JP2010218003A - Medium controller - Google Patents

Abstract

A media controller for protecting a medium from overcurrent is provided.
A media controller 100 that is mounted on a host device and controls transmission / reception of data between the host device and a medium connected to the host device, the switch 31 switching on / off of power supply to the medium; An overcurrent detection circuit 32 that detects an overcurrent flowing from the switch to the medium, and a media control that outputs a power control signal that starts power supply when the medium is connected to the host device. Unit 2 and a power control unit 4 that controls on / off switching of the switch in accordance with the power control signal, and the power control unit 4 detects the first current after the overcurrent detection circuit detects the overcurrent. The switch is switched from on to off when a predetermined time has elapsed.
[Selection] Figure 1

Description

  The present invention relates to a media controller that controls media such as a memory card.

  A host device (for example, a personal computer) that transmits / receives data to / from a medium (for example, a memory card) includes a media controller that controls read / write of the medium, and a power switch that switches on / off power supply to the medium. I have. The medium is connected to the host device and operates when power is supplied from the power switch of the host device, and transmits and receives data to and from the host device.

  Further, in the field of inverters for driving motors, there is an overcurrent protection circuit that prevents an overcurrent from flowing to a power switching element that constitutes an inverter unit and destroying the power switching element (see Patent Document 1). This overcurrent protection circuit detects the overcurrent flowing through the inverter unit, and when the overcurrent continuously flows for a predetermined time and the rate of change of the overcurrent value becomes smaller than the predetermined value, the power switching The element gate input is shut off. That is, the output of the power switch is controlled based on signals from the overcurrent protection circuit and the timer circuit.

  Various types of memory cards such as PC cards, SD cards, Memory Sticks, and xD_Pictures are manufactured by manufacturers as media for storing data. Since the characteristics of the media vary from manufacturer to manufacturer, overcurrent may continue to flow from the host device to the media while the media is operating, depending on the characteristics of the media. If overcurrent continues to flow, the media may be destroyed. However, there is no function for protecting the media from overcurrent in the conventional host device.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a media controller that protects media from overcurrent.

  The present invention is a media controller that is mounted on a host device and controls transmission / reception of data between the host device and a medium connected to the host device, and includes a switch that switches on / off of power supply to the medium, and a switch An overcurrent detection circuit that detects an overcurrent flowing through the medium; a media control unit that outputs a power control signal that starts supplying power when the medium is connected to a host device; and a power A power control unit that controls on / off switching of the switch in accordance with the control signal, and the power control unit detects when the first predetermined time has elapsed since the overcurrent detection circuit detected the overcurrent. The switch is switched from on to off.

  The first predetermined time may be set by the user.

  The power control unit switches the switch when the first predetermined time has elapsed after the overcurrent detection circuit detects the overcurrent only when the second predetermined time has elapsed since the start of power supply to the medium. Switching from on to off may be performed.

  The second predetermined time may be set by the user.

  An I / O cell that transmits data to the medium and receives data transmitted from the medium may be further provided, and power output from the power switch may be supplied to the I / O cell.

  The power control unit outputs an error interrupt signal to the media control unit when the first predetermined time has elapsed after the overcurrent detection circuit detects the overcurrent, and the media control unit receives the error interrupt signal from the power control unit. When an error interrupt signal is received, an error interrupt signal may be output to the host device.

  You may further have a test control part which controls at least one among a power switch, a power control part, and a media control part, and tests the operation | movement of a power switch.

  According to the present invention, a power switch is provided that includes a switch that switches on / off of power supply to a medium and an overcurrent detection circuit that detects an overcurrent flowing through the medium, and the overcurrent detection circuit detects an overcurrent for a predetermined time or more. Is detected, the power supply to the media is stopped. Therefore, it is possible to prevent the overcurrent from continuing to flow through the medium and destroy the medium due to the overcurrent. That is, the media can be protected from overcurrent.

The block diagram which shows the media controller of embodiment of this invention Flow chart showing control by power control unit of media controller Timing chart showing various waveforms

  A media controller according to an embodiment of the present invention is provided in a host device (in this embodiment, a personal computer) and controls media (in this embodiment, a memory card) connected to the host device. It is characterized by having a function of protecting from overcurrent.

1. Configuration of Media Controller FIG. 1 shows a media controller of this embodiment and media controlled by the media controller. The media 200 controlled by the media controller 100 is a memory card such as a PC card, an SD card, a Memory Stick, and xD_Picture.

  The media controller 100 includes an I / O cell group 1 that performs data input / output and a media control unit 2 that controls data input / output of the I / O cell group 1. The I / O cell group 1 is electrically connected to the medium 200, transmits data in the host device to the medium 200, and receives data transmitted from the medium 200. Based on the control of the host device, the media control unit 2 transmits the data in the host device to the medium 200 via the I / O cell group 1 and transmits the data input to the I / O cell group 1 to the host device. Transmit internally. The media control unit 2 further outputs a power control signal for controlling start / stop of power supply to the media 200. Specifically, when the media control unit 2 detects that the media 200 is connected to the I / O cell group 1, the media control unit 2 outputs a power control signal for starting power supply to the media 200, and the media 200 is disconnected. When it is detected that the state has been reached, a power control signal for stopping the power supply to the medium 200 is output. Further, when an error interrupt signal is input, the media control unit 2 performs error processing in the media control unit 2 and outputs an error interrupt signal to the host device. The host device that has received the error interrupt signal performs error processing by the driver in the host device using the error interrupt signal as a trigger. For example, the media control unit 2 stops data transmission / reception.

  The media controller 100 further includes a power switch 3 that switches on / off power supply to the medium 200, a power control unit 4 that controls the power switch 3 based on a power control signal output from the media control unit 2, Have Based on the switch switching signal output from the power control unit 4, the power switch 3 measures the potential difference between the switch 31 that switches on / off the power supply to the medium 200 and both ends of the switch 31, thereby An overcurrent detection circuit 32 for detecting a flowing overcurrent. In the present embodiment, the switch 31 is a transistor. When the switch 31 is on, the power supply voltage Vcc is supplied to the medium 200. At the same time, the power supply voltage Vcc is supplied to the I / O cell group 1. Since the power switch 3 is built in the media controller 100, the power of the I / O cell group 1 can be supplied from the inside of the media controller 100, and external power is input to the I / O cell group 1. Power supply input terminals are not required. When the overcurrent detection circuit 32 detects that an overcurrent flows through the medium 200, the overcurrent detection circuit 32 outputs an error signal indicating that the overcurrent is flowing.

  The power control unit 4 includes a power switching unit 41 that outputs a switch switching signal for switching on / off of the switch 31 according to the power control signal output from the media control unit 2, and a counter 42 that counts time using an internal clock. And having. The media controller 100 further includes a register 6 that stores predetermined threshold values respectively indicating the predetermined time α and the predetermined time β. The predetermined time α is a threshold for ignoring an error signal output from the overcurrent detection circuit 32 immediately after the power supply is started, and is 16 msec in the present embodiment. The predetermined time β is a threshold value for setting the stop of power supply based on the overcurrent detection time, and is 8 msec in the present embodiment. If the predetermined time β is too long, the medium 200 may be destroyed. If the predetermined time β is too short, the medium cannot be stably operated. Therefore, the length of the predetermined time β allows the medium 200 to operate stably. In addition, it is preferable to set the time to prevent destruction of the media 200.

  The counter 42 counts the time T1 from the input of the power control signal instructing the start of power supply and the time T2 during which the error signal is output from the overcurrent detection circuit 32 using the internal clock. . Note that the internal clock used by the counter 42 is not stopped under other operating conditions, but may be stopped when the power of the medium is OFF. The power switching unit 41 compares the threshold value stored in the register 6 with the count value of the counter 42 and controls the output of the switch switching signal and the error interrupt signal. Specifically, the power switching unit 41 has a time T1 after inputting a power control signal instructing the start of power supply (that is, a time after outputting a switch switching signal for turning on the switch 31). When the predetermined time α is exceeded and the time T2 during which the error signal is input exceeds the predetermined time β, a switch switching signal for turning off the switch 31 is output to the power switch 3. At the same time, an error interrupt signal is output to the media control unit 2.

  In the above configuration, the overcurrent detection circuit 32, the power switching unit 41, the counter 42, and the register 6 realize the overcurrent protection function in the present embodiment.

  The media controller 100 further includes a test control unit 5 that tests the operation of the power switch 3 by controlling the power switch 3, the power control unit 4, and the media control unit 2. The test control unit 5 controls the power control unit 4, the power switch 3, and the media control unit 2 to test whether the power switch 3 operates normally before the host device is shipped. Specifically, for example, the test control unit 5 causes the overcurrent detection circuit 32 to forcibly output an error signal. In addition, the power control signal for instructing the start of power supply to the media control unit 2 is forcibly output, or the switch control signal for forcibly turning on the power control unit 4 is forcibly output to force the switch 31. To turn on. At this time, the threshold value indicating the predetermined time α and the predetermined time β stored in the register 6 may be set to various values to perform a test when an error occurs. For example, by increasing the values of the predetermined time α and the predetermined time β, even if an error signal is output from the power switch 3, the error signal is forcibly ignored, and a switch that instructs the switch 31 to turn on The switching signal may be continuously output.

2. Operation of Media Controller FIG. 2 shows control of the power control unit 4. When the medium 200 is inserted into the host device and electrically connected to the I / O cell group 1, the media control unit 2 outputs a power control signal that instructs the start of power supply to the medium 200. The power control unit 4 determines whether a power control signal instructing the start of power supply to the medium 200 from the media control unit 2 is input (S201). When a power control signal for instructing the start of power supply is input, the power control unit 4 outputs a switch switching signal for turning on the switch 31 (S202). As a result, the switch 31 is turned on, and power from the power supply voltage Vcc is supplied to the medium 200. Further, the counter 42 starts counting the time T1 after the power is supplied using the internal clock.

  When the overcurrent detection circuit 32 detects that an overcurrent flows through the medium 200, the overcurrent detection circuit 32 outputs an error signal. The power control unit 4 determines whether an error signal from the overcurrent detection circuit 32 has been input (S203). When the error signal starts to be input, the counter 42 starts counting the time T2 after the error signal is input. When an error signal is input, the power switching unit 41 compares the count value of the counter 42 with the threshold value of the register 6 and determines whether or not the time T1 after the start of power supply exceeds a predetermined time α (S204). .

  Immediately after the power supply is started, the ON resistance of the switch 31 is large, so that even if the current flowing through the medium 200 is small, the potential difference between both ends of the switch 31 is large. Therefore, the overcurrent detection circuit 32 that detects this large potential difference outputs an error signal. However, actually, an overcurrent does not flow through the medium 200. Therefore, when the time T1 after the start of power supply does not exceed the predetermined time α (No in S204), it can be determined that the error signal is not an error due to overcurrent. Therefore, the power control unit 4 continues to output a switch switching signal instructing to turn on the switch 31 (S202).

  On the other hand, when the time T1 after the start of power supply exceeds the predetermined time α (Yes in S204), it can be determined that the error signal output from the overcurrent detection circuit 32 is due to an overcurrent error. If an overcurrent continues to flow through the medium 200 for a long time, the medium 200 may be destroyed. Therefore, the power supply to the medium 200 must be stopped. On the other hand, depending on the type of media, a very short overcurrent may flow during the operation of the media, and the power supply to the media 200 is stopped each time the overcurrent flows. Cannot be operated. Therefore, the power control unit 4 compares the count value of the counter 42 with the threshold value of the register 6, and determines whether or not the time T2 after the error signal is input exceeds the predetermined time β (S205).

  If the time T2 after the error signal is input does not exceed the predetermined time β (No in S205), it can be determined that the medium 200 is not likely to be destroyed. The output continues (S202).

  If the time T2 after the error signal is input exceeds the predetermined time β (Yes in S205), it can be determined that the medium 200 may be destroyed, and therefore the power control unit 4 switches the switch 31 off. A switch switching signal is output (S206), and an error interrupt signal is output to the media control unit 2 (S207). As a result, the switch 31 of the power switch 3 is switched off based on the switch switching signal instructing to turn off. Therefore, no power is supplied to the medium 200. Also, the media control unit 2 that has received the error interrupt signal performs error processing in the media control unit 2 and outputs an error interrupt signal to the host device. As a result, the host device instructs the media control unit 2 to cancel data transmission / reception.

  FIG. 3 shows a timing chart of each waveform when the above control is performed. 3, (a) shows a switch switching signal output from the power control unit 4, (b) shows the power supplied from the power switch 3 to the medium 200, and (c) shows the power supplied from the power switch 3 to the medium 200. (D) shows an error signal output from the power switch 3, and (e) shows an error interrupt signal output from the power control unit 4.

At time t1, the medium 200 is inserted into the host device, and the media control unit 2 outputs a power control signal instructing the start of power supply. The power control unit 4 outputs a switch switching signal for turning on the switch 31 in accordance with the power control signal. Thereby, power supply from the power switch 3 to the medium 200 starts, and current starts to flow from the power switch 3 to the medium 200. Immediately after starting the power supply to the medium 200, the overcurrent detection circuit 32 outputs an error signal (time t1 to time t2). However, since this error signal is not due to an overcurrent, the power control unit 4 does not output an error interrupt signal until the time T1 after the start of power supply exceeds the predetermined time α.

  An overcurrent has occurred at time t3. However, since the time T2 during which the overcurrent flows is shorter than the predetermined time β, the power control unit 4 does not output an error interrupt signal (time t3 to time t4).

  At time t5, overcurrent occurs again. Since the time T2 during which the overcurrent flows at this time exceeds the predetermined time β, the power control unit 4 outputs an error interrupt signal and switches off the switch 31 (time t6).

  As described above, according to the present embodiment, the power supply to the switch 31 is stopped when the overcurrent continues to flow beyond the predetermined time β after the elapse of the predetermined time α from the start of power supply.

3. Summary According to the present embodiment, when the overcurrent continues to flow to the medium 200 for a predetermined time β, the switch 31 is turned off and the power supply to the medium 200 is stopped. Therefore, the medium 200 can be protected from overcurrent, and destruction of the medium 200 can be prevented. Further, when the time during which the overcurrent is flowing is equal to or shorter than the predetermined time β, the power supply to the medium 200 is continued. Thereby, the medium 200 can be operated stably without being affected by the characteristics of the medium 200.

  Further, according to the present embodiment, the power supply to the medium 200 is stopped even if an error signal is output from the overcurrent detection circuit 32 until the predetermined time α elapses after the power supply is started. Absent. Therefore, the medium 200 can be operated normally without being affected by the unstable output voltage when the power switch 3 rises.

  When the power switch 3 is externally attached to the media controller 100, a timer circuit using a CR delay or the like is required in order to measure the error signal output time. In this case, it is difficult to accurately measure the time due to variations in the elements of the timer circuit and ambient temperature changes. However, according to this embodiment, since the power switch 3 is built in the media controller 100, the internal clock can be used for measuring the output time of the error signal. Therefore, accurate time can be measured. Thereby, the continuation and stop of power supply can be controlled more accurately.

  According to this embodiment, since the power switch 3 is built in the media controller 100, the output voltage of the power switch 3 can be used as a power source for the media I / O cell group 1 by the internal wiring. Therefore, the power input terminals of the I / O cell group 1 can be reduced.

  According to the present embodiment, the error interrupt signal is output to the host device at the same time as the switch switching signal is switched off. Therefore, in the host device, the software controlling the media 200 can know that the power source of the media 200 has been turned off due to an overcurrent. As a result, the software that controls the media 200 can perform post-processing so that no abnormality occurs in the host device.

  In addition, since the test controller 5 is built in the media controller 100, the power switch 3 can be easily tested in the configuration in which the power switch 3 is built in the media controller 100. The power supply environment, for example, the power supply to the I / O cell group 1 and the power supply between the medium 200 and the power switch 3 vary depending on the application of the camera, personal computer, or the like and the type of media card to be connected. Therefore, it is necessary to perform a test of the power switch 3 itself and a test of the entire media card controller system. At this time, for example, when the power switch 3 is not built in the media controller 100, the operation test related to the power switch 3 and the power control unit 4 can only be performed independently, so that an accurate operation test cannot be performed. . Specifically, it is necessary to prepare terminals on the power switch side and the media controller side, and further, because the test is not synchronized for each application and media used, the test signal on the power switch side and the media clock side There is a need to synchronize and accurate media system testing cannot be performed accurately. However, according to the present embodiment, since the power switch 3 is built in the media controller 100, an operation test can be accurately performed. According to the present embodiment, regarding media card control in which a plurality of types of media cards can be mounted, the circuit related to power control can be handled with the same circuit configuration in any system, and more accurate power control and operation test are realized. can do. As described above, the media control device that realizes an accurate operation test includes a media controller circuit that supports a plurality of types of media cards, a power switch circuit that supplies power to the media cards, and a power that controls power supply of the power switch. The power switch circuit has a potential difference comparison circuit that compares the potential difference between the media controller side potential and the power source side potential, and the power control circuit has a comparison result of the potential difference comparison circuit exceeding a predetermined potential difference. Using a counter that counts the time based on the internal clock, the timing value of the register that stores the timing value that outputs the OFF signal is compared with the counter value to control the on / off of the power switch circuit and synchronize with the internal clock. Output test signals to the power control circuit and power switch circuit, Having a test circuit for performing.

  Note that the threshold values indicating the predetermined time α and the predetermined time β stored in the register 6 are not limited to the present embodiment. Further, the predetermined time α and the predetermined time β may be set by the user. Thereby, various media can be operated safely.

  According to the media controller of the present embodiment, the media can be protected from an overcurrent, and is useful for all host devices that transmit / receive data to / from the media.

DESCRIPTION OF SYMBOLS 1 I / O cell group 2 Media control part 3 Power switch 4 Power control part 5 Test control part 6 Register 31 Switch 32 Overcurrent detection circuit 41 Power switching part 42 Counter 200 Media

Japanese Patent No. 2998531

Claims (7)

A media controller that is mounted on a host device and controls transmission / reception of data between the host device and a medium connected to the host device,
A power switch comprising: a switch that switches on / off power supply to the medium; and an overcurrent detection circuit that detects an overcurrent flowing from the switch to the medium;
A media control unit for outputting a power control signal for starting supply of power when the media is connected to the host device;
A power control unit for controlling on / off switching of the switch according to the power control signal;
Have
The power controller is configured to switch the switch from on to off when a first predetermined time has elapsed since the overcurrent detection circuit detected an overcurrent.   The media controller according to claim 1, wherein the first predetermined time is set by a user.   When the first predetermined time has elapsed since the overcurrent detection circuit detected an overcurrent only when the second predetermined time has elapsed since the power control unit started supplying power to the medium The media controller according to claim 1, wherein switching of the switch from on to off is performed.   The media controller according to claim 3, wherein the second predetermined time is set by a user. An I / O cell that transmits data to the medium and receives data transmitted from the medium;
The media controller according to claim 1, wherein power output from the power switch is supplied to the I / O cell. The power control unit outputs an error interrupt signal to the media control unit when a first predetermined time has elapsed since the overcurrent detection circuit detected an overcurrent,
The media controller according to claim 1, wherein the media control unit outputs an error interrupt signal to the host device when receiving an error interrupt signal from the power control unit.   The media controller according to claim 1, further comprising a test control unit that controls at least one of the power switch, the power control unit, and the media control unit to test an operation of the power switch.

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