JP2005182370A - Memory card system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a conventional high-speed small-sized memory card drives an output signal with the same drive capability as that in a high-speed operation mode even for a host device not supporting the mode, so that a disturbance is caused by unnecessary radiation and electric power is consumed uselessly. <P>SOLUTION: The drive capability is not switched by a command output from a host device 100, but a signal waveform of the output signal from a transmitting device 103 is monitored by a drive capability switching automated device 206 and the transmitting device 103 is controlled so as to make the drive capability optimum. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a small memory card system using a nonvolatile memory.

  Recently, when video signals such as MPEG2 and MPEG4 are converted into digital signals, a large amount of data is handled. Under such circumstances, the amount of data handled by a small memory card has increased, and a small card system has been demanded in which the data transfer speed between the host device and the small memory card is increased. Therefore, in the conventional high-speed compatible small memory card system, the register that changes the drive capability of the data transmission device can be changed by changing the command issued by the host device, and it can be changed (for example, non-patent) Reference 1).

Here, a conventional technique will be described with reference to FIG.
When the small memory card 102 is inserted, the host device 100 transmits a command / data signal 100S to the small memory card 102.

  The small memory card 102 has a receiving device 101 that receives a command / data signal 100S transmitted from the host device 100 and a drive capability switching function, and transmits a response / data signal 103S to the host device 100. A transmission device 103 and a nonvolatile memory control device 104 that controls the nonvolatile memory 105 are provided.

  The transmission device 103 includes a response generation circuit (not shown) that generates a response corresponding to a command transmitted from the host device 100.

  The command / data signal 100 </ b> S is a command for controlling the small memory card 102 or a data signal stored in the nonvolatile memory 105 of the small memory card 102. The response / data signal 103 </ b> S is a response to a command transmitted from the host device 100 or a data signal read from the nonvolatile memory 105.

An example of the operation of the conventional memory card system configured as described above will be described below.
When the small memory card 102 is inserted into the host device 100, a command is transmitted from the host device 100 to the small memory card 102. On the small memory card 102 side, the command transmitted from the host device 100 is analyzed by the receiving device 101.

  When a command instructing writing to the nonvolatile memory 105 is transmitted from the host device 100, the receiving device 101 uses the data signal transmitted from the host device 100 next to the command as a write signal 101S as the nonvolatile memory. Output to the control device 104. Then, the nonvolatile memory control device 104 adds the identification information and the error correction code to the write signal 101 </ b> S and writes it in the nonvolatile memory 105.

When a command instructing data reading from the non-volatile memory 105 is transmitted from the host device 100, the receiving apparatus 101 outputs a signal 101S indicating the instruction content to the non-volatile memory control apparatus 104 to control the non-volatile memory. The device 104 reads out the data signal 105S from the nonvolatile memory 105, corrects the error, outputs the error-corrected data signal 104S to the transmission device 103, and transmits the data signal 104S from the transmission device 103 to the host device 100. When a command instructing switching of drive capability is transmitted from the host device 100, the receiving device 101 activates the first drive capability switching signal 111S and outputs it to the transmitting device 103, and the transmitting device 103 The drive capability is switched by the input of the first drive capability switching signal 111S, and the data signal 104S read from the nonvolatile memory 105 is transmitted to the host device 100.
“The Multi Media Card System Summary”, [online], [searched July 22, 2003], Internet MMCA homepage <URL: http://www.mmca.org/tech/MMC-System-Summary-v3. 31.pdf>

  However, the conventional high-speed compatible small memory card as shown in FIG. 8 drives the output signal to the host device that does not support the high-speed operation mode with the same drive capability as in the high-speed operation mode. There was a problem of causing interference and wasteful power consumption.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a small memory card system capable of preventing occurrence of interference due to unnecessary radiation.

  In order to solve the above problems, a small memory card system according to claim 1 of the present invention is a small memory card system comprising a host device and a small memory card that operates according to a command transmitted from the host device. A small memory card includes a receiving device that receives a command or data signal transmitted from the host device, a non-volatile memory control device that controls a non-volatile memory based on the command transmitted from the host device, and a drive Having a function of switching the capability, monitoring a signal waveform of a response to the command or a data signal read from the nonvolatile memory to the host device and a signal waveform of an output signal of the transmission device; Drive capability to control the transmitter to optimize drive capability With an automatic detection device replacement, and it is characterized in.

  This makes it possible to automatically determine the optimum value of drive capability from the output signal of the transmission device, resulting in reduced power consumption and a high-speed mode small memory card for host devices that do not support high-speed mode. When inserted or when a small memory card that does not support high-speed mode is inserted into a host device that supports high-speed mode, it is possible to prevent unnecessary radiation.

  A small memory card system according to claim 2 of the present invention is a small memory card system comprising a host device and a small memory card that operates in accordance with a command transmitted from the host device. A function of switching a drive capability between a receiving device that receives a command or data signal transmitted from a host device, a non-volatile memory control device that controls a non-volatile memory based on the command, and a response to the command Alternatively, the transmission device that transmits the data signal read from the nonvolatile memory to the host device and the signal waveform of the output signal of the transmission device are monitored, and the optimum value of the drive capability of the transmission device is determined. Drive capacity switching automatic detection device and drive capacity switching automatic detection device A drive capability switching automatic detection signal temporary storage device that temporarily stores the determined optimum value of the drive capability of the transmission device and writes the value to the nonvolatile memory after a predetermined time has elapsed. It is characterized by.

  This makes it possible to automatically determine the optimum value of drive capability from the output signal of the transmission device, resulting in reduced power consumption and a high-speed mode small memory card for host devices that do not support high-speed mode. When a small memory card that does not support high-speed mode is inserted in the case of a host crisis that supports high-speed mode, unnecessary radiation can be prevented, and the optimal drive capacity value is stored in nonvolatile memory. As a result, when the small memory card is inserted into the host device again and started up, the initialization setting can be performed using the optimum value of the previous drive capability.

  A small memory card system according to claim 3 of the present invention is the small memory card system according to claim 1 or 2, wherein the transmitting device continuously uses a variable current source to output a current amount of an output signal. The driving capability is switched by changing the driving ability.

  Thereby, the drive capability can be finely controlled by changing the amount of current of the output signal of the transmission device.

  A small memory card system according to a fourth aspect of the present invention is the small memory card system according to the first or second aspect, wherein the transmission device outputs two or more constant current sources connected in parallel. The drive capability is switched by discretely varying the amount of signal current.

  Thereby, the drive capability can be finely controlled by changing the amount of current of the output signal of the transmission device.

  A small memory card system according to claim 5 of the present invention is the small memory card system according to claim 1 or 2, wherein the transmitting device switches drive capability by varying a slew rate of an output signal. It is characterized by that.

  As a result, the drive capability can be finely controlled by changing the slew rate of the output signal of the transmission apparatus.

  A small memory card system according to claim 6 of the present invention is the small memory card system according to claim 1 or 2, wherein the transmitter switches the drive capability by varying the power supply voltage of the output signal. It is characterized by that.

  As a result, the drive capability can be finely controlled by changing the power supply voltage of the output signal of the transmitter.

  A small memory card system according to a seventh aspect of the present invention is the small memory card system according to the first or second aspect, wherein the drive capability switching automatic detection device is configured to overshoot an output signal of the transmission device. A voltage and an undershoot voltage are detected, and the drive capability of the transmission device is controlled based on a result of comparing the detected voltage value with a reference value.

  Thereby, the undershoot and overshoot of the output signal of the small memory card can be reduced.

  The small memory card system according to claim 8 of the present invention is the small memory card system according to claim 1 or 2, wherein the drive capability switching automatic detection device uses an output signal of the transmission device as a fast Fourier transform. The drive capability of the transmission apparatus is controlled based on the result of conversion and the result of comparison of the converted result with a reference value.

  Thereby, the undershoot and overshoot of the output signal of the small memory card can be reduced.

  The small memory card system according to claim 9 of the present invention is a small memory card system comprising a host device and a small memory card that operates according to a command transmitted from the host device. The transmitter for transmitting commands or data signals to the small memory card, and monitoring the signal waveform of the output signal of the transmitter, so that the transmitter can be optimized for drive capability. It comprises a drive capacity switching automatic detection device to be controlled and a receiving device for receiving a response or data signal transmitted from the small memory card.

  This makes it possible to automatically determine the optimum value of drive capability from the output signal of the transmission device, resulting in reduced power consumption and a high-speed mode small memory card for host devices that do not support high-speed mode. When inserted or when a small memory card that does not support high-speed mode is inserted in a host crisis that supports high-speed mode, it is possible to prevent unnecessary radiation.

  A small memory card system according to a tenth aspect of the present invention is the small memory card system according to the ninth aspect, wherein the transmitting device continuously varies the amount of current of the output signal using a variable current source. And switching drive capability.

  Thereby, the drive capability can be finely controlled by changing the amount of current of the output signal of the transmission device.

  A small memory card system according to an eleventh aspect of the present invention is the small memory card system according to the ninth aspect, wherein the transmitting device uses a constant current source connected in parallel with two or more current amounts of output signals. The drive capability is switched by discretely changing the drive capacity.

  Thereby, the drive capability can be finely controlled by changing the amount of current of the output signal of the transmission device.

  A small memory card system according to a twelfth aspect of the present invention is the small memory card system according to the ninth aspect, characterized in that the transmitting device changes the slew rate of the output signal to switch the drive capability. It is what.

  As a result, the drive capability can be finely controlled by changing the slew rate of the output signal of the transmission apparatus.

  A small memory card system according to a thirteenth aspect of the present invention is the small memory card system according to the ninth aspect, wherein the transmitting device changes the power supply voltage of the output signal to switch the drive capability. It is what.

  As a result, the drive capability can be finely controlled by changing the power supply voltage of the output signal of the transmitter.

  A small memory card system according to a fourteenth aspect of the present invention is the small memory card system according to the ninth aspect, wherein the drive capacity switching automatic detection device includes an overshoot voltage of an output signal of the transmission device and an undershoot voltage. The chute voltage is detected, and the drive capability of the transmitter is controlled based on the result of comparing the detected voltage value with a reference value.

  Thereby, the undershoot and overshoot of the output signal of the host device can be reduced.

  The small memory card system according to claim 15 of the present invention is the small memory card system according to claim 9, wherein the drive capacity switching automatic detection device performs fast Fourier transform on the output signal of the transmission device, and The drive capability of the transmission apparatus is controlled based on the result of comparison of the converted result with a reference value.

  Thereby, the undershoot and overshoot of the output signal of the host device can be reduced.

  A small memory card system according to a sixteenth aspect of the present invention is the small memory card system according to any one of the first, second, or ninth aspect, wherein the host device and the small memory card are used. A terminal resistor is connected between the signal line between the ground and the ground.

  Thereby, undershoot and overshoot of the output signal of the host device and the output signal of the small memory card can be reduced.

  A small memory card system according to a seventeenth aspect of the present invention is the small memory card system according to any one of the first, second, and ninth aspects, wherein the host device and the small memory card are used. A low-pass filter is inserted in the signal line between them.

  Thereby, undershoot and overshoot of the output signal of the host device and the output signal of the small memory card can be reduced.

  A small memory card system according to claim 18 of the present invention is a small memory card system comprising a host device and a small memory card that operates according to a command transmitted from the host device. A terminal resistor is connected between the signal line between the cards and the ground.

  Thereby, undershoot and overshoot of the output signal of the host device and the output signal of the small memory card can be reduced.

  A small memory card system according to a nineteenth aspect of the present invention is a small memory card system comprising a host device and a small memory card that operates according to a command transmitted from the host device. A low-pass filter is inserted in a signal line between cards.

  Thereby, undershoot and overshoot of the output signal of the host device and the output signal of the small memory card can be reduced.

  According to the small memory card system of the present invention, the signal waveform of the transmission device of the small memory card or the transmission device of the host device is monitored and controlled so that the drive capability of the transmission device is optimized. When a small memory card that supports high-speed mode is inserted into a host device that does not support high-speed mode, or when a small memory card that does not support high-speed mode is inserted into a host device that supports high-speed mode, power consumption is reduced. Can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, embodiment shown here is an example to the last, Comprising: It is not necessarily limited to this embodiment.

(Embodiment 1)
The small memory card system according to the first embodiment of the present invention will be described below.
FIG. 1 is a diagram showing a small memory card system according to the first embodiment. In the figure, the same reference numerals are used for the same or corresponding components as in FIG. 8, and the description thereof is omitted.

  Reference numeral 206 denotes a drive capability switching automatic detection device that monitors the signal waveform of the output signal 103S of the transmission device 103 and controls the transmission device 103 so that the drive capability is optimized. FIG. The configuration is shown. As shown in FIG. 2, the drive capability automatic detection device 206 includes a fast Fourier transform device 802 that converts the response / data signal 103S input via the response / data signal input terminal 800 into frequency spectrum data, and the fast Fourier transform. A reference value comparison device 803 that activates the second drive capability switching signal 206S and outputs it to the transmission device 103 based on the result of comparing the conversion signal 802S output from the conversion device 802 with a reference value. It is.

  Here, a case will be described in which the drive capability switching automatic detection device 206 is configured by the drive capability switching automatic detection device 206 by a high-speed Fourier transform device 802 and a reference value comparison device 803, but a voltage detection device is used. It can also be realized. In this case, the voltage detection device detects the overshoot voltage and the undershoot voltage of the response / data signal 103S output from the transmission device 103, and transmits based on the result of comparing the detected voltage value with the reference value. The drive capability of the device 103 may be controlled.

Next, the transmission apparatus 103 with a drive capability switching function of the present invention will be described with reference to FIG.
The transmission device 103 with a drive capability switching function shown in FIG. 3 includes a first drive capability switching signal 111S input via the first drive capability switching signal input terminal 521 or a second drive capability switching signal input terminal 522. The switching signal generator 524 generates a switching signal using the second drive capability switching signal 206S input via the switch, and the switches 510 to 515 are controlled to be turned on / off by this switching signal, so that the third input The amount of current of the read signal 104S input via the terminal 523 is adjusted.

  For example, when the read signal 104S is HIGH, the switch 516 is turned on, the current amount of the read signal 104S is adjusted by the constant current sources 500 to 502, and the output terminal 520 as the response / data signal 103S whose drive capability is optimized. Is output via.

  Further, when the read signal 104S is LOW, the switch 517 is turned on, the current amount of the read signal 104S is adjusted by the constant current sources 503 to 505, and the output terminal 520 as the response / data signal 103S in which the drive capability is optimized. Is output via.

  The switching signal generation device 524 receives either the first drive capability switching signal 111S output from the receiving device 101 or the second drive capability switching signal 206S output from the drive capability switching automatic detection device 206. In the above description, the switching signal is generated, but the switching signal may be generated using a logical sum of the first drive capability switching signal and the second drive capability switching signal.

  Next, an example of the operation of the small memory card system according to the first embodiment will be described below. Except for the drive capability switching automatic detection device 206, the operation of each part is not significantly different from that shown in FIG.

  The drive capability switching automatic detection device 206 monitors the signal waveform of the response / data signal 103S output from the transmission device 103, and sets the second drive capability switching signal 206S so that the drive capability of the transmission device 103 is optimized. The data is output to the transmission device 103.

  In the transmission device 103, the drive capability is switched by the input of the second drive capability switching signal 206S, and the response / data signal 103S is transmitted to the host device 100.

  As a method for switching the drive capability of the transmission device 103, as shown in FIG. 3, the current amount of the output signal 103S of the transmission device 103 is changed by using two or more constant current sources connected in parallel, and the drive capability is changed. Although the case of switching in stages has been described, the drive capability may be continuously varied by linearly changing the current amount of the variable current source. The variable current source can be realized by a transistor operating in a non-saturation region, a current mirror device, a variable resistance device, or the like.

  Further, as a method for switching the drive capability of the transmission apparatus 103, the slew rate of the response / data signal 103S is changed instead of changing the current amount of the response / data signal 103S as described above, or the transmission apparatus 103 The drive capability may be switched by controlling the power supply voltage of the output stage. As a method for supplying the power supply voltage, one supplied from the outside or generated internally (regulator, DC-DC converter, etc.) is used.

  In the small memory card system shown in the first embodiment, the small memory card 102 includes the drive capability switching automatic detection device 206, and the drive capability switching automatic detection device 206 monitors the signal waveform of the output signal of the transmission device 103. Since the transmission device 103 is controlled so that the drive capability is optimized, the high-speed mode is not supported when a high-speed mode small memory card is inserted in the host device that does not support the high-speed mode or the host device that supports the high-speed mode. When a small memory card is inserted, unnecessary radiation can be prevented.

(Embodiment 2)
The small memory card system according to the second embodiment of the present invention will be described below.
The difference from the first embodiment is that in the first embodiment, the drive capability switching automatic detection device 206 is provided on the small memory card 102 side, whereas in the second embodiment, the drive capability switching automatic detection device is provided. 206 is provided on the host device 100 side.

FIG. 4 is a diagram showing a small memory card system according to the second embodiment. In addition, the same code | symbol is used about the component which is the same as that of FIG. 1, or is equivalent, and the description is abbreviate | omitted.
In FIG. 4, reference numeral 301 denotes a receiving device that receives the response / data signal 103 </ b> S transmitted from the small memory card 102. Reference numeral 303 denotes a transmission device with a drive capability switching function, which switches the drive capability based on the second drive capability switching signal 206S output from the drive capability switching automatic detection device 206, and sends a command / data to the small memory card 102. The signal 103S is transmitted. Note that the configuration of the host device 100 illustrates only functional blocks necessary for explaining the present invention.

  Next, an example of the operation of the small memory card system according to the second embodiment will be described below. Except for the drive capability switching automatic detection device 206, the operation of each unit is not much different from that of a conventional host device, and therefore only the operation of the drive capability switching automatic detection device 206 is shown.

  On the host device 100 side, the drive capability switching automatic detection device 206 sequentially monitors the signal waveform of the command / data signal output from the transmission device 303, and the second drive capability switching signal 206S is used to drive the transmission device 303. Control the ability to be optimal. In this way, the command / data signal 100S is transmitted to the small memory card 102 with the optimum drive capability. The receiving device 301 receives the response / data signal returned from the small memory card 102.

  In the second embodiment, the host device 100 is provided with the drive capability switching automatic detection device 206, and the drive capability switching automatic detection device 206 monitors the signal waveform of the output signal of the transmission device 303 to optimize the drive capability. Since the transmission device 303 is controlled so as to become, any type of small memory card can be supported, and generation of unnecessary radiation can be prevented.

(Embodiment 3)
The small memory card system according to the third embodiment of the present invention will be described below.
FIG. 5 is a diagram showing a small memory card system according to the third embodiment. In the figure, the same reference numerals are used for the same or corresponding components as in FIG. 1, and the description thereof is omitted.

  In FIG. 5, reference numeral 407 denotes a drive capability switching automatic detection signal temporary storage device that temporarily stores the second drive capability switching signal 206S and writes it into the nonvolatile memory 105 after a predetermined time has elapsed. .

  Next, an operation example of the small memory card system according to the third embodiment will be described below. Except for the drive capability switching automatic detection signal temporary storage device 407, the operation of each unit is not significantly different from that shown in FIG. 1, and therefore only the operation of the drive capability switching automatic detection signal temporary storage device 407 is shown.

  The drive capability switching automatic detection signal temporary storage device 407 temporarily stores the second drive capability switching signal 206S generated by the drive capability switching automatic detection device 206, and passes through the nonvolatile memory control device 104 after a certain period. And stored in the nonvolatile memory 105.

  The second drive capability switching signal 206S stored in the non-volatile memory 105 is read from the non-volatile memory 105 upon initialization when the small memory card 102 is started up, and passes through the non-volatile memory control device 104. The drive capability switching automatic detection signal is output to the temporary storage device 407. Then, the read second drive capability switching signal 206S is output to the transmission device 103 as a drive capability switching initial signal 417S.

  In the transmission device 103, the drive capability is determined based on the drive capability switching initial signal 417S. At this time, since the drive capability of the transmitter 103 with the drive capability switching function has already been determined, the power consumption can be reduced if the operation of the drive capability switching automatic detection device 206 is stopped.

  In the third embodiment, the small memory card 103 includes the drive capability switching automatic detection device 206 and the drive capability switching automatic detection signal temporary storage device 407, and the second drive generated by the drive capability switching automatic detection device 206. Since the capability switching signal 206S is temporarily stored in the drive capability switching automatic detection signal temporary storage device 407 and stored in the nonvolatile memory 105 after a certain period of time, the small memory card 103 is again connected to the host device 100. Can be initialized using the previous second drive capability switching signal 206S stored in the nonvolatile memory 105, and as a result, the small memory card 103 is started up. The small memory card 102 can be operated with the optimum drive capability for each time.

  In each of the first to third embodiments, the case has been described in which the drive capability switching automatic detection device 206 is provided in the small memory card 102 or the host device 100 to automatically switch the drive capability of the transmission device 103. A terminal resistor or a low-pass filter may be provided between the small memory card 102 and the host device 100.

  FIG. 6 shows a configuration diagram of a small memory card system in which terminal resistors 600 and 601 are provided between the small memory card 102 and the host device 100. In this case, the first termination resistor 600 can reduce overshoot or undershoot of the signal waveform that is the source of unwanted radiation of the command / data signal 100S, and the second termination resistor 601 can reduce the response / It is possible to reduce overshoot and undershoot of a signal waveform that is a source of unnecessary radiation of the data signal 103S. Note that the first termination resistor 600 may be built in the host device 100, and the second termination resistor 601 may be built in the small memory card 102. Alternatively, the first termination resistor 600 and the second termination resistor 601 may be variable resistors, and the resistance values may be varied according to the second drive capability switching signal 206S generated by the drive capability switching automatic detection device 206. .

  FIG. 7 shows a configuration diagram of a small memory card system when low-pass filters 700 and 701 are provided between the small memory card 102 and the host device 100. In this case, the first low-pass filter 700 can reduce overshoot and undershoot of the signal waveform that is the source of unwanted radiation of the command / data signal 100S, and the second low-pass filter 701 can reduce the response / It is possible to reduce overshoot and undershoot of a signal waveform that is a source of unnecessary radiation of the data signal 103S. The first low-pass filter 700 may be built in the host device 100, and the second low-pass filter 701 may be built in the small memory card 102. Further, the cutoff frequency of the first low-pass filter 700 and the second low-pass filter 701 can be varied, and the cut-off frequency is cut in accordance with the second drive capability switching signal 206S generated by the drive capability switching automatic detection device 206. The off frequency may be varied.

  Further, if the small memory card system shown in the first to third embodiments is combined with the small memory card system shown in FIGS. 6 and 7, that is, the first to third embodiments are shown. In the small memory card system, if a termination resistor or a low-pass filter is provided between the small memory card 102 and the host device 100, generation of unnecessary radiation can be prevented more reliably.

  The small memory card system according to the present invention can realize a small memory card system or a small memory card system capable of automatically optimizing the drive capability from the signal waveform of the output signal of the host device. It is useful as a small memory card such as a multimedia card, memory stick, compact flash (registered trademark), smart media, or a miniature memory card such as a miniSD memory card. It can also be applied to uses such as VCOs and IC cards.

It is a block diagram of the small memory card system by Embodiment 1 of this invention. It is a block diagram of the drive capability switching automatic detection apparatus of this invention. It is a figure which shows the structure of the transmitter with a drive capability switching function of this invention. It is a block diagram of the small memory card system by Embodiment 2 of this invention. It is a block diagram of the small memory card system by Embodiment 3 of this invention. It is a figure which shows the structure of the small memory card system of this invention at the time of providing termination resistance between a small memory card and a host apparatus. It is a figure which shows the structure of the small memory card system of this invention at the time of providing a low-pass filter between a small memory card and a host apparatus. It is a block diagram of the conventional small memory card system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Host apparatus 101 Receiving device 102 Small memory card 103 Transmitting device 104 with drive capability switching function Non-volatile memory control device 105 Non-volatile memory 206 Drive capability switching automatic detection device 301 Receiving device 303 Transmitting device with drive capability switching function 407 Drive capability switching Automatic detection signal temporary storage devices 500 to 505 Constant current sources 510 to 517 Switch 520 Output terminal 521 First input terminal 522 Second input terminal 523 Third input terminal 524 Switching signal generation circuits 600 and 601 Termination resistors 700 and 701 LPF
800 Response / data signal input terminal 801 Second drive capability switching signal output terminal 802 Fast Fourier transform device 803 Reference value comparison device

Claims (19)

In a small memory card system comprising a host device and a small memory card that operates according to a command transmitted from the host device,
The above small memory card
A receiving device for receiving a command or data signal transmitted from the host device;
A nonvolatile memory control device for controlling the nonvolatile memory based on a command transmitted from the host device;
A transmission device that has a function of switching drive capability, and that transmits a response to the command or a data signal read from the nonvolatile memory to the host device;
A drive capability switching automatic detection device that monitors the signal waveform of the output signal of the transmission device and controls the transmission device so that the drive capability is optimized, and
A small memory card system. In a small memory card system comprising a host device and a small memory card that operates according to a command transmitted from the host device,
The above small memory card
A receiving device for receiving a command or data signal transmitted from the host device;
A nonvolatile memory control device for controlling the nonvolatile memory based on the command;
A transmission device that has a function of switching drive capability, and that transmits a response to the command or a data signal read from the nonvolatile memory to the host device;
A drive capability switching automatic detection device that monitors the signal waveform of the output signal of the transmission device and determines the optimum value of the drive capability of the transmission device;
The drive capability switching automatic detection signal determined by the drive capability switching automatic detection device is temporarily stored, and the drive capability switching automatic detection signal is temporarily stored in the nonvolatile memory after a predetermined time has elapsed. A device comprising:
A small memory card system. The small memory card system according to claim 1 or 2,
The transmission device uses a variable current source to continuously change the current amount of the output signal to switch the drive capability.
A small memory card system. The small memory card system according to claim 1 or 2,
The transmission device switches the drive capability by discretely varying the amount of output signal current using two or more constant current sources connected in parallel.
A small memory card system. The small memory card system according to claim 1 or 2,
The transmission device changes the slew rate of the output signal and switches the drive capability.
A small memory card system. The small memory card system according to claim 1 or 2,
The transmission device changes the power supply voltage of the output signal and switches the drive capability.
A small memory card system. The small memory card system according to claim 1 or 2,
The drive capability switching automatic detection device detects an overshoot voltage and an undershoot voltage of the output signal of the transmission device, and compares the detected voltage value with a reference value to determine the drive capability of the transmission device. To control the
A small memory card system. The small memory card system according to claim 1 or 2,
The drive capability switching automatic detection device performs a fast Fourier transform on the output signal of the transmission device, and controls the drive capability of the transmission device based on a result of comparing the converted result with a reference value.
A small memory card system. In a small memory card system comprising a host device and a small memory card that operates according to a command transmitted from the host device,
The host device is
A transmission device having a function of switching drive capability, and transmitting a command or data signal to the small memory card;
A drive capability switching automatic detection device that monitors the signal waveform of the output signal of the transmission device and controls the transmission device so as to optimize the drive capability;
A response transmitted from the small memory card, or a data signal, and a receiving device for receiving,
A small memory card system. The small memory card system according to claim 9,
The transmission device uses a variable current source to continuously change the current amount of the output signal to switch the drive capability.
A small memory card system. The small memory card system according to claim 9,
The transmission device switches the drive capability by discretely varying the amount of output signal current using two or more constant current sources connected in parallel.
A small memory card system. The small memory card system according to claim 9,
The transmission device changes the slew rate of the output signal and switches the drive capability.
A small memory card system. The small memory card system according to claim 9,
The transmission device changes the power supply voltage of the output signal and switches the drive capability.
A small memory card system. The small memory card system according to claim 9,
The drive capability switching automatic detection device detects an overshoot voltage and an undershoot voltage of the output signal of the transmission device, and compares the detected voltage value with a reference value to determine the drive capability of the transmission device. To control the
A small memory card system. The small memory card system according to claim 9,
The drive capability switching automatic detection device performs a fast Fourier transform on the output signal of the transmission device, and controls the drive capability of the transmission device based on a result of comparing the converted result with a reference value.
A small memory card system. The small memory card system according to claim 1, claim 2, or claim 9.
A termination resistor is connected between the signal line between the host device and the small memory card and the ground;
A small memory card system. The small memory card system according to claim 1, claim 2, or claim 9.
A low-pass filter is inserted into the signal line between the host device and the small memory card;
A small memory card system. In a small memory card system comprising a host device and a small memory card that operates according to a command transmitted from the host device,
A termination resistor is connected between the signal line between the host device and the small memory card and the ground;
A small memory card system. In a small memory card system comprising a host device and a small memory card that operates according to a command transmitted from the host device,
A low-pass filter is inserted into the signal line between the host device and the small memory card;
A small memory card system.

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