JP2007041798A - Information processor and memory rewriting method for information processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information processor and the memory rewriting method of the information processor for normally completing rewriting even when processing is interrupted due to power source disconnection or the like in temporarily preparing data for rewriting in a backup area in a nonvolatile memory, and rewriting the data of a rewriting object area by using the data for rewriting. <P>SOLUTION: A check sum 21 for verifying the reliability of a backup area 12a and a backup plug 22 for designating the writing object sector of a flash ROM 12 are written in a backup area 12a. When restart of power source disconnection, whether or not the data of the backup area 12a are normal is confirmed from the check sum 21. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an information processing apparatus such as a printer and a scanner and a memory rewriting method of the information processing apparatus, and more particularly to a rewriting method of a nonvolatile memory provided in the information processing apparatus.

  Conventionally, as information processing apparatuses, for example, a printer as an image recording apparatus that records an image on a sheet, a scanner as an image reading apparatus that reads an image recorded on a sheet, and the like are known. These information processing apparatuses execute image recording or image reading while communicating with a host computer by a CPU provided therein executing firmware.

  The firmware includes an execution program for controlling the information processing apparatus and reference value data that the execution program refers to at the time of execution, and is normally stored in a rewritable nonvolatile memory such as a flash ROM or an EEPROM. When adding new control to the information processing device to expand the function or to solve the problem of the existing firmware, the host computer sends rewrite data to the information processing device, and the data in the non-volatile memory The firmware is updated by rewriting.

  When updating firmware, data before rewriting is usually erased by rewriting. Therefore, when a power interruption occurs during data rewriting or a communication error occurs, incorrect data is written, causing the information processing apparatus to become inoperable.

  In order to solve this problem, the recording apparatus of Patent Document 1 is configured to determine whether rewriting has been normally performed, and to perform rewriting again when rewriting has not been completed normally. Yes.

  More specifically, the recording apparatus of Patent Document 1 includes a flash ROM having a user program area and a download program area for storing a rewrite program for rewriting the user program area. In the download mode (rewrite mode), the recording device creates a rewrite ROM image in the RAM using update data received from the host computer, and transfers the created ROM image from the RAM to the flash ROM. Rewrite the user program area. When the rewriting is completed, the checksum of the user program area is verified. If the checksum value is not normal, the flash ROM rewriting is performed again.

  In addition, when rewriting is interrupted due to power interruption or the like during rewriting of the user program area, the checksum of the user program area is verified in the process at startup, and if the checksum is abnormal, the host computer again The update data is received from, and the flash ROM is rewritten again.

  By the way, the recording apparatus described in Patent Document 1 is a system in which a ROM image is created in a RAM, which is a volatile memory, based on update data received from a host computer, and the flash ROM is rewritten with the created ROM image. . Therefore, if a power interruption or the like occurs during rewriting, rewriting cannot be executed unless data is received again from the host computer.

For this reason, some information processing apparatuses are configured to temporarily create rewrite data in a backup area in a nonvolatile memory and rewrite the data in the rewrite target area using this rewrite data. . By configuring in this way, even if writing is interrupted due to power interruption or the like when writing data from the backup area to the rewrite target area, if data is turned on again, data can be rewritten without receiving data again from the host computer. Can be executed.
JP 2005-63050 A

  However, if the rewrite data is temporarily created in the backup area and the data in the rewrite target area is rewritten using this rewrite data, the rewrite target area is set by the flag set in the backup area. Whether or not the data has been correctly written is checked. Depending on the timing of power-off, the rewrite target area may be rewritten with incorrect data due to this flag.

  Specifically, referring to FIG. 5, in the data rewriting in the flash ROM, the backup area is first set in the nonvolatile memory (for example, the flash ROM or the EEPROM) in a state where the information processing apparatus has shifted to the rewriting mode. The new write data received from the host computer is written to the backup area, and necessary information to be used after rewriting existing in the rewrite target area of the flash ROM is written to the backup area to generate write data ( Step S101).

  When write data is generated in the backup area, a backup flag indicating that writing to the rewrite target area is necessary is written at the end of the write data (step S102).

  Next, the sectors in the rewrite target area are collectively erased (step S104), and the write data in the backup area is written into the rewrite target area (step S105). When the rewriting to the rewriting target area is completed, the data in the backup area is deleted (step S105). By this erasure, the backup flag is also erased and the rewriting is completed.

  Here, let us consider a state in which the processing is interrupted due to power interruption or the like during the data erasing in step S105, and the backup flag is not yet erased. This state means that although the backup area data is incomplete, the backup flag exists, so the entire backup area still needs to be written to the rewrite target area. .

  In this state, when the information processing apparatus is restarted by turning on the power or the like, the data recovery process is resumed due to the presence of the backup flag (step S106).

  In this case, it is determined that data has not yet been written in the rewrite target sector, and the processing after step S104 is substantially resumed to erase the rewrite target sector (step S107). Then, the incomplete data existing in the backup area that was being erased is written to the rewrite target area (step S108). As a result, the data in the rewrite target area is destroyed and the firmware becomes incomplete. It cannot be recovered by itself.

  Further, for example, when the flag written in the backup area designates an area in which the data in the backup area is written, rewriting is interrupted due to a power interruption or the like during the erasing of the backup area in the above step S105, If rewriting is interrupted in the middle of writing the flag that specifies the area to which the data in the backup area is written, the flag may be erased halfway and the rewriting target area specified by the flag may be changed. Is done.

  To explain this, in the sector erase of the flash ROM, the data in the sector is sequentially rewritten to 0 with a certain regularity, and after all the bits become 0, the bits are randomly 1 and finally all The bit becomes 1. Accordingly, there are many states in which 0 and 1 are mixed in the flash ROM even during erasure, and the flag may be rewritten to an interpretable flag depending on the timing.

  In this way, if the flag is rewritten to an interpretable flag and the rewrite target area specified by the flag is changed, the intended rewrite target area is correctly rewritten, but the unintended area is newly rewritten. And incomplete data in the middle of erasing is written and destroyed in this area, resulting in incomplete firmware. Even in this case, it may be impossible for the user alone to recover.

  The present invention has been made in view of the above, and is configured to temporarily create rewrite data in a backup area in a nonvolatile memory and rewrite the data in the rewrite target area using this rewrite data. An object of the present invention is to provide an information processing apparatus and a memory rewriting method for the information processing apparatus that can complete rewriting normally even if the processing is interrupted due to power interruption or the like.

(1) a data transmission / reception unit for transmitting / receiving data to / from a host computer;
A drive unit that performs a predetermined operation;
A non-volatile memory having a plurality of sectors and storing firmware in the plurality of sectors;
Controlling the drive unit by executing firmware in the nonvolatile memory, and a control unit for rewriting the firmware based on data transmitted from the host computer,
When rewriting the nonvolatile memory, the control unit generates data for writing in a backup area in the nonvolatile memory based on data transmitted from the host computer, and verifies the reliability of the backup area. By writing a verification value and a flag designating the write target sector of the nonvolatile memory in the backup area, and writing the write data written in the backup area into the write target sector designated by the flag An information processing apparatus that performs rewriting of the nonvolatile memory and erases data in the backup area.
(2) After starting, the control unit determines the presence or absence of the flag, and if the flag exists, the designation of the flag is a predetermined definition area and the verification value is used to specify the backup area. The nonvolatile memory is rewritten by writing the write data written in the backup area to the write target sector specified by the flag only when the reliability is verified. The information processing apparatus according to (1).
(3) The information processing apparatus according to (1) or (2), wherein the verification value is a checksum calculated by a checksum method.
(4) The information processing apparatus according to (1) or 2, wherein the verification value is a CRC value calculated by a CRC method.
(5) The information processing apparatus according to any one of (1) to (4), wherein the nonvolatile memory is a flash ROM.
(6) A memory rewriting method for an information processing apparatus for rewriting firmware stored in a nonvolatile memory based on data transmitted from a host computer,
When rewriting the nonvolatile memory, generating write data in a backup area in the nonvolatile memory based on data transmitted from the host computer;
Calculating a verification value for verifying the reliability of the backup area, and writing to the backup area;
Writing a flag designating a write target sector of the nonvolatile memory to the backup area;
The step of rewriting the nonvolatile memory by writing the data for writing written in the backup area to the write target sector designated by the flag, and the step of erasing the data in the backup area. A memory rewriting method for an information processing apparatus.
(7) comprising a step of determining the presence or absence of the flag after activation;
When the flag is present, the writing for writing in the backup area is performed only when the designation of the flag is a predetermined domain and the reliability of the backup area is verified using the verification value. The memory rewriting method for an information processing apparatus according to (6), wherein the nonvolatile memory is rewritten by writing data to the write target sector designated by the flag.
(8) The memory rewriting method for an information processing apparatus according to (6) or (7), wherein the verification value is a checksum calculated by a checksum method.
(9) The memory rewriting method for an information processing apparatus according to (6) or (7), wherein the verification value is a CRC value calculated by a CRC method.
(10) The memory rewriting method for an information processing apparatus according to any one of (6) to (9), wherein the nonvolatile memory is a flash ROM.

  In the information processing apparatus of the present invention, when rewriting the nonvolatile memory, write data is generated in the backup area in the nonvolatile memory based on the data transmitted from the host computer. By configuring in this way, even if writing is interrupted due to power interruption or the like when writing data from the backup area to the rewrite target area, if data is turned on again, data can be rewritten without receiving data again from the host computer. Can be executed.

  In addition, the information processing apparatus of the present invention is configured to write a verification value for verifying the reliability of the backup area to the backup area in addition to the flag designating the write target sector of the nonvolatile memory. Therefore, even if the memory rewriting process is interrupted due to power interruption or the like, it is possible to determine that the data in the backup area is incomplete based on the verification value. Therefore, the problem of rewriting the nonvolatile memory with erroneous data does not occur, and the highly reliable nonvolatile memory can be rewritten.

As the verification value, a checksum calculated by the checksum method or a CRC value calculated by the CRC method can be suitably used.
In addition, this nonvolatile memory rewriting can be particularly suitably applied to flash ROM rewriting.

  Hereinafter, embodiments of an information processing apparatus and a memory rewriting method of the information processing apparatus according to the present invention will be described with reference to the drawings. In the following description, a printer is taken as an example of the information processing apparatus.

  FIG. 1 is a schematic block diagram showing the printer of this embodiment, FIG. 2 is a schematic diagram of the flash ROM of this embodiment, and FIG. 3 shows the flow of rewriting the flash ROM of this embodiment. FIG. 4 is a flow chart, and FIG. 4 is a schematic diagram for verifying the effect of rewriting the flash ROM of this embodiment.

  The printer 10 of the present embodiment is an image recording apparatus that is communicably connected to an external host computer 20, operates according to various commands transmitted from the host computer 20, and executes printing and image reading. The printer 10 mainly includes a CPU 11, a flash ROM 12, a RAM 13, a data transmission / reception unit 14, an operation unit 15, an EEPROM 16, and an image recording unit 17, which are electrically connected by an internal bus 60. Although FIG. 1 schematically illustrates that each unit is connected by a single internal bus 60, it may be connected by another configuration as long as each unit functions.

  The CPU 11 is a control center of the printer 10, and configures a control unit that controls the operation of each unit of the printer 10 by executing firmware written in the flash ROM 12.

  The flash ROM 12 is a non-volatile memory having a plurality of sectors and capable of electrically rewriting data. The flash ROM 12 stores printer control firmware, various setting values, and the like. In the flash ROM 12, when data is erased, data is erased collectively in units of sectors.

  The RAM 13 is a volatile storage area in the printer 10. In FIG. 1, one RAM 13 is schematically illustrated, but a plurality of RAM chips may be provided depending on the application. The RAM 13 is provided with a reception buffer for temporarily storing data received from the host computer, a print buffer for temporarily storing developed print data, an image buffer for storing image data, and the like.

  The data transmission / reception unit 14 is a control unit that communicates with the external host computer 20. Data received from the host computer 20 and data transmitted to the host computer 20 are all transmitted / received via this data transmitting / receiving unit.

  The operation unit 15 is a user interface such as a paper feed switch installed in the casing of the printer 10. When the operation unit 15 is operated, the printer 10 receives an instruction from the user and responds to the instruction. Operate.

  The EEPROM 16 is a non-volatile memory that can electrically rewrite data every 1 byte. For example, the EEPROM 16 stores a nonvolatile maintenance counter for holding a counter value even when the power is turned off.

  The image recording unit 17 includes a paper feed mechanism, a head drive mechanism, and a driver circuit for driving these. The image recording unit 17 executes printing according to various instructions and print data from the CPU 11 transmitted according to the firmware. In the present embodiment, the image recording unit 17 constitutes a drive unit that performs a predetermined operation.

  Next, the flash ROM 12 will be described with reference to FIG. As shown in FIG. 2, the flash ROM 12 has, for example, 10 sectors, and firmware or various setting values are stored in each sector. In the flash ROM 12 of this embodiment, the sector 10 is prepared as a general-purpose data storage area, and this sector 10 functions as a backup area 12a when data is rewritten in the flash ROM.

  The backup area 12a is an area in which rewriting data written to the rewriting target sector is temporarily created and held when the flash ROM 12 is rewritten. That is, in the present embodiment, the data for the sector to be rewritten is rewritten using the rewriting data. With this configuration, even when writing is interrupted due to power interruption or the like when data is written from the backup area to the sector to be rewritten, if the power is turned on again, the data is not received again from the host computer 20 without being received again. Write can be performed.

  In the backup area 12a, the checksum 21 and the backup flag 22 are stored at the end of the data.

  The checksum 21 is a verification value used for checking the reliability of the data in the backup area 12a. This checksum 21 is calculated when rewriting data is created in the backup area 12a, and inverts the sum obtained by adding words from the start address to the last address of the backup area 12a. It is the value.

  The backup flag 22 is set when the data for rewriting the backup area 12a is created, and has a value indicating in which sector the data in the backup area 12a should be written.

  In the above description, the backup area 12a is formed in the flash ROM 12. However, if a separate flash ROM or other nonvolatile memory exists, the backup area 12a may be provided there.

  Next, the flow of rewriting processing of the flash ROM in the present embodiment will be described with reference to FIGS.

  In the data rewrite in the flash ROM 12, the CPU 11 executes the rewrite program written in the RAM 13 from the flash ROM 12 or the flash ROM 12, whereby the flash ROM rewrite mode is activated and processing is performed in this mode.

  In this flash ROM rewrite mode, as shown in FIGS. 3 and 4, first, a backup area 12a is secured in the flash ROM 12, and new write data received from the host computer 20 is written into the backup area 12a. Necessary information to be used after rewriting existing in the rewriting target sector is written in the backup area 12a. As a result, write data is generated in the backup area 12a (step S1).

  When the write data is generated in the backup area 12a, the first address to the last address of the backup area 12a are added in units of words, and the inverted value is written as the checksum 21 in the backup area 12a (step). S2).

  When the checksum 21 is obtained, the backup flag 22 designating the sector number of the rewrite target sector is written at the end of the write data written in the backup area 12a (step S3).

  Next, the sectors of the sector to be rewritten are erased collectively (step S4), and the write data in the backup area 12a is written to the sector to be rewritten (step S5). When the writing to the sector to be rewritten is completed, the data in the backup area 12a is erased (step S6). When this erasure is completed, the backup flag 22 is also erased and the rewriting is completed.

  Here, let us consider a state in which the processing is interrupted due to power interruption or the like during the data erasing in step S6, and the backup flag 22 has not yet been erased. This state means that the data in the backup area 12a is still incomplete, but the backup flag 22 exists, so that the entire backup area 12a still needs to be written to the sector to be rewritten. is doing.

  In this state, when the information processing apparatus is restarted by turning on the power or the like, the presence / absence of the backup flag 22 and the checksum 21 are verified.

  First, when the backup flag 22 exists, the rewrite target sector specified by the backup flag 22 is specified. If the designation of the backup flag 22 is outside the predetermined domain, the backup flag 22 is regarded as invalid and no data recovery processing is performed.

  On the other hand, if the designation of the backup flag 22 is within a predetermined definition area, the data from the head address to the last address of the backup area 12a is added in units of words and stored in the backup area 12a in order to verify the data in the backup area 12a. The checksum 21 is summed and it is confirmed whether it becomes 0xFFFF (FIG. 5, step S7).

  Here, if 0xFFFF, it is determined that the data in the backup area 12a is normal, and the data recovery process is resumed. When the process is resumed, the processes from step S4 to step S6 are executed.

  However, in this case, the processing is interrupted due to power interruption or the like during the data erasing in step S6, and the backup flag 22 has not yet been erased. Accordingly, the comparison between the calculated value and the checksum 21 becomes 0xFFFF with a very low probability, and data writing from the backup area 12a to the rewrite target sector is not executed at this time. Therefore, it is possible to prevent the recorded data in the flash ROM 12 from being damaged, and to improve the reliability of the rewriting process and the printer processing system. In addition, since the flash ROM 12 is not rewritten so that it cannot be recovered by the user alone, the user's trouble can be prevented.

  Here, there may be a case where the checksum coincides with the calculated value by chance due to the power interruption, but the probability is 0% in the case of the power interruption during the writing of the backup flag, and the probability of the power interruption during the backup area erasing. In some cases, the probability is 0.000016% (in the case of a checksum of 16 bits). This is a sufficiently low probability as compared with the number of times of rewriting of the flash ROM 12 during the use period of the printer, and erroneous rewriting can be substantially prevented sufficiently.

  In the above description, the checksum method is used for calculating the verification value. However, the present invention is not limited to this, and other methods may be used as long as the reliability of the backup area 12a can be confirmed. An example of an alternative to the checksum method is the CRC method. In this CRC method, a cyclic algorithm (generator polynomial) is applied to generate redundant data (CRC value) called a CRC code from data in the backup area 12a, and an inverted value of the redundant data may be used as a verification value. This method is characterized by high detection accuracy of multi-bit errors. Even in this case, the basic processing flow is the same as that when a checksum is used.

1 is a schematic block diagram illustrating a printer according to an embodiment of the present invention. It is a schematic diagram of flash ROM. It is a flowchart which shows the flow of flash ROM rewriting. It is a schematic diagram for verifying the effect of flash ROM rewriting. It is a schematic diagram for demonstrating the problem of the conventional flash ROM rewriting.

Explanation of symbols

10 Printer 11 CPU
12 Flash ROM
12a Backup area 13 RAM
14 Data transmission / reception unit 15 Operation unit 16 EEPROM
17 Image recording unit 20 Host computer 21 Checksum 22 Backup flag

Claims (10)

A data transmitter / receiver for transmitting / receiving data to / from the host computer;
A drive unit that performs a predetermined operation;
A non-volatile memory having a plurality of sectors and storing firmware in the plurality of sectors;
Controlling the drive unit by executing firmware in the nonvolatile memory, and a control unit for rewriting the firmware based on data transmitted from the host computer,
When rewriting the nonvolatile memory, the control unit generates data for writing in a backup area in the nonvolatile memory based on data transmitted from the host computer, and verifies the reliability of the backup area. By writing a verification value and a flag designating the write target sector of the nonvolatile memory in the backup area, and writing the write data written in the backup area into the write target sector designated by the flag An information processing apparatus that performs rewriting of the nonvolatile memory and erases data in the backup area.   The controller determines whether or not the flag is present after activation, and if the flag exists, the flag is designated in a predetermined domain and the reliability of the backup area is determined using the verification value. The non-volatile memory is rewritten by writing the write data written in the backup area into the write target sector specified by the flag only when verified. The information processing apparatus described in 1.   The information processing apparatus according to claim 1, wherein the verification value is a checksum calculated by a checksum method.   The information processing apparatus according to claim 1, wherein the verification value is a CRC value calculated by a CRC method.   The information processing apparatus according to claim 1, wherein the nonvolatile memory is a flash ROM. A memory rewriting method of an information processing apparatus for rewriting firmware stored in a nonvolatile memory based on data transmitted from a host computer,
When rewriting the nonvolatile memory, generating write data in a backup area in the nonvolatile memory based on data transmitted from the host computer;
Calculating a verification value for verifying the reliability of the backup area, and writing to the backup area;
Writing a flag designating a write target sector of the nonvolatile memory in the backup area;
Rewriting the nonvolatile memory by writing the write data written in the backup area to the write target sector designated by the flag;
Erasing data in the backup area;
A memory rewriting method for an information processing apparatus, comprising: A step of determining the presence or absence of the flag after activation;
When the flag is present, the writing for writing in the backup area is performed only when the designation of the flag is a predetermined domain and the reliability of the backup area is verified using the verification value. 7. The memory rewriting method for an information processing apparatus according to claim 6, wherein rewriting of the nonvolatile memory is executed by writing data to the write target sector designated by the flag.   8. The memory rewriting method for an information processing apparatus according to claim 6, wherein the verification value is a checksum calculated by a checksum method.   8. The memory rewriting method for an information processing apparatus according to claim 6, wherein the verification value is a CRC value calculated by a CRC method.   10. The memory rewriting method for an information processing apparatus according to claim 6, wherein the nonvolatile memory is a flash ROM.

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