JP2003345674A - Input/output device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized input/output device which improves reliability in resending of a stream, and then keeps the substantial data transmission rate high and maintains high reliability in data communication. <P>SOLUTION: On an input/output device SD card 11 as an embodiment of the present invention, a transmission error detection part 4A detects a transmission error as to packets exchanged between a host H and a data communication part 2A. When the transmission error is detected, the transmission error detection part 4A connects a 1st communication part 21 to a memory part 5A or radio communication part 5B by a 1st switch SW1 to switch the communication mode of the data communication part 2A to a 1st communication mode. Further, the 1st communication part 21 is connected to a command line CMD by a 2nd switch SW2 to switch a data transmission line from a 1st data line DAT to the command CMD. Consequently, unsent packets and packets to be resent are transmitted through the command line CMD. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input / output device for performing data communication with an external information processing device,
In particular, the present invention relates to a device that is connected to an external information processing device via a bus including a plurality of data lines and exchanges data.

[0002]

2. Description of the Related Art With the rapid progress and explosive spread of information technology, various types of information processing devices are interconnected and can exchange various data. In such data communication, an enormous amount of data such as image data can be exchanged. Therefore,
For input / output devices (interfaces) responsible for data communication, versatility of various information processing devices including backward compatibility, and high-speed data transfer capability are required.
In addition, with the demand for reduction in size and weight of the entire information processing apparatus, reduction in size and weight of the input / output device itself is also required.

As an example of a conventional input / output device, an interface conforming to the SD standard (hereinafter, referred to as an SD interface) is known. In the SD standard, a small card of several cm square including an SD interface (hereinafter, referred to as an SD card)
Is defined. The SD card is inserted into a dedicated slot provided in the information processing device (host), and exchanges data with the host through an SD interface in the slot.

[0004] SD card types include SD memory cards and SDI / O cards. An SD memory card is a card-type recording medium with a built-in flash memory. A plurality of hosts realize mutual data exchange through sharing of the same SD memory card. The SDI / O card is an interface card for connecting a host to an information processing device or a network different from the host. For example,
The SDI / O card connects the host to a mobile phone or internal wireless communicator. Thereby, the host realizes data exchange with another information processing device through the mobile phone network or the wireless LAN. In the SD standard, various functional units connected to the host through the SD interface, such as the flash memory and the wireless communication unit, are referred to as functions. By expanding the functions, the SD card acquires versatility for various types of information processing devices.

The SD card is a multimedia card (MM)
C, registered trademark). For example, M
The size of the SD card is set so that the slot can be shared with the MC. Further, the following two modes are set for digital data communication between the host and the SD card. The first communication mode is a serial transfer mode in which digital data is serially transferred bit by bit. The data communication in the first communication mode is common to the data communication by the MMC. The second communication mode is a parallel transfer mode in which digital data is transferred in parallel, for example, every 4 bits. Data communication in the second communication mode is M
It is faster than data communication by MC. Thus, SD
In the data communication using the card, both the backward compatibility with the MMC and the high-speed data transfer are realized through the use of the two modes.

FIG. 9 is a block diagram showing data exchange between a conventional SD card 100 and a host H. The SD card 100 has a host H and, for example, four data lines DAT0 to DAT3,
They are connected by a bus including a clock line CLK, a power supply line VDD, a ground line VSS, and a command line CMD.

The host interface 101 is an SD card 100
And receives a command from the host H through the command line CMD and decodes it. For example,
When the command is a read command for the function unit (function) 102, the host interface 101 reads data from the function unit 102. Here, the function unit 102 is, for example, a flash memory. Alternatively, a wireless module connected to an external network or the like may be used. The read data is transferred to the host H through the data lines DAT0 to DAT3. At that time, the host interface 101 performs data transfer by synchronous communication. That is, the clock line CLK
The data is transferred in synchronization with the clock transferred from the host H through. The host interface 101 further performs data transfer in either the first communication mode or the second communication mode. Here, the communication mode is selected, for example, according to an instruction from the host H. In the first communication mode, data is serially transferred bit by bit only through the first data line DAT0. In the second communication mode, all data lines
Data is transferred in parallel by 4 bits through DAT0-3.

When a command from the host H is a write command to the functional unit 102, the host interface 101
Receives data through the data lines DAT0 to DAT3. At that time, data transfer is performed on the clock line
It is executed in either the first communication mode or the second communication mode synchronized with the clock from CLK and selected by the host H. The data received by the host interface 101 is transferred to the function unit 102. Thereby,
The data is stored in a flash memory or transferred to an external information processing device or the like.

FIG. 10 shows a conventional SD card 1 by the host H.
FIG. 9 is a timing chart for data exchange between the SD card 100 and the host H when reading data from 00. The host H sends a read command 53 to the SD card 100,
Transmit through CMD. The host interface 101 decodes the read command 53 and instructs the function unit 102 to output read target data. At the same time, a response RES is returned to the host H through the command line CMD.

A series of data to be read is output from the function unit 102 as one stream ST1. The host interface 101 generally divides the stream ST1 into a plurality of blocks. Further, a predetermined header and an error detection code CRC are added to each block, and a plurality of packets P
Construct 1 to PN. The packets are serially transmitted 1 bit at a time through the first data line DAT0 in the first communication mode, and are transmitted in parallel by 4 bits at a time through the four data lines DAT0 to 3 in the second communication mode to the host H. Transmitted.
At that time, the packets P1 to PN are continuously output. host
After finishing reading one stream ST1, H issues a new read command 53. Thereby, the new stream ST2 is stored in the SD card 100 in the same manner as the stream ST1.
Transmitted to the host H.

While the stream ST1 is transmitted through the data lines DAT0 to DAT3, the predetermined command 52 and its response RES may be exchanged through the command line CMD. For example, the host H checks each of the packets P1 to PN in the stream ST1 for a code error, and notifies the SD card 100 of the check result using the command 52. For example, when the detection of a code error is reported for the n-th packet Pn (1 ≦ n ≦ N), the SD card 100 stops transmitting the stream ST1, and retransmits the stream ST1 from the n-th packet Pn. Thus, the conventional SD card 100 maintains high reliability for stream transmission.

[0012]

The conventional SD card 100
In order to maintain a high data transmission rate, the above-described stream retransmission was executed in the same mode as the original stream transmission. That is, the stream portion to be retransmitted is the first data line in the first communication mode.
The data was transmitted serially one bit at a time through DAT0, and in the second communication mode, transmitted in parallel four bits at a time through all four data lines DAT0-3. However, when the cause of the code error is not a transient one such as accidental noise but a permanent one such as deterioration of a specific data line, simply retransmitting the stream in the same mode may result in retransmission. The possibility of detecting a code error in a packet was also high. As a result, the average number of retransmissions increased, and the actual data transmission rate decreased.

[0013] The present invention provides a small input / output device that improves the reliability of stream retransmission, thereby maintaining a substantial data transmission rate, and maintaining high reliability for data communication. Aim.

[0014]

An input / output device according to one aspect of the present invention includes: (A) a bus including a command line and a data line, which is connected to an external information processing device; A command control unit for exchanging commands with the information processing device; (C) a data communication unit for performing data communication with an external information processing device through a data line; and (D) a data communication by the data communication unit. Medium, when a command indicating a transmission error is input from the external information processing device, or when a transmission error is detected for data received from the external information processing device, the data transmission path in the data communication by the data communication unit is switched to the command line. A transmission error detection unit for

In the above input / output device, when a transmission error is detected during data communication by the data communication unit, the data transmission path is switched to the command line and continued. As a result, data communication can be continued while avoiding use of a data line having a high possibility of causing a transmission error. As a result, interruption of data communication due to a transmission error can be avoided, so that high reliability of data communication can be maintained. Here, the switching of the data transmission path may be independently determined by the input / output device and notified to the external information processing device (host). Other,
The host may instruct the input / output device to switch the data transmission path in response to the detection of the transmission error.

In the above input / output device, (A) the data communication unit performs data communication by block transfer; (B) the transmission error detection unit detects a transmission error by detecting an error for each block; (C) the transmission error After switching the data transmission path by the detector,
The data communication unit may retransmit the block in which the transmission error has been detected.

At this time, the retransmission target block may be mixed between the remaining blocks of the same stream and retransmitted. In addition, the stream portion after the retransmission target block may be continuously retransmitted. By these retransmissions, the reliability of data communication can be maintained high. In particular, the data transmission path at the time of retransmission is a command line, which is different from the data line which is a data transmission path at the time of occurrence of a transmission error. Therefore, the same transmission error can be prevented from recurring for the retransmission target block. As a result, data retransmission can be executed reliably. Further, since the retransmission of the block is performed during the transmission of the stream to which the block belongs, a substantial reduction in the data transmission speed due to the retransmission can be suppressed.

An input / output device according to another aspect of the present invention includes: (A) a bus including a command line and n data lines (an integer n is 2 or more) and connecting to an external information processing device; ) A command control unit for exchanging commands with an external information processing device through a command line; (C) Digital data is transmitted in m bits through m data lines (the integer m is 1 or more and less than n). The first communication mode to be exchanged, and digital data is passed through all data lines.
A data communication unit for performing data communication with an external information processing device in each of a second communication mode in which bits are exchanged bit by bit; and (D) an external device during data communication in the second communication mode by the data communication unit. Transmission error detection for switching the communication mode of the data communication unit to the first communication mode when a command indicating a transmission error is input from the information processing device or when a transmission error is detected for data received from the external information processing device. Part;

In the above input / output device, when a transmission error is detected in the data communication in the second communication mode, the data communication is switched to the first communication mode and is continued.
In the first communication mode, the number of data lines used is smaller than in the second communication mode. Therefore, the data communication can be continued while avoiding the use of the data line which is likely to include the cause of the transmission error. As a result, interruption of data communication due to a transmission error can be avoided, so that high reliability of data communication can be maintained. Here, the switching of the data transmission path may be independently determined by the input / output device and notified to the external information processing device (host). Alternatively, the host may instruct the input / output device to switch the data transmission path in response to the detection of the transmission error.

In the above input / output device, during transmission of data in the first communication mode by the data communication unit, when the transmission error detection unit inputs a command indicating a transmission error from the external information processing device, When a transmission error is detected for the data received from, some or all of the m data lines may be switched to another data line. Further, the switching of the data line may be repeated until no transmission error is detected. As a result, it is possible to easily avoid using a data line that is likely to cause a transmission error, so that the reliability of data communication can be maintained high and a substantial decrease in data transmission speed can be suppressed.

In the above input / output device, (A) the data communication unit performs data communication by block transfer; (B) the transmission error detection unit detects a transmission error by detecting an error for each block; (C) the transmission error After the communication unit is switched by the detection unit, the data communication unit may retransmit the block in which the transmission error has been detected.

At this time, the retransmission target block may be mixed between the remaining blocks of the same stream and retransmitted. In addition, the stream portion after the retransmission target block may be continuously retransmitted. By these retransmissions, the reliability of data communication can be maintained high. In particular, since the data transmission path at the time of retransmission is generally a different path from that at the time of occurrence of a transmission error, occurrence of the same transmission error can be suppressed for the retransmission target block. As a result, data retransmission can be executed reliably. Further, since the retransmission of the block is performed during the transmission of the stream to which the block belongs, a substantial reduction in the data transmission speed due to the retransmission can be suppressed.

In the above input / output device, the command control unit may retransmit the block to be retransmitted through the command line in parallel with the data communication by the data communication unit. Thereby, the retransmission of a block can be performed in parallel with the transmission of the stream to which the block belongs, so that a substantial reduction in data transmission speed due to the retransmission can be avoided.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below with reference to the drawings by way of preferred embodiments.

Embodiment 1 FIG. 1 is a block diagram showing data exchange between a host H and an SD card 11 according to Embodiment 1 of the present invention. The SD card 11 includes a host interface 1 and a memory unit 5A and a wireless communication unit 5B as functions conforming to the SD standard. The memory unit 5A includes a flash memory and stores data from the host H. The wireless communication unit 5B is, for example, an external wireless LAN
Is connected to

The host interface 1 includes four data lines DAT0 to DAT3, a clock line CLK, a power supply line VDD, and a ground line V
A bus including five types of lines, SS and a command line CMD, is connected to the host H. The four data lines DAT0 to DAT3 are lines for actually transmitting the data to be transmitted, and are arranged in parallel from the first data line DAT0 to the fourth data line DAT3. The clock line CLK is a line for transmitting a communication clock from the host H to the host interface 1. Communication on the data line is performed by synchronous communication according to the communication clock. Here, the communication clock is set by the host H, for example, within a range of 0 to about 25 MHz. The power supply line VDD is a line for supplying power from the host H to the SD card 11, and is maintained at a constant high potential. The ground line VSS is a line grounded in the host H, and is kept at a constant ground potential. The command line CMD is a line for transmitting a command exchanged during data communication and a control command issued by the host H to each function of the SD card 11. With the control command, the host H controls the memory unit 5A and the wireless communication unit 5B in the SD card 11.

The host interface 1 is a data communication unit 2
A, a command control unit 3, and a transmission error detection unit 4A.
The data communication unit 2A is connected to the host H via four data lines DAT0 to DAT3 and exchanges digital data D. Data communication unit 2
A includes, for example, two modules of a first communication unit 21 and a second communication unit 22, and connects one of these modules to the memory unit 5A and the wireless communication unit 5B by the first switch SW1. Accordingly, the data communication unit 2A performs data communication in the following two modes: in the first communication mode, the first communication unit 21 transmits digital data D serially by 1 bit only through the first data line DAT0. Transmit. At that time, the remaining three data lines DAT1 to DAT3 are in an idle state. Since the data communication in the first communication mode is equivalent to the data communication by the MMC, the SD card 11 maintains backward compatibility with the MMC. In the second communication mode, the second communication unit 22 transmits the digital data DAT through all four data lines DAT0 to DAT3.
Are transmitted in 4-bit units in parallel. Thereby, data communication at higher speed than in the first communication mode is realized.

In any of the two modes, data communication is performed by synchronous communication in accordance with a communication clock from the host H. A series of data to be transmitted (stream) is divided into blocks each having a predetermined data amount, for example, 512B. Further, a predetermined header and an error detection code (for example, a cyclic code) are added to each block to form a packet. The data communication unit 2A transmits data for each packet. The data communication unit 2A switches the first switch SW1 according to a command from the host H. Thereby, the host H selects one of the two modes according to its own data processing speed.

The data communication unit 2A further includes a second switch SW2, and switches a data transmission path for data communication by the first communication unit 21 from the first data line DAT0 to the command line CMD. Thereby, the data communication unit 2A can realize data communication in the first communication mode through the command line CMD. Switching of the transmission path from the first data line DAT0 to the command line CMD is performed according to the transmission error detection unit 4A.

The command control unit 3 uses a command line CMD to
Connected to H. Thereby, the command from the host H is received and decoded. Further, a response to the command is returned. Commands from host H include, for example,
Read and write commands for functions such as the memory unit 5A or the wireless communication unit 5B, and an SD card
There are 11 ID or status requests, etc. When the data requested by the command from the host H is relatively small, such as an ID and a status, the command control unit 3 usually inserts the data into a response to the command. On the other hand, the command control unit 3 normally instructs the data communication unit 2A to transmit relatively large data such as a stream output from the function.

At the time of data communication between the host H and the data communication unit 2A, the host H checks a transmission error for each packet transmitted from the data communication unit 2A. Similarly,
The transmission error detection unit 4A checks a transmission error for each packet transmitted from the host H to the data communication unit 2A. Here, the transmission error check is, for example, error detection using an error detection code included in the packet.

When detecting a transmission error, the host H issues a packet retransmission command. Thus, the command control unit 3 is notified of the ID of the packet in which the transmission error has been detected. The transmission error detection unit 4A monitors a command from the host H through the command control unit 3. Thereby, the packet retransmission command issued from the host H is received.

When detecting a transmission error in the packet received by the data communication unit 2A, the transmission error detecting unit 4A notifies the host H of the detection of the transmission error. Host H
When a transmission error detection notification is received from the transmission error detection unit 4A, or when a transmission error is detected for a packet received from the data communication unit 2A, the transmission error detection unit 4A
Issue the above packet retransmission instruction. In response to the retransmission command, the transmission error detection unit 4A first switches the communication mode of the data communication unit 2A to the first communication mode by using the first switch SW1. Next, the data transmission path is moved from the first data line DAT0 to the command line by the second switch SW2.
Switch to CMD. Thus, the host H and the data communication unit 2A
When a transmission error is detected for any of the packets exchanged between the data lines DAT0 to
Switch from 3 to the command line CMD. As a result, data lines DAT0 to DAT3 which are likely to include the cause of the transmission error are avoided, and the recurrence of the transmission error is suppressed. As a result, the reliability of data communication is kept high.

The data communication between the host H and the SD card 11 will be specifically described below, particularly the data transmission from the SD card 11 to the host H. The same applies to data transmission from the host H to the SD card 11. Figure 2
FIG. 4 is a timing chart for data exchanged between the SD card 11 and the host H when data is transmitted from the SD card 11 to the host H according to the first embodiment.

The host H communicates through the command line CMD to the memory
The command control unit 3 is notified of a read command 53 for 5A or the wireless communication unit 5B. The command control section 3 decodes the read command 53. When the read command 53 has been normally received, a response RES for notifying the reception of the read command 53 and a reception error otherwise is returned. Read instruction 5
When the command 3 is received normally, the command control unit 3 reads the stream requested by the read command 53 from the memory unit 5A or the wireless communication unit 5B, and transfers the stream to the data communication unit 2A. Further, it instructs the data communication unit 2A to the communication mode specified by the read command 53, for example, the second communication mode.

The data communication unit 2A divides the stream to be transmitted into, for example, 512B blocks to form a plurality of packets DP1, DP2,. Further, each packet is transmitted in parallel in the second communication mode TM2. At this time, the parallel signals P1, P2,... P (L−1), PL (the integer L is 1 or more) pass through all four data lines DAT0 to DAT3, and the corresponding packets DP1, DP2 , ... DP (L-1),
Output in the order of DPL.

The host H receives parallel signals P1, P2,... PL
, The corresponding packets DP1, DP2,... DP
L is reconstructed, and a code error is checked using each error detection code CRC. Here, the k-th packet DPk (1 ≦ k
Regarding <L), it is assumed that the host H detects a code error. At that time, the host H outputs the retransmission command 52 and notifies the command control unit 3 of the ID of the k-th packet DPk. Here, the retransmission command 52 may be any command that is transmitted in parallel with the data communication by the data communication unit 2A and can include a packet ID as a parameter.

The command control unit 3 decodes the retransmission command 52,
Check whether it was received normally. When the retransmission command 52 is normally received, the command control unit 3 notifies the host H of the fact with the response RES. Transmission error detector 4A
Reads the ID of the k-th packet DPk from the retransmission command 52 and notifies the data communication unit 2A of the ID. Further, the communication mode of the data communication unit 2A is switched to the first communication mode by the first switch SW1, and the data transmission path from the data communication unit 2A to the host H is switched to the command line CMD by the second switch SW2.

Subsequently, the host H issues a retransmission packet read command 54A. When the command 54A is normally received, the data communication unit 2A returns a response including the data of the k-th packet DPk corresponding to the ID notified from the transmission error detection unit 4A. Thereafter, each time the retransmission packet read command 54B, 54C,... From the host H is normally received, the (k + 1) -th and subsequent packets DP (k + 1), DP (k + 2),. Is resent. Here, when the size of the retransmission packet exceeds the maximum size of data that can be included in the response, the packet is divided and included in a plurality of responses. The host H repeatedly issues a retransmission packet read command according to the division number. In this way, the packet is retransmitted while maintaining the correspondence of one response per command. At that time, the communication mode is the first communication mode TM1
And the data transmission path is a command line CMD. The packets DPk, DP (k + 1), DP (k + 2), ... are converted into serial signals R1, R2, R3, ... and transmitted through the command line CMD.

In FIG. 2, all packets subsequent to the k-th packet DPk specified by the retransmission command 52 are retransmitted. Alternatively, only the k-th packet DPk may be mixed between untransmitted packets and retransmitted. FIG. 3 is a timing chart showing data transmission at that time. Second communication mode
Through data communication in TM2, up to a parallel signal PL including the L-th packet DPL is output. In parallel with its output,
The retransmission command 52 is transmitted from the host H. Thereby, the communication mode of the data communication unit 2A is switched to the first communication mode TM1, and the data transmission path is switched to the command line CMD. Thereafter, when receiving the first retransmission packet read command 54A from the host H, the first serial signal R1 including the k-th packet DPk is first output through the command line CMD. Then, each time a retransmission packet read command 54B, 54C,... From the host H is received, (L +
1) th and subsequent unsent packets DP (L + 1), DP (L + 2), ...
Are converted into serial signals R2, R3,... And output via the command line CMD.

As described above, the SD card 11 according to the first embodiment
In, when a transmission error is detected in a transmitted packet, the packet in which the transmission error is detected is retransmitted without interrupting data communication. At that time, the data transmission path is switched from the data line to the command line. Thus, in the data communication after the detection of the transmission error, the use of the data line which is likely to include the cause of the transmission error is avoided. Therefore, recurrence of transmission errors is suppressed, and the reliability of data communication is improved.

Embodiment 1 of the present invention is an SD card. However, the implementation target of the present invention is not limited to the SD card. That is, the present invention can be implemented in the same manner as in the first embodiment for an input / output device such as an IC card connected to a host via a bus including a command line and a data line as separate signal lines.

Embodiment 2 FIG. 4 is a block diagram showing data exchange with a host H for an SD card 12 according to Embodiment 2 of the present invention. The SD card 12 according to the second embodiment differs from the SD card 11 according to the first embodiment in a data communication unit 2B and a transmission error detection unit 4B. Other configurations are the same as those of the SD card 11 according to the first embodiment.
In FIG. 4, those similar components are denoted by the same reference numerals as in FIG. Further, for those similar components, the description in Embodiment 1 is cited.

The data communication section 2B has four data lines DAT0 to DAT3.
Is connected to the host H to exchange digital data D.
The data communication unit 2B includes, for example, a first communication unit 21 and a second communication unit 22.
And one of those modules is connected to the memory unit 5A and the wireless communication unit 5B by the first switch SW1. Accordingly, the data communication unit 2B performs data communication in the following two modes: In the first communication mode, the first communication unit 21 transmits digital data D through only one of the data lines DAT0 to DAT3. Data is transmitted serially one bit at a time. At that time, the remaining three data lines are in an idle state. Further, the data transmission path is switched by the third switch SW3. Usually, the first data line DAT0 is selected as the data transmission path. At that time, since the data communication in the first communication mode is equivalent to the data communication by the MMC, the SD card 12 maintains backward compatibility with the MMC.
In the second communication mode, the second communication unit 22 has four data lines.
Digital data D is transmitted in 4-bits in parallel through all of DATs 0 to 3. Thereby, data communication at higher speed than in the first communication mode is realized.

In any of the two modes, data communication is performed by synchronous communication according to a communication clock from the host H. The transmission target stream is divided into blocks, for example, every 512B, and forms a packet together with a predetermined header and an error detection code (for example, a cyclic code). The data communication unit 2B transmits data for each packet. The data communication unit 2B switches the first switch SW1 according to a command from the host H. Thereby, the host H selects one of the two modes according to its own data processing speed.

The transmission error detection unit 4B checks a transmission error for each packet transmitted from the host H to the data communication unit 2B. Here, the transmission error check is, for example, error detection using an error detection code included in the packet. The transmission error detection unit 4B monitors commands from the host H through the command control unit 3 as in the first embodiment. Thereby, when a transmission error is detected by the host H,
Receive a packet retransmission command issued from the host H.

During data communication in the second communication mode by the data communication unit 2B, the transmission error detection unit 4B
When a transmission error is detected for the packet received by 2B for the first time, the host H is notified of the first detection of the transmission error. When the host H first receives a notification of transmission error detection from the transmission error detection unit 4B or detects a transmission error for a packet received from the data communication unit 2B for the first time, the host H Issue a resend command. In response to the first retransmission command, the transmission error detection unit 4B switches the communication mode of the data communication unit 2B to the first communication mode by using the first switch SW1. On the other hand, by the third switch SW3, first, the data transmission path,
For example, it is set to the first data line DAT0. Here, the switching destination of the data transmission path is specified by the host H through the first retransmission command.

During data communication in the first communication mode by the data communication unit 2B, the transmission error detection unit 4B
When the transmission error is detected for the packet received by the host H, the host H is notified of the detection of the transmission error. When receiving notification of transmission error detection from the transmission error detection unit 4B or detecting a transmission error for a packet received from the data communication unit 2B, the host H issues a packet retransmission instruction to the transmission error detection unit 4B. I do. In response to the retransmission command, the transmission error detection unit 4B switches the data transmission path from, for example, the first data line DAT0 to the second data line DAT1 by the third switch SW3. Here, the switching destination of the data transmission path is specified by the host H through a retransmission instruction.

Thereafter, each time the transmission error detecting section 4B or the host H detects a transmission error, the host H switches the data transmission path to another data line so as to switch to another data line.
Instruct 4B. In this way, when a transmission error is detected for any of the packets exchanged between the host H and the data communication unit 2B, the data transmission path is connected to the four data lines DA.
It can be switched between T0-3. As a result, data lines DAT0 to DAT3 likely to include the cause of the transmission error are avoided,
Suppresses reoccurrence of transmission errors. As a result, the reliability of data communication is kept high.

The data communication between the host H and the SD card 12 will be specifically described below, particularly the data transmission from the SD card 12 to the host H. The same applies to data transmission from the host H to the SD card 12. Figure 5
FIG. 9 is a timing chart for data exchanged between the SD card 12 and the host H when data is transmitted from the SD card 12 to the host H according to the second embodiment.

The host H communicates through the command line CMD to the memory
The command control unit 3 is notified of a read command 53 for 5A or the wireless communication unit 5B. The command control section 3 decodes the read command 53. When the read command 53 has been normally received, a response RES for notifying the reception of the read command 53 and a reception error otherwise is returned. Read instruction 5
When the command control unit 3 receives the stream normally, the command control unit 3 reads the stream requested by the read command 53 from the memory unit 5A or the wireless communication unit 5B, and transfers the stream to the data communication unit 2B. Further, it instructs the data communication unit 2B to communicate in the communication mode specified by the read command 53, for example, the second communication mode.

The data communication unit 2B divides the transmission target stream into, for example, 512B blocks, and
1, DP2,... Further, those packets are transmitted in parallel in the second communication mode TM2. At this time, the parallel signal P is passed through all four data lines DAT0 to DAT3.
1, P2,... P (L−1), PL (the integer L is 1 or more)
The corresponding packets DP1, DP2,... DP (L−1) are output in the order of DPL.

The host H receives parallel signals P1, P2,... PL
, The corresponding packets DP1, DP2,... DP
L is reconstructed, and a code error is checked using each error detection code CRC. Here, the k1th packet DPk1 (1
For ≦ k1 <L), it is assumed that the host H detects a code error. The host H then outputs the first retransmission command 52A and notifies the command control unit 3 of the ID of the k1th packet DPk1 and the data designating the first data line DAT0 as the data transmission path switching destination. . Here, the first retransmission instruction 5
The command 2A may be any command that is transmitted in parallel with the data communication by the data communication unit 2B and can include a packet ID and a data transmission path switching destination as parameters.

The command control section 3 decodes the first retransmission command 52A and checks whether or not it has been normally received. When the first retransmission command 52A is normally received, the command control unit 3
Notifies the host H to that effect with a response RES. The transmission error detection unit 4B reads the ID of the k1st packet DPk1 from the first retransmission command 52A and notifies the data communication unit 2B.
Further, the first data line DAT0 is used as a switching destination of the data transmission path.
Then, the communication mode of the data communication unit 2B is switched to the first communication mode by the first switch SW1, and the data transmission path from the data communication unit 2B to the host H is set to the first data line DAT0.

The data communication unit 2B retransmits the packets DPk1, DP (k1 + 1), DP (k1 + 2),... In order from the k1th packet DPk1 corresponding to the ID notified from the transmission error detection unit 4B. At that time, the communication mode is the first communication mode TM1
, And the data transmission path is the first data line DAT0. The packets DPk1, DP (k1 + 1), DP (k1 + 2), ... are converted into serial signals Q1, Q2, Q3, ... and transmitted through the first data line DAT0.

In FIG. 5, all the packets subsequent to the k1th packet DPk1 specified by the first retransmission command 52A are retransmitted. Alternatively, only the k1-th packet DPk1 may be mixed between untransmitted packets and retransmitted. FIG. 6 is a timing chart showing data transmission at that time. The L-th packet is transmitted by data communication in the second communication mode TM2.
A parallel signal PL including DPL is output. In parallel with the output, a first retransmission command 52A is transmitted from the host H. Thereby, the communication mode of the data communication unit 2B is switched to the first communication mode TM1. After that, the first serial signal Q1 including the k1st packet DPk1 is first output through the first data line DAT0. Subsequently, the untransmitted packets DP (L + 1), DP (L + 2),... After the (L + 1) th are converted into serial signals Q2, Q3,. You.

FIG. 7 is a timing chart showing data exchange when the second retransmission command 52B and the third retransmission command 52C are issued from the host H following the first retransmission command 52A. As described above, the data communication unit 2B
Is switched from the second communication mode TM2 to the first communication mode TM1. At that time, the data transmission path is first set to the first data line DAT0. Each packet including the k1th packet DPk1 is a serial signal
Are converted to Q1, Q2,... Q (M−1), QM (the integer M is 1 or more) and transmitted through the first data line DAT0.

Assume that the host H detects a code error for the k2th packet DPk2 (k1 ≦ k2). The host H then outputs the second retransmission command 52B, and stores the ID of the k2th packet DPk2 and the data specifying the second data line DAT1 as the data transmission path switching destination in the command control unit.
Notify 3. Here, the second retransmission command 52B is a command of the same type as the first retransmission command 52A, is transmitted in parallel with the data communication by the data communication unit 2B, and sets the packet ID and the data transmission path switching destination as parameters. Included as

The command control section 3 decodes the second retransmission command 52B and checks whether or not the command has been normally received. When the second retransmission command 52B is normally received, the command control unit 3
Notifies the host H to that effect with a response RES. The transmission error detection unit 4B reads the ID of the k2th packet DPk2 from the second retransmission command 52B and notifies the data communication unit 2B of the ID.
Further, the second data line DAT1 is used as a data transmission path switching destination.
The data communication unit 2B is specified by the third switch SW3.
A data transmission path from the first data line DAT0 to the host H.
To the second data line DAT1. Thereafter, the data communication unit 2B transmits a plurality of packets including the k2th packet DPk2 to the serial signals Q (M + 1),.
Is (M + 1) or more) and transmitted through the second data line DAT1.

Further, it is assumed that the host H detects a code error for the k3rd packet DPk3 (k2 ≦ k3). The host H then outputs a third retransmission command 52C, and k3
The command control unit 3 is notified of the ID of the third packet DPk3 and the data specifying the third data line DAT2 as the switching destination of the data transmission path. Here, the third retransmission command 52C is a command of the same type as the first retransmission command 52A,
B transmitted in parallel with the data communication by
D and the switching destination of the data transmission path are included as parameters.

The command control section 3 decodes the third retransmission command 52C and checks whether or not it has been normally received. When the third retransmission command 52C is normally received, the command control unit 3
Notifies the host H to that effect with a response RES. The transmission error detection unit 4B reads the ID of the k3rd packet DPk3 from the third retransmission command 52C and notifies the data communication unit 2B.
Further, a third data line DAT2 is used as a data transmission path switching destination.
The data communication unit 2B is specified by the third switch SW3.
A data transmission path from the second data line DAT1 to the host H.
To the third data line DAT2. Thereafter, the data communication unit 2B converts the plurality of packets including the k3th packet DPk3 into serial signals Q (N + 1),.
Data is transmitted through the third data line DAT2.

As described above, the SD card 12 according to the second embodiment has four data transmission paths each time a transmission error is detected for any of the packets exchanged between the host H and the data communication unit 2B. It is switched between data lines DAT0-3. Thereby, the data lines DAT0 to DAT3, which are likely to include the cause of the transmission error, are avoided, and the recurrence of the transmission error is suppressed. As a result, data retransmission is reliably performed, and the reliability of data communication is improved.

In FIGS. 5 to 7, the packet to be retransmitted is transmitted in the same communication mode through the same data transmission path as other packets. Alternatively, the packet to be retransmitted may be transmitted, for example, via the command line CMD in parallel with the transmission of other packets. FIG. 8 is a timing chart showing data transmission at that time. The host H notifies the command controller 3 of the read command 53 via the command line CMD. Command control unit 3
Returns a predetermined response RES and decodes the read command 53. Thereby, the read instruction 53
Is read from the memory unit 5A or the wireless communication unit 5B and transferred to the data communication unit 2B. Further, it instructs the data communication unit 2B to the communication mode specified by the read command 53, for example, the second communication mode.

The data communication unit 2B divides the transmission target stream into, for example, 512B blocks, and
1, DP2,... Further, those packets are transmitted in parallel in the second communication mode TM2. At this time, the parallel signal P is passed through all four data lines DAT0 to DAT3.
1, P2,... P (L−1), PL (the integer L is 1 or more)
The corresponding packets DP1, DP2,... DP (L−1) are output in the order of DPL.

The host H receives parallel signals P1, P2,... PL
, The corresponding packets DP1, DP2,... DP
L is reconstructed, and a code error is checked using each error detection code CRC. Here, the k-th packet DPk (1 ≦ k
Regarding <L), it is assumed that the host H detects a code error. The host H outputs the retransmission command 52 at that time, and notifies the command control unit 3 of the ID of the k-th packet DPk and the data specifying the first data line DAT0 as the switching destination of the data transmission path. Here, the retransmission command 52 is the same as in the first embodiment.

The command control section 3 decodes the retransmission command 52,
Check whether it was received normally. When the retransmission command 52 is normally received, the command control unit 3 notifies the host H of the fact with the response RES. Transmission error detector 4B
Reads the ID of the k-th packet DPk from the retransmission command 52 and notifies the data communication unit 2B of the ID. Furthermore, the first switch
SW1 switches the communication mode of the data communication unit 2B to the first communication mode. At that time, the first data line DAT0 is specified as the data transmission path switching destination from the retransmission command 52,
The data transmission path from the data communication unit 2B to the host H is set to the first data line DAT0.

The data communication unit 2B sequentially transmits the (L + 1) th and subsequent untransmitted packets DP (L + 1), DP (L + 2), DP (L + 3),... To serial signals Q1, Q2, Q3,. The data is converted and transmitted through the first data line DAT0. On the other hand, the data communication unit 2B transfers the k-th packet DPk corresponding to the ID notified from the transmission error detection unit 4B to the command control unit 3. Host H
Is a command for reading a retransmission packet through the command line CMD 54.
Is output to the command control unit 3. Here, the retransmission packet read command 54 may be any command that can be transmitted to the command control unit 3 in parallel with the data communication by the data communication unit 2B.

The command controller 3 returns a response 55 to the retransmission packet read command 54. At that time, the response 55 is the k-th packet D which is the packet to be retransmitted.
Pk is included as data. Thus, retransmission of the packet is realized in parallel with the data communication by the data communication unit 2B. Thereby, retransmission of a packet does not reduce the substantial transmission speed of data communication by the data communication unit 2B.

Embodiment 2 of the present invention is an SD card. However, the implementation target of the present invention is not limited to the SD card. That is, the present invention can be implemented in the same manner as in the second embodiment for an input / output device such as an IC card connected to a host by a bus including a command line and a plurality of data lines as separate signal lines.

[0070]

As described above, in the input / output device according to the present invention, when a transmission error is detected during data communication by the data communication unit, the data transmission path is changed from the original data line to another data line or command line. Switched and continued. As a result, data communication can be continued while avoiding use of a data line having a high possibility of causing a transmission error. As a result, interruption of data communication due to a transmission error can be avoided, so that high reliability of data communication can be maintained.

In the above input / output device, especially when data communication is performed by block transfer, the retransmission target block may be mixed between the remaining blocks of the same stream and retransmitted. In addition, the stream portion after the retransmission target block may be continuously retransmitted. By these retransmissions, the reliability of data communication can be maintained high. In particular, the data transmission path at the time of retransmission is different from that at the time of occurrence of a transmission error. Therefore, the same transmission error can be prevented from recurring for the retransmission target block. As a result, data retransmission can be executed reliably. Further, since the retransmission of the block is performed during the transmission of the stream to which the block belongs, a substantial reduction in the data transmission speed due to the retransmission can be suppressed.

In the above input / output device, the command control unit may retransmit the block to be retransmitted through the command line in parallel with the data communication by the data communication unit. Thereby, the retransmission of a block can be performed in parallel with the transmission of the stream to which the block belongs, so that a substantial reduction in data transmission speed due to the retransmission can be avoided.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating data exchange with a host H for an SD card 11 according to a first embodiment of the present invention.

FIG. 2 is a timing chart of data exchanged between the SD card 11 and the host H when data is transmitted from the SD card 11 to the host H according to the first embodiment of the present invention. Here, all packets after the retransmission target packet DPk are retransmitted.

FIG. 3 is a timing chart for data exchanged between the SD card 11 and the host H when data is transmitted from the SD card 11 to the host H according to the first embodiment of the present invention. Here, unlike FIG. 2, only the retransmission target packet DPk is mixed between the untransmitted packets DP (L + 1), DP (L + 2),... And retransmitted.

FIG. 4 is a block diagram illustrating data exchange with a host H for an SD card 12 according to a second embodiment of the present invention.

FIG. 5 is a timing chart of data exchanged between the SD card 12 and the host H when data is transmitted from the SD card 12 to the host H according to the second embodiment of the present invention. Here, all packets after the retransmission target packet DPk are retransmitted.

FIG. 6 is a timing chart of data exchanged between the SD card 12 and the host H when data is transmitted from the SD card 12 to the host H according to the second embodiment of the present invention. Here, unlike FIG. 5, only the retransmission target packet DPk is mixed between the untransmitted packets DP (L + 1), DP (L + 2),... And retransmitted.

FIG. 7 is a diagram illustrating a second retransmission command 52B and a third retransmission command 52C transmitted from the host H following the first retransmission command 52A during data transmission from the SD card 12 to the host H according to the second embodiment of the present invention. FIG. 4 is a timing diagram illustrating data exchange when issued.

FIG. 8 illustrates an untransmitted packet DP (L + 1), DP (L +) during data transmission from the SD card 12 to the host H according to the second embodiment of the present invention.
2) is a timing chart showing retransmission of a retransmission target packet DPk in parallel with transmission of 2),...

FIG. 9 is a block diagram showing data exchange between a conventional SD card 100 and a host H.

FIG. 10 is a timing chart for data exchange between the SD card 100 and the host H when data is transmitted from the SD card 100 to the host H in the related art.

[Explanation of symbols]

2A Data communication section SW1 First switch SW2 Second switch 5A memory section D Digital data (stream) CMD command line DAT0 1st data line DAT1 Second data line DAT2 Third data line DAT3 fourth data line CLK clock line VDD power line VSS Ground line

Claims (6)

[Claims] (A) including a command line and a data line,
A bus connected to an external information processing device; (B) a command control unit for exchanging commands with the external information processing device through the command line; and (C) a command control unit through the data line to communicate with the external information processing device. A data communication unit for performing data communication; and (D) during data communication by the data communication unit, when a command indicating a transmission error is input from the external information processing device, or data received from the external information processing device. And a transmission error detecting unit for switching a data transmission path in data communication by the data communication unit to the command line when a transmission error is detected. 2. (A) the data communication unit performs the data communication by block transfer; (B) the transmission error detection unit detects the transmission error by error detection for each block; (C) the transmission error 2. The input / output device according to claim 1, wherein after switching of the data transmission path by the detection unit, the data communication unit retransmits the block in which the transmission error is detected. 3. (A) A command line and n data lines (integer)
(n is 2 or more), and a bus connected to an external information processing device; (B) a command control unit for exchanging commands with the external information processing device through the command line; (C) m data lines (the integer m is 1 or more and less than n)
And a second communication mode in which digital data is exchanged by m bits through all of the data lines, and a second communication mode in which digital data is exchanged by n bits through all of the data lines. And (D) during data communication in the second communication mode by the data communication unit, when a command indicating a transmission error is input from the external information processing device, or when the external information An input / output device comprising: a transmission error detection unit for switching a communication mode of the data communication unit to the first communication mode when a transmission error is detected for data received from a processing device. 4. The data communication unit according to claim 1, wherein said transmission error detection unit inputs a command indicating a transmission error from said external information processing apparatus during data communication in said first communication mode, or 4. The input / output device according to claim 3, wherein a part or all of the m data lines are switched to another data line when a transmission error is detected for data received from the device. (A) the data communication unit performs the data communication by block transfer; (B) the transmission error detection unit detects the transmission error by detecting an error for each block; (C) the transmission error The input / output device according to claim 3, wherein, after switching of the communication mode by the detection unit, the data communication unit retransmits the block in which the transmission error is detected. 6. The data communication unit performs the data communication by block transfer; (B) the transmission error detection unit detects the transmission error by detecting an error for each block; and (C) the data communication. The input / output device according to claim 3, wherein the command control unit retransmits the block in which the transmission error is detected through the command line in parallel with data communication by the unit.