JP2001202479A - Ic card reader and writer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an IC card reader/writer which can settle a problem where a recent IC card apparently has a normal operation even when a defective touch occurs at a VCC contact and then has a malfunction when the current consumption is increased. SOLUTION: When the voltage drop of reset signal of an IC card is detected by a comparator, the proper processing is carried out to the IC card.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC card reader / writer for reading and writing data from and to an IC card, and more particularly to a contact for supplying power to the IC card, resetting the IC card, and communicating data. It relates to an IC card reader / writer.

[0002]

2. Description of the Related Art A contact failure is detected in an IC card reader / writer utilizing the fact that a communication failure occurs when the voltage of a communication signal is low as in the case of the IC card reader / writer described in Japanese Patent Publication No. 6-325222. There is a way.

FIG. 7 is an example of a block diagram showing a configuration of a conventional IC card reader / writer. The IC card 1 has its power supply line 3 in the IC card reader / writer 20,
The communication signal 4 and the ground line 7 are respectively connected via contacts. Then, the power supply voltage VCC of the IC card reader / writer 20 is supplied via the power supply line 3 and the ground line 7. The IC card reader / writer 20 compares the signal voltage transmitted from the IC card 1 via the communication signal 4 with the reference potential Vref obtained by dividing VCC by the voltage dividing resistors RV and RG in the comparator 21 and comparing the signal voltage with Vref or more. The level signal is read to the CPU 22 as an L level,
If the communication is defective, the IC card 1 is ejected as a defect to prevent a failure such as writing defective data to the IC card 1 due to a contact failure or the like.

[0004]

In the conventional IC card reader / writer, the H level guarantee voltage of the communication data on the IC card side is 0.7 × VCC or more, and it is determined that the voltage is correct up to this voltage. Must-have. Therefore, it is necessary to set the reference potential Vref to 3.5 V or less if the IC card is driven by 5 V. However, in the case of a recent low power consumption type IC card, the H level of the communication data is VCC-0.6 to VC even in the state of poor contact of VCC.
There is a problem that it is not possible to detect a contact failure state of VCC with the above method at about C-1V.

An object of the present invention is to provide an IC card reader / writer that prevents an IC card from malfunctioning due to a power supply failure due to a contact failure of a contact.

[0006]

According to the present invention, there is provided an IC card reader / writer as claimed in claim 1, further comprising a contact for supplying power to the IC card, resetting and communicating with the IC card. A comparison device for comparing the voltage of the reset signal with a predetermined reference voltage, and a detection means for examining a voltage drop of the reset signal after reset release from the output of the comparison device.

[0007] Further, the comparison device constituted by a comparator is such that a reference voltage to be inputted to one input of the comparator is generated by a DA converter.

The reference voltage input to the comparator is IC
From the value of the supply voltage to the card, the minimum voltage that the reset signal after reset release must observe is determined, and the voltage of the reset signal when the CPU in the IC card is in a standby state is measured by the AD converter and measured. When the voltage is equal to or higher than the minimum voltage that must be maintained by the reset signal, a voltage that is lower than the detected voltage and equal to or higher than the minimum voltage is generated by the DA converter.
Further, by restarting the IC card after obtaining an appropriate reference voltage, it is possible to monitor the voltage of the reset signal after the reset is released.

Further, the IC card reader / writer of the present invention may be arranged such that the reset signal voltage measured by the AD converter after reset release is lower than the minimum voltage that must be observed, or the reset signal voltage is set to a reference voltage. That the voltage is less than the voltage is detected from the output of the comparison device, and the external device is notified that the IC card is in an irregular state.

According to a fifth aspect of the present invention, the minimum voltage which the reset signal after reset release must observe is determined from the value of the voltage supplied to the IC card, and the minimum voltage required when the CPU inside the IC card is in a standby state. AD voltage of reset signal
When the voltage measured by the converter is equal to or higher than the minimum voltage that the reset signal must observe, the voltage that is lower than the measured voltage and equal to or higher than the minimum voltage is the DA.
After setting to be the reference voltage generated by the converter,
Detecting from the output of the comparison device that the voltage of the reset signal after the reset and the program in which the IC card is restarted is lower than the minimum voltage that the reset signal must observe, or has decreased; A program for notifying an external device that the IC card is in an irregular state is stored.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a recent IC card, power is supplied from a reset terminal or the like to a power supply line inside the IC card via a parasitic diode or the like inside the IC card even without power supply. In addition, since the current consumption has been reduced, the voltage of the reset signal hardly decreases when the IC card is in the standby state. In addition, since the operating voltage of the IC card has been widened, the CPU in the IC card may operate. However, current consumption increases when the CPU inside the IC card is operating, or when the coprocessor unit that performs access to the memory inside the IC card and performs the encryption process is increased, and is not originally intended to supply power. For a reset signal or the like having a relatively high impedance, a voltage drop increases due to an increase in supply current, and a voltage drop at a terminal portion with the IC card is observed. For this reason, a voltage drop occurs in the power supply line inside the IC card, and there is a possibility that a failure occurs in writing to a memory inside the IC card, an operation of the coprocessor, and the like. If the IC card stops due to an increase in current consumption due to the operation of the CPU,
This is not a problem because it can be recovered by re-applying the contact.However, it is difficult to deal with the damage of the memory contents and the operation error of the coprocessor by the recovery processing by the IC card application. Regardless, subsequent IC card processing may not be possible.

According to the present invention, there is provided a comparison device having a contact for performing power supply to an IC card, resetting, and communication, and comparing a voltage of a reset signal with a predetermined reference voltage. Detecting the voltage drop of the reset signal after reset release, monitoring the voltage of the reset signal after reset release, and detecting the voltage change of the reset signal when the current consumption of the IC card increases. Is made possible. Also, the comparison device is composed of a comparator, and a reference voltage to be input to one input of the comparator is generated by a DA converter, so that a normal voltage value of a reset signal due to a difference in an operation voltage of an IC card and a difference in input impedance of a reset input. Can be corrected by changing the program or the like. In addition, the minimum voltage that the reset signal after reset release must observe is determined from the value of the supply voltage to the IC card, and the voltage when the CPU inside the IC card is in the standby state is measured by the AD converter and measured. When the voltage is equal to or higher than the minimum voltage that the reset signal must observe, the reference voltage is set by setting a voltage that is lower than the measured voltage and equal to or higher than the minimum voltage to be the reference voltage generated by the DA converter. It can be optimized for each IC card. After the optimum reference voltage is determined, the contact state of the power supply terminal can be monitored from the timing after reset release by restarting the IC card.

The reset signal voltage measured by the A / D converter after reset release is lower than the minimum voltage that the reset signal must observe, or the reset signal voltage after reset release is lower than the reference voltage. Even if it is detected from the output of the comparison device, since the IC card is normally mounted, it should not be immediately deactivated depending on the application. Therefore, the fact that the IC card is in an irregular state is notified to a computer system or the like which controls the external IC card reader / writer so that it is supported by the subsequent processing method.

In the storage medium, the minimum voltage that the reset signal after reset release must observe is determined from the value of the supply voltage to the IC card, and the voltage of the reset signal when the CPU in the IC card is in a standby state is determined. When the voltage measured by the AD converter is equal to or higher than the minimum voltage that the reset signal must observe, the voltage that is lower than the measured voltage and equal to or higher than the minimum voltage is the reference voltage generated by the DA converter. Whether the voltage of the reset signal after reset or the program that is set is lower than the minimum voltage that the reset signal must observe,
Alternatively, a program that detects from the output of the comparison device that the voltage is less than the reference voltage and notifies the external device that the IC card is in an irregular state is stored.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

The IC card 1 is connected to an IC card reader / writer 2 and a power line 3, a communication signal 4, a reset line 5, a clock line 6, and a ground line 7 via respective contacts. A resistor 8 is inserted into the reset line 5 and the clock line 6 in order to prevent the output element from being damaged due to a short circuit at the contact portion with the IC card 1. For this reason, the impedance of the reset line 5 has a higher impedance than the power supply line 3 and the like. The comparison device 9 includes a comparator 10 and compares the voltage of the reset signal on the reset line 5 with a predetermined reference voltage 11. Detecting means 12
Is composed of a flip-flop 13 and a CPU 14. The flip-flop 13 is configured to recognize the reset signal voltage output from the comparator 10 even when the output time indicating that the reset signal voltage has dropped below the predetermined reference voltage 11 is short. The output of the comparator 9 is input to the clock input of the flip-flop 13, and the output of the flip-flop 13 continues to output that the abnormality has occurred even after the voltage of the reset signal returns to the reference voltage 11 or more. To It is necessary to initialize the flip-flop 13 immediately after reset release. At the same time, the output of the detecting means 12 is input to the general-purpose input of the CPU 14 so that even if the output of the detecting means 12 is not a pulse signal, it can be detected. The output of the flip-flop 13 is input to an interrupt input or a general-purpose input of the CPU 14. When the reset of the IC card 1 is released, the IC card 1 transmits the ATR. At this time I
When the CPU inside the C card operates and the power supply to the IC card 1 is not normally performed, the voltage of the reset signal decreases, so that the abnormality can be detected. Therefore, an appropriate measure can be taken before the memory contents and the like become inappropriate due to a malfunction of the CPU or the like in the IC card, and a state in which the subsequent processing cannot be performed.
Further, even when the contact is separated during operation due to vibration or the like, the flip-flop 13 holds the state, so that it is possible to avoid at least inadvertently continuing the subsequent processing.

FIG. 2 is a block diagram showing the configuration of the comparison device of the present invention.

By realizing the reference power supply 11 shown in FIG. 1 with the DA converter 15, the difference in the normal voltage value of the reset signal for each IC card due to the difference in the operating voltage of the IC card and the difference in the input impedance of the reset input can be programmed. Can be corrected by a change in DA converter 15 is C
It is controlled by the PU 14. If the IC card reader / writer is used in a specific application and the type of IC card 1 used is fixed and limited,
The PU 14 experimentally determines a reference voltage 11 applicable to the entire IC card 1 to be used, and generates the reference voltage 11 with the DA converter 15. However, when the type of the IC card 1 cannot be specified, means for determining the reference voltage 11 is required.

FIG. 3 is a block diagram showing a configuration for determining a reference voltage.

The IC card 1 already has a 5V specification product, 3.3
There is a V specification product, and the CPU 14 switches the switching circuit 1 if necessary.
7 to supply the power supply voltage required by the IC card 1. The means for judging the supply voltage is out of the scope of the present invention, and will not be described.
Is held as data. Since the reset voltage after reset release is normally a value obtained by subtracting 0.7 V from this supply voltage, 0.7 V is subtracted from the supply voltage to find the minimum voltage that the reset signal after reset release must observe. Next, the voltage in a standby state in which the IC card 1 is not performing writing to the memory inside the IC card is AD
It is measured by the converter 16. Since the current consumption of the IC card 1 in the standby state in recent years is extremely small, the voltage of the reset signal detected in the standby state has a value similar to that in a normal state even when power supply is not performed normally. IC
Since the card 1 normally enters the standby state after transmitting the ATR, the AD converter 16 may measure the reset voltage after receiving the ATR. The measurement may be performed in accordance with an instruction from an external computer system. Since the timing of the standby state may vary depending on the application mounted on the IC card 1,
The CPU 14 needs to adjust the timing of measuring the reset voltage for each application. Further, the reset voltage may be measured by obtaining information from a host computer system or the like to which the IC card reader / writer of the present invention is connected. If the measured reset voltage is already less than the minimum voltage, it can be determined that the state is already in an irregular state. If the measured reset voltage is equal to or higher than the minimum voltage, a voltage that is lower than the measured voltage and equal to or higher than the minimum voltage is set as a reference voltage generated by the DA converter 15. Thereafter, the IC card 1 is restarted.
As a method for restarting, activation can be performed after hot reset and deactivation.

FIG. 4 is a block diagram showing an example of connection between an external device and an IC card reader / writer.

If the contact to the power supply terminal has not been in contact from the beginning, processing such as deactivation can be performed before the IC card 1 causes a malfunction or the like. If they are separated, it is necessary to perform processing such as normalization of the memory contents. Since it is inappropriate to deal with such complicated correspondence by the program of the IC card reader / writer 2, a computer system 18 capable of managing applications is provided separately from the CPU 14 of the IC card reader / writer 2. The computer system 18 and the CPU 14 are connected by a communication line 19. Via the communication line 19, the CPU 14 can notify the computer system 18 that the IC card 1 is in an irregular state. Further, the computer system 18 can notify the CPU 14 of what action should be taken with respect to the IC card 1 according to the progress of the processing at the time when the abnormality is notified.

FIG. 5 is a flowchart of a process for detecting an abnormality in the reset voltage.

Hereinafter, the description will be made according to the flowchart.

In step (1), the IC card 1 is activated to receive the ATR.

In step (2), the AD converter 16
Measure the voltage of the reset signal with.

In step (3), the voltage of the reset signal measured in step (2) is compared with the lowest voltage of the reset signal obtained from the value of the supply voltage. If the voltage of the reset signal is lower than the minimum voltage, step (8) is executed, and if it is higher than the minimum voltage, step (4) is executed.

In step (4), a reference voltage is set. The reference voltage is also obtained by subtracting factors such as the fluctuation of the power supply voltage of the IC card 1 and the sensitivity of the comparator 10 from the voltage value of the reset signal measured by the AD converter.

In step (5), the IC card 1 is restarted.

Step (6) may be started by an interrupt, or may be started at the timing of transmission to an IC card. This step is a step for recognizing that the detecting means 12 has detected a voltage drop of the reset signal. If the reset voltage drop is not detected, step (7) is executed. If a drop in the reset signal voltage is detected, step (8) is executed.

In step (7), the processing is performed normally. I
If it is started at a timing such as transmission to the C card, step (6) is executed again at a predetermined timing.

In step (8), the external device is notified via the communication line 19 or the like that the IC card 1 is in an irregular state.

Step (9) is in a state of waiting for notification of the subsequent processing from the external device.

It should be noted that what is realized by the program of the present invention can be easily implemented by another independent computer system by recording it on a recording medium such as a floppy disk and transferring it. FIG.
FIG. 3 is a diagram for explaining a case where this is performed on a floppy disk.

FIG. 6A is a diagram showing an example of the physical format of the floppy disk 20, which is the main body of the recording medium.
Create a track from the concentric outer circumference to the inner circumference,
16 are divided into sectors in the angular direction. The program is recorded according to the allocated area.

FIG. 6B is a view for explaining a case for storing the floppy disk 20. From the left, a front view of the floppy disk case 21, a sectional view thereof, and a floppy disk 20 are shown. By storing the floppy disk 20 in the case in this way, the disk can be protected from dust and external impact, and can be transported safely.

FIG. 6C is a diagram for explaining recording and reproduction of a program on the floppy disk 20. By connecting the floppy disk drive 24 to the computer system 23 as shown in the figure, it is possible to record and reproduce programs on the floppy disk 20. The floppy disk 20 is inserted into and removed from the floppy disk drive 24 via the floppy disk insertion slot 22. When recording, the program is recorded from the computer system 23 to the floppy disk 20 by the floppy disk drive 24. For reproduction, the floppy disk drive 24 reads the program from the floppy disk 20 and transfers it to the computer system 23.

In this embodiment, a description has been given using a floppy disk as a recording medium.
The same can be done using an optical disk. The recording medium is not limited to these, but can be similarly implemented as long as the program can be recorded thereon, such as an IC card or a ROM cassette.

[0040]

As is apparent from the above description, according to the first aspect of the present invention, the reset signal voltage is reduced.
It is possible to detect that the voltage supply to the IC card is not performed normally, and it is possible to prevent the IC card from malfunctioning. Further, according to the second aspect of the present invention, since the reference voltage to be compared can be appropriately changed, the same comparison device can be used only for the change of the IC card by changing the program. When a fixed reference voltage is used, it is necessary to change the reference voltage source, and it becomes very difficult to cope with a change in the IC card. According to the third aspect of the present invention, the difference in the supply voltage to the IC card and the difference in the characteristics of each IC card can be reflected in the reference voltage, so that the erroneous detection of the comparison device can be eliminated. Further, according to the invention of claim 4, the IC
A malfunction of the card can be prevented beforehand, and even if a power supply failure occurs during the operation, the IC card can be restored as much as possible. According to the storage medium of the fifth aspect, the program optimizes the reference voltage of the comparison device, and when the reset signal voltage is lower than the predetermined minimum voltage or lower than the reference voltage, the IC card is used. It is determined that power is not supplied correctly, and appropriate processing for restoring the IC card can be performed. In addition, portability and distribution can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a comparison device of the present invention.

FIG. 3 is a block diagram showing a configuration for determining a reference voltage;

FIG. 4 is a block diagram showing an example of connection between an external device and an IC card reader / writer.

FIG. 5 is a flowchart of a process for detecting a reset voltage abnormality;

6A is a diagram showing an example of a physical format of a floppy disk which is a recording medium main body. FIG. 6B is a diagram illustrating a case for storing a floppy disk. FIG. 6C is a diagram illustrating recording and reproduction of a program on a floppy disk. Figure

FIG. 7 is a block diagram showing a configuration of a conventional IC card reader / writer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 IC card 2 IC card reader / writer 3 Power supply line 4 Communication signal 5 Reset line 6 Clock line 7 Ground line 8 Switch circuit 9 CPU 10 Memory 11 Inspection means 12 A / D converter 13 IO buffer 14 Pull-up resistor 15 Communication line 16 Host computer 17 Switching circuit 18 Computer system 19 Communication line

Claims (5)

[Claims] A comparison device for comparing the voltage of the reset signal with a predetermined reference voltage, and a reset after reset from the output of the comparison device. An IC card reader / writer, comprising: detection means for detecting a voltage drop of a signal. 2. The IC card reader / writer according to claim 1, wherein the comparator comprises a comparator, and a reference voltage input to one input of the comparator is generated by a DA converter. 3. A minimum voltage which must be maintained by a reset signal after reset release is determined from a value of a supply voltage to the IC card, and the voltage of the reset signal when the CPU in the IC card is in a standby state is converted to an AD converter. In the case where the detected voltage is equal to or higher than the minimum voltage that the reset signal must observe, the voltage that is lower than the detected voltage and equal to or higher than the minimum voltage is set to be the reference voltage generated by the DA converter. An IC card reader / writer for detecting a voltage drop of a reset signal after reset release by restarting the IC card. 4. The comparison device according to claim 1, wherein the reset signal measured by the AD converter after the reset is released is lower than a minimum voltage to be maintained, or the reset signal voltage after the reset is lower than a reference voltage. An IC card reader / writer which, when detected from an output, notifies an external device that the IC card is in an irregular state. 5. The minimum voltage that the reset signal after reset release must keep from the value of the supply voltage to the IC card is determined, and the voltage of the reset signal when the CPU in the IC card is in a standby state is converted to an AD converter. If the detected voltage is equal to or higher than the minimum voltage that the reset signal must keep, the voltage that is lower than the detected voltage and equal to or higher than the minimum voltage is set to be the reference voltage generated by the DA converter. The program and the voltage of the reset signal after reset release are detected from the output of the comparison device as being lower than the minimum voltage that the reset signal must observe or lower than the reference voltage. A storage medium storing a program for notifying that the IC card is in an irregular state.