JP2001282467A - Method for reading/writing data from/in sd card certification area and data communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that processing is complicated because communication data between a PC and a communication LSI is processed in a variable length state in the case of reading/writing data from/in an SD card certification area. SOLUTION: All the lengths of communication command data, reading data and other data among a PC driver, the communication LSI and a microcomputer are fixed length. At the time, padding data independent of the command data are added to set up the length of the command data to the same fixed length as the transfer length of read data and other data. A regulated communication method that sending and receiving commands are surely communicated as a pair of commands is adopted. In order to inform of a state whether normal reading operation or the like is executed or not from the PC side to the SD card side or from the SD card side to the PC side, prescribed check data are padded in the free area of the padding data and returned to the opposite side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls a regular command from a PC by a communication LSI and a microcomputer when performing read and write operations to an authentication area of an SD card. The present invention relates to a technique for performing processing such as accurate reading and writing of data.

[0002]

2. Description of the Related Art In a communication procedure for reading and writing between a driver of a PC and a solid-state memory, several bytes of data such as a command and a data length are required in addition to read and write data. Conventionally, the number of transfer bytes of the communication LSI is changed each time to exchange data. In order to provide flexibility, the setting of several bytes is set for each communication. However, the data length and the location where the data is stored are different each time, and the processing is complicated, so it is necessary to pay attention.

[0003]

Conventionally, in data reading and writing from a PC to a solid-state memory, it has always been necessary to be aware of data transfer data. However, the operation processing has various data lengths and commands and differs each time, so that the microcomputer software processing becomes complicated. This may cause malfunctioning of the system.

[0004]

[Means for Solving the Problems] PC driver and communication L
The communication command between the SI and the microcomputer, and the length of read / write data are all fixed lengths. At this time, unrelated PADDING data is added to the command data so that the command data always has the same fixed length as the read or write data transfer length.
In addition, by adopting a regularly determined communication method such as always transmitting a Send command and a Receive command in pairs, it is possible to perform the same software processing accurately and without regard to the data length.

Further, in order to inform the other party of the communication whether the PC or SD card and the opposite side have performed normal read and write operations, the free area of the PADDING when the data length is the same. Is filled with predetermined check data and returned to the communication check data partner, enabling accurate transmission and reception.

[0006]

FIG. 2 shows a PC driver and a communication L.
An example of a format in which the length of commands and data between the SI and the microcomputer is all fixed and communication is performed. CM
D is a command, and STAT is a status for the command. If the command length is n bytes and the fixed length is m bytes, the added PADDING length is mn bytes. Here, it is assumed that m> n.

When the command length is variable, the command length is 1 byte, and when the fixed length is m bytes, the number of bytes of PADDING to be embedded can be expressed as ml.
Transmission and reception with a fixed length of m bytes can always be realized.

[0008] Send command from PC driver and R
The communication pattern of the data format following the receive command will be described in detail.

FIG. 2A shows a format when there is no transfer data. This can be used for checking whether the PC and the reader / writer can normally transmit and receive.

FIG. 2B shows a format in the case of a read command in which the transfer data is smaller than a fixed length (m bytes). If the transfer data is smaller than the fixed length in the Send command from the PC, the gap is filled with the PADDING data to make the length fixed. At this time, a value irrelevant to the command may be entered in the PADDING data. Next, the status and read data for the command to the SD card are returned by the Receive command. The PADDING data at this time may have any value.

Similarly, FIG. 2C shows a format in the case where the transfer data is a write command smaller than a fixed length (m bytes). If the command and the write data length are equal to or less than the fixed length of the communication even when the command and the write data length are combined, this communication format is used.

FIG. 2D shows a format in the case of a read command in which transfer data exceeds a fixed length (m bytes). The difference from FIG. 2B is that the read data has a number of bytes exceeding the fixed length. The transmission / reception processing at this time is a fixed-length continuous communication processing.

Similarly, FIG. 2E shows a format in the case of a write command in which transfer data exceeds a fixed length (m bytes). As in the case of the read, the processing when the write data has the number of bytes exceeding the fixed length is as described above.

By performing communication in a fixed length and in a regularly determined form as described above, data is transmitted and received between the PC and the SD card.

Although transmission and reception can be performed only by this method, as a method for further increasing the reliability of transmission and reception, as shown in the example of FIG.
Information for confirming the state between the PC and the communication LSI is included.

As shown in FIG. 3A, communication check data determined when data is transmitted from the PC is transmitted to the PAD.
It is included in the DING area.

This is confirmed on the receiving side, and if the communication state is normal, the data and communication check data indicating that the state is normal are rewritten and returned to the PC side (FIG. 3).
(B)).

If the communication state is abnormal, the data and the communication check data indicating that the state is abnormal are rewritten and returned to the PC. In the example of FIG. 3C, the same data is returned.

By executing the communication check data at the same time as the communication of the fixed-length format described above, it is possible to perform more reliable communication.

[0020]

According to this method, the lengths of commands and data between the PC driver and the communication LSI and the microcomputer are all fixed lengths, and a fixed communication method is employed, so that the software processing is easy to understand and more accurate. Communication can be performed, and transmission / reception processing can be realized with the same configuration irrespective of the data length.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of the present invention.

FIG. 2 is a diagram showing a data configuration example of the present invention.

FIG. 3 is a diagram showing an example of a transmission / reception check data communication unit according to the present invention.

[Explanation of symbols]

 1 PC (personal computer) 2 Reader / writer 3 SD card

Claims (5)

[Claims] 1. A method for reading and writing data to an authentication area of an SD card by a communication command from a personal computer. 2. A communication command data between a PC (personal computer) and a communication LSI which has no relation to a command.
A method of performing communication by embedding data, making the length equal to the data transfer length of read or write, and making the command into a regular transmission / reception format. 3. Using the irrelevant PADDING data added to the communication command data between the PC (personal computer) and the communication LSI, the PC determines whether the processing accompanying the data transfer of read or write is normal or abnormal. A method of transmitting and receiving to and from a PC by returning to 4. A communication command data between a PC (personal computer) and a communication LSI which is not related to the command.
In the case of adding data, even if the command length is variable, P for the length obtained by subtracting the command length from the fixed length
A method in which ADDING data is added and fixed-length transmission / reception is always performed. 5. A data communication device which is a reader / writer comprising a communication LSI and a control circuit of a microcomputer, and controls communication between a PC and an SD card.