JP2002175193A - Device and method for rewriting program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for rewriting program capable of reducing the storage capacity of RAM and ROM. SOLUTION: This device includes a first ROM 7 of storing a firmware for activation having an activation program of activating a microcomputer system 1 and a communication program of conducting communication with a host computer 2, a RAM 5 of temporarily storing data down loaded from the host computer 2, and a second ROM 8 of storing a firmware for control of controlling the operation of an electronic appliance. A deletion/writing program for deleting and writing the firmware for control stored in the second ROM 8 and the firmware for control are transmitted from the host computer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a program rewriting program for rewriting firmware of a microcomputer system by downloading another firmware from a host computer connected by communication means to a microcomputer system storing firmware for controlling the operation of an electronic device. The present invention relates to an apparatus and a program rewriting method.

[0002]

2. Description of the Related Art A microcomputer system for controlling the operation of an electronic device has a ROM in which firmware as a control program is stored. In order to change the firmware, it is necessary to remove the ROM from the board and re-install the ROM storing another firmware, which has a problem that the number of steps is increased. For this reason, Japanese Patent Application Laid-Open No. 10-25469
Patent Document 4 discloses a program rewriting device that changes firmware without removing a ROM from a substrate.

FIG. 5 shows this program rewriting device. The microcomputer system 10 and the host computer 30 are connected to each other by a communication cable 41. Each part of the microcomputer system 10 is controlled by a CPU and peripheral ICs.
Is performed by the MPU 11 having The flash memory 12 and the driver 13 are connected to the MPU 11 by a bus line.
And a RAM 14 are connected. The driver 13 exchanges firmware data and control information with the host computer 30.

[0004] The flash memory 12 is composed of a non-volatile memory, which electrically writes and erases stored contents and retains stored contents regardless of the presence or absence of a power supply voltage. As shown in FIG. 6, the flash memory 12 stores firmware including a start-up program 12a, a spare program 12b, and a download program 12c.

The startup program 12a describes a series of procedures when the microcomputer system 10 is newly started by reset. The download program 12c is copied to the RAM 14, and the MPU 11
14 to control the components of the microcomputer system 10 and the electronic devices by executing the program temporarily stored in the microcomputer 14. The spare program 12b describes the same contents as the download program 12c for the purpose of reserve in case the download program 12c is damaged.

FIG. 7 is a flowchart showing the operation of the data rewriting device having the above configuration. In step # 10, it is confirmed whether the download program 12c stored in the flash memory 12 is normal. If normal, in step # 11, the download program 12c
4 If not, the preliminary program 12b is copied to the RAM 14 in step # 12. R
The program stored in the AM 14 is an execution program, and a pointer is set at the start address of the execution program in step # 13.

[0007] By executing the execution program stored in the RAM 14, communication with the host computer 30 is performed.
In step # 14, it is determined whether the driver 13 has received data for the download program 12c from the host computer 30. If not received, the process proceeds to step # 17 and the control processing of the ordinary electronic device is performed by the MPU1.
1 is performed. If received, step # 15
Then, the download program 12c stored in the flash memory 12 is erased by the execution program stored in the RAM 14.

Then, in step # 16, the data for the download program 12c received from the host computer 30 is written in the flash memory 12 by the execution program stored in the RAM 14. Then, the startup program 12a is restarted and the rewritten download program 12c is copied to the RAM 14,
In step # 17, a new execution program is executed by the MPU 11 to perform control processing of the electronic device. Thus, the control program (12c) stored in the flash memory 12 can be rewritten online from the host computer 30.

[0009]

However, according to the above-described conventional program rewriting device, the same spare program 12b as the download program 12c is arranged in the flash memory 12 in case the download program 12c is damaged. For this reason, the flash memory 1 is used for the spare program 12b which is not frequently used.
The two ROMs require a large storage capacity, which increases the cost of the program rewriting device.

Further, the download program 12c in the flash memory 12 is temporarily copied to the RAM 14 and
It is necessary to rewrite the download program 12c in the flash memory 12 by executing a communication program, a write program, and the like from the AM 14. For this reason, RAM
14 requires a large storage capacity to temporarily store not only temporary storage of variables and the like at the time of calculation but also all data of the size of the download program 12c.

An object of the present invention is to provide a program rewriting device and a program rewriting method capable of reducing the storage capacity of a RAM or a ROM.

[0012]

In order to achieve the above object, a program rewriting apparatus according to the present invention comprises a host computer connected via communication means to a microcomputer system storing control firmware for controlling the operation of electronic equipment. In a program rewriting device that downloads another control firmware from a computer and rewrites the control firmware of the microcomputer system, the microcomputer system includes a start program that starts the microcomputer system and a communication program that communicates with the host computer. The first storing the boot firmware having
It is characterized by comprising a ROM, a RAM for temporarily storing data downloaded from the host computer, and a second ROM for storing control firmware.

According to this configuration, when the control firmware is rewritten, the boot firmware stored in the first ROM is executed to start up the microcomputer system and communicate with the host computer. Thereby, the control firmware for rewriting is downloaded from the host computer and stored in the RAM.
Then, the control firmware in the second ROM is erased, and the new control firmware is copied from the RAM.

Further, according to the present invention, in the program rewriting device having the above structure, the control firmware downloaded to the RAM and the control firmware written in the second ROM are executed in parallel, and the divided control firmware is downloaded. In which the RAM is sequentially overwritten.

According to this configuration, when the control firmware is divided and partly downloaded to the RAM, the second R
When the part is written in the OM, and the next part is downloaded and overwritten in the RAM, the part is written in the second ROM. This operation is repeatedly performed, and the control firmware of the second ROM is rewritten.

According to the present invention, there is also provided a program rewriting device having the above configuration, wherein an erasing program for erasing the control firmware stored in the second ROM;
A writing program for writing the control firmware to the OM is transmitted from the host computer.

According to this configuration, the erase program and the write program of the control firmware are downloaded from the host computer and stored in the RAM. Then, the control firmware in the second ROM is erased by the erase program, and the second firmware is erased by the write program.
The control firmware is written in the ROM.

Further, the present invention is characterized in that, in the program rewriting device having the above configuration, the writing program is downloaded after erasing of the second ROM is completed.

Further, according to the present invention, in the program rewriting device having the above configuration, the second RO is stored in the boot firmware.
M is characterized by including the same program as the control firmware in M. According to this configuration, the second RO
By erasing the new control firmware stored in M, the operation of the original control firmware can be executed by the boot firmware.

According to the present invention, in the program rewriting device having the above configuration, the first ROM is composed of a partially erasable and writable nonvolatile memory, and the second ROM is a first ROM.
It is characterized by being shared with OM. According to this configuration, the first ROM composed of the nonvolatile memory stores the boot firmware and the control firmware, and the control firmware is rewritten while leaving the boot firmware.

Further, according to the present invention, in the program rewriting apparatus having the above configuration, the first ROM is a mask ROM,
M or a flash memory.

Also, the program rewriting method of the present invention
In a program rewriting method for downloading another control firmware from a host computer connected via communication means to a microcomputer system storing control firmware for controlling the operation of an electronic device and rewriting the control firmware of the microcomputer system, ,
The microcomputer system includes a first ROM that stores boot firmware having a boot program that starts the microcomputer system and a communication program that communicates with the host computer, and a RAM that temporarily stores data downloaded from the host computer. A second ROM for storing the control firmware, an erasing program for erasing the control firmware stored in the second ROM, a writing program for writing the control firmware in the second ROM, and a new control program. Firmware is transmitted from the host computer, the erase program and the write program are executed, and the control firmware of the second ROM is rewritten.

Further, according to the present invention, in the program rewriting method having the above-described structure, the control firmware downloaded to the RAM and the control firmware written to the second ROM are performed in parallel, and the control firmware divided and downloaded is divided. In which the RAM is sequentially overwritten.

Further, the present invention is characterized in that, in the program rewriting method having the above configuration, the writing program is downloaded after erasing of the second ROM is completed.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of the program rewriting device of the first embodiment. In the program rewriting device, a microcomputer system 1 and a host computer 2 are connected to each other by a communication cable 3.

The microcomputer system 1 transmits and receives data to and from the host computer 2 via the communication interface 6. Control of each part of the microcomputer system 1 is performed by the CPU 4. The first and second ROMs 7 and 8, the RAM 14, and the communication interface 6 are connected to the CPU 4 via a bus line.

The first and second ROMs 7 and 8 are mask ROMs,
It is composed of a nonvolatile memory such as a PROM or a flash memory, and electrically writes and erases stored contents and retains stored contents regardless of the presence or absence of a power supply voltage. The first ROM 7 stores a start-up program describing a series of procedures when the microcomputer system 10 is newly started up by reset, and a start-up firmware including a communication program for communicating with the host computer 2 and the like. . The startup program includes a recognition program for recognizing the second ROM 8.

The second ROM 8 stores control firmware including a control program for controlling electronic devices connected to the microcomputer system 1. The RAM 14 temporarily stores calculation results and the like at the time of execution of control programs and the like, and also temporarily stores data downloaded from the host computer 2 via the communication interface 6.

The host computer 2 has a second ROM 8
Erasing program 21 for erasing the storage contents of the second ROM
8 stores a writing program 22 for writing firmware and firmware data 23 including a predetermined control program.

When the microcomputer system 1 is started, FIG.
Is executed. First, in step # 61, the boot firmware of the first ROM 7 is executed. As a result, the startup program and the communication program are executed, the microcomputer system 1 is started, communication with the host computer 2 is enabled, and the recognition of the second ROM 8 is performed by the recognition program.

Next, in step # 62, it is determined whether or not the control firmware in the second ROM 8 is normal. If the control firmware works effectively, step #
In 63, the control firmware in the second ROM 8 is executed, and the electronic devices connected to the microcomputer system 1 are controlled.

If it is determined in step # 62 that the control firmware is not functioning effectively, the flow shifts to step # 64, where the control firmware is rewritten as described later. When the rewriting of the control firmware in the second ROM 8 is completed, the process proceeds to step # 63, where the rewritten control firmware in the second ROM 8 is executed.

The rewriting process is executed according to an instruction from the host computer 2 at the time of version up due to addition of a function of the control firmware or bug fix or the like, and rewrite of the control firmware in the second ROM 8 is performed. Further, as described above, the process is also executed when the control firmware in the second ROM 8 is not operating normally.

FIG. 3 shows a flowchart of the rewriting process. In the figure, A shows the operation of the microcomputer system 1, and B shows the operation of the host computer 2. First, at step # 51, a command to transmit the version number of the control program stored in the second ROM 8 is issued from the host computer 2, and the version number is transmitted from the microcomputer system 1 at step # 21. Thereby, the host computer 2 acquires the version number of the control program.

Next, in step # 52, the erasure program 21 is transmitted from the host computer 2, and the microcomputer system 1 receives this via the communication interface 6 (step # 22). At step # 23, the erasing program 21 is downloaded to the RAM 5, and at step #
At 24, the erase program 21 is executed from the RAM 5.
As a result, the control firmware in the second ROM 8 is erased.

In step # 25, it is determined whether or not the erasure of the control firmware has been normally performed, and the success or failure of the erasure is notified to the host computer 2 (steps # 26 and # 27). If the erasure has failed, the writing process of the microcomputer system 1 ends, and the host computer 2 that has received the notification determines the content of the notification in step # 53 and ends the writing process.

If the erasure is normal, a reset code is transmitted from the host computer 2 in step # 54.
Upon receiving the reset code, the microcomputer system 1 resets the system in step # 28, and the boot firmware in the first ROM 7 is executed.

Accordingly, the above-described flowchart of FIG. 2 is executed, and the write process is called in step # 64 (see FIG. 2). At this time, since the erasing of the control firmware has been completed, the processing of the host computer 2 jumps to step # 55 by setting the flag.

In step # 55, the host computer 2 transmits the write program 22 and the firmware data 23 of the control firmware. The microcomputer system 1 executes the writing program 22 in step # 29.
And firmware data 23 of control firmware
Is received and downloaded to the RAM 5 in step # 30.

In step # 32, the write program 22 is executed from the RAM 5, and the control firmware on the RAM 5 is written into the second ROM 8. At this time, the firmware data 23 is transmitted from the host computer 2 for each divided block. One block of the control firmware is downloaded to the RAM 5 and the second RO
M8 is written.

When the writing of one block is completed, the next block is downloaded to the RAM 5 and the second block is downloaded.
The data is written to the ROM 8. By sequentially performing this operation, the entire control firmware is written. By dividing the download and writing the data in the second ROM 8 in parallel, the storage capacity of the RAM 5 required for downloading the firmware data 23 can be secured by one block, and the storage capacity of the RAM 5 can be reduced. I can do it.

When the writing of the new control firmware to the second ROM 8 is completed, it is determined in step # 33 whether or not the writing has been performed normally, and the success or failure of the erasure is notified to the host computer 2 (step # 33). #
34, # 35). If the erasure has failed, the writing process of the microcomputer system 1 ends, and the host computer 2 that has received the notification determines the content of the notification in step # 56 and ends the writing process. Thus, the host computer can detect that the control firmware has not been correctly rewritten, and can take measures such as re-executing the writing process.

If the writing is normal, step # 57
, A reset code is transmitted from the host computer 2. When receiving the reset code, the microcomputer system 1 resets the system in step # 36,
The boot firmware in is executed. Then, the writing process is called from the flowchart of FIG.
By the setting of the flag, the processing of the host computer 2 jumps to step # 58.

In step # 58, the host computer 2
Sends a command to transmit the version number of the control program stored in the second ROM 8, and the microcomputer system 1 transmits the version number in step # 37. As a result, the host computer 2 acquires the version number of the control program, confirms that the version has been updated, and ends the processing.

According to the program rewriting device of the present embodiment, since the boot firmware has the communication program, even if the control firmware for controlling the electronic device connected to the microcomputer system 1 is damaged, the host computer 2 can perform the same. It can be repaired by downloading. Therefore, it is not necessary to provide the conventional spare program 12b (see FIG. 6) in the microcomputer system 1, and the storage capacity of the first and second ROMs 7 and 8 can be reduced.

The first and second ROMs 7 and 8 do not store the erasing program or the writing program of the control firmware but download and execute the program from the host computer 2. Therefore, the storage capacities of the first and second ROMs 7 and 8 can be further reduced. Further, since only the control firmware is stored in the second ROM 8 and the communication program and the startup program are not stored, the storage capacity can be further reduced.

Since the writing program 22 is downloaded after the erasure of the second ROM 8 is completed, the RA
The erase program 21 and the write program 22 are not stored in M5 at the same time, and the storage capacity of the RAM 5 can be reduced. The download of the control firmware and the writing from the RAM 5 to the second ROM 8 are performed in parallel. Therefore, the RAM 5 only needs to secure the capacity of the firmware data 22 and the writing program 23 which are divided and downloaded, and the storage capacity of the RAM 5 can be further reduced.

Since the spare program 12b (see FIG. 6) is not provided, it is necessary to execute the control program from the second ROM 8 without copying the control program to the RAM 5 in order to make the address of the control program accessed from the CPU 4 constant. Can be. For this reason, when the control firmware is executed, the RAM 5 only needs to have a capacity capable of temporarily storing the calculation result and the like, and the RAM 5 can be provided in a capacity necessary for downloading the firmware data by dividing as described above.

Further, for the microcomputer system 1 using different types of nonvolatile memories as the second ROM 8,
It is necessary to change the erase program and the write program for operating the second ROM 8, but it is not necessary to change the control program for controlling the electronic device. Since the second ROM 8 stores the control firmware including only the control program, the control firmware can be easily rewritten using the firmware data 23 as it is.

When the power supply to the microcomputer system 1 and the host computer 2 is cut off during the rewriting process of the control firmware, the contents stored in the ROM 5 are lost. In this case, even if the contents of the second ROM 8 are erased, the contents stored in the first ROM 7 are not erased. Therefore, the boot firmware stored in the first ROM 7 is executed and the control firmware is downloaded to easily recover. Can be.

Next, a program rewriting device according to a second embodiment will be described with reference to the drawings. The configuration of the program rewriting device of this embodiment is the same as that of the first embodiment shown in FIG. The difference from the first embodiment is that the first ROM
7 in the boot firmware stored in the second ROM.
8 has a control program initially stored.

FIG. 4 is a flowchart showing the operation of the program rewriting device of this embodiment. When the microcomputer system 1 is started, first in step # 71, the first ROM
7 is executed. This allows
The startup program and the communication program are executed to start up the microcomputer system 1 to enable communication with the host computer 2 and to execute the second RO by the recognition program.
Recognition of M8 is performed.

Next, at step # 72, it is determined whether or not the second ROM 8 is normally recognized and whether or not the control firmware in the second ROM 8 is normal. If the second ROM 8 is normally recognized and the control firmware functions effectively, the process proceeds to step # 73 where the control firmware in the second ROM 8 is executed and the microcomputer system 1
The control of the electronic device connected to is performed.

If it is determined in step # 72 that the control firmware is not functioning effectively, the flow shifts to step # 74 where the control program stored in the first ROM 7 is executed. Thus, control of the electronic device is performed.

Further, by performing the rewriting process similar to that of FIG. 3 described above, the control firmware in the second ROM 8 is rewritten according to an instruction from the host computer 2. At this time, it may be confirmed in step # 53 that the erasing of the control firmware has been successful, and the rewriting process may be ended. By doing so, the microcomputer system 1 controls the electronic device by the control program of the initial version in the first ROM 7, and can easily return the control operation to the initial state.

According to the present embodiment, since the control program is stored in the first ROM 7, the electronic device can be controlled even when the second ROM 8 cannot be recognized. In addition, the first R than the first embodiment is equivalent to the control program.
Although a large storage capacity of the OM 7 is required, the storage capacity can be reduced as compared with the related art since the erasing program and the writing program are not stored.

In the first and second embodiments, the first,
Although the second ROMs 7 and 8 are composed of different nonvolatile memories, when a nonvolatile memory that can be partially erased and written is used as the first ROM 7, the first RO
The control firmware is stored in one area of M7 and the second R
The OM 8 may be used also as the first ROM 7.

[0058]

According to the present invention, since the boot firmware stored in the first ROM has the communication program, even if the control firmware for controlling the electronic device connected to the microcomputer system is damaged, the host computer can execute the firmware. It can be repaired by downloading. Therefore, there is no need to provide a conventional spare program in the microcomputer system.
The storage capacity of the ROM can be reduced.

Further, since the erase program and the write program of the control firmware are not stored in the first and second ROMs but are downloaded from the host computer and executed, the storage capacity of the first and second ROMs can be further reduced. Furthermore, since only the control firmware is stored in the second ROM and the communication program and the start-up program are not stored, the storage capacity can be further reduced.

Further, since the writing program is downloaded after the erasing of the second ROM is completed, the erasing program and the writing program are not stored in the RAM at the same time, and the storage capacity of the RAM can be reduced. Also,
Download of control firmware and second from RAM
Since writing to ROM is performed in parallel, RAM
It is sufficient to secure the capacity of the firmware data and the writing program to be divided and downloaded, and the storage capacity of the RAM can be further reduced.

When a different nonvolatile memory is used as the second ROM, it is necessary to change the erase program and the write program for operating the second ROM, but it is not necessary to change the control program for controlling the electronic device. Since the control firmware including only the control program is stored in the second ROM, the control firmware can be easily rewritten using the firmware data as it is.

Further, since the boot firmware stored in the first ROM has a communication program for communicating with the host computer, and the stored contents of the first ROM are not erased, the microcomputer system is not rewritten during the control firmware rewriting process. Even if the power supply to the host computer is cut off, the recovery can be easily performed by executing the boot firmware stored in the first ROM and downloading the control firmware.

According to the present invention, by storing the control program in the first ROM, the control operation of the electronic device can be easily returned to the initial state, and the second RO can be returned.
Even when M cannot be recognized, the electronic device can be controlled. In addition, although a large storage capacity is required for the control program, the storage capacity can be reduced as compared with the related art since the erase program and the write program are not stored.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a program rewriting device according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the program rewriting device according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation of a rewriting process of the program rewriting device according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating an operation of a program rewriting device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional program rewriting device.

FIG. 6 is a memory map showing a ROM of a conventional program rewriting device.

FIG. 7 is a flowchart showing the operation of a conventional program rewriting device.

[Explanation of symbols]

 1, 10 Microcomputer system 2, 30 Host computer 3, 41 Communication cable 4 CPU 5, 14 RAM 6 Communication interface 7 First ROM 8 Second ROM 11 MPU 12 Flash memory 13 Driver 21 Erase program 22 Write program 23 Firmware data

Claims (10)

[Claims] 1. Downloading another control firmware from a host computer connected via communication means to a microcomputer system storing control firmware for controlling the operation of an electronic device, and downloading the control firmware of the microcomputer system. In a program rewriting device for rewriting, the microcomputer system includes: a first ROM storing boot firmware having a boot program for booting the microcomputer system and a communication program for communicating with the host computer; and data downloaded from the host computer. And a second ROM for storing control firmware. 2. The method according to claim 1, wherein downloading of the control firmware to the RAM and writing of the control firmware to the second ROM are performed in parallel, and the RAM is sequentially overwritten by the divided and downloaded control firmware. The program rewriting device according to claim 1. 3. An erasing program for erasing control firmware stored in a second ROM;
The program rewriting device according to claim 1 or 2, wherein a write program for writing control firmware to the host computer is transmitted from the host computer. 4. The program rewriting device according to claim 3, wherein the writing program is downloaded after erasing of the second ROM is completed. 5. The program rewriting apparatus according to claim 1, wherein the boot firmware contains the same program as the control firmware in the second ROM. 6. The first ROM is composed of a partially erasable and writable nonvolatile memory, and the second ROM is replaced with the first ROM.
The program rewriting device according to claim 1, wherein the program rewriting device is also used. 7. The first ROM is a mask ROM, a PROM,
7. The program rewriting device according to claim 1, wherein the program rewriting device is made of any one of flash memories. 8. Downloading another control firmware from a host computer connected via communication means to a microcomputer system storing control firmware for controlling the operation of the electronic device, and downloading the control firmware for the microcomputer system. In the method for rewriting a program, the microcomputer system comprises: a first ROM storing boot firmware having a boot program for booting the microcomputer system and a communication program for communicating with the host computer; and data downloaded from the host computer. And a second ROM for storing control firmware. An erasing program for erasing the control firmware stored in the second ROM, and a control firmware stored in the second ROM. A program for writing data and writing new control firmware from the host computer, and executing the erase program and the write program to rewrite the control firmware of the second ROM. Method. 9. The control firmware download to the RAM and the control firmware writing to the second ROM are performed in parallel, and the RAM is sequentially overwritten by the divided and downloaded control firmware. 9. The program rewriting method according to claim 8, wherein: 10. The program rewriting method according to claim 8, wherein the writing program is downloaded after erasing of the second ROM is completed.