JP2010225012A - Electronic appliance and program update method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability of a program update function for completing update after power supply recovery even when power supply is interrupted during the update. <P>SOLUTION: In program update for modifying a part of a program embedded in an electronic appliance, while the electronic appliance is operable by power from a first power supply, a block as a part of the program is rewritten on the basis of the differential data, information indicating the progress of overwrite is stored in a memory circuit which has a second power source and a memory and performs read/write operation to a memory by power from the second power supply, overwrite of a part of the program interrupted due to interruption of power supply from a first power supply is restarted from an incomplete stage on the basis of information stored in the memory circuit when power supply from the first power supply is restarted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electronic device that operates according to a program and a method for updating a program incorporated in the electronic device.

  A mobile phone is an electronic device having many functions such as calling, sending and receiving e-mails, shooting, website browsing, and games. In order to realize these functions, a program having a data amount of 50 to 100 Mbytes or more is incorporated in the mobile phone. In general, a rewritable non-volatile memory is used for storing the program, so that the incorporated program can be updated to an improved or modified program.

  Mobile phones in recent years have a so-called air download function that automatically updates a program. This function receives update data distributed by the server by wireless communication, and partially rewrites the program stored in the nonvolatile memory based on the received data. During the update, the operation by the user is not accepted, and the process for update is forcibly executed regardless of the presence or absence of the operation. For this reason, as a consideration for the user, the update is normally performed in the late-night time period when the use of the mobile phone is statistically small, and the user is notified of the scheduled update date and time by e-mail in advance.

  However, the user may remove the battery from the mobile phone in an attempt to stop the automatic program update. If the automatic update is stopped due to a system down, the mobile phone may not operate normally even if a battery is subsequently installed and the power is restored. The cause is that a part of the program disappears or the memory state becomes unstable. In this case, the program is restored at a dealer or a service center.

  Regarding automatic program update, there is a prior art in which a program is backed up before rewriting, and rewriting is started after a flag indicating rewriting is set in a nonvolatile memory storing the program (Patent Document 1). Even if the power is cut off during the update, the flag continues to indicate that rewriting is in progress. The flag is checked after the power is restored, and if the flag indicates that rewriting is in progress, the memory state storing the program before the update start is restored using the backup data. As a result, the update can be redone.

JP 2005-215841 A

  The above prior art has a problem that the bit value of the flag becomes unstable when the power is shut off while the flag indicating whether or not the program is being rewritten is being rewritten. The program cannot be correctly updated if the rewriting in progress indicates rewriting completion, or the rewriting completion does not indicate.

  In view of such circumstances, an object of the present invention is to improve the reliability of a program update function that completes an update after power is restored even if the power is shut off during the update.

  An electronic device that achieves the above object is an electronic device that operates in accordance with a program, and includes a power supply circuit that supplies power by a first power supply, a second power supply, and a memory, and the power from the second power supply is A memory circuit that performs a read / write operation on the memory; a program storage unit that stores the program; a differential data storage unit that stores difference data indicating changes in at least one block that is part of the program; and the power supply A program update unit that rewrites the block based on the difference data in a state in which the circuit supplies power, and information that indicates a progress stage of rewriting by the program update unit in a state in which the power supply circuit supplies power. Update management unit to be stored in the circuit, and supply from a state where the power supply circuit does not supply power When it is that condition, the by referring to the information memory circuit stores, and a resume updating auxiliary section rewritten from unfinished stage of the block.

  A method for achieving the above object is a program update method for partially changing a program incorporated in an electronic device, wherein the electronic device is partially operable in a state where the electronic device can be operated by electric power from a first power source. Is rewritten based on the difference data, and information indicating the progress stage of rewriting is stored in a memory circuit having a second power source and a memory and performing a read / write operation on the memory with power from the second power source. Based on the information stored in the memory circuit, when the power supply from the first power supply is resumed, the rewriting of the part of the program interrupted due to the stop of the power supply from the first power supply is performed. And resume from the unfinished stage.

  Since the memory circuit performs a read / write operation with the power from the second power supply, the power supply from the first power supply is stopped while the information indicating the progress of rewriting by the program update unit is being written to the memory in the memory circuit. However, there is no problem in writing information. The written information is held in the memory circuit depending on whether the memory is nonvolatile or the storage state is maintained by the second power supply. When power supply by the first power supply is resumed, it is possible to determine to which stage the rewriting by the program update unit has been completed by referring to the information in the memory circuit, and to rewrite from an incomplete stage. There is no need to rewrite from the beginning by the program update unit.

  According to the present invention, it is possible to store information that correctly indicates the progress stage of the program update, so that the reliability of the program update function that completes the update after the power is restored even if the power is shut off during the update is enhanced.

It is a figure which shows the outline | summary of the procedure of a program update. It is a figure which shows the relationship between the rewriting status flag and the process performed after a power supply return. It is a figure which shows the hardware constitutions of a mobile telephone. It is a figure which shows the hardware constitutions of IC chip incorporated in the mobile telephone. It is a figure which shows an example of the file structure in an IC chip. It is a figure which shows the function structure of the principal part of a mobile telephone. It is a flowchart of the starting process after a power supply return. It is a flowchart of an update restart process. 10 is a flowchart of a memory recovery buffer preparation process. It is a flowchart of the preparation process of a difference reflection buffer. It is a flowchart of a difference rewriting process. It is a flowchart of a program operation memory rewriting process. It is a flowchart which shows operation | movement of an IC chip. It is a figure which shows the other example of the relationship between a rewriting state flag and the process performed after a power supply return. It is a flowchart of the modification of the restart process of an update.

  A mobile phone is given as an example of an electronic device that updates a program. However, the program update function described below is useful for an electronic device in which a program for controlling operations is incorporated. The mobile phone acquires data indicating the contents of the program update by wireless communication. In an electronic device that does not have a wireless communication function, data indicating update contents is exchanged by online communication or a method using a removable memory device.

  As shown in FIG. 1, the program to be updated is written in a program storage area 60 that is a part of the memory area of the rewritable ROM 16. Almost all operations of mobile phones follow this program. In other words, the program controls the operation of the mobile phone 1. The program update is for a part of the program occupying the program storage area 60, and the bit data in the program storage area 60 is rewritten in units of an address space having a predetermined fixed amount of data. Hereinafter, a portion of the program written in the address space for one unit of rewriting is referred to as “block”. Usually, the update is performed for a plurality of blocks. Some addresses of the plurality of blocks may be continuous, or all the addresses of all the blocks may not be continuous between each other. In any case, it is updated one block at a time.

  In the example of FIG. 1, three blocks 61, 62, and 63 are to be updated. However, in practice, four or more blocks are often targeted. Of the three blocks 61, 62, 63, the first block 61 has already been updated, and the second block 62 is the current update target. The third block 63 is the next update target scheduled to be rewritten after the block 62 has been updated.

  In updating each block, four stages of processing are basically performed. In the figure, each stage is represented by [1], [2], [3], [4].

  In the first step [1], one block 62 that is the current update target is copied from the program storage area 60 to the memory recovery buffer 65 provided for backup in the ROM 16.

  In the process [2] in the second stage, the block 62 is copied from the program storage area 60 (or the memory restoration buffer 65) to the difference reflection buffer 75 provided as a working memory area in the RAM 17.

  In the third step [3], the difference data downloaded in advance from the server by wireless communication and stored in the memory area 64 in the ROM 16 is applied to the block 62 of the difference reflection buffer 75. That is, write data (write image) to the program storage area 60 is created in the difference reflection buffer 75. Since the difference data is compressed, the data is expanded in the third stage.

  In the fourth step [4], the write data in the difference reflection buffer 75 is stored in place of the block 62 in the program storage area 60. That is, the block 62 in the program storage area 60 is rewritten with write data. When the rewriting is completed, the update for the block 62 ends.

  A rewrite status flag 5 is used to manage the progress of these four stages of processing. The contents of the rewrite status flag 5 are updated at the start time and completion time of each stage of processing. By referring to the rewrite status flag 5, it can be known to which stage the update of each block has progressed.

  In the present embodiment, the rewrite status flag 5 is stored in the nonvolatile memory 26 in the IC chip 2 built in the mobile phone. By storing in the IC chip 2, the reliability of the rewrite status flag 5 increases as will be described later. Unlike storing in the ROM 16, it is complicated to provide a plurality of flags and confirm the authenticity of the flag status. Control becomes unnecessary.

  The rewrite status flag 5 is stored as a countermeasure against a situation where the power supply by the battery of the main power supply stops during a series of updates in which a plurality of blocks are rewritten in order. Since a series of updates starts after confirming that the battery has enough charge, a power shortage usually does not occur during the update, but the user of the mobile phone may remove the battery . When the power supply is stopped, the execution of the update process is inevitably stopped at that time. The contents of the ROM 16 are retained, but the contents of the difference reflection buffer 75 are lost. After that, when the main power supply with the battery mounted again is restored, if the update interrupted by the power interruption is not completed, the old and new programs may be mixed in the program storage area 60, which may hinder the operation of the mobile phone. There is. Therefore, the rewrite status flag 5 is used. If the rewrite status flag 5 is referred to when the main power supply is restored, the update can be resumed from the incomplete stage and completed.

  FIG. 2 shows which stage of the four stages should be resumed when the main power supply is restored. If the rewrite status flag 5 is “initial state” or “memory recovery buffer rewriting”, it indicates that the power has been shut off before or during the first stage. In this case, the first stage process [ Resume from 1]. If the rewrite status flag 5 is “memory recovery buffer rewriting complete”, “difference reflection buffer rewriting in progress”, “difference reflection buffer rewriting complete”, “differential rewriting complete” or “differential rewriting complete”, Resume from processing [2]. If the rewrite status flag 5 is “program operation memory rewriting”, it indicates that the power supply is cut off during the fourth stage. In this case, after the process [5] for restoring the program storage area 60 by copying the block 62 backed up in the memory recovery buffer 65 to the program storage area 60, the processes [1] to [4] are performed again. I do. However, since the block 62 has already been backed up in the memory recovery buffer 65, the process [2] can be omitted. Redoing the process [1] without omitting the process [2] has an advantage that the management of the process can be simplified. The reason why the process [5] to be restored is performed is that the data corresponding to the block 62 in the program storage area 60 may be broken due to the power interruption during the process [4].

  Hereinafter, the configuration of the mobile phone will be described in more detail.

  As shown in FIG. 3, the mobile phone 1 includes a main body 1A that is a main part that realizes various functions including telephone calls and e-mails, and an IC (Integrated Circuit) chip 2 related to additional functions represented by electronic money. The IC chip 2 is built in the cellular phone 1 in a form that is fixedly assembled to the circuit board of the main body 1A.

  The main body 1 </ b> A includes a CPU 10, a display circuit 11, a wireless communication circuit 13, a power supply circuit 14, the above-described ROM 16, the above-described RAM 17, a non-contact reader / writer 19, and an access LED (Light Emitting Diode) 19.

  The CPU 10 executes a program incorporated in the mobile phone 1 by writing in the ROM 16 and controls the operation of the mobile phone 1. The function of the mobile phone 1 is realized by the CPU 10. The function of the mobile phone 1 includes a function of automatically updating the program by communicating with a server that distributes the difference data of the program.

  The display circuit 11 has a liquid crystal display 12 and displays various operation screens including a standby screen. There are two types of display related to program updates: a message that informs the date and time of the update and a message that informs that the update is in progress.

  The wireless communication circuit 13 is responsible for transmission / reception in telephone calls and data communication. The difference data of the program is downloaded from the server by the wireless communication circuit 13.

  The power supply circuit 14 supplies the power from the rechargeable battery 15 as the first power supply to the power consuming elements in the main body 1 </ b> A including the CPU 10. Further, when an external power supply is connected, the power supply circuit 14 charges the battery 15. The battery 15 is detachable from the main body 1A. Although this makes it easy to replace the battery 15, a situation may occur in which the battery 15 is removed by the user during the program update operation.

  The ROM 16 is a nonvolatile memory device. In the present embodiment, a NOR type flash memory is used as the ROM 16. Thus, the CPU 10 can directly access the ROM 16 and execute the program without loading the program from the ROM 16 to the RAM 15 in order to execute the program. That is, the ROM 16 is a so-called program operation memory. However, a NAND flash memory or other nonvolatile memory device can be used for storing programs instead of the ROM 16.

  The non-contact reader / writer 19 is an interface for accessing the IC chip 2. When the CPU 10 is accessing the IC chip 2, the access LED 19 is lit. When the program is updated, the program is frequently accessed to rewrite the write state flag 5 sequentially. In general, many users recognize that it is better to refrain from operating when the access LED 19 is lit. For this reason, lighting of the access LED 19 during program update has an effect of suppressing removal of the battery 15 by the user.

  On the other hand, as shown in FIG. 4, the IC chip 2 includes a CPU 20, an induced current power generation unit 24, a power storage unit 25, a non-volatile memory 26, and a non-contact reader / writer 28. The IC chip 2 is a memory circuit that performs a read / write operation with electric power from the power storage unit 25 as a second power source. The IC chip 2 receives a command for requesting reading or writing of data from an external device related to the additional service of the main body 1A and the mobile phone 1.

  In response to the access request received via the non-contact reader / writer 28, the CPU 20 executes a control program specialized for controlling the read / write operation for accessing the nonvolatile memory 26. Electric power necessary for access is supplied from the power storage unit 25.

  The power storage unit 25 is charged by the induced current power generation unit 24 that generates power using the energization of the main body 1A. If power can be supplied only while the CPU 20 is accessing the nonvolatile memory 26, the reliability of the stored data can be maintained. Therefore, the capacity of the power storage unit 25 may be a capacity that allows access only for a few seconds, for example, even when the energization of the main body 1A is stopped.

  The non-volatile memory 26 of the IC chip 2 stores an electronic money file 4 and a rewrite status flag file 5 for program update as shown in FIG. The electronic money file 4 is a file for electronic money settlement as an additional function, and shows a balance, a transaction history, and the like. An important purpose of incorporating the IC chip 2 in the mobile phone 1 is to securely store data related to the additional function such as the electronic money file 4. Since the mobile phone having the additional function has an IC chip built-in, the rewrite status flag file 5 is stored by using the IC chip for the additional function, thereby improving the reliability of program update without increasing the number of parts. Can do.

  FIG. 6 shows a functional configuration related to program update in the mobile phone 1. As shown in FIG. 6, the main body 1 </ b> A of the mobile phone 1 includes an air download unit 101, a program management unit 102, and a communication unit 103. These are functional elements realized by the CPU 10 executing the control program. This control program is also written in the above-described program storage area 60 as a program storage unit in the ROM 16. Further, the IC chip 2 has a communication unit 203. This is a functional element realized by the CPU 20 executing the control program.

  The air download unit 101 controls the wireless communication circuit 13 to acquire difference data indicating program update contents from an external server, and stores the difference data in the memory area 64 (see FIG. 1) serving as a difference data storage unit.

  The program management unit 102 comprehensively manages program execution. The program management unit 102 includes an update unit 121, an update management unit 122, and an update auxiliary unit 123. The program update unit 121 rewrites the blocks 61, 62, and 63 to be updated based on the difference data in a state where the battery 15 is attached and the power supply circuit 14 supplies power. The update management unit 122 causes the IC chip 2 to store the rewrite status flag file 5 that is information indicating the progress stage of rewriting by the program update unit 121 in a state where the power supply circuit 14 supplies power. That is, the update manager 122 is responsible for updating the rewrite status flag file 5. The update assisting unit 123 rewrites the current time stored in the IC chip 2 when the power supply circuit 14 is switched from a state in which power is not supplied, for example, when the removed battery 15 is returned to the mounting position. With reference to the status flag file 5, rewriting of the blocks 61, 62, and 63 is resumed from an incomplete stage.

  The communication unit 103 of the main body 1A and the communication unit 203 of the IC chip 2 control transmission / reception of commands and data relating to access to the rewrite status flag file 5.

  Hereinafter, the operation of the mobile phone 1 according to the program update function will be described with reference to the flowchart.

  When the discharged battery 15 is charged or the battery 15 that has not been mounted is mounted and the power supply starts, the startup process of FIG. 7 is executed by the program management unit 102.

  First, the update management unit 122 accesses the IC chip 2 in cooperation with the communication unit 103 and captures the contents of the rewrite status flag file 5. Specifically, a file selection command with a file ID “rewrite status flag” is sent (# 10). A read command is sent after waiting for a response indicating that a file has been selected (# 11, # 12).

  Next, the update management unit 122 analyzes the contents of the rewrite status flag file 5 read from the IC chip 2 (# 13). If the rewrite status flag does not indicate updating, the program management unit 102 executes normal activation processing (# 20). As a result, a standby screen is displayed on the display 12. On the other hand, when the rewrite status flag indicates that updating is in progress, the power supply is stopped during the program update. In this case, the process is taken over by the update assisting unit 123.

  The update assistant unit 123 checks whether recovery is unnecessary (# 14). Specifically, it is checked whether or not the rewrite status flag is “program operation memory rewriting” (see FIG. 2). If restoration is necessary, the update assistant unit 123 performs a restoration process (the above process [5]) for copying the block backed up in the memory restoration buffer 65 to a predetermined position in the program storage area 60 (# 15). . If the restoration is unnecessary, the update assistant unit 123 executes an update restart process (# 16). The update restart process is a process of resuming the update from an incomplete stage and finishing the update of the block for one block that is the current update target at the time when the update is interrupted. Details will be described later. When the update restart process is completed, the process is transferred from the update auxiliary unit 123 to the program update unit 121.

  The program update unit 121 that has taken over the process executes an update completion process (# 17). In this process, when there is an unprocessed block that should be updated, the process [1] to [4] for updating the block is executed to complete a series of updates for a plurality of blocks. It is a process to make.

  When the update completion processing is completed, the rewrite status flag file 5 is initialized by the update management unit 122 (# 18), and the restart processing is executed by the program management unit 102 (# 19).

  As shown in FIG. 8, in the update restart process, an incomplete process among the processes [1] to [4] is performed according to the contents of the rewrite status flag file 5. The relationship between the contents of the rewrite status flag file 5 and the processing to be performed is as described with reference to FIG.

  FIG. 9 shows the procedure of the memory recovery buffer preparation process which is process [1]. The process for preparing the memory recovery buffer is performed by the update auxiliary unit 123 and the update management unit 122 as part of the update restart process of # 16 in FIG. 7, or as part of the update completion process of # 17 and It is executed by the update management unit 122.

  One block is copied from the program storage area 60 to the memory recovery buffer 65 by the update assistant 123 or the update manager 122 (# 45). Prior to this, the update management unit 122 accesses the IC chip 2 and sets the rewrite status flag file 5 to “rewriting memory recovery buffer” (# 41 to # 44). In response to the end of copying of the block, the update management unit 122 sets the rewrite status flag file 5 to “memory recovery buffer rewrite completion” (# 46 to # 48). When the update management unit 122 sends a command to the IC chip 2, the update management unit 122 always confirms whether or not there is a response from the IC chip 2 before sending the next command, and sends the next command after receiving a normal response notification. As a result, the progress stage of the update in the main body 1A and the progress stage indicated by the rewrite status flag file 5 in the IC chip 2 can be matched more reliably.

  FIG. 10 shows the procedure of the difference reflection buffer preparation process which is process [2]. The difference reflection buffer preparation process is performed by the update auxiliary unit 123 and the update management unit 122 as part of the update restart process of # 16 in FIG. 7 or the program update unit 121 and the update as part of the update completion process of # 17. It is executed by the management unit 122.

  One block is copied from the program storage area 60 to the difference reflection buffer 75 of the RAM 17 by the update assistant 123 or the update manager 122 (# 55). Prior to this, the update management unit 122 accesses the IC chip 2 and sets the rewrite status flag file 5 to “differential reflection buffer rewriting” (# 51 to # 54). In response to the end of copying of the block, the update management unit 122 sets the rewrite status flag file 5 to “difference reflection buffer rewriting completed” (# 56 to # 58). Also in this routine, when the update management unit 122 sends a command to the IC chip 2, the update management unit 122 always checks whether there is a response from the IC chip 2 before sending the next command, and receives the normal response notification before receiving the next command. Send.

  FIG. 11 shows the procedure of the differential rewriting process which is the process [3]. The difference rewriting process is performed by the update auxiliary unit 123 and the update management unit 122 as part of the update restart process of # 16 in FIG. 7, or as a part of the update completion process of # 17, the program update unit 121 and the update management unit 122. It is executed by.

  Based on the difference data in the memory area 64, the update auxiliary unit 123 or the update management unit 122 performs difference rewriting to create rewrite data (rewrite image) in the difference reflection buffer 75 (# 65). Prior to this, the update management unit 122 accesses the IC chip 2 and sets the rewrite status flag file 5 to “differential rewriting” (# 61 to # 64). In response to the completion of the differential rewriting, the update management unit 122 sets the rewrite status flag file 5 to “differential rewriting completed” (# 66 to # 68). Also in this routine, when the update management unit 122 sends a command to the IC chip 2, the update management unit 122 always checks whether there is a response from the IC chip 2 before sending the next command, and receives the normal response notification before receiving the next command. Send.

  FIG. 12 shows the procedure of the program operation memory rewriting process which is the process [4]. The program operation memory rewriting process is performed by the update auxiliary unit 123 and the update management unit 122 as a part of the update restart process of # 16 in FIG. 7 or the program update unit 121 and the update management as a part of the update completion process of # 17. This is executed by the unit 122.

  The update auxiliary unit 123 or the update management unit 122 copies the rewrite data in the difference reflection buffer 75 by overwriting the current update target block in the program storage area 60 of the ROM 16 (#). 75). Prior to this, the update management unit 122 accesses the IC chip 2 and sets the rewrite status flag file 5 to “program operation memory rewriting” (# 71 to # 74). In response to the end of copying, the update management unit 122 sets the rewrite status flag file 5 to “program operation memory rewriting complete” (# 76 to # 78). Also in this routine, when the update management unit 122 sends a command to the IC chip 2, the update management unit 122 always checks whether there is a response from the IC chip 2 before sending the next command, and receives the normal response notification before receiving the next command. Send.

  FIG. 13 shows the operation of the IC chip 2. The IC chip 2 includes a command reception unit, a file management unit, and a command transmission unit as functional elements realized by the CPU 20. The command reception unit analyzes the command received via the non-contact reader / writer 28, the file management unit controls the nonvolatile memory 26 according to the command, and the command transmission unit transmits a response notification.

  If the analyzed command is file selection (SELECT-FILE), a memory access point is set at the head address of the file in the nonvolatile memory 26 according to the file ID added to the command (# 91, # 92, # 93). , # 94). Then, it is notified that the file can be accessed (# 95).

  If the analyzed command is file update (UPDATE), the file selection status is checked (# 96, # 97). If access to the file is not possible, an error is notified (# 98). If the file can be accessed, the data added to the command is written to the nonvolatile memory 26 from the memory access point (# 99). Then, it notifies that the writing has been completed (# 100).

  Even when the analyzed command is read (READ), the file selection status is checked (# 101, # 102). If access to the file is not possible, an error is notified (# 103). If the file can be accessed, the data added to the command is sequentially read from the memory access point of the nonvolatile memory 26 (# 104). Then, the read data is sent to the request source (# 105).

  If the analyzed command is another command that is not any of file selection, file update, and reading, processing corresponding to the command is performed (# 106).

  In the above-described embodiment, since the rewrite status flag file 5 is sequentially changed in accordance with the progress of processing, it is not necessary to back up all of a plurality of blocks to be updated in series, and only one block is stored. Should be backed up. This contributes to a reduction in the required capacity of the ROM 16.

  In the above-described embodiment, the difference reflection buffer 75 is provided in the volatile RAM 17. However, when the difference reflection buffer 75 is provided in a nonvolatile memory to create a write image, the processing to be performed after the power is restored and the write state flag 5. The relationship of the contents of is as shown in FIG. The procedure for restarting the update in this case is shown in FIG.

1 Mobile phone (electronic equipment)
2 IC chip (memory circuit)
14 power circuit 15 battery (first power supply)
25 Power storage unit (second power supply)
26 Non-volatile memory 60 Program storage area (program storage unit)
64 memory area (difference data storage)
121 Program update unit 122 Update management unit 5 Rewrite status flag file (information indicating progress stage of rewrite)
123 Update auxiliary unit 61, 62, 63 Block 65 Memory recovery buffer (recovery storage unit)
75 Difference reflection buffer (working memory area)
101 Air Download Department (Download Department)

Claims (10)

An electronic device that operates according to a program,
A power supply circuit for supplying power by a first power supply;
A memory circuit having a second power source and a memory, and performing a read / write operation on the memory by power from the second power source;
A program storage unit for storing the program;
A difference data storage unit that stores difference data indicating the change contents of at least one block that is part of the program;
In a state where the power supply circuit supplies power, a program update unit that rewrites the block based on the difference data;
In a state where the power supply circuit supplies power, an update management unit that stores information indicating a progress stage of rewriting by the program update unit in the memory circuit;
An update assisting unit that restarts rewriting of the block from an unfinished stage with reference to information stored in the memory circuit when the power supply circuit is in a state of supplying power from a state of not supplying power. Electronic equipment characterized by The program update unit, when changing a plurality of blocks of the program, rewrites the plurality of blocks one by one in order,
The electronic device according to claim 1, wherein the update assisting unit restarts rewriting from an unwritten block among the plurality of blocks. In addition, it has a recovery storage unit,
Prior to rewriting the block, the program update unit stores the block in the recovery storage unit,
The update assisting unit rewrites the block by applying the difference data to the block stored in the recovery storage unit when the information indicates the middle of writing to the program storage unit. The electronic device according to 1 or 2. The program update unit includes a first-stage process for storing the block in the recovery storage unit, a second-stage process for copying the block to a work memory area, and the difference data in the work memory area. Performing a third stage process for creating rewrite data based on the above and a fourth stage process for storing the rewrite data in the program storage unit instead of the block,
The electronic apparatus according to claim 3, wherein the update management unit sequentially updates the information so as to indicate that the processes in the first, second, third, and fourth stages are being executed and completed. The electronic device according to claim 4, wherein the program update unit executes a process of a next stage after receiving a notification indicating that the information update is completed from the memory circuit. The electronic device according to claim 5, wherein the first power source is a battery that can be attached to and detached from the power circuit. The electronic device according to claim 6, further comprising a download unit that acquires the difference data by wireless communication and stores the difference data in the difference data storage unit. A program update method for partially changing a program incorporated in an electronic device,
In a state in which the electronic device is operable by the power from the first power source, the block that is a part of the program is rewritten based on the difference data, and information indicating the progress stage of the rewriting is included in the second power source and the memory. And by a memory circuit that performs a read / write operation on the memory with power from the second power source,
Based on the information stored in the memory circuit when the power supply from the first power supply is resumed, the rewriting of the part of the program interrupted due to the stop of the power supply from the first power supply is performed. A program update method characterized by restarting from an incomplete stage. When a series of rewrites for sequentially changing a plurality of blocks of the program one by one is interrupted with the stop of power supply from the first power supply, when power supply from the first power supply is resumed The program update method according to claim 8, wherein rewriting is resumed from a portion of the plurality of blocks that has not been rewritten. A computer program for a computer included in an electronic device,
When executed by the computer,
Program update means for rewriting based on block difference data that is part of the computer program in a state where power is supplied by the first power source;
In a state in which power is supplied from the first power source, information indicating the progress stage of rewriting by the program update unit includes a second power source and a memory, and a read / write operation is performed on the memory by the power from the second power source. Update management means for storing in a memory circuit that
Program update assistance that resumes rewriting of the block from an incomplete stage with reference to information stored in the memory circuit when the power supply from the state where the power supply by the first power supply is stopped is changed to a state where power supply is performed Means for causing the computer to realize the means.

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