JP2854609B2 - Portable electronic devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a nonvolatile data memory and a CP
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable electronic device having a built-in IC (integrated circuit) chip having a control element such as U, and more particularly to a portable electronic device having an improved method of controlling data writing to a data memory.

(Prior Art) In recent years, as a new portable data storage medium, a so-called IC having a built-in erasable non-volatile data memory (memory unit) and an IC chip having a control element such as a CPU for controlling the same has been incorporated. Cards are being developed.

Normally, this type of IC card operates by receiving an operating power supply, a reset signal, a clock pulse, or the like from an external device (for example, a terminal device), and operates by accessing a built-in data memory by a built-in control element.
Data input / output with the outside is selectively performed.

By the way, in such an IC card, the conventional data write control to the data memory is performed by a write signal output from a control element.

(Problems to be Solved by the Invention) As described above, since data is written to the memory unit by the write signal output from the control element, for example, an abnormal operation of the power supply, a contact unit for communicating with an external device, etc. There is a problem that a malfunction of the control element occurs due to chattering, noise of a signal line, or the like, and accordingly, there is a possibility that improper writing to the memory unit or a change in the contents of the memory unit may occur.

Therefore, the present invention provides a control element which malfunctions due to, for example, abnormal operation of a power supply, chattering of a contact portion for communicating with an external device, noise of a signal line, etc. It is an object of the present invention to provide a portable electronic device capable of reliably preventing a change in the contents of the electronic device.

[Constitution of the Invention] (Means for Solving the Problems) A portable electronic device according to the present invention has a memory section and a control element for writing and reading data to and from the memory section, and is selectively provided. Wherein the memory unit outputs a write state signal in response to an input write enable signal, and the address data output from the control element is specified. An access generator that outputs a first signal in the case of the address, a write signal, a read signal, and a write signal that are output from the control element and are provided between the control element and the memory section. A write enable signal for the memory based on the write state signal to be written, and a write control signal for controlling writing of data to the memory unit. A write control section, wherein the write control section outputs a first signal from the access generator, outputs a write signal from the control element, and does not output a write state signal from the memory section. Holding means for holding a write permission state in the case;
An output unit that outputs a write enable signal to the memory unit while the write enable state is output by the holding unit and a write signal is output from the control element; and a write state output from the memory unit. A write-inhibiting means for resetting the holding means for holding the write-enabled state upon termination of the signal.

Further, the portable electronic device of the present invention has a memory unit and a control element for writing and reading data to and from the memory unit, and selectively performs input and output of data with the outside. In the electronic device, an access generator that outputs a first signal when address data output from the control element is a specific address, and is provided between the control element and a memory unit, and is output from the control element. A write control unit that outputs a write enable signal to the memory unit based on a write signal, a read signal, and a write state signal output from the memory unit, and controls writing of data to the memory unit. The write control unit outputs a first signal from the access generator, and outputs a write signal from the control element. A holding unit for holding a write permission state when a write state signal is not output from the memory unit; a write permission state being output by the holding unit; and a write signal being output from the control element. An output unit that outputs a write enable signal to the memory unit, a power supply detection circuit that monitors an abnormality of a power supply voltage supplied to the portable electronic device from outside, and a read signal is output by the control element. In the case, or when an abnormality of the power supply voltage is detected by the power supply detection circuit, a write inhibit means for resetting a holding means for holding the write permission state is provided.

(Operation) According to the present invention, data write to the memory unit is controlled by giving a write signal from the control element to the memory unit via the write control unit, and the state signal output from the memory unit is controlled. By controlling the write operation by the write control unit to a prohibited state, even if the control element malfunctions due to, for example, abnormal operation of the power supply, chattering of a contact portion for communicating with an external device, noise of a signal line, or the like, In addition, it is possible to reliably prevent the illegal writing into the memory unit or change in the contents of the memory unit, and secure the data in the memory unit.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an IC as a portable electronic device according to the present invention.
3 shows a configuration of a card. That is, 1 in the contact portion for obtaining an external device (e.g., terminal) electrical contact, the power supply terminals 1 ₁ to the power supply voltage Vcc is supplied,
Ground (GND) terminal 1 _2, input and output data (I / O) pins 1 _3, pulse input terminal 1 ₄ of the clock pulse CLK is input, and includes a reset signal input terminal 1 ₅ a reset signal RST is input I have.

2 is a control element for overall control, 3 is a data memory (memory unit) such as an EEPROM for storing various data, 4 is an access generator, 5 is a memory access control unit (write control unit), and 6 is a power supply detection circuit It is. Control element 2
Includes a CPU, a program mask ROM for storing an operation program for the CPU, and a serial input / output control unit for transmitting data to and from an external device. The control element 2, data memory 3, access generator 4, memory access control unit 5, and power supply detection circuit 6
The address bus 7 is connected to the data bus 8 and various control signal lines.

Control element 2 has a function of selectively inputting and outputting data to and from an external device, and a function of controlling data memory 3, access generator 4, and memory access control unit 5. Power supply detection circuit 6, a power supply terminal 1 ₁ from an external device
The power supply voltage Vcc supplied to the memory is detected and determined, and the determination result is sent to the memory access control unit 5. The memory access control unit 5 determines the result of the control element 2 and the data memory 3
A write cycle information, controls the write enable terminal WE of the data memory 3 by the judgment result of the reset signal RST, and a power supply detection circuit 6 is supplied to the reset signal input terminal 1 ₅ from the external device.

FIG. 2 is a circuit diagram showing the memory access control unit 5 in detail. That is, a D-type flip-flop circuit (memory element, hereinafter simply referred to as FF circuit) 11 for memory access permission / prohibition control is assigned to a specific address in a memory space and on a specific data bit, for example. Is managed by In FIG. 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 and 19 are AND circuits.

In this embodiment, the data bit DO is set to “1” at the address OUT1.
When FF is written, the FF circuit 11 is set, and the writing to the data memory 3 is enabled. When "0" is written, the FF circuit 11 is set.
11 is reset to be in a state where writing to the data memory 3 is prohibited. The prohibition condition of the FF circuit 11 corresponds to the reset signal RST from the outside, the judgment result (PDET) of the power supply detection circuit 6, the read access of the data memory 3, and the termination of the write state signal (WRCYC) of the data memory 3. I do.

FIG. 3 shows the state signal WR output from the data memory 3.
6 is a timing chart for prohibiting a write operation by CYC. For example, when the address is "AAAA", the address OUT1 is generated from the access generator 4, and when "1" is written to the bit "0" of the data bus 8, the FF circuit 11 is set and the writing is enabled. Next, at the address "X000", the address OUT2 is generated from the access generator 4 and the data on the data bus 8 is written. If the FF circuit 11 is in the enabled state, the write pulse WRENB is output and the data bus 8 The above data is written into the data memory 3. At this time, the write state signal W is output from the data memory 3 at the fall of the write pulse WRENB.
RCYC is output.

Next, when the addresses “X001” and “X002” and OUT2 are generated from the access generator 4 and the data on the data bus 8 are sequentially written, if the FF circuit 11 is in the enabled state, the write pulse WRENB is output, The data is sequentially written to the memory 3. Then, when the write state signal WRCYC from the data memory 3 rises, the FF circuit 11 is reset to a write inhibit state. Thereafter, when data on the data bus 8 is written to the address “X003”, the FF circuit 11 is in a write-protected state, and the write pulse WRENB is not generated.

[Effects of the Invention] As described above in detail, according to the present invention, a write signal from a control element is given to a memory unit via a write control unit to control data writing to the memory unit, and from the memory unit. By controlling the write operation by the write control unit to a prohibited state by the output state signal, for example, the control element is controlled due to abnormal operation of the power supply, chattering of a contact portion for communicating with an external device, noise of a signal line, and the like. Therefore, even if the device malfunctions, it is possible to provide a portable electronic device that can reliably prevent improper writing to the memory unit or change in the contents of the memory unit, and secure data in the memory unit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of the present invention. FIG. 1 is a block diagram showing a configuration of an IC card, FIG. 2 is a block diagram showing a configuration of a memory access control unit, FIG. The figure is a timing chart for prohibiting a write operation by a state signal output from the data memory. DESCRIPTION OF SYMBOLS 1 ... Contact part, 2 ... Control element, 3 ... Data memory (memory part), 4 ... Access generator, 5 ...
... Memory access control unit (write control unit), 6... Power supply detection circuit, 7... Address bus, 8.

Claims (2)

(57) [Claims] A memory unit and a control element for writing and reading data to and from the memory unit;
In a portable electronic device that selectively inputs and outputs data to and from the outside, the memory unit outputs a write state signal in response to an input write enable signal, and the address data output from the control element. An access generator that outputs a first signal when is a specific address; a write signal, a read signal output from the control element, and a write signal that is provided between the control element and the memory unit; A write control unit that outputs a write enable signal to the memory based on the output write state signal, and controls writing of data to the memory unit. Is output, a write signal is output from the control element, and a write state is output from the memory unit. Holding means for holding a write permission state when a state signal is not output; and a write permission state being output by the holding means, and while the write signal is being output from the control element, the memory section has a write permission state. Output means for outputting a write enable signal; and write-inhibiting means for resetting the holding means for holding the write-enabled state upon completion of the write state signal output from the memory unit. Portable electronic devices. And a control unit for writing and reading data to and from the memory unit.
A portable electronic device that selectively inputs and outputs data to and from an external device, an access generator that outputs a first signal when address data output from the control element is a specific address; and the control element and a memory. A write signal output from the control element, a read signal, and a write enable signal to the memory unit based on a write state signal output from the memory unit.
A write control unit that controls writing of data to the memory unit, wherein the write control unit outputs a first signal from the access generator, outputs a write signal from the control element, and Holding means for holding a write permission state when a write state signal is not output from the unit; and a write permission state being output by the holding means, and a write signal being output from the control element. An output unit that outputs a write enable signal to the memory unit, a power supply detection circuit that monitors an abnormality of a power supply voltage supplied to the portable electronic device from outside, and a read signal is output by the control element.
A portable electronic device, comprising: a write-inhibiting unit that resets a holding unit that holds the write-enabled state when an abnormality in the power supply voltage is detected by the power supply detection circuit.