JPH06259616A - Self-diagnostic method for information recording medium incorporated with cpu - Google Patents

Abstract

PURPOSE:To report a correct diagnostic result to the outside regardless of the occurrence of a defect in registers. CONSTITUTION:Actual data is read out from a register after being written to confirm one normal register (S10), and contents of this confirmed normal register are transferred to another register, and contents of both registers are compared with each other to diagnose another register (S30) Next, the normal register is used to diagnose a RAM (S40), and the normal register is used to transmit the diagnostic result to the outside (S50). If all registers are defective, the potential level of an I/O line is directly controlled by a CPU to report the diagnostic result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-diagnosis method for an information recording medium having a built-in CPU, and more particularly to a self-diagnosis method for a volatile memory.

[0002]

2. Description of the Related Art IC cards have attracted attention as a new information recording medium replacing magnetic cards. Especially CPU
Since the IC card having a built-in card has a high degree of security, it is expected to be used in various fields. Generally I
C card has 3 such as RAM, ROM, EEPROM
It has built-in types of memory, both of which are accessed by the built-in CPU. The reader / writer device exchanges data with the IC card. When a given command is given from the reader / writer device to the IC card, this command is executed by the CPU in the IC card. For example, in the case of a data write command, the data given to the IC card from the reader / writer device is written in the memory in the IC card, and in the case of a data read command, the data read from the memory in the IC card. Is transferred to the reader / writer device.

[0003] A portable information recording medium such as an IC card is usually carried in a pocket or a handbag and often handled under physically severe conditions. Therefore, the built-in hardware is likely to be physically damaged. In order to regularly check the presence or absence of such hardware damage, an IC card with a built-in CPU has a self-diagnosis function. For example, self-diagnosis for RAM, which is a volatile memory,
Usually, this is performed by writing predetermined data to each address of the RAM by the CPU, then reading this data, and determining whether this is correct data. When such a writing / reading test is performed, the data originally stored in the RAM is lost. Therefore, such a self-diagnosis for the RAM is generally performed at reset. RA
Since M is a memory used as a work area of the CPU, there is no problem even if the stored contents are lost at the time of reset.

A general procedure for accessing the IC card starts with an operation of inserting the IC card into the reader / writer device. When the IC card is inserted into the reader / writer device, the reader / writer device gives a reset signal to the IC card. That is, the CPU built in the IC card is reset. The CPU executes a predetermined reset routine,
Normally, a self-diagnosis is performed on the RAM as part of this reset routine.

[0005]

In order to perform the above-mentioned write / read test for the RAM, it is necessary to use a register. However, if this register itself has a problem, the RAM cannot be correctly tested. Moreover, the trouble of the register itself becomes a serious defect rather than the trouble of the specific address of the RAM. Even if some defect is found by the self-diagnosis, it does not make sense unless the diagnosis result is finally reported to the outside (reader / writer device side). Since the conventional self-diagnosis method does not assume that the register itself has a defect, if the register itself has a defect, the correct self-diagnosis cannot be performed and it may be reported to the outside. Can not.

Therefore, the present invention provides a self-diagnosis method for an information recording medium having a built-in CPU, which can report a correct diagnosis result to the outside even if the register has a defect. To aim.

[0007]

[Means for Solving the Problems]

(1) The first invention of the present application is at least a volatile memory,
In a self-diagnosis method of diagnosing the operation of a volatile memory by the CPU, with respect to an information recording medium having a CPU having a function of accessing this memory, a normal operation is performed from a plurality of registers prepared for the CPU. Check one register that works in the above, and if at least one normal register is found, use this normal register or newly confirmed normal register to check other registers and volatile memory. Diagnosis is performed and the diagnosis result is transmitted to the outside through a predetermined I / O line using a normal register. When no normal register is confirmed, the potential of the I / O line is detected by the CPU. The diagnostic result is transmitted to the outside by directly controlling the level.

(2) In the second invention of the present application, in the above-mentioned first invention, in order to directly control the potential level of the I / O line, a command to keep the I / O line at a high level, and a command to keep it at a low level. The instruction and the instruction for setting the waiting time are used.

[0009]

[Operation] In the diagnostic method of the present invention, first, it is confirmed that there is at least one normal register. When the existence of the normal register is confirmed, the normal register is used to diagnose another register or the volatile memory, and the result is reported to the outside using the normal register. On the other hand, if there is no normal register, the diagnosis result cannot be reported using the register. Therefore, the CPU directly controls the potential level of the I / O line to display the diagnosis result. Report to the outside. By such a method, it becomes possible to report a correct diagnosis result to the outside even if the register has a defect.

[0010]

The present invention will be described below based on illustrated embodiments. FIG. 1 is a block diagram showing a state in which a general IC card 10 is connected to a reader / writer device 20. IC
In the card 10, an I / O device 11 for connecting to the reader / writer device 20, a CPU 12, a RAM 13,
The ROM 14 and the EEPROM 15 are built in. The I / O device 11 and the reader / writer device 20 are
It is connected by an O line 30. The I / O line 30 is used as a signal transmission path from the reader / writer device 20 to the IC card 10, and in the opposite direction, that is, as a signal transmission path from the IC card 10 to the reader / writer device 20. Is also used. CP
The U12 receives an instruction given from the reader / writer device 20 via the I / O line 30 and executes it.
In addition to the I / O line 30, a power supply line, a clock supply line, a reset line, etc. are connected between the reader / writer device 20 and the IC card 10, but they are not shown in FIG. ing.

Of the three types of memories, the RAM 13 is a volatile memory and is used as a work area for the CPU 12. The ROM 14 and the EEPROM 15 are both non-volatile memories, but the ROM 14 is read-only, whereas the EEPROM can be rewritten at any time. Therefore, the ROM 14 has a CPU 1
2 has a program to be executed by the EEPROM 1
Various information (file directory, user data, etc.) necessary for using this IC card 10 for a specific purpose is recorded in 5.

The CPU 12 has a function of performing self-diagnosis on the RAM 13. In this embodiment, the CPU 12
Prepared in the ROM 14 when a self-diagnosis command is given from the reader / writer device 20 through the I / O line 30 or a reset signal is given from the reader / writer device 20 through a reset line (not shown). RAM1 based on the self-diagnosis program
The self-diagnosis process for 3 is performed. The feature of this self-diagnosis processing is that the diagnosis of the register is first performed before the write / read test for the RAM 13. As shown in FIG. 2, the main constituent elements of the CPU 12 are a central logical operation unit ALU and a plurality of registers A to F. In the self-diagnosis processing of the present invention, first,
The diagnosis of the registers A to F is performed before the diagnosis of the RAM 13.

Now, the procedure of the self-diagnosis method according to the present invention will be described with reference to the flowchart of FIG. First, in step S10, a process of confirming one normal register is performed. Any method may be adopted as long as it can be confirmed that only one of the registers A to F shown in FIG. 2 is normal. Here, this step S
An example of a specific procedure for implementing step 10 will be described based on the flowchart shown in FIG. First, in step S11 of the flowchart of FIG. 4, the parameter i for indicating the register number is set to the initial value 1. Then, step S1
In 2, the actual data X is stored in the i-th register. The actual data X is predetermined data described in the program in the ROM 14. If i = 1, the actual data X will be stored in the register A. Next, in step S13, the contents of the i-th register and the actual data X are compared. Here, if they match, it can be determined that the i-th register is normal.
Therefore, if they match, the process branches from step S14 to step S15 to confirm that the i-th register is normal, and this procedure is terminated. On the other hand, if they do not match, this means that some trouble has occurred in the i-th register. Therefore, the process branches from step S14 to step S16, updates the parameter i, and then returns to step S12 via step S17. In this way, it is similarly determined whether or not the next register is normal. If at least one normal register is confirmed, the procedure ends after step S15. When trouble has occurred in all N registers, when i> N, the process branches from step S17 to step S18, and it is determined that a normal register cannot be confirmed. Of course, the procedure of FIG. 4 is shown as an example of the procedure of performing step S10 in FIG. I don't care.

Now, in the flow chart of FIG. 3, step S
When step 10 is completed, it is determined in the next step S20 whether or not one normal register has been confirmed. If it can be confirmed, in step S30, the normal register that has been confirmed is used to diagnose other remaining registers. An example of a specific procedure for carrying out step S30 will be described based on the flowchart shown in FIG. First, in step S31 of the flowchart of FIG. 5, the parameter j for indicating the number of the remaining registers is set to the initial value i + 1. This is already done in step S10.
Since the diagnosis up to the i-th register has been completed at, in this case, from the i + 1-th register to N
This is to diagnose the second register. For example, as shown in FIG. 2, there are six registers A to F (N = 6), and since the register A (i = 1) is abnormal in the procedure of step S10, the next register B (i
= 2) is confirmed as the first normal register, in the procedure of step S30, the remaining registers C (j = 3) to
The diagnosis may be performed up to the register F (j = 6).

First, in step S32, a process of transferring the contents of the i-th register (register confirmed as normal in step S10) to the j-th register is performed. In the above example, the process of transferring the content of the register B confirmed to be normal to the register C is performed. Specifically, since the actual data X remains in the register B, this actual data X is transferred to the register C.
Next, in step S33, the contents of the i-th register and the contents of the j-th register are compared. Here, if the two match, it can be determined that the j-th register is normal. Therefore, if they match, the process branches from step S34 to step S35 to confirm that the j-th register is normal. On the other hand, if the two do not match, this means that some trouble has occurred in the j-th register. Therefore, the process branches from step S34 to step S36 to confirm that the j-th register is abnormal. Next, in step S37, the parameter j
Is updated, the process returns to step S32 through step S38. In this way, it is similarly determined whether or not the remaining registers are normal, and when the diagnosis of all N registers is completed, this procedure is completed through step S38. Of course, the procedure of FIG. 5 is shown as an example of the procedure of performing step S30 in FIG. 3, and in short, another register can be diagnosed using the normal register confirmed in step S10. As long as it is processing, any processing may be performed. For example, if it is confirmed that the register A is normal, transfer from register A to register B, and
Register B → Register C, Register C → Register D, Register D → Register E, Register E → Register F, and so on.
If the contents of and the contents of register A match,
A method of determining that all the registers are normal is also possible.

By the way, both the procedure shown in FIG. 4 and the procedure shown in FIG. 5 are the same in that the purpose is to diagnose whether or not the register is normal. However, the former adopts the method of storing the actual data X in the register to be diagnosed and confirming it, while the latter transfers the content of the normal register to the register to be diagnosed and confirms it. The method is adopted. This is because when writing data to a register, the method of "transferring the contents of another register" reduces the number of bytes of the instruction code more efficiently than the method of "storing the actual data X". This is because it can be executed. That is, unless a normal register is found, there is no choice other than the method of "storing the actual data X", but the normal register is 1
After one is found, the execution time can be shortened by adopting the efficient method of "transferring the contents of this normal register".

In this way, when step S30 in the flowchart of FIG. 3 is completed and diagnosis of all registers is completed, RAM diagnosis using normal registers is performed in subsequent step S40. Writing to this RAM /
The read test is a method generally used conventionally. That is, the contents of the register are written to each address of the RAM 13 and a test for reading the contents is performed. If the read contents match the contents of the original register, it can be determined that the address is normal.
Since the diagnosis of the RAM is performed by using the register which is confirmed to be normal by the diagnosis of the register in the previous stage, there is no erroneous diagnosis due to the trouble of the register.

When the RAM diagnosis is completed, in the final step S50, a process of transmitting the diagnosis result to the outside is performed. That is, the CPU 12 commands the I / O device 11 to output the data indicating the diagnosis result to the outside. In response to this command, the I / O device 11 outputs a diagnostic result on the I / O line 30, which is transmitted to the reader / writer device 20. Of course, the diagnostic result thus reported includes not only the diagnostic result for the RAM 13 but also the diagnostic result for each register. Since the CPU 12 reports the diagnosis result by using the register confirmed as normal, the abnormality of the register does not hinder the report of the diagnosis result.

Although the procedure in the case where at least one normal register exists has been described above, it is possible that all registers will be disturbed. In such cases,
It is not possible to report the diagnostic result by the usual method via the I / O line 30. This is because the CPU 12 needs to use a register in order to make such a report. If the register cannot be used, the CPU 12 cannot send the data indicating the diagnosis result to the I / O line 30. Conventionally, when such a situation occurs, there is no response from the IC card 10 side, and the reader / writer device 20 side must interrupt access to the IC card 10 without obtaining any information. I didn't get it. In the present invention, when such a situation occurs, a negative determination is made in step S20 in the flowchart of FIG. 3, and the process branches to step S60. In step S60, the CPU 12 directly controls the potential level of the I / O line 30 to transmit the diagnosis result to the outside. Generally, the CPU 12
A command for directly controlling the potential level of the I / O line 30 is prepared. Therefore, if a diagnostic result transmission routine in which such a direct control command for the potential level is combined is prepared as a part of the self-diagnosis program in the ROM 14, the diagnostic result can be reported without using a register. .

FIG. 6 shows an example of such a transmission routine. The command "SERIAL IN" on the first line is a command executed when the program is started. By executing this command, the I / O line 30 is in the input mode (information is transferred from the reader / writer device 20 to the IC card 10). It becomes a transmission mode). In this input mode, the potential of the I / O line 30 becomes “N (Neutral)”, and if there is no signal transmission from the reader / writer device 20, the I / O line 30
Becomes a high impedance state. The routines described in the second to sixth lines are diagnostic result transmission routines. Two
The command "SERIAL HIGH OUT" in the line sets the potential of the I / O line 30 to "H (High)" and outputs the output mode (mode for transmitting information from the IC card 10 to the reader / writer device 20). Is the command to
The command “RIAL LOW OUT” is a command to set the potential of the I / O line 30 to “L (Low)” and set the output mode. The commands "DELAY #AA" and "DELAY #BB" on the 3rd and 5th lines are waiting commands corresponding to #AA and #BB, and the "SERIAL IN" command on the 6th line.
Is an instruction to put the I / O line 30 into the input mode again. If the routine consisting of such a combination of instructions is executed, the signal on the I / O line 30 will be as shown in FIG.
become that way. 7 in FIG. 7 correspond to those in the routine shown in FIG. If the diagnostic result "all registers are abnormal" is indicated by such a signal, the diagnostic result can be transmitted to the reader / writer device 20 side without using the register. Note that FIG.
Each instruction of the routine shown in is for convenience of explanation, and the code of each instruction is unique to the CPU used.

The present invention has been described above based on the illustrated embodiment, but the present invention is not limited to this embodiment and can be implemented in various modes other than this. For example, the above-described embodiment is an example in which the present invention is applied to an IC card, but the present invention can be widely applied to an information recording medium having a built-in CPU. Further, in the above embodiment, R
Although the self-diagnosis of AM has been described, the present invention is widely applicable to the diagnosis of general volatile memory including registers.

[0022]

As described above, according to the self-diagnosis method of the information recording medium having the built-in CPU according to the present invention, first, the register is diagnosed, and the volatile memory is diagnosed by using the normal register. In addition, when all the registers are defective, the I / O line is directly controlled to report the diagnosis result. You will be able to report correct diagnostic results.

[Brief description of drawings]

FIG. 1 illustrates a general IC card 10 and a reader / writer device 2
It is a block diagram which shows the state connected to 0.

FIG. 2 is a block diagram showing a schematic configuration of a general CPU.

FIG. 3 is a flowchart showing a procedure of a self-diagnosis method according to the present invention.

FIG. 4 is a flowchart showing a detailed procedure of step S10 in the flowchart shown in FIG.

5 is a flowchart showing a detailed procedure of step S30 in the flowchart shown in FIG.

6 is a diagram showing an example of a specific program routine for performing step S60 in the flowchart shown in FIG.

FIG. 7 shows an I / O line 30 according to the routine shown in FIG.
It is a figure which shows the signal output above.

[Explanation of symbols]

 10 ... IC card 11 ... I / O device 12 ... CPU 13 ... RAM 14 ... ROM 15 ... EEPROM 20 ... Reader / writer device 30 ... I / O line

Claims (2)

[Claims] 1. A self-diagnosis method for diagnosing the operation of the volatile memory by the CPU for an information recording medium having at least a volatile memory and a CPU having a function of accessing the memory, Check one register that operates normally from the multiple registers prepared for, and if at least one normal register is confirmed, check this normal register or newly confirmed normal register. Diagnosis of other registers and volatile memory is performed using the registers, and the diagnosis result is transmitted to the outside through a predetermined I / O line using normal registers, and even one normal register is confirmed. If not, the CPU directly controls the potential level of the I / O line to transmit the diagnostic result to the outside. A self-diagnosis method for an information recording medium having a built-in CPU, which is characterized by reaching. 2. The self-diagnosis method according to claim 1, wherein I / O is used to directly control the potential level of the I / O line.
A self-diagnosis method for an information recording medium having a built-in CPU, characterized in that an instruction for keeping a line at a high level, an instruction for keeping a line at a low level, and an instruction for setting a waiting time are used.