JP2005327210A - Electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent data corruption of a flash memory when battery power is lowered while writing data in a non-volatile memory in an electronic device having the non-volatile memory. <P>SOLUTION: When power of the battery 10 is lowered below predetermined voltage while writing the data in the flash memory 100, power is supplied to a CPU 90, the flash memory 100 and a RAM 100 with charged voltage of capacitors 80, 81, the CPU 90 compares time until the charged voltage becomes below operation voltage by which writing is maintained with time until the writing is completed, when it is judged that the writing can be completed, continues the writing until it is completed as it is. On the other hand, corruption of the data to be written in the flash memory 100 is prevented by interrupting the writing when it is judged that the writing can not be completed by the charged voltage by the capacitors 80, 81, and by restarting the writing from an interrupted place when power of the battery 10 is restored. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic device including a nonvolatile memory capable of writing data.

In recent years, for example, in a vehicle electronic device, the latest software can be written and updated in a nonvolatile memory such as a flash memory via a LAN in a vehicle mounted state. However, if the battery voltage drops while the data is being written to the nonvolatile memory or the electronic device is turned off, the operating voltage for writing data to the nonvolatile memory cannot be maintained and There is a problem that it can not be done normally. In the invention described in Patent Document 1, the power supplied from the battery is stored by adopting a capacitor. If the accessory switch is turned off while data is being written to the nonvolatile memory, the power is stored in the capacitor. The interruption of data writing is avoided by supplying the remaining power to the nonvolatile memory for a certain period.
JP 2003-241863 A

  However, the invention described in Patent Document 1 assumes that writing to the nonvolatile memory is completed by the power stored in the capacitor. For example, if the amount of data to be written is large and only the power of the capacitor is used. If writing to the end is impossible, writing still cannot be performed normally.

  In view of the above problems, the present invention performs normal writing regardless of the amount of data to be written even if the battery voltage drops while writing data to the nonvolatile memory, thereby destroying the data. An object of the present invention is to provide an electronic device capable of preventing the above-described problem.

  An electronic device according to claim 1 is a battery for supplying an operating voltage, stores data, and a nonvolatile memory in which data to be stored is written when the operating voltage is supplied from the battery, and a battery Is supplied with an operating voltage, recognizes a scheduled write completion time according to the amount of data to be written, writes control means for writing data to the nonvolatile memory, power supply detection means for detecting battery voltage, and battery Switching means for switching between conduction and interruption with respect to supply of the operating voltage from the battery, and when the power supply detection means detects that the battery has become a predetermined voltage or less. The switching means is in a cut-off state, and is controlled so as to be in a conductive state when the voltage exceeds a predetermined voltage. And a power supply means for supplying power for maintaining a write to the nonvolatile memory for a predetermined time when the switching means is in a shut-off state, the write control means switching means in the middle of writing data to the nonvolatile memory Is interrupted, if the scheduled data write completion time is longer than a predetermined time for supplying power that the power supply means can maintain writing, the data writing is interrupted.

  As described above, the electronic device according to claim 1 detects when the voltage of the battery becomes equal to or lower than a predetermined voltage while data is being written to the nonvolatile memory, and detects it for a predetermined time by another power supply source. By supplying power to the non-volatile memory, the operating voltage is secured and abnormal termination of writing is avoided. If the writing from the power supply source can be completed to the end with respect to the remaining amount of data to be written, the writing is continued as it is and completed to the end. On the other hand, if the writing cannot be completed to the end even by the power supply source, the writing is interrupted halfway to avoid data destruction due to abnormal termination of writing.

  In the electronic device according to claim 2, when the writing control unit interrupts the writing of data to the nonvolatile memory, the writing control unit writes information regarding the writing interruption to a predetermined address of the nonvolatile memory, and then the voltage of the battery is When the voltage is restored to a predetermined voltage or higher, the writing is resumed from the point where the writing is interrupted based on the information regarding the interruption of writing.

  As described above, in the electronic device according to claim 1, when writing is temporarily interrupted, information related to the writing interruption (for example, an address of the nonvolatile memory in which writing is completed) is stored, and then writing is performed. When resuming, the information can be read to resume from where the writing was interrupted.

  The electronic device according to claim 3 is characterized in that the nonvolatile memory is a flash memory.

  In this way, by using flash memory as a non-volatile memory, data can be written and erased electrically, eliminating the need for a power source for data retention, contributing to equipment miniaturization, weight reduction, and power saving. it can.

  In the electronic device according to claim 4, the power supply means stores the power supplied from the battery via the switching means, and supplies the stored power to the nonvolatile memory for a time corresponding to the stored power. It is characterized by that.

  As a result, it is not necessary to prepare a backup power supply device separately from the battery, so that the device can be made compact.

  As in the electronic device according to claim 5, a capacitor may be used as means for storing electric power. Thereby, it is realizable with a simple structure as an electric power supply means.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the present embodiment, a vehicle electronic device mounted on a vehicle will be described as an example of the electronic device.

  FIG. 1 is a block diagram showing a schematic configuration of a vehicle electronic device 200 according to an embodiment of the present invention. As shown in the figure, the vehicle electronic device 200 includes a battery 10, a switch 20, resistance elements 30, 31, a protection circuit 32, an A / D converter 40, a power control CPU 50, a semiconductor switch 60, a power circuit 70, The capacitors 80 and 81, the CPU 90, the RAM 110, and the flash memory 100 are configured.

  The battery 10 is a power supply source for operating the vehicle electronic device 200. For example, when the vehicle electronic device 200 is a navigation device, electric power is supplied into the device by the battery 10, and the current position of the vehicle can be detected and displayed on the screen. In general, an electronic device for a vehicle is operated by being supplied with electric power from a lead storage battery having an output voltage of 12 V mounted on the vehicle. In the present invention, the battery 10 is included as a constituent element of the invention. However, an external battery may be used as long as it can supply power as described above.

  The switch 20 is provided to supply or cut off the electric power of the battery 10 to the vehicle electronic device 200. By turning on the switch 20, the vehicle electronic device 200 can receive a supply of electric power from the battery 10 and perform a predetermined operation. Examples of the switch 20 include a switch that is automatically turned ON when the engine is started, a switch ON / OFF switch by a remote control operation, a switch by a direct user operation, and the like.

  The CPU 90 receives a predetermined operating voltage from the battery 10 and executes control processing related to various operations of the vehicle electronic device 200. In particular, the present invention plays a role as a write control unit that reads or writes data stored in the flash memory 100 or the RAM 110 or interrupts the writing. The data to be written in this embodiment includes an execution program for upgrading the version of the vehicle electronic device, and the data is read from the writing device 300 provided outside the vehicle electronic device and stored in the flash memory 100. To do. As the writing device 300, a device corresponding to a supply source of data to be written, such as a CD-ROM or a DVD-ROM driving device, can be considered.

  The flash memory 100 is a kind of non-volatile memory, and is an element capable of storing data such as a control program for an electronic device. In addition, as a nonvolatile memory, there is a ROM (Read Only Memory). When writing data, the flash memory 100 needs to be supplied with an operating voltage for maintaining the writing from the outside, and once the data is written, the data can be retained even without power supply. Can do. In the present embodiment, the flash memory 100 includes a control program that controls writing of data to the flash memory 100, other control programs that control the operation of the vehicle electronic device 200 other than writing, and data other than the control program (for example, In the case of a navigation device, current position data, route data to a destination, etc.) are stored (FIG. 2).

  On the other hand, the RAM 110 is a kind of volatile memory, such as DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory). The RAM 110 can store data in the same manner as the flash memory 100, but generally has a higher degree of integration and storage speed than a nonvolatile memory. In addition, since it is necessary to secure a predetermined operating voltage to hold the stored data, if the voltage of the battery 10 of the electronic device 200 decreases or the switch 20 is turned off, the stored data is deleted. End up. Therefore, data accompanying the control process of the CPU 90 is temporarily stored in the RAM 110. In this embodiment, when data is written to the flash memory 100, the CPU 90 reads the write control program stored in the flash memory 100, and transfers the program to the RAM 110 for writing.

  The power supply circuit 70 converts the power supplied from the battery 10 into an operable voltage for the CPU 90, the flash memory 100, and the RAM 110, and outputs the converted voltage. Generally, electric power for a vehicle is supplied from a DC 12V battery mounted on the vehicle, but an operating voltage for operating a CPU or the like of the electronic device is a predetermined value (for example, lower than the battery voltage). 5V), and the normal battery voltage and the operating voltage of the CPU are different. Therefore, also in this embodiment, the operating voltage supplied from the battery 10 is converted (DC-DC conversion) by the power supply circuit 70.

  Capacitors 80 and 81 can store electric power supplied from the battery 10. If the voltage of the battery 10 decreases, the stored electric power is supplied to the CPU 90, the flash memory 100, and the RAM 110 instead for a predetermined time. To do. As a result, if the voltage of the battery 10 decreases while data is being written to the flash memory 100, the writing can be continued for a predetermined time without abnormal termination.

  The predetermined time is determined by the charging voltage of the capacitors 80 and 81, the power consumption of the capacitors 80 and 81, the CPU 90, the flash memory 100, and the RAM 110. Therefore, when data is written to the flash memory 100 by the charging voltages of the capacitors 80 and 81, it is possible to predict in advance how long the data can be written.

  Capacitor 80 and capacitor 81 are both the same in the meaning of the above-mentioned role, but by providing these two capacitors, more power can be stored than when only one capacitor is provided. The power can be supplied to the CPU 90, the flash memory 100, and the RAM 110 for a long time. However, it is not necessary to provide two capacitors as in the present embodiment.

  The power control CPU 50 turns on and off the semiconductor switch 60 according to the voltage value of the battery 10 and informs the CPU 90 of the information. As a result, when the voltage value of the battery 10 becomes a predetermined value or less, the semiconductor switch 60 is turned OFF (shut off state) to prevent the data stored in the flash memory 100 from being destroyed due to the abnormality of the battery. On the other hand, the power supply source to the CPU 90, the flash memory 100, and the RAM 110 can be switched to the capacitors 80 and 81. Thereafter, when the battery 10 recovers to a predetermined voltage, the power supply control CPU detects it and turns on the semiconductor switch 60 (conducting state).

  The semiconductor switch 60 may be a mechanical relay as long as it switches between the battery 10 and the CPU 90, the flash memory 100, and the RAM 110. The semiconductor switch 60 includes a bipolar transistor and a field effect transistor (FET).

  Hereinafter, means for the power supply control CPU 50 to recognize the battery voltage value will be described.

  The voltage of the battery 10 is divided into a predetermined voltage by the resistance elements 30 and 31, and the divided voltage is converted from an analog value to a digital value by the A / D converter 40. The power supply control CPU 50 receives the digital signal, and determines whether the semiconductor switch 60 is ON or OFF based on the signal. The protection circuit 32 limits the input voltage to, for example, a predetermined upper limit voltage or less in order to prevent the A / D converter from being damaged by the abnormal voltage if the voltage of the battery 10 increases abnormally. is there.

  Hereinafter, in the present embodiment, when the voltage of the battery 10 decreases during the writing of data to the flash memory 100 or the switch 20 is turned OFF, the means for protecting the data being written is shown in the flowchart and FIG. 4 will be described.

  First, in step S10, the power supply control CPU 50 determines whether or not the voltage of the battery 10 is equal to or lower than a predetermined voltage V1. Note that the means for recognizing the voltage of the battery 10 is as described above. Here, if it is determined that the voltage of the battery 10 is not equal to or lower than the predetermined voltage V1 (negative determination), it is determined that the battery 10 is normal, and no special data protection processing is performed.

  On the other hand, if it is determined (affirmative determination) that the voltage has become equal to or lower than the predetermined voltage V1, it is determined that the voltage of the battery 10 has decreased or the switch 20 of the vehicle electronic device 200 has been turned off, and the process proceeds to step S20 ( FIG. 4 (1)).

  In step S20, a process for turning off (shut off) the semiconductor switch 60 is performed based on an instruction from the power supply control CPU 50, and the process proceeds to the next step S30 (FIG. 4 (2)). This prevents destruction of data stored in the flash memory 100 due to battery abnormality. Further, as the semiconductor switch 60 is shut off, the electric power stored in the capacitors 80 and 81 is discharged to the CPU 90, the flash memory 100, and the RAM 110 (FIG. 4 (3)).

  The semiconductor switch 60 is a bipolar transistor or a field effect transistor (FET) that is turned off (cut off) when receiving a low level signal from the power control CPU 50 and turned on (conductive) when receiving a high level signal. Is called.

  In step S <b> 30, the CPU 90 determines whether data is being written to the flash memory 100. Here, when it is determined that writing is not in progress (negative determination), no special processing is performed.

  On the other hand, if it is determined that writing is in progress (positive determination), the process proceeds to step S40.

  In step S <b> 40, the CPU 90 determines whether or not the data being written can be completely written by supplying power from the capacitors 80 and 81. That is, the write completion scheduled time T2 in FIG. 4 (4) is larger or smaller than the time T1 (hereinafter referred to as the discharge time T1) until the charging voltage of the capacitors 80 and 81 is discharged to the minimum voltage Vmin that can maintain the writing. Compare Here, the minimum voltage Vmin at which the charging voltages of the capacitors 80 and 81 can maintain the writing is determined from the operating voltage of the flash memory 100, the operating voltage of the CPU 90, and the operating voltage of the RAM 110. As described above, the time T1 until the charging voltage of the capacitors 80 and 81 is discharged to the minimum voltage at which writing can be maintained is the charging voltage of the capacitors 80 and 81 and the capacitors 80 and 81 and the CPU 90, the flash memory 100, and the RAM 110. The CPU 90 recognizes the scheduled write completion time T2 in advance from the amount of data to be written and the writing speed. The write completion scheduled time T2 may be calculated by the CPU 90 based on the amount of data to be written or the like, or may be given to the CPU 90 together with the data to be written by the writing device 300.

  Here, when the write completion scheduled time T2 is shorter than the discharge time T1 as shown in FIG. 4 (4b) (No in step S40), the write process is continued and the write is completed to the end (FIG. 3, step S70, S80).

  On the other hand, when the scheduled write completion time T2 is longer than the discharge time T1 as shown in FIG. 4 (4a) (Yes determination in step S40), the process proceeds to step S50 in order to interrupt the writing process.

  In step S50, when the writing is interrupted, information regarding the interruption (interruption flag) is written in a predetermined address of the flash memory 100. Thereafter, the writing process is interrupted (step S60). The timing for interrupting the writing may be interrupted before the charging voltage of the capacitors 80 and 81 becomes equal to or lower than the minimum voltage Vmin that can maintain the writing. Note that a written address is added to the interruption flag. Thereby, when the battery 10 is recovered, the presence or absence of the interruption flag is checked, and when the interruption flag is written, writing can be resumed from the address next to the address added to the interruption flag.

  Hereinafter, processing for resuming writing that has been interrupted when the battery 10 recovers will be described with reference to the flowchart of FIG. 5.

  In step S90, the power supply control CPU 50 determines whether or not the voltage of the battery 10 is equal to or higher than a predetermined voltage V1. The determination process is the same as the process in step S10 in FIG.

  Here, when it is determined that the voltage of the battery 10 is not equal to or higher than V1 (negative determination), it is determined that the battery 10 has not yet recovered and enters a standby state.

  On the other hand, when the power supply control CPU 50 determines (affirmative determination) that the voltage of the battery 10 has become equal to or higher than the predetermined voltage V1, it determines that the battery 10 has recovered and proceeds to the next step (step S100).

  In step S100, a process of turning on (conducting) the semiconductor switch 60 based on an instruction from the power supply control CPU 50 is performed, and the process proceeds to the next step S110. Thereby, the supply of the power of the battery 10 to the CPU 90, the flash memory 100, and the RAM 110 is resumed.

  In step S110, it is determined whether or not an interruption flag is written at a predetermined address of the flash memory 100. If it is determined that the interruption flag has not been written (negative determination), it is determined that the writing has not been interrupted before.

  On the other hand, if it is determined that the interruption flag has been written (affirmative determination), it is determined that the writing has been interrupted before, and processing is performed in subsequent steps (steps S120 and S130) in order to resume writing. Proceed.

  In step S120, data transmission from the writing device 300 is started by transmitting a write request to the writing device 300, and writing is resumed from the address next to the written address added to the interruption flag checked in step S110. To do. The writing process is continued until all data is written to the flash memory 100 (step S130).

  As described above, in the present embodiment, for example, the voltage of the battery 10 is reduced to a predetermined voltage or lower while data such as a control program is written in the flash memory 100 by upgrading the version of the vehicle electronic device 200 or mounting in the factory. In the case of a decrease, the time T1 when the write voltage can be maintained is reduced to a time T1 that is lower than the minimum voltage Vmin, and the time T2 until the write is completed is determined. In such a case, the data in the flash memory 100 can be prevented from being destroyed by temporarily interrupting it. Further, when the battery 10 is recovered thereafter, the writing can be resumed from the point where the writing was interrupted. If the voltage of the battery 10 drops below a predetermined voltage before the capacitors 80 and 81 are fully charged, the above-described write data protection process is performed according to the discharge time T1 corresponding to the charge amount of the capacitors 80 and 81 at that time. I do.

It is a block diagram which shows schematic structure of the electronic device for vehicles concerning this embodiment. FIG. 3 is a diagram showing a data storage status of the flash memory 100 according to the present embodiment. 6 is a flowchart showing a write continuation or interruption process when a voltage drop of the battery 10 occurs while writing data to the flash memory 100 according to the present embodiment. FIG. 4 is a diagram illustrating each operation of writing to the battery 10, the semiconductor switch 60, the capacitors 80 and 81, and the flash memory 100 according to the present embodiment. It is a flowchart which shows the restart process of writing in case the battery 10 recovers after writing interruption concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 200 Vehicle electronic device 10 Battery 20 Switch 30 Resistance element 31 Resistance element 32 Protection circuit 40 A / D converter 50 Power supply control CPU
60 Semiconductor Switch 70 Power Supply Circuit 80 Capacitor 81 Capacitor 90 CPU
100 flash memory 110 RAM
300 writing device

Claims (5)

A battery for supplying an operating voltage;
A non-volatile memory for storing data, in which data to be stored is written when an operating voltage is supplied from the battery;
A write control unit that is supplied with an operating voltage from a battery, recognizes a scheduled write completion time according to the amount of data to be written, and writes data to the nonvolatile memory;
Power detection means for detecting the voltage of the battery;
Switching means provided between the battery and the non-volatile memory, and switching between conduction and interruption with respect to supply of an operating voltage from the battery;
Switching control for controlling the power supply detection means so that the switching means is in a cut-off state when it detects that the battery is lower than a predetermined voltage, and is in a conduction state when it is higher than the predetermined voltage. Means,
Power supply means for supplying power that can maintain the writing to the nonvolatile memory for a predetermined time when the switching means is cut off;
The write control means is a predetermined time for supplying the power for the power supply means to maintain the writing when the switching means is interrupted while the data is being written to the nonvolatile memory. The electronic device is characterized in that the writing of the data is interrupted if the length is longer than that.   The write control means writes information relating to the write interruption to a predetermined address of the non-volatile memory when interrupting the writing of data to the non-volatile memory, and then the voltage of the battery is restored to a predetermined voltage or higher. 2. The electronic device according to claim 1, wherein the writing is resumed from the point where the writing is interrupted based on the information regarding the interruption of writing.   The electronic device according to claim 1, wherein the nonvolatile memory is a flash memory.   The power supply means stores the power supplied from the battery via the switching means, and supplies the stored power to the nonvolatile memory for a time corresponding to the stored power. The electronic device according to any one of 1 to 3.   The electronic device according to claim 4, wherein the power supply unit is a capacitor.

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