JP3191996B2 - External memory control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to, related to the external memory control how to connect the memory card.

[0002]

2. Description of the Related Art Conventionally, as an external memory control device for connecting a memory card, for example, Japanese Unexamined Patent Publication No.
There is one described in JP-B-47. In this control device, both SRAM and DRAM control circuits are connected, and the SRAM or DRAM is selected by a designation circuit. Thereby, for example, an SRAM for message reproduction
And a DRAM for recording and reproduction can be connected to one control circuit. At the time of DRAM write, buses A ₀ to
Outputs a row address to A _8, after latching the memory RAS signals, and then outputs the digit address latched in the memory CAS signal. DRAM data is input / output in a basic cycle without passing through a serial / parallel circuit. On the other hand, SRA
During M lights, byte address is sent to the bus A ₃ to A _17, using the CAS signal as the chip select signal. The data of the SRAM is 1/8 of the basic cycle.
In a cycle of

[0003]

Conventionally, SRAM, DRAM, mask ROM, EE
A PROM or the like is used. However, as described above, since control signals, addresses, access times, and the like are different from each other, a separate interface is defined for each memory card. Therefore, different types of memory cards cannot be connected to the same socket. That is, conventionally, interface standards are separately provided for DRAM and other memory cards. For example, in a system in which both an SRAM and a DRAM can be connected, a connector is separately provided, or both control circuits are provided in a conventional manner, and a control circuit of a memory to be connected is selected. Therefore, a method of connecting with one socket is used. However, these methods result in useless sockets or circuits. The object of the present invention is to solve these conventional problems, without causing unnecessary sockets and circuits,
An object of the present invention is to provide an external memory control method capable of connecting a plurality of types of memory cards.

[0004]

In order to achieve the above object, an external memory control method according to the present invention is an external memory control method for a system in which a plurality of types of memory cards are connected by a single connector, and comprises an SRAM. Program the control circuit
Configured as a mable logic array and
Write data randomly and read the written data.
If the read data is correct data
If the above memory card is determined to be SRAM,
And if the read data is not correct, D
RAM control circuit configured in programmable logic array
And randomly write data to the memory card
Read the written data and read the read data.
If the data is correct, the memory card
Judge as RAM, start access, and read
If the data is not correct, the above memory card cannot be processed
It is characterized by judging.

[0005]

The most important feature of the present invention is that (a) a programmable logic array is provided as a common control circuit for a plurality of types of connected memory cards. Each memory card is provided with a means for determining the type of memory, for example, a determination signal indicating the type of memory, so that the control circuit of the determined type of memory can write a program suitable for the programmable logic array. Configure. In this case, an arbitrary type of memory card can be connected without providing a plurality of sockets and providing a plurality of control circuits and selecting the memory card with a selection circuit. Furthermore, since the type of memory is automatically determined, writing a program to a programmable logic array allows any type of memory card.
Can be connected. (B) By providing a selection means for each memory card, for example, a memory selection switch, a control circuit of the memory card selected by the switch is configured by writing a program suitable for a programmable logic array. In this case, since the memory is selected from the outside, it is not necessary to provide a special judgment signal or the like in the memory card, the type of the memory can be judged, and the program can be written in the programmable logic array. Any memory can be connected. (C) The connected memory cards are sequentially written / read by a plurality of control circuits, and subsequent control accesses are executed by the control circuit when the writing / reading is correctly performed. In this case, since the MPU automatically determines the type of memory, there is no need to provide an external selection means or a memory card determination signal, and the memory can be determined.
By writing a program in the programmable logic array, an arbitrary memory card can be connected.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of an external memory control device showing one embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a microprocessor unit (MPU) for controlling the external memory control device of the present invention; 12, a programmable logic array in which some programs are set in advance;
Is a memory card socket for inserting a plurality of types of memory cards, 14 is a memory card connected to the apparatus, and 15 is a memory card socket.
Is an amplifier for amplifying a signal from the memory card socket 13, 16 is a memory selection switch for selecting a memory from a plurality of types of memory cards, and 17 is an MPU bus. As described above, according to the external memory control device of the present invention, as a control circuit connected between the memory card 14 and the MPU bus 17, a programmable logic array for configuring a control circuit corresponding to each memory card is provided. -12 is installed. The program set in the programmable logic array 12 is input from a specific terminal and written by the MPU 11 through the bus 17 via a program signal line.

The following three methods (a), (b) and (c) can be used to determine the type of memory. First, (a)
In this method, a determination signal indicating the type of memory is prepared in the memory card 14, and the MPU 11 makes a determination based on the signal. The method (b) is a method in which a switch 16 for externally selecting the type of the memory card 14 is provided, and determination is made based on a signal from the selection switch 16. Also, (c)
The method of (1) is a method of executing write / read to the memory card 14 and judging that the memory of the control circuit in which the write / read has been correctly performed is connected. In FIG. 1, both methods (a) and (b) are provided, the output of the amplifier 15 is used as a memory type determination signal, and the memory selection switch 1 is used.
6 are provided. The memory selection switch 16 is provided so that either operation can be performed according to the operator's preference and that the memory type designation signal provided in the memory card can be used when a failure occurs. When the type of the connected memory is determined, the MPU 11 programs the programmable logic array 12 with a control circuit for the determined memory. The MPU 11 accesses the memory card 14 after programming, so that a signal corresponding to each memory is generated from the control circuit.

FIG. 2 shows the case of the SRAM shown in FIG.
FIG. 4 is a diagram illustrating generated signals in the case of a RAM. In FIG. 2, the upper address and the R / W signal are signals from the MPU for the DRAM, and the lower address, WRB (write) and RD (read) signals are the signals from the MPU for the SRAM. . A write signal (negative voltage) is written at the same time as the address in the memory write cycle, and is read at the same time as the address in the memory read cycle. If a voltage is detected, "1" is read, and if no voltage is detected, "0" is read. FIG. 3 is a diagram showing a method of generating a determination signal indicating the type of memory in FIG. As a specific example of a method of generating a determination signal indicating the type of memory and a specific example of the determination method, an open or ground connection pin 19 is prepared on the memory card 14 side, and for example, in a DRAM card, an open state is provided. In the case of the Pun or SRAM card, it is set to the ground. This is read by a general-purpose port on the system side to determine the type of memory. That is, SR
By inserting the memory card 14 of the AM into the card socket 13, the pin 19 becomes the ground as shown in FIG. 3, so that the ground pin 19, the IC card 14, the memory card socket 13 and the + 5V Current flows through the path,
When the amplifier 15 transmits the “L” level to the MPU bus 17, the MPU 11 determines that the SRAM is the SRAM. Conversely, when the memory card 14 of the DRAM is inserted into the card socket 13, the amplifier 15 becomes "H".
By transmitting the level to the MPU bus 17, the DRA
M is determined.

The programmable logic array shown in FIG.
As a method of setting a program for the second, first, as in a programmable ROM, the program is set in a program mode,
A prescribed program is written from the MPU 11 to the programmable logic array 12 from the determined terminal via the MPU bus 17 and the program signal line. FIG.
FIG. 4 is a flowchart showing a procedure for executing write / read to the memory card in FIG. 1 and judging that the memory of the control circuit in which the write / read was correctly performed is connected.
First, the control circuit of the SRAM is configured in the programmer block logic array 12 (step 101). Next, data is randomly written into the memory (step 10).
2). Next, the written data is read (step 1).
03). It is determined whether the read data is correct (step 104). If it is correct, the IC card determines that it is an SRAM (step 111), and starts normal access (step 112). On the other hand, if the data is not correct, the control circuit of the DRAM is constructed in the programmable logic array 12 (step 10).
5). Next, data is randomly written in the memory (step 106), the written data is read (step 107), and it is determined whether or not the data is correct (step 108). If the data is correct, IC
The card is determined to be a DRAM (step 109), and normal access is started (step 112). If the data is not correct, the IC card is determined to be NG (step 110).

[0010]

As described above, according to the present invention,
(A) Since a programmable logic array is provided and a memory card is provided with a means for indicating the type of memory, a plurality of sockets or a plurality of control circuits are provided, and without being selected by a selection circuit, any arbitrary Different types of memory cards can be connected. (B) Since the memory card is selected externally by providing the memory card selecting means, the memory card can be judged without giving a special judgment signal to the memory card itself. An arbitrary memory card can be connected by writing a program. Further, (c) the memory cards are sequentially connected, data writing / reading is performed, and the memory type can be automatically determined when the data has been correctly written, so that any type of memory can be connected. Can be. In this case, the MPU automatically
Since the type of the memory card is determined, the memory can be determined without an external selection circuit or a memory card determination signal.

[0011]

[Brief description of the drawings]

FIG. 1 is a block diagram of an external memory control circuit showing one embodiment of the present invention.

FIG. 2 is a diagram showing read / write signal waveforms of a DRAM and an SRAM in FIG. 1;

FIG. 3 is an explanatory diagram showing a method of generating a determination signal indicating a memory type in FIG. 1;

FIG. 4 is a flowchart showing a procedure of a method for judging the type of a memory when reading / writing to a memory is correct in FIG.

[Explanation of symbols]

 11 MPU 12 Programmable Logic Array 13 Memory Card Socket 14 Memory Card 15 Amplifier 16 Memory Select Switch 17 MPU Bus 18 Positive Power Supply in Memory Card Socket 19 Memory Card Terminal Pin

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06F 3/08 G06F 12/00-12/06 G06F 12/16 G06F 13/16-13/18 G06K 17 / 00

Claims (1)

(57) [Claims] 1. A external memory control method of the system for connecting the one connector plurality of types of memory cards in and constitute a control circuit of the SRAM in a programmable logic array, write random data to the memory card, The written data is read, and if the read data is correct, the memory card is determined to be an SRAM and access is started. If the read data is not correct, the control circuit of the DRAM is switched to a programmable logic array. The data is randomly written in the memory card, the written data is read, and if the read data is correct data, the memory card is determined to be a DRAM, access is started, and the read is performed. If the data is not correct, An external memory control method, wherein a mode is determined to be impossible.