JP2004078483A - Method of changing firmware program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a boot program changeable even after storing a flash memory to a printed circuit board. <P>SOLUTION: In a system provided with an external flash memory 2 and an RAM 3 at a microcomputer 1, a secondary boot program for changing the boot program is prepared in a firmware program of the flash memory, and the secondary boot program is operated by setting at the reset of the system. The boot program is transferred to the RAM through an external storage device 4 or a transmission interface 5, and after erasing the boot program of the flash memory, the boot program on the RAM is written in the flash memory. In the case a joint test action group (JTAG) is used, a change is made by transferring the boot program and the firmware program from an incircuit emulator to the RAM. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for changing a firmware program in a microcomputer system using a flash memory.
[0002]
[Prior art]
At present, there are the following methods for storing a firmware (hereinafter referred to as F / W) program in a microcomputer system.
[0003]
(1) Method of Using EPROM An F / W program is written in an EPROM which can be erased by ultraviolet rays, the EPROM is mounted on a ROM socket on a printed board of a microcomputer system, and the F / W program is written on the EPROM. Let it work.
[0004]
In order to change the F / W program by this method, the EPROM on the printed board is removed, the contents of the EPROM are rewritten using a ROM writer, and the EPROM is mounted on the printed board. This method has been most commonly used.
[0005]
(2) Method using flash memory (1)
A flash memory has recently been used in place of the EPROM. Many of these flash memories are surface-mounted components, and cannot be repeatedly mounted on and removed from a printed circuit board as in EPROM. Usually, a predetermined F / W program is written at the time of manufacturing a flash memory, and the F / W program is left mounted on a printed board. Therefore, when the written F / W program is changed once, a special operation is required.
[0006]
(3) Method of Using RAM A boot program (startup program) is previously written in an EPROM or a flash memory. EPROM or flash memory is usually left mounted on a printed circuit board. The boot program has a function of transferring the firmware program from the external recording device to the RAM via the transmission path. When the power is turned on, the boot program operates, receives the F / W program from the external storage device through the transmission interface (serial transmission, LAN transmission), transfers it to the RAM, and transfers the F / W program to the RAM when the transfer ends normally. Of the F / W program is started.
[0007]
In this method, if only the boot program is stored in advance in the EPROM or the flash memory, the F / W program can be freely changed.
[0008]
(4) Method using flash memory (part 2)
This method is used in a one-chip microcomputer with a built-in flash memory. A flash memory, a RAM, and a serial transmission interface are built in the one-chip microcomputer. A boot program is also stored as a ROM. When the flash memory write mode is set at the time of resetting the one-chip microcomputer, the boot program operates, receives the F / W program via the serial interface built in the one-chip microcomputer, and receives the F / W program. Write to RAM. When a certain amount of the F / W program is received, the built-in flash memory is block erased and the F / W program received in the RAM is written to the flash memory. This is sequentially executed for the entire size of the F / W program by the number of blocks of the flash memory, and the F / W program is written to the flash memory. When the flash memory write mode setting of the one-chip microcomputer is released and reset, the F / W program of the built-in flash memory operates.
[0009]
[Problems to be solved by the invention]
(1) Method using EPROM Even now, this method is widely used. However, the mounting density of the printed board has been improved, and it has become difficult to use an EPROM having a large component area.
[0010]
(2) Method using flash memory (1)
Since the flash memory is still mounted on the printed board, a special operation is required to change the once written F / W program. There is a method in which a boot program for changing the flash memory is written in a part of the flash memory, and the other part of the flash memory is rewritten using the boot program. However, the boot program itself cannot be changed.
[0011]
(3) Method using RAM Even with this method, the boot program in the EPROM or flash memory mounted on the printed board cannot be changed.
[0012]
(4) Method using flash memory (part 2)
In a one-chip microcomputer with a built-in flash memory, the capacity of the built-in flash memory is limited. If it is desired to use an F / W program exceeding the limitation, it is necessary to separately prepare a flash memory outside the one-chip microcomputer. In this case, an external flash memory rewriting program may be prepared in the built-in flash memory. However, this is not possible with microcomputers other than one-chip microcomputers.
[0013]
An object of the present invention is to provide a firmware program change method that solves the above-mentioned problems.
[0014]
[Means for Solving the Problems]
According to the present invention, in order to solve the above-mentioned problem, a secondary boot program for changing a boot program is created in a firmware program of a flash memory, and this is operated at the time of resetting the system, and the boot program is stored in a RAM. After transferring and erasing the boot program in the flash memory, a method of writing the boot program in the RAM to the flash memory, or by connecting an in-circuit emulator to the microcomputer by JTAG, and transferring the boot program and firmware from the in-circuit emulator to the RAM Transfer the program, prepare the flash memory copy program in the firmware program, and send the flash memory in the firmware program on the RAM from the in-circuit emulator. Start copy program, a flash memory copy program erases the entire flash memory, the boot program and firmware program in the RAM intended to be how to copy the flash memory, characterized by the following method.
[0015]
(1) A method of changing a firmware program in a microcomputer system in which an external flash memory and a RAM are provided in a microcomputer,
Means for creating a secondary boot program for changing the boot program in the firmware program of the flash memory,
Means for allowing the secondary boot program to operate with settings at the time of system reset;
The secondary boot program transfers the boot program to the RAM via an external storage device or a transmission interface, erases the boot program in the flash memory, and then writes the boot program in the RAM to the flash memory. Means,
It is characterized by having.
[0016]
(2) A method of changing a firmware program in a microcomputer system having an external flash memory and a RAM in a microcomputer that can use JTAG,
Means for connecting the in-circuit emulator to the microcomputer by the JTAG;
Means for transferring a boot program and a firmware program from the in-circuit emulator to the RAM;
Means for preparing a flash memory copy program in the firmware program,
Means for starting a flash memory copy program in the firmware program on the RAM from the in-circuit emulator;
Means for erasing the entire flash memory and copying a boot program and a firmware program on the RAM to the flash memory;
It is characterized by having.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
FIG. 1 is a configuration diagram of a microcomputer system showing an embodiment of the present invention, which is a system in which a flash memory 2 and a RAM 3 are mounted outside a microcomputer 1.
[0018]
In this configuration, the F / W program is written into the RAM 3 by the boot program stored in the flash memory 2 from the external storage device 4 mounted on the printed board or the external storage device 6 via the transmission interface 5 at the time of reset. Is executed. As an external storage device, the F / W program can be written in an area other than the boot program of the flash memory 2.
[0019]
To take in the F / W program, a boot program is written in advance when the flash memory 2 is manufactured, and the boot program is mounted on a printed board. Thereafter, the F / W program is transferred to the RAM 3 via the external storage device 4 or the transmission interface 5 in the microcomputer system, and the F / W program on the RAM 3 is transferred to the F / W program area of the flash memory 2. Thus, the F / W program can be transferred to the flash memory 2.
[0020]
The problem is when changing the boot program. Changing the boot program is realized by the following procedure.
[0021]
(1) A secondary boot program for changing the boot program is created in the firmware program of the flash memory 2.
[0022]
(2) The secondary boot program operates in accordance with the setting at the time of resetting the microcomputer system.
[0023]
(3) The secondary boot program transfers the boot program to the RAM 3 via the external storage device 4 or the transmission interface.
[0024]
(4) The secondary boot program writes the boot program in the RAM 3 to the flash memory 2 after erasing the boot program in the flash memory 2.
[0025]
Therefore, in the present embodiment, it is possible to change the boot program even after mounting a flash memory which is not normally possible on a printed board. Also, no special device is required. Also, the present invention can be applied to a microcomputer system without JTAG.
[0026]
(Embodiment 2)
FIG. 2 is a block diagram of a microcomputer system showing an embodiment of the present invention. The microcomputer is a microcomputer which can use JTAG, has an external flash memory 2 and a RAM 3, and boots from an ICE (in-circuit emulator) 7 at reset. The program and the firmware program are written in the RAM 3, and the boot program and the firmware program are written in the flash memory 2.
[0027]
This method is realized by the following procedure.
[0028]
(1) ICE7 is connected to the microcomputer system by JTAG8.
[0029]
(2) The boot program and the firmware program are transferred from the ICE 7 to the RAM 3 of the microcomputer system.
[0030]
(3) A flash memory copy program is prepared in the firmware program.
[0031]
(4) The ICE 7 starts the flash memory copy program in the F / W program on the RAM 3.
[0032]
(5) The flash memory copy program erases the entire flash memory 2.
[0033]
(6) The flash memory copy program copies the boot program and the firmware program on the RAM 3 to the flash memory 2.
[0034]
Therefore, in this embodiment, rewriting of the flash memory can be performed at a higher speed than in the first embodiment in which the F / W program is transferred by the transmission interface. In particular, there is no need to prepare a boot program.
[0035]
【The invention's effect】
As described above, according to the present invention, a secondary boot program for changing the boot program is created in the firmware program of the flash memory, and this is operated when the system is reset, and the boot program is transferred to the RAM. Since the boot program in the RAM is written into the flash memory after erasing the boot program in the flash memory, the boot program can be changed even after mounting the flash memory which is not normally possible on a printed board. Also, no special device is required. Also, the present invention can be applied to a microcomputer system without JTAG.
[0036]
Also, the in-circuit emulator is connected to the microcomputer by JTAG, the boot program and the firmware program are transferred from the in-circuit emulator to the RAM, and a flash memory copy program is prepared in the firmware program. The flash memory copy program in the above firmware program is started, and the flash memory copy program erases the entire flash memory and copies the boot program and the firmware program on the RAM to the flash memory. It can be performed at high speed, and it is not necessary to prepare a boot program.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing a first embodiment of the present invention.
FIG. 2 is a system configuration diagram showing a second embodiment of the present invention.
[Explanation of symbols]
1. Microcomputer 2. Flash memory 3. RAM
4, 6 external storage device 5 transmission interface 7 in-circuit emulator

Claims (2)

A method of changing a firmware program in a microcomputer system provided with an external flash memory and a RAM in a microcomputer,
Means for creating a secondary boot program for changing the boot program in the firmware program of the flash memory,
Means for allowing the secondary boot program to operate with settings at the time of system reset;
The secondary boot program transfers the boot program to the RAM via an external storage device or a transmission interface, and after erasing the boot program in the flash memory, writes the boot program in the RAM to the flash memory. Means,
A method for changing a firmware program, comprising: A method of changing a firmware program in a microcomputer system having an external flash memory and a RAM in a microcomputer that can use JTAG,
Means for connecting the in-circuit emulator to the microcomputer by the JTAG;
Means for transferring a boot program and a firmware program from the in-circuit emulator to the RAM;
Means for preparing a flash memory copy program in the firmware program,
Means for starting a flash memory copy program in the firmware program on the RAM from the in-circuit emulator;
Means for erasing the entire flash memory and copying a boot program and a firmware program on the RAM to the flash memory;
A method for changing a firmware program, comprising:

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