JPH0335386A - Portable electronic device - Google Patents

Abstract

PURPOSE:To prevent the unjust writing to a memory part or the change of contents regardless of the malfunction of a control element by controlling the data write to the memory part by a write control part and controlling the write operation of the write control part to the inhibition state at the time of reading out data from the memory part. CONSTITUTION:The write signal from a control element 2 is given to a memory part 3 through a write control part 5 to control the data write to the memory part 3, and the write operation of the write control part 5 is controlled to the inhibition state at the time of reading out data from the memory part 3. Thus, the unjust write in to the memory part 3 or the change of contents in the memory part 3 is surely prevented regardless of the malfunction of a control element 2 due to the abnormal operation of a power source, chattering of a contact part 1 for communication with an external device, the noise on a signal line, or the like, and data in the memory part 3 is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the invention] (Industrial application field) The present invention is applicable to non-volatile data memory and
The present invention relates to a portable electronic device called an IC card that has a built-in IC (integrated circuit) chip having a control element such as a U, and more particularly to a portable electronic device with an improved method of controlling data writing to a data memory.

(Prior Art) In recent years, so-called ICs have been developed as new portable data storage media, which have a built-in IC chip that has erasable non-volatile data memory (memory section) and control elements such as a CPU that controls them. cards are being developed.

Normally, this type of IC card operates by receiving operating power, reset signals, clock pulses, etc. from an external device (for example, a terminal device), and accesses the built-in data memory using a built-in control element.
It is designed to selectively input and output data to and from the outside.

Now, in such an IC card, writing of data into the conventional data memory has been controlled by a write signal output from a control element.

(Problems to be Solved by the Invention) As described above, since data was written to the memory section by the write signal output from the control element,
For example, malfunction of the control element may occur due to abnormal operation of the power supply, chattering of the contact section for communicating with an external device, noise of the signal line, etc., resulting in improper writing to the memory section or changes in the contents of the memory section. There was a problem that this could occur.

Therefore, the present invention prevents the control element from malfunctioning due to abnormal operation of the power supply, chattering of the contact section for communicating with an external device, noise of the signal line, etc., and causing illegal writing to the memory section. An object of the present invention is to provide a portable electronic device that can reliably prevent content changes from occurring.

[Structure of the Invention] (Means for Solving the Problems) The present invention has a memory section and a control element for writing and reading data to and from the memory section, and selectively transfers data to and from the outside. A portable electronic device for performing human output includes a write control section that is located under the control of the control element and controls writing of data to the memory section; and a write control section that controls writing of data to the memory section; and control means for controlling the data write operation to a prohibited state.

(Function) Data writing to the memory section is controlled by applying a write signal from the control element to the memory section via the write control section, and when data continues to be output from the memory section, the write operation by the write control section is controlled. By controlling the device to a prohibited state, even if the control element malfunctions due to abnormal operation of the power supply, chattering of the contact section for communicating with an external device, noise on the signal line, etc., illegal writing to the memory section will not be performed. It is possible to reliably prevent changes in the contents of the memory section and secure the data in the memory section.

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

FIG. 1 shows an IC as a portable electronic device according to the present invention.
This shows the configuration of the card. That is, 1 is a contact part for obtaining electrical contact with an external device (for example, a terminal device), and a power supply terminal 1 to which a power supply voltage VeC is supplied.
0, ground (GND) terminal 12, data input/output (Ilo
) terminal 13, a pulse input terminal 14- to which a clock pulse CLK is input, and a reset signal input terminal 15 to which a reset signal R3T is manually input.

2 is a control element that controls overall control; 3 is a data memory (memory unit) such as EEPROM that stores various data;
4 is an access generator, 5 is a memory access control section (write control section), and 6 is a power supply detection circuit. The control element 2 includes a CPU, a program mask ROM that stores a program for its operation, and a serial input/output control unit that performs data transmission with an external device. A control element 2, a data memory 3, an access generator 4,
The memory access control section 5 and the power supply detection circuit 6 are connected to each other by an address bus 7, a data bus 8, and various control signal lines.

The control element 2 has a function of selectively outputting data to/from an external device, and a function of controlling the data memory 3, the access generator 4, and the memory access control unit 5. The electric power detection circuit 6 detects and determines the power supply voltage Vcc supplied to the power supply terminal 11 from an external device,
The determination result is sent to the memory access control section 5. The memory access control unit 5 receives the determination result of the control element 2, write cycle information of the data memory 3, and a reset signal RST supplied from an external device to a reset signal input terminal 15.

Based on the determination result of the power supply detection circuit 6, the data memory 3
The write enable terminal WE is controlled.

FIG. 2 is a circuit diagram showing the memory access control section 5 in detail. That is, a D-type flip-flop circuit (memory element, hereinafter simply referred to as an FF circuit) 11 for memory access permission/inhibition control is assigned, for example, to a specific address in the memory space and to a specific data bit, and the control element 2 managed by. In addition, in Figure 2,
12 is a NOR circuit, 13, 14, and 15 are OR circuits, 16 is a three-state bus driver, 17 is an inhibit circuit, and 18.19 is an AND circuit.

In this embodiment, when "1" is written to the data bit DO at address 0UT1, the FF circuit 11 is set and the write to the data memory 3 is enabled, and when "0" is written, the FF circuit 11 is set. It is reset, and writing to the data memory 3 is prohibited. The prohibition conditions for the FF circuit 11 are:
The reset signal R3T from the outside, the judgment result (PDET) of the power supply detection circuit 6, and the information (WRCYC) on the read access of the data memory 3 and the data memory write state
).

FIG. 3 is a timing chart for inhibiting a write operation when reading data from the data memory 3. For example, at address rAAAAJ, address 0UT1 is generated from access generator 4, and bit "
When "1" is written to "0", the FF circuit 11 is set and enters a write permission state. Next, at address rXOOOJ,
When address 0UT2 is generated from the access generator 4 and data on the data bus 8 is written, if the FF circuit 11 is in an enabled state, it outputs a write pulse WRENB,
The data on the data bus 8 is written to the data memory 3. At this time, write state information WRCYC is output from the data memory 3 at the falling edge of the write pulse WRENB.

Next, 0UT2 is generated from the address "X001", rXOO2J and the access generator 4, and data is sequentially written on the data bus 8. If the FF circuit 11 is in the enabled state, it outputs a write pulse WRENB and the data memory 3
Write sequentially to Then, when the address bus 000J is read by the read pulse RD from the control element 2, F
The F circuit 11 is reset to write-inhibited state. Thereafter, when data on the data bus 8 is written to the address rXOO3J, the FF circuit 11 is in a write inhibited state and no write pulse WRE N B is generated.

[Effects of the Invention] As described in detail above, according to the present invention, data writing to the memory section is controlled by applying a write signal from the control element to the memory section via the write control section, and data writing from the memory section is controlled. When reading data, by controlling the write operation by the write control unit to a prohibited state, the control element can be prevented from malfunctioning due to, for example, abnormal operation of the power supply, chattering of the contact part for communicating with an external device, noise in the signal line, etc. Therefore, it is possible to provide a portable electronic device that can reliably prevent illegal writing to the memory section or change of the contents of the memory section, and secure the data in the memory section.

[Brief explanation of drawings]

The figures show one embodiment of the present invention. Fig. 1 is a block diagram showing the structure of an IC card, Fig. 2 is a block diagram showing the structure of a memory access control section, and Fig. 3 is a write operation when reading data. This is a timing chart that prohibits DESCRIPTION OF SYMBOLS 1... Contact part, 2... Control element, 3... Data memory (memory part) 4... Access generator, 5... Memory access control part (write control part) 6
...Power detection circuit, 7...Address bus, 8...
data bus.

Claims (1)

[Scope of Claims] A portable electronic device comprising a memory section and a control element for writing and reading data to and from the memory section, and selectively inputting and outputting data to and from the outside, comprising: a write control unit that is located under the control of a control element and controls writing of data to the memory unit; and a control unit that inhibits data write operations by the write control unit when reading data to the memory unit. A portable electronic device characterized by comprising: