JPH0536550U - Memory card control method - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the data retained in the memory card from being destroyed by the generation of erroneous signals when the power is turned on. A memory card control system having a memory card 3 and a driver circuit 1 for writing information to the memory card 3 or reading the written information, wherein a write signal or the like during a write or read operation is validated. , A flip-flop 4 for invalidating a write signal or the like in another state is provided, and when the write or read operation of information is performed by the flip-flop 4, a write operation or the like is performed by validating a control signal or the like. In other states, All signals are invalidated and the information in the memory card is retained.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a memory card control system having a function of preventing information destruction due to a malfunction of a readable / writable memory.

[0002]

[Prior Art]

 FIG. 2 is a block diagram showing a conventional memory card control system.

In the figure, 11 is a driver circuit, 12 is an interface connector, and 13 is a memory card. The memory card 13 is inserted into the interface connector 12 and read / write operations are possible. The memory card 13 has a built-in battery inside so that the stored data can be held even when power is not supplied from the outside. When the memory card 13 is inserted into the interface connector 12, power is supplied from the device side including the driver circuit 11, the interface connector 12, the memory card 13 and the CPU (not shown).

The memory card 13 can be used both as an information storage means for storage and as a part of the internal memory of the device. Therefore, the driver circuit 11 drives a control signal composed of an address signal, a data signal, a chip enable signal, a write enable signal, and an output enable signal to control read / write of data in the memory card 13.

[0005]

[Problems to be solved by the device]

 In the memory card control method described above, an erroneous signal may be generated when the power is turned on, when the power is turned off, when the memory card is inserted or removed (when inserting or removing), or when the program runs out of control. Then, if this erroneous signal becomes the same as the above-mentioned signal, there is a problem that the data held in the memory card 13 may be destroyed.

The present invention has been made in view of the above-mentioned problems, and it is possible to reliably prevent the data held in the memory card from being destroyed by the occurrence of an erroneous signal when the power is turned on. It is an object of the present invention to provide a memory card control method that can be performed.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a memory card control system having a memory card and a driver circuit for writing information to the memory card or reading the written information. A signal control circuit for enabling signals and the like and invalidating write signals and the like in other states is provided.

[0008]

[Action]

 With the above configuration, when the information writing or reading operation is performed, the signal control circuit determines that the control signal is valid, and the writing operation or the like is performed. In the states other than the write or read operation, all the signals are invalidated by the signal control circuit and the information in the memory card is retained as it is.

[0009]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a memory card control system of this embodiment.

In the figure, 1 is a driver circuit, 2 is an interface connector, and 3 is a memory card, which has the same structure as the conventional memory card control system. Further, 4 is a flip-flop as a signal control circuit, 5 is an inverter, 6 is a transistor, and 7 is a CPU.

The flip-flop 4 controls the driver circuit 1 and the transistor 6 under the control of the CPU 7. Specifically, an OFF signal (Lo signal) is output by a reset signal, the transistor 6 is activated, and the memory card 3 is supplied with power from the outside. In the driver circuit 1, the OFF signal from the flip-flop 4 is inverted by the inverter 5 and becomes an ON signal (Hi signal), which is input, and the address signal, data signal and control signal input to the driver circuit 1 are judged to be invalid. Not output to the memory card 3.

When the enable signal is input to the flip-flop 4 and the set signal is input in the OFF state, the output signal from the flip-flop 4 is turned on, and the transistor 6 supplies the external power to the memory card 3. The address signal, the data signal and the control signal which are supplied and input by the driver circuit 1 are judged to be valid and are output to the memory card 3.

The CPU 7 controls the whole and outputs an address signal, a data signal, and a control signal including a chip enable signal, a write enable signal and an output enable signal to the driver circuit 1, and at the same time, has a processing function shown in FIG. It is stored.

The memory card control system configured as described above operates as follows.

Normally (when the memory card 3 is not operating), the enable signal is set to OFF. In this state, the output signal of the flip-flop 4 is maintained in the OFF state, and the driver circuit 1 does not output the address signal, the data signal and the control signal input to this circuit 1 to the memory card 3 side. Further, in the transistor 6, the memory card 3 is not supplied with the power required for the read / write operation.

As a result, the CPU 7 side and the memory card 3 side are completely disconnected, and immediately enter the high impedance state. Even when the power is turned on and off on the device side, the memory card 3 is inserted and removed. Even if the operation is performed, the control signal and the like are not erroneously output to the memory card 3 and the data in the memory card 3 is not destroyed. Similarly, even if the program of the CPU 7 runs out of control, the driver circuit 1 does not output control signals to the memory card 3 and the data in the memory card 3 is not destroyed.

When reading / writing the memory card 3, as shown in FIG. 3, the enable signal is turned on and output (step 1), and at the same time, the set signal is turned off and output. As a result, the output signal from the flip-flop 4 is turned on, and the address signal, the data signal, the control signal, etc. are output to access the memory card 3 (step 2). Next, it is judged whether or not the access is completed (step 3). If it is not completed, the procedure returns to step 2, and if completed, the enable signal is turned off and output (step 4), and at the same time, the set signal is turned off. Output. As a result, the output signal from the flip-flop 4 is turned off and the high impedance state is set, and erroneous writing to the memory card 3 is prevented.

The operation will be described with reference to the time chart of FIG. 4. The output signal from the flip-flop 4 is turned off by the reset signal, and erroneous writing to the memory card 3 is prevented. Then, the set signal (OFF signal) is output with the enable signal turned on, and the output signal from the flip-flop 4 is turned on. In this state, read / write operation is performed. Then, the set signal (OFF signal) is output with the enable signal turned off, and the output signal from the flip-flop 4 is turned off to bring the state to the above.

[0020]

[Effect of the device]

 As described above in detail, according to the present invention, there is provided a signal control circuit for enabling the write signal or the like during the write or read operation and invalidating the write signal or the like in other states. When writing or reading information, the control signal is judged to be valid and the writing operation is performed. In other states, all signals are invalid and the information in the memory card is retained as it is. Therefore, it is possible to reliably prevent the data retained in the memory card from being destroyed by the generation of an erroneous signal when the power is turned on.

[Brief description of drawings]

FIG. 1 is a block diagram showing a memory card control system of the present invention.

FIG. 2 is a block diagram showing a conventional memory card control system.

FIG. 3 is a flowchart showing a processing operation in a CPU according to the present invention.

FIG. 4 is a time chart showing a processing operation in the memory card control system of the present invention.

[Explanation of symbols]

 1 Driver Circuit 2 Interface Connector 3 Memory Card 4 Flip Flop 5 Inverter 6 Transistor 7 CPU

Claims (1)

[Scope of utility model registration request] 1. A memory card control method comprising: a memory card; and a driver circuit for writing information to the memory card or reading the written information from the memory card. A memory card control method characterized in that a signal control circuit for invalidating a write signal in the state of is provided.