JPS61117681A - Ic card - Google Patents

Abstract

PURPOSE:To prevent erroneous reset release by detecting the change of an input signal inputted from a host system to supply a reset release signal to an internal circuit and detecting the signal stop to supply a reset signal to the internal circuit. CONSTITUTION:When an IC card 1 is set to a host system 4, a clock signal is applied to a CLK terminal 6, and a reset control circuit 8 detects this application to supply the reset release signal to the reset terminal of an interface circuit 3. The interface circuit 3 and a memory 2 are held in the set state while this signal is supplied, and hereafter, data is transmitted and received through an I/O terminal 5 between the card 1 and the host system 4 by the application of clock pulses from the host computer 4. When this transmission and reception of data is terminated, the application of clock pulses is stopped, and the reset control circuit 8 detects this stop to apply the reset signal to a reset terminal 7, and the interface circuit 3 and the memory 2 are reset. Thus, erroneous reset release is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a system that includes a built-in integrated circuit (hereinafter referred to as IC) such as a memory and a microcomputer, and
The present invention relates to an IC card that is attached to a computer and used for exchanging data.

[Prior Art] In recent years, IC cards are being used that are assembled with dedicated ICs such as microcomputers and memories onto thin substrates and exchange data with host systems.

FIG. 2 is a schematic configuration diagram showing a conventional IC card. In the figure, (1) is the IC card body, (2) is the memory, and (3) is the IC card body.
) is a memory read/write interface circuit.

(4) is a host system such as a terminal device.

The IC card (1) generally has several electrode terminals externally for exchanging data with the host systems t, (fl), but these terminals and the terminals of the host systems t, (q) are always connected. The number of terminals was limited because of mechanical reliability problems, which tend to cause poor contact because they are mechanically connected or scorched. Therefore, by serially transferring input/output (hereinafter referred to as I10) data, the number of I10 terminals 1'-(5) is reduced.

It had a CLK terminal (6) for applying a clock signal and a set terminal 'r-(7) for applying a signal for canceling the recent reset.

When such an IC card (1) is sent to the host system (4) at 1 o'clock, the reset of the interface circuit (3) and memory (2) is released by a reset release signal from the host system (4) to the terminal (7). The IC card (1) is removed from the host system (4) after the internal circuits (2) and (3) are reset by a reset signal from the host system (4). It will be done. Therefore, an IC card (1
) is normally in a reset state, and has the functions of inhibiting writing to memory, powering down, and maintaining the current status of internal circuits.

[Problems to be Solved by the Invention] As mentioned above, conventional IC cards are reset and canceled by a reset control signal from the host system, so the IC card's reset terminal (7) The reset may not be applied due to poor contact between the IC card and the terminal of the host system, or the reset terminal may be exposed to the outside of the IC card, and for some reason a signal may be sent to that terminal while the IC card is being carried and the reset may not be performed. There is a possibility that the stored contents of the IC memory may be destroyed due to the release. Also, the external reset terminal may be damaged due to mechanical shock while carrying the IC card or when inserting or removing it from the host system.

There was also a risk that the lead wire to it might break.

As described above, conventional IC cards have had the drawback of reliability problems.

The present invention was made to eliminate the above-mentioned drawbacks, and it is an object of the present invention to provide a highly reliable IC card in which the reset state is reliably maintained.

[Means for Solving the Problems] The IC card according to the present invention detects a change in at least one input signal input when the host system is installed, and transmits a reset release signal and a reset signal to a memory, a microcomputer, etc. It is equipped with a reset control circuit that outputs to the internal circuit.

[Function] In this invention, there is no receptacle terminal on the outer surface of the IC card, and changes in input signals input manually from the host system to other input terminals are detected, for example, signal application is detected. and send the reset release signal.

It detects a signal stop and supplies a reset signal to the internal circuit to control its current. In this way, the reset signal is sent directly from the outside, and the reset is canceled (the RJ is not manually operated, and the reset is canceled after confirming that it is installed in the host system by detecting changes in other input signals6). There is no risk that the reset will be canceled or that the reset terminal will be damaged.

[Example 1] FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. In the figure, (1) to (7) indicate the same or corresponding parts as the same reference numerals in FIG. 2, and (8) ) is a reset control circuit that detects the application of a clock signal from the host system (4) to the CLK terminal (6), sends a reset release signal to the reset terminal (7) of the interface circuit (3), and stops the clock signal. is detected and reset (No. 8 is applied.) These memory (2), interface circuit (3), and reset control circuit (8) are composed of an IC or a large-scale integrated circuit (LSI).

When the IC card (1) configured as described above is inserted into the host system (4), the host system (4) connects the IC card (1) to the CLK terminal (6).
number is applied. The reset control circuit (8) detects this clock signal 918 and supplies a reset release signal to the reset terminal (7) of the interface circuit (3). While this signal is being supplied, the interface circuit (3) and memory (2) remain set.

After that, the host system (4) is connected via the I10 terminal (5) under the application of clock pulses from the host system (4).
4) Data is exchanged between the two.

When this data exchange is completed, the application of the clock pulse stops, and the reset control circuit (8) detects this and applies a reset signal to the reset terminal (7) to activate the interface circuit (3) and memory (2). Reset.

In the above embodiment, the presence or absence of the clock (D) is detected by the reset control circuit, but other input signals may also be detected, or a combination of Clock No. 11 and other input signals may be detected. It is clear that the present invention can be applied not only to a mere memory as described above, but also to an IC card having a built-in microcomputer.

[Effects of the Invention] Since the present invention is configured as described above, there is no possibility that the reset will be canceled by mistake, and the number of electrode terminals in contact with the host computer etc. can be reduced.
This has the effect of making it possible to obtain an IC card with improved reliability.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing a conventional IC card. In the figure, (1) is the IC card body, (2) is the memory,
(3) is an interface circuit, (4) is a host system, (7) is a center terminal, and (8) is a reset control circuit. The same reference numerals in the drawings indicate the same or corresponding parts. 1st Figure 5: Input/output Naruko 6: R0 rough 41% application Hatoko 7: Su1.・Nodo kllll diagram 2

Claims (1)

[Claims] An IC that has a built-in integrated circuit (IC) such as a memory or microcomputer that has functions such as stopping memory writing, powering down, and maintaining the current status of internal circuits in a reset state, and is used by attaching it to a host system and exchanging data. The card is characterized by being provided with a reset control circuit that detects a change in at least one input signal that is input when the card is installed in the host system, and outputs a reset release signal and a reset signal to the memory, microcomputer, etc. IC card.