JPS63279344A - Detecting device for connection of memory unit - Google Patents

Abstract

PURPOSE:To prevent the breakage of data as well as the runaway of a program although a card is mistakenly inserted in or taken out of a card reader, by writing the data into a specific address of the card to confirm the presence or absence of the card and also checking periodically the data to discontinue the execution of other processes until the coincidence is secured with the initial state of the data in case the data has a change from its initial state. CONSTITUTION:When the pulses are supplied to a CPU 4 from a timer 9, the CPU 4 reads the data 1c out of a memory card 1. At the same time, the data 1c of the card 1 is latched by a latch circuit 5. Then the pulses are periodically supplied to the CPU 4 from the timer 9. Thus the CPU 4 compares the data read out of the card 1 with the latched contents of the circuit 5. If it is known from said comparison that the card received from the card 1 has a change, the CPU 4 discontinue the execution of other processes until the data contents are coincident with its initial state. Thus it is possible to prevent the breakage of data as well as the runaway of a program.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a memory unit connection device, and in particular, the present invention relates to a memory unit connection device, and in particular, it is connected to a terminal device in a freely insertable and removable manner, and periodically checks the connection state of a data file card that is read or written. detect,
This relates to a memory unit connection detection device that maintains the entire system as necessary.

[Prior art]

Memory cards have traditionally been often used as data files, and are connected to terminal devices to read and write data. By the way, this memory card is removably connected to the terminal device, and can be inserted and removed even while reading or writing is in progress.

[Problem that the invention seeks to solve]

Since the memory card can be inserted into and removed from the terminal device as described above, if the memory card is accidentally removed from the terminal device while reading or writing, the data operation on the memory card may end prematurely. becomes. Therefore, if a subsequent program is executed in such a state, data may be destroyed or the program may run out of control.

The present invention has been devised in view of the above-mentioned circumstances and to eliminate the problem, and is intended to solve the problem that a memory card is accidentally inserted or removed while the memory card is being read or written. The present invention also aims to provide a connection detection device that can prevent data destruction and program runaway.

[Means for solving problems]

In order to achieve the above object, the present invention is a memory unit connecting device in which a data file card is removably connected to a terminal device and reads or writes data, and the presence or absence of a card at a specific address of the card is checked. In addition to writing data for the initial state, this data is checked periodically, and if there is a change from the initial state, a control means is provided for stopping other processing until the state matches the initial state.

[Effect]

According to the configuration of the present invention, the control means periodically checks the data written on the card to confirm the presence or absence of the card, and when there is a change from the initial state, other processing is performed until the data matches the initial state. cancel.

[Example] The configuration of the present invention will be explained based on an example shown in the drawings.

Fig. 1 is a circuit diagram showing the overall configuration of the memory unit connection detection device, Fig. 2 is an explanatory diagram showing the connection relationship between the memory card and the card connector, and Fig. 3 shows the procedure for detecting the insertion/removal status of the memory card. It is a flowchart.

The memory card 1 has a plurality of connection pins 1a arranged in a row on its edge. This memory card 1 is a terminal device 2 which will be described later.
is inserted into the card connector 3 and connected. That is, the card connector 3 has a plurality of connection pins 3a arranged in a row on the edge, and when the memory card 1 is inserted into the card connector 3, the connection pins 1a and 3a are connected to each other in correspondence. . Connection pin la and connection pin 4a have a power supply pin (VCC) and a ground pin (GND) on both ends, respectively.
) will be provided. Furthermore, a data IC indicating "card present" is written in a specific address 1b of the memory card 1. Therefore, by checking the "card present" data 1c at the address 1b of the memory card 1, it is possible to check whether the memory card 1 is connected to the terminal device 2 or not.

The terminal device 2 to which the memory card 1 is connected has various functions such as reading data from the memory card 1 and writing data from the memory card 1. This terminal device 2 includes a card connector 3 to which a memory card 1 can be inserted and removed, and a CPU that controls the overall operation of the terminal device 2.
4, interposed between the card connector 3 and the CPU 4,
A latch circuit 5 temporarily holds a signal for checking whether the memory card 1 is connected to the card connector 3, that is, whether it is inserted or removed, a RAM 6 for storing data, and a necessary program stored therein. ROM
7 and an input/output device 8. Further, 9 is a timer, and this timer 9 outputs a signal to the CPU 4 instructing to detect whether or not the memory card 1 is connected to the card connector 3 at regular intervals.

Between the CPU 4 and the card connector 3, the CPU 4
A data bus or the like for exchanging data between the card connector 3 and the card connector 3 is provided. Also, card connector 3
A signal output when the memory card 1 is inserted or removed is held in the latch circuit 5 and simultaneously transmitted to the CPU 4.

Next, the operation of the connection detection device having the above configuration will be explained.

When the CPU 4 receives a pulse from the timer 9, the CPU 4 reads out the data IC of the memory card 1, and the latch circuit 5 latches the data IC of the memory card 1. Next, when a pulse signal is periodically input to the CPU 4 from the timer 9, the CPU
4 inputs the data read from the memory card 1 and the contents latched by the latch circuit 5, and compares the two. In this comparison, when memory card 1 is not inserted, both contents are "no card", and conversely, when memory card 1 is inserted, both contents are "card present". be. Then, when the memory card 1 inserted into the card connector 3 is removed for some reason, the contents of the latch circuit 5 are "Card present", and the contents read by the CPU 4 are "No data"; When the memory card I is inserted into the connector 3, the contents of the latch circuit 5 are "No data J, data read by CPU 4 is i card present". As a result of this comparison, if the signal status from the memory card l changes from "card present" to "no data" or from "no data" to "card present", the CPU 4 By periodically inputting pulses from the timer 9, the data read out from the memory card l and the launch circuit 5 are read out again.
The CPU 4 inputs the latch contents of , compares the two, and suspends other processing until the data contents match the initial state.

In this way, it is possible to detect the insertion/removal status of the memory card 1 in the terminal device 2, and when there is a change in the data from the memory card 1, the CPU 4 stops other processing until the data matches the initial state. It is possible to prevent accidents such as data destruction and runaway programs.

The procedure for detecting the insertion and removal of the memory card l described above is shown in FIG.
), (B) will be explained based on the flowcharts. Third
Figure (A) shows the main routine in CPU4,
First, insert memory card 1.

5TEP■) to detect the connected state, then receive an interrupt (STEP■), perform the necessary processing in the terminal device 2 (STEP■), and return to 5TEP■ at an appropriate cycle to check again whether the memory card 1 is inserted or removed. (STEP■
). At 5TEP■, the subroutine shown in FIG. 3(B) is executed. In the subroutine, first check the contents of the data from the memory card l ("card present" or "no data") (5TEP■), and compare the result with the initial state of the data checked last time (STEP■
). If there is no change in the data at 5 TEP (2), the process returns to the main routine of FIG. 3(A), the subsequent necessary processing is continued, and the above procedure is repeated.

If it is determined at 5TE)'■ that the data contents have changed from the initial state, the process moves to 5TEP■, where the data IC is checked again, and compared with the initial state at 5TEP■. As a result of the comparison of 5TEP■, if it is determined that the data content in 5TEP [phase] has changed from the initial state,
Return to 5TEP ■ and repeat 5TE until it matches the initial state.
The procedure from P■ to [phase] is repeated, and when a match is found, the process moves to 5TEP■. 5TEP (ill will process the data that could not be written or read last time, so the process returns to the main routine in Figure 3 (A) again, and the subsequent necessary processing continues, and the above steps are repeated. be done.

It goes without saying that the memory unit connection detection device of the present invention can be realized by a hardware configuration or by software.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, it is possible to confirm the insertion/removal status of the card by checking the data written to a specific address of the card, and if there is a change from the initial status, the initial status can be confirmed. Since other processing is stopped until a match is made, even if a card is inserted or removed by mistake during card reading or writing, data destruction and program runaway can be prevented and the entire system can be maintained.

[Brief explanation of drawings]

The drawings show an embodiment of the memory unit connection detection device according to the present invention, FIG. 1 is a circuit diagram showing the overall configuration, FIG. 2 is an explanatory diagram showing the connection relationship between the memory card and the card connector, and FIG. 3 is a flowchart showing a procedure for detecting insertion/removal status of a memory card. (Brief explanation of the drawing showing the main parts) 1...Memory card 1a...Connection pin lb...Specific address

Claims (1)

[Claims] A data file card is removably connected to a terminal device, and in a memory unit connection device that reads or writes data, data is written to a specific address of the card to confirm the presence or absence of the card, and this data is periodically transmitted. 1. A memory unit connection detection device characterized by comprising a control means for checking the initial state and stopping other processing until the state matches the initial state when there is a change from the initial state.