFlash card (CF card), Smart Media card (SM card), Multi Media card (MMC card), Memory Stick card (MS card), Secure Digital card (SD card), etc. Different types. All kinds of small memory cards are different in appearance size, mechanical structure, electrical contact position, communication protocol, software instruction code, control process, etc., and each has its own advantages and disadvantages.

Small memory cards are widely used in various portable digital devices, including mobile phones, digital cameras, digital music players, portable digital assistants (PDAs), etc. In order to expand its application fields, in addition to the storage function, there are also products that open up other application fields. For example: modem card and network card with CF interface; digital camera card with Memory Stick interface, Blue Tooth communication card; Blue Tooth communication card with SD interface, etc. In order to be different from memory cards that only have storage functions, the applications of the above-mentioned other functions are generally referred to as IO cards.

Although the above-mentioned various small memory card interfaces are applicable to various portable digital devices and different applications, they are regrettable because each has its own shortcomings. As far as the lack of specifications is concerned, here are a few examples to illustrate:

As far as the Compact Flash card is concerned, its interface requires 50 sets of contacts. The mechanism adopts a combination of pins and jacks. The electrical interface adopts a parallel data bus with 8-bit and 16-bit coexistence, and an address bus with 11 sets of signals. And multiple sets of control signal lines for various purposes.

The disadvantages of the Compact Flash interface are as follows: 1. The mechanism must have 50 sets of connection terminals, which is the largest number, resulting in higher cost of the connector and taking up more space. 2. The combination design of pin and jack for probes requires high force for insertion and withdrawal. 3. When the positioning of the pin coupling jack is inaccurate, it is easy to cause the pins to be skewed and damaged. 4. The parallel bus design is adopted. When multiple cards are connected, the electronic application device must provide a start selection signal separately, and multiple cards cannot be connected in parallel. 5. There is no anti-write protection design, which cannot ensure that the memory content will not be damaged.

As far as the Smart Media card is concerned, its interface needs 22 groups of contacts, and the mechanism adopts the contact type of reeds and flat contact terminals. Another two sets of reeds are required to detect whether the memory card is inserted and positioned, and whether to paste the anti-write conductive sticker.

The disadvantages of the Smart Media interface are as follows: 1. The mechanism must have 22 sets of connecting terminals, as well as reeds for detection and positioning and anti-write conductive stickers, resulting in higher cost of the connector and taking up more space. 2. The connection terminals are arranged in front and back double rows. When inserting or withdrawing, the first row of contact positions will be connected to the second row of connection terminals first, resulting in instability during insertion. 3. The power supply connection signals VCC and GND are located between the two rows of connection terminals, which traverse the entire group of connection positions, and are prone to unstable phenomena such as short circuits between terminals. 4. Labeling is used to distinguish whether the memory card is write-proof or not. A special conductive write-proof label is required, and the write-proof function does not directly protect the contents of the memory card, but relies on the electronic application device to detect and identify the write-proof state. 5. The physical addressing method cannot directly support the linear logic addressing method adopted by general systems, which increases the cost and development difficulty of electronic application devices. 6. Due to the physical addressing method, whenever the capacity of the storage medium is increased, it is necessary to adapt to the planned format of the silicon chip and revise the new version of the specification to support the rewritable silicon chip with a larger capacity.

As far as the MMC card is concerned, its interface needs 7 groups of contacts, and the mechanism adopts the contact type of reed and flat contact terminal. Another set of reeds is needed to detect whether the memory card is inserted or not.

The disadvantages of the MMC interface are: 1. The serial communication transmission mode is adopted, and only 1 bit is transmitted in each clock cycle, and the transmission rate is low. 2. The software anti-write protection mode is adopted, which requires special software control, and the protection function is less practical.

As far as the SD card is concerned, its interface needs 9 groups of contacts, and the mechanism adopts the contact type between the reed and the flat contact terminal. Another two sets of reeds are needed to detect whether the memory card is inserted and positioned, and to detect the position of the write protection slider.

The disadvantage of the SD card interface is that the anti-write protection slider requires the electronic application device to detect its position and support the anti-write function.

As far as the MS card is concerned, its interface requires a total of 10 sets of contacts, and the mechanism adopts the contact type of reeds and flat contact terminals. The connection interface has a card detection signal, and the memory card itself has a write-protection switch, so the memory card itself can support the write-protection function as an advantage.

The disadvantages of the MS card interface are: 1. The serial communication transmission mode is adopted, and only 1 bit can be transmitted per clock cycle, and the transmission rate is low. 2. The physical addressing method cannot support the linear logic addressing method adopted by general systems, which increases the cost and development difficulty of electronic application devices. 3. Due to the physical addressing method, whenever the capacity of the storage medium increases, it is necessary to adapt to the planned format of the silicon chip and revise the new version of the specification to support the rewritable silicon chip with a larger capacity.

In view of the fact that many memory card standards are different, each has its own advantages and disadvantages, and the personal computer needs to be expanded with an additional USB interface, PCMCIA interface or IDE interface memory card electronic application device, in order to achieve the ability to communicate and exchange digital information with the memory card Purpose, the present inventor has proposed a more advanced and novel standard, overcomes above-mentioned many deficiencies in one fell swoop, and develops: 1, volume is smaller, faster, more suitable for portable digital device application; The application device can be easily connected to the personal computer system; 3. A novel standard interface that takes into account the advantages of IO application expandability, etc., and is called a multi-functional small memory card interface.

Contents of the invention

The purpose of the present invention is to provide a multi-functional small memory card, wherein the multi-functional small memory card has the design of 4 pins and 8 pins at the same time, and can support the traditional USB interface and the SFMI interface defined in the present invention at the same time , so it can be applied to computer equipment and various electronic application devices. However, the currently used electronic application device can use the multifunctional small memory card interface of the present invention to perform data conversion with the computer device, without the need to convert the data format through an adapter like the traditional memory card.

In order to achieve the above object, the present invention provides a multifunctional small memory card for storing digital information and supporting other IO functions, including a memory card I/O function module for storing digital information, and a memory for storing digital information. And a main controller is connected between the memory card I/O function module and the memory. The multifunctional compact memory card has both 4-pin and 8-pin designs. The 4-pin design is used for basic USB interface. The 8-pin design is called the SFMI interface, which consists of a 4-bit bidirectional command/data/status bus, a clock synchronization signal, a system interface, a memory card insertion detection signal, and power and ground. Same as the power and ground pins in the USB interface.

The present invention also provides a multifunctional small memory card slot, which has a design of 4 pins and 8 pins, wherein the design of 4 pins is used for the basic USB interface, and the design of 8 pins is used for the SFMI interface. The 8-pin SFMI interface has four pins that are the same as the 4-pin of the USB interface, and the other four pins are distributed between the four pins of the USB interface. The slot is divided into a male slot and a female slot.

Description of drawings

Fig. 1 is the basic structure of the interface of the multifunctional small memory card of the present invention and the docking read-write device

Fig. 2 is the definition and the function of each pin of SDM interface among the present invention;

Fig. 3 is the basic structure of main controller among the present invention;

FIG. 4A is a component configuration diagram of a state where the detection circuit of the present invention is connected to the SDM interface;

FIG. 4B is a component configuration diagram of a state where the detection circuit of the present invention is connected to a USB interface;

Fig. 5 is the content of packet identification code among the present invention;

Fig. 6 is the data structure of packet identification code among the present invention and the relationship figure of this data structure and clock;

Fig. 7 is the data structure of communication end point among the present invention and the relationship diagram of this data structure and clock;

Fig. 8 is the data structure of data length among the present invention and the relationship diagram of this data structure and clock;

Fig. 9 is the data structure of the data transmission sequence in the present invention and the relationship diagram between the data structure and the clock;

Fig. 10 is a data structure of an error check code in the present invention and a relationship diagram between the data structure and a clock;

FIG. 11 is a diagram showing the data structure of the packet status code and the relationship between the data structure and the clock in the present invention.

Detailed ways

The multifunctional compact memory card of the present invention is mainly divided into two types, the first type is mainly used for storing digital information, and the second type is mainly used for supporting other IO functions. Both functions must be possessed: 1. The main controller 220 supporting the interface of the multifunctional small memory card provides the function of storing digital information, and its main controller 220 must also have a control interface of rewritable non-volatile memory; For the IO function, the main controller 220 must also have a control interface that can support the IO function module. 2. To provide the function of storing digital information, it must have a large-capacity rewritable non-volatile memory storage module to store digital information; to provide IO functions, it must have an IO function module that supports IO functions.

The multifunctional compact memory card of the present invention is shown in FIG. 1 , wherein the multifunctional compact memory card 200 includes a memory card I/O function module 210 , a main controller 220 , and a memory 230 . After the device is integrated on the printed circuit board, a multifunctional small memory card interface terminal is provided on the printed circuit board, which is exposed outside to connect the device electronics 100 . Finally, a circuit board with complete electrical functions is added with a plastic injection-molded shell to assemble a complete multi-function memory card or IO card. The electronic application device 100 docked with the multi-function compact memory card includes a device module 110 . Format Converter 120, Device I/O 130.

The memory card I/O function module 210 is a function module for data input and output of the memory card and includes connection terminals and related circuit structures. The multi-functional compact memory card of the present invention can simultaneously support the USB interface and the SFMI interface defined in the present invention. Wherein the terminal has a design of 4 pins and 8 pins. The design of 4 pins is used for the basic USB interface, which includes a VCC pin which provides DC power to the pins of the multi-functional compact memory card of the present invention from the docked device end, so as to give the multi-functional compact memory card Can, a GND (grounding pin), is to provide grounding protection and reference potential for the design of the present invention, and the other two pins are respectively D+ and D-pins, which are data transmission pins.

The multi-functional small memory card interface of the present invention is an 8-pin design, which consists of 4-bit bidirectional command/data/status bus (D0-D3), clock synchronization signal (CLK), system interface and memory card insertion detection The test signal (CD), and the power pin (VCC) and the ground pin (GND), only need 8 sets of contacts in total. The anti-write protection function is selected by switching the position of the anti-write protection switch built in the multi-function compact memory card, and notifies the electronic application device 100 through interface communication. Wherein the VCC is a DC power contact, which is used to provide DC current to the multi-function compact memory card to empower the multi-function compact memory card; GND is a ground contact, which is used to provide contact protection and reference potential; when CLK is synchronized Pulse signal, which provides synchronous clock pulse for output and input data, so as to facilitate the timing reconstruction and signal alignment of data signals. BD_CD is a detection signal for system interface and memory card insertion, which is used to detect whether input and output data are for USB interface signal, or SFMI interface signal. D0 is the bidirectional command/data/status bus signal bit0, which is the D- signal line in the USB mode; D1 is the bidirectional command/data/status bus signal bit1, which is the D+ signal line in the USB mode; D2 is the bidirectional Instruction/data/status bus signal bit2, this signal line does not exist in USB mode; and D3 is bidirectional command/data/status bus signal bit3, in USB mode, this signal line does not exist

It can be understood from the above description that the SFMI interface of the present invention shares four contacts with the basic USB interface. Namely VCC, GND, D-(D0) and D+(D1). In addition, the present invention also includes four contacts of CLK, BD_CD, D2 and D3. Therefore, in the design of the plug-in structure (including the plug-in terminal and the slot), four contacts can be arranged between the four contacts of the original USB interface, so that the plug-in structure of the SFMI interface of the present invention can be compared with the plug-in structure of the USB interface. The connection structure is shared, and there is no need to configure different plug structures.

Another feature of this interface is that two sets of signal lines D0 and D1 in the 4-bit bidirectional bus, when the electronic application device 100 uses the USB interface to connect to the memory card, the USB interface operation mode is adopted. And become the D+ and D- signal lines required by the USB interface. It also supports the communication mode of the standard USB interface, so that it can be installed on a personal computer or a digital device supporting the USB system interface without any additional electronic application device 100 .

Referring to FIG. 3 , the main controller 220 of the present invention includes four components, an I/O controller 221 , a memory controller 222 , a formatter 223 , and a deformatter 224 . Wherein the I/O controller 221 is used to control the memory card I/O function module 210, including determining whether the memory card I/O function module 210 operates in an input mode or an output mode, or uses an SFMI interface or USB interface mode operation, etc. The memory controller 222 is used to control the memory 230, and the formatter 223 and a deformatter 224 perform format conversion of the USB interface signal and the SFMI interface signal to match the operation mode of the memory card I/O function module 210 . The actions of the formatter 223 and the de-formatter 224 will be described below.

System interface and memory card insertion detection signal:

The memory card insertion detection signal is connected to the multi-function I/O control signal of the control chip inside the memory card, and connected to the power supply through a resistor at the end of the electronic application device 100 supporting the multi-function small memory card interface. This signal is not connected to the interface supporting the USB system side, so that the multi-function memory card can use this signal to detect the system interface adopted by the electronic application device 100, and the electronic application device 100 can also use this signal to realize the detection of the small memory card Whether to insert the positioning function.

The interface detection circuit of the memory card I/O function module includes a power supply 310, a BD input detection terminal 320, a CD output detection terminal 330, a first diode 360, and a second diode 370 , a first resistor 340, and a second resistor 350.

The function of the memory card I/O function module is to determine whether the insertion port is a USB interface or an SFMI interface by detecting the presence or absence of the system interface and the memory card insertion detection signal (BD_CD).

The small memory card is inserted into the electronic application device 100 that supports the small memory card interface. Since the electronic application device 100 continues to supply power regardless of whether the small memory card is inserted, the small memory card should first maintain the CD signal in a high impedance state when starting the small memory card. , so as not to affect the BD_CD signal detection check action. Then immediately check the state of the BD_CD signal. If the state of the BD_CD signal is a high potential, it means that the system side supports the small memory card interface, and enters the small memory card interface operation mode, and then drives the output CD signal to a low potential, notifying the electronic application device 100 that the small memory card has been inserted and positioned; Conversely, if the BD_CD signal is low, it means that the system does not connect the BD_CD signal to the power supply through a resistor, which means it supports the USB interface and enters the USB interface operation mode.

In the circuit shown in FIG. 4A and FIG. 4B, the VCC contact is connected to the power supply 310, the system interface and memory card insertion detection signal BD_CD is connected to the BD input detection terminal 320 through the first diode 360 connected in the forward direction, and is connected to the BD input detection terminal 320 through The second diode 370 connected in reverse is connected to the CD output detection terminal, and the system interface and memory card insertion detection signal BD_CD is connected to the ground terminal GND through a second resistor, and the VCC is connected to the system interface and memory card insertion The first resistor is connected between the detection signals. In the figure, the first resistance is 10KΩ and the second resistance is 100KΩ, which is a preferred embodiment of the present invention. Other appropriate values can also be applied in the present invention, and are not limited to the preferred ones in the drawings. Example. The function of the first resistor and the second resistor is to boost BD_CD and VCC to provide the required circuit operation.

When the USB interface is inserted into the multifunctional compact memory card, referring to FIG. 4A , the first diode 360 will be turned on and the BD input terminal 320 will be turned on, so it can be known that the inserted interface is an SFMI interface. Conversely, when the system interface and the memory card insertion detection signal BD_CD are not input, the first diode 360 is not turned on, so it is known that the input signal is a USB interface signal.

On the contrary, in the output mode, when the output signal is the SFMI interface signal, the second diode 370 is turned on, and the output signal is the SFMI interface signal, otherwise it is the USB interface signal. When the multi-functional compact memory card detects that the insertion interface is an SFMI interface, it immediately turns the BD_CD signal into an output mode, and outputs a low potential to notify the read-write device that the card has been inserted and positioned.

Description of the communication protocol of the multi-function compact memory card:

The multi-functional small memory card interface adopts half-duplex, 4-bit serial mode, with CLK signal as the reference, and each clock can transmit 4-bit information. The information transmission method is controlled by the electronic application device, and the transmission length of the data phase is determined after the transmission command and the transmission length are issued. In order to improve the applicability of this interface and simplify the overall system design, the unit of interface transmission is data packet (packet). And the communication protocol uses the simulated communication endpoint (endpoint) in the memory card as the source (source) or target (sink) of information transmission.

All memory cards or IO cards that support the "functional small memory card interface" must support at least one set of communication endpoints, called "control endpoints" (Control Endpoint), whose endpoint address is 0. The electronic application device can obtain the detailed description of the memory card or IO card through this control endpoint, know its function and the settings of other communication endpoints. And after making appropriate settings, start its function and carry out data transmission.

(1) Start bit/end bit-Start bit/End bit

When the electronic application device and the memory card start data transmission, they must generate a start bit of clock cycle D0-D3 at the beginning of the data packet, and add two clock cycles D0-D3 at the end of the data packet. All end bits are 1.

(2) Packet identification code - Packet Identifier (PID)

Please refer to FIG. 5 , the communication packet starts with a Packet Identification Code (PID), and depending on the type of the PID, it must be used in different occasions. Each group of data packets includes: 1. Packet identification code: indicating the direction of data transmission in the packet, the address of the transmission end point, and the length of the data; 2. Payload data, including a set of CRC data error detection codes; 3. Packet status code, the party receiving the payload data will return the receiving status to confirm whether the data is received correctly. The PID 0001 indicates that the electronic application device will perform data output transmission. The packet ID 1001 indicates that the electronic application device will transmit data input. The packet ID 1101 indicates that the electronic application device will set or obtain relevant information for the control endpoint. The packet identification code 0010 indicates that the information receiving end confirms that the data packet has been received. The packet ID 1010 indicates that the information receiving end cannot receive information temporarily, or the sending end cannot send information temporarily. The packet ID 1110 indicates that the communication endpoint is out of work, or the control endpoint does not support the control command.

The PID identification code has a total of 4 bits. In order to prevent communication errors, 4 bits are added in reverse to form a total of 8 bits arranged in ascending powers, and the transmission is completed in two sets of clocks. As shown in Figure 6. When the receiving end receives the correct and complete PID and PID', and PID=(PID')', it confirms that the received PID is correct.

(3) Communication endpoint-Endpoint

A communication endpoint is a basic unit for data transmission between a small memory card or an IO card supporting a small memory card interface and an electronic application device. Corresponding to individual communication endpoints, there is a data buffer with a specific capacity in the small memory card or IO card, which is used to temporarily store the data carried in the communication packet between the electronic application device and the small memory card.

The small memory card or IO card that supports the small memory card interface can support up to 16 groups of communication endpoints, and the communication endpoint addresses in the communication packets are used to specify the object to be transmitted by the packet.

A small memory card or an IO card supporting the small memory card interface must have at least one set of communication endpoints, whose address is set to 0. After the electronic application device detects the insertion of the small memory card through the small memory card interface, it can obtain the identification code, function type, number of supported communication endpoints, addresses of each communication endpoint and communication information of the small memory card through the communication endpoint 0. Endpoint form and other related information.

The communication endpoints are divided into the following four types, which are respectively suitable for different types of data transmission between the electronic application device and the small memory card or IO card.

Control endpoints - small memory cards and IO cards must have a set of control endpoints whose endpoint address is 0. The function of the control endpoint is to allow the electronic application device to obtain relevant information such as the identification code, function type, number of supported communication endpoints, address of each communication endpoint, and communication endpoint form of the small memory card when the small memory card is activated.

Data input endpoint - used to allow electronic application devices to input large amounts of data from compact memory cards or IO cards.

Data output endpoint - used to allow electronic applications to output large amounts of data to a small memory card.

Status interrupt input terminal-used to allow the compact memory card or IO card to be configured to require the electronic application device to repeatedly input status interrupt input information from the compact memory card or IO card at a set interval.

As shown in FIG. 7 , the transmission marker packet designates the communication endpoint corresponding to the subsequent data packet or status packet by marking the communication endpoint. In the transmission identification packet, the communication endpoint completes the transmission with 4 bits followed by the PID in one clock period.

(4) Data Length - Data Length

As shown in FIG. 8, after ENDP, 12 bits of DATL representing the length of DATA are transmitted within 3 clock cycles. DATL takes 1 BYTE as the unit, 0x000 represents 4096 BYTEs, and the minimum value is 0x001 represents 1 BYTE

(5) Payload Data-Payload Data

The actual data carried by the packet (PDAT), and the information transmitted to the communication endpoint. DATL sets payload data length. During transmission, each byte is transmitted within 2 clock cycles. The transmission direction is specified by the electronic application device in the PID. As shown in FIG. 9 , CRC16 error checking codes of 16 clock cycles are appended at the end of the payload data. Wherein, the calculation algorithm of CRC16 is division by 2 and remainder division, and further may be polynomial division by 2 and remainder division in the form of G(X)=X16+X15+X2+1. The data transmission sequence is shown in Figure 10.

(6) Packet Status Code-Packet Status Acknowledge

The party receiving the data, after receiving the payload data, confirms whether the check code matches, and then confirms whether the received data is correct according to the receiving result. If the reception is completed correctly, ACK will be returned. If the reception cannot be completed temporarily, or the check code shows that the data is wrong, NAK will be returned to request retransmission. If an error occurs inside the memory card, or an error occurs in the execution command result, STALL will be returned. . As shown in Figure 11.

(7) Data format

All communication packets are initiated by the electronic application device (system side) for transmission. The sequence of data packets is start bit, packet identification code, communication endpoint, data length, payload data, packet status code, data format, end bits. The data transmission is initiated by the system to generate a packet identification code, specify the communication endpoint and data length.

If the packet is an IN packet, if the device fails to generate the required data immediately after receiving the above information, it can respond with the device status code NAK, and the system will stop the subsequent transmission immediately, and then restart the data transmission, and try to obtain the data again packet. If the device can respond to the required data, the device will generate a start bit, and then begin to return the information stored in the internal communication endpoint of the device. After the data length required by the system is met, 16 bits will be added. The CRC check code of the element. After receiving the check code, the system can send back ACK after checking and confirming that it is correct. If the data is wrong, NAK will be returned, and the packet can be restarted to obtain the correct data.

If the packet belongs to OUT or SETUP packet, the system will start to transfer the data to be transferred after completing the packet identification code, communication endpoint address, and data length. After the data length required by the system is reached, it will add 16 Bit CRC check code. After the device side receives the check code, it can send back ACK after checking and confirming that it is correct. If the data is wrong, NAK will be sent back, and the main control of the system will decide whether to restart the packet to obtain the correct data.

(8) Control transmission mode

The electronic application device can obtain information related to the multi-function memory card from the default transmission endpoint 0 or set its related functions by controlling the transmission mode. The control transmission mode is divided into SETUP phase, DATA phase, and STATUS phase, and its format is as follows:

In the SETUP stage, the system sends a SETUP packet, including the SETUP packet identification code, the communication endpoint address is 0, and the data length is 8 bytes. Then the system device sends 8-byte SETUP command code and parameters and 2-byte CRC16, and finally the status code is returned by the device to confirm whether the packet is received normally.

Among the 8-byte commands and parameters, starting from the first byte, they respectively represent: bmRequestType, bRequest, wValue, wIndex, wLength, etc. Please refer to the USB standard for their definitions and uses. The meaning of each parameter can be found in the control transmission data format table in Table 1: offset address field name Occupied space (bytes) set value illustrate 0 bmRequestType 1 bit value Command form: D7: Data transmission direction 0 = output from read-write device to small memory card 1 = output from small memory card to read-write device D6...5: command type 0 = standard command 1 = device-specific command 2 = manufacturer-specific Special command 3=reserved D4...0: command target object 0=device itself 1=interface 2=communication endpoint 3=others 4...31=reserved 1 bRequest 1 set value Set command code (code refer to Table 2) 2 wValue 2 set value The setting value has different meanings according to different command codes, and the length is two bytes 4 wIndex 2 set value Set values with different meanings according to different instruction codes, used to specify index value or offset value 6 wLength 2 value set data length

Table 1 Control transmission data format table

In addition to the standard command codes, device type-specific commands and manufacturer-specific special commands are determined by individual devices or formulated by manufacturers themselves. The small memory card or the IO card that supports the standard interface of the small memory card must support the standard instruction code. Please refer to the table below for the definition of standard script codes: bmRequestType bRequest wValue wIndex wLength Data 00000000B00000001B00000010B CLEAR_FEATURE FeatureSelector 0 0 none 1000000B GET_CONFIGURATION 0 0 1 Configuration setpoint 1000000B GET_DESCRIPTOR Descriptor type and index value 0 or language code descriptor length description metadata 10000001B GET_STATUS 0 0 interface code endpoint code 2 Get device, interface, or transport endpoint status 0000000B SET_ADDRESS device address 0 0 none 0000000B SET_CONFIGURATION Configuration setpoint 0 0 none 0000000B SET_DESCRIPTOR Descriptor type and index code 0 or language code descriptor length Descriptor 00000000B00000001B00000010B SET_FEATURE FeatureSelector 0 interface code endpoint code 0 none 00000001B SET_INTERFACE Alternate Setting interface code 0 none

Table 2 Standard instruction code table

In the data stage, depending on the bRequest code and wLength, determine the direction and length of the subsequent data stage transmission. It is started by the system side according to the general data transmission operation, and the transmission length is set according to wLength.

In the status phase, after the data phase is completed, depending on the direction of the data phase, the party receiving the data returns a status code to confirm whether the data transmission result is correct.

(9) Application of multifunctional small memory card interface

The multifunctional compact memory card interface can be applied to applications of different purposes, and the foregoing only covers the definition of the physical layer, and does not limit its application field. Supplementary development of applicable instruction sets and communication protocols can be applied to storage devices, communication devices, or other applicable application fields.

Claims (12)

1. A multifunctional small memory card for storing digital information and supporting data input and output; the multifunctional small memory card interface includes: A memory card I/O function module for supporting IO functions; a memory for the function of storing digital information; and A main controller, equipped with a control interface of a rewritable non-volatile memory and a control interface that can support an IO function module, is connected between the memory card I/O function module and the memory, so as to realize the storage of digital Control of information and supporting IO; It is characterized in that: the multi-functional small memory card has 4-pin and 8-pin designs at the same time, wherein the 4-pin design is used for the basic USB interface, and the other interface of the multi-functional small memory card is an 8-pin The design, called SFMI interface, consists of 4-bit bidirectional command/data/status bus, clock synchronization signal, system interface and memory card insertion detection signal, as well as power supply and grounding. Only 8 groups are needed in total. The contacts, wherein the power pin and the ground pin are the same as the power pin and the ground pin in the USB interface. 2. The multifunctional compact memory card according to claim 1, wherein the main controller also includes: An I/O controller is used to control the memory card I/O function module, including determining whether the memory card I/O function module operates in input mode or output mode, or operates in SFMI interface or USB interface mode operate; a memory master controller for controlling the memory; a formatter for formatting the output data from the memory into a format receivable by the receiving device; and A deformatter is used for deformatting the data from the receiving device into data received by the memory for storage. 3. The multifunctional compact memory card according to claim 1, wherein two signal buses in the 4-bit bidirectional command/data/status bus are the same as the signal buses of the USB interface. 4. The multifunctional compact memory card according to claim 3, characterized in that: D0 is a bidirectional command/data/status bus signal bit0, which is a D-signal line in the USB mode; D1 is a bidirectional command/data/status The bus signal bit1 is the D+ signal line in the USB mode; D2 is the bidirectional command/data/status bus signal bit2, which does not exist in the USB mode; and D3 is the bidirectional command/data/status bus signal bit3, in USB mode, this signal line does not exist. 5. The multifunctional small memory card according to claim 1, characterized in that: the memory card I/O function module, main controller, and memory are integrated on the circuit board, and a multifunctional small memory card is provided on the circuit board. The memory card interface terminal is exposed to the outside to connect with the electronic application device. 6. The multifunctional compact memory card according to claim 1, wherein the circuit board is a printed circuit board. 7. The multifunctional compact memory card according to claim 1, characterized in that: the interface of the memory card I/O function module includes a detection circuit, and the interface for detecting coupling is a USB interface or an SFMI interface . 8. The multifunctional compact memory card according to claim 7, characterized in that: the detection circuit comprises: a power supply, an input detection terminal, an output detection terminal, a first unidirectional current element, a first Two unidirectional current elements, a first resistor, and a second resistor; The VCC contact is connected to the power supply, the system interface and the memory card insertion detection signal are connected to the input detection terminal through the first unidirectional current element connected in the forward direction, and the output detection terminal is connected to the second unidirectional current element connected in the reverse direction. , and the system interface and the memory card insertion detection signal are connected to the ground terminal through a second resistor, and the first resistor is connected between the VCC and the system interface and the memory card insertion detection signal. 9. The multifunctional compact memory card according to claim 8, wherein the unidirectional current element is a diode. 10. The multifunctional compact memory card according to claim 1, wherein the memory is a large-capacity rewritable non-volatile memory storage module for storing digital information. 11. A multifunctional small memory card slot with 4-pin and 8-pin designs, of which the 4-pin design is used for the basic USB interface, the 8-pin design is used for the SFMI interface, and the 8-pin The 4-pin SFMI interface has four pins that are the same as the 4 pins of the USB interface, and the other four pins are distributed among the four pins of the USB interface. 12. The multifunctional compact memory card slot according to claim 11, wherein the slot is divided into a male slot and a female slot.

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