JP2003131898A - Electronic device and rewriting system for flash memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely carry out rewriting of a flash memory for an electronic device by using a commonly used connector already provided to the electronic device. SOLUTION: In the system, a control program for rewiring the stored content of the flash memory 22 and a program to be stored to the flash memory 22 is stored to a hard disk of a personal computer 12, the personal computer 12 is connected to a test terminal group 21b of a micro processor 21 through an exclusive cable 14, a main logic circuit 21c is controlled by the personal computer 12 through the test terminal groups 21b, the program to be stored to the flash memory 22 is transferred from the personal computer 12 to the micro processor 21, and the program is stored to the flash memory 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device including a flash memory and a flash memory rewriting system.

[0002]

2. Description of the Related Art As is well known, as various electronic devices,
There is a flash memory in which a boot program for booting and a program such as an operating system are stored. Since the storage contents of the flash memory can be rewritten from the outside, it is possible to deal with the discovery of a bug in the program and the specification change by rewriting the program without replacing the memory.

For example, in Japanese Unexamined Patent Publication No. 8-83175, a boot program for booting and a program such as an operating system are stored in an external memory having a capacity equal to or larger than that of a flash memory of an electronic device. There is disclosed a technique of connecting to the electronic device through a bus or a control line, transferring a program from the external memory to a flash memory of the electronic device, storing the program, and thereby rewriting the flash memory.

In Japanese Patent Laid-Open No. 2000-122884, a boot program for booting and programs such as an operating system are stored in an external computer, the serial interface of the external computer is connected to an electronic device, and the external computer is connected. A technique has been disclosed in which a program is transferred from a computer to a flash memory of an electronic device and stored, and thereby the flash memory is rewritten.

[0005]

However, in the technique disclosed in Japanese Unexamined Patent Publication No. 8-83175, since the external memory is connected to the electronic device through the bus and the control line, the number of signal lines between the two is large, and There is a problem that the structure of the connector used for connection becomes complicated.

Further, in the technique disclosed in Japanese Patent Laid-Open No. 2000-122884, the electronic device is booted by the boot program in the flash memory. Therefore, before erasing the flash memory, if the electronic device stops due to an unintentional accident such as a power failure when the stored contents including the boot program of the flash memory are erased, turn on the power of the electronic device again. However, a situation occurred in which the electronic device did not restart and the flash memory could not be rewritten.

Therefore, the present invention has been made in view of the above conventional problems, and it is possible to reliably rewrite a flash memory of an electronic device by using an existing general connector for the electronic device. An object is to provide a possible electronic device and a flash memory rewriting system.

[0008]

In order to solve the above problems, the present invention provides a flash memory, an expansion connector for inputting / outputting various data, and an external device for receiving an operation test by the external device. In an electronic device including a test terminal group to be connected, the connection of the expansion connector in the electronic device is switched, and the expansion connector is used from the input / output of various data to the connection between the external device and the test terminal group. Is provided with a switching means.

According to the electronic device of the present invention having such a configuration, the operation test of the electronic device can be performed through the test terminal group. If the control of the electronic device through this test terminal group is applied, the flash memory of the electronic device can be rewritten. Also, the expansion connector is usually
It is used for inputting and outputting various data, and is diverted by the switching means to connect an external device and a test terminal group. Therefore, the external device can rewrite the flash memory by controlling the electronic device through a general connector existing in the electronic device. Also,
Since the electronic device is controlled through the test terminal group without using the boot program for booting in the flash memory or the program such as the operating system, even if the program in the flash memory is erased carelessly, the flash memory of the electronic device Can be surely rewritten.

Further, in the electronic device of the present invention, the switching means switches the connection of the expansion connector in the electronic device in response to a signal from a preset terminal of the expansion connector.

In this case, the application of the expansion connector can be changed by switching the connection of the expansion connector in the electronic device only by generating a signal from a preset terminal of the expansion connector.

The present invention also provides an electronic device including a flash memory, an expansion connector for inputting / outputting various data, and a test terminal group connected to the external device for receiving an operation test by the external device, and the electronic device. In a flash memory rewriting system that includes an external device that rewrites the stored contents of a flash memory of the device, the electronic device switches the connection of an expansion connector in the electronic device to change the input / output of various data from the external device to the external device. The external device controls the operation of the electronic device when the external device is connected to the test terminal group through the expansion connector of the electronic device, by including switching means for changing the use of the expansion connector to the connection between the test terminal groups. The stored contents of the flash memory of the electronic device are rewritten.

According to the system of the present invention having such a configuration, in the electronic device, the expansion connector is usually used for inputting / outputting various data, and the expansion connector is connected to the external device by switching the switching means. It is diverted to connect between test terminal groups. When the external device is connected to the test terminal group through the expansion connector of the electronic device, the external device controls the operation of the electronic device and rewrites the content stored in the flash memory of the electronic device. Therefore, the flash memory of the electronic device can be rewritten through the existing general connector of the electronic device. Further, since the electronic device is controlled through the test terminal group without using a boot program for booting in the flash memory or a program such as an operating system, even if the program in the flash memory is accidentally erased, It is possible to reliably rewrite the flash memory.

The test terminal group of the electronic equipment according to the present invention is, for example, a committee of electric and electronic engineers (IE) of the United States.
There is a standard (hereinafter referred to as JTAG standard) defined by JTAG (Joint Test Action Group) of EE).

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of a rewriting system of the present invention. The rewriting system according to the present embodiment includes an electronic device 11 and a personal computer 1.
The two are connected via a normal cable 13 or a dedicated cable 14.

The electronic device 11 includes a microprocessor 21.
And a flash memory 22 storing a boot program for booting and a program such as an operating system.
R to be a work area for storing various data
An AM 23, an expansion connector 24 connected to the normal cable 13 or the dedicated cable 14, and a switching circuit 25 for switching and connecting the expansion connector 24 to either the normal input terminal group 21a or the test terminal group 21b of the microprocessor 21. ing. The normal input terminal group 21a includes a data output terminal TXD, a data input terminal RXD, and the like. The test terminal group 21b is, for example, JTAG (Joint Test A) of the United States Committee for Electrical and Electronic Engineers (IEEE).
ction group) (hereinafter referred to as the JTAG standard) and includes a data input terminal TDI, a test data output terminal TDO, a test clock terminal TCK, a test mode select terminal TMS, a test reset terminal TRST, etc. .

The expansion connector 24 corresponds to, for example, RS-232 standardized by the American Electronics Industry Association (EIA). When connected to the expansion connector 24, the normal cable 13 opens or grounds a preset terminal 24a of the expansion connector 24 as shown in FIG. Further, the dedicated cable 14 is dedicated to the rewriting system of the present embodiment, and when connected to the extension connector 24, the power supply voltage Vcc is applied to the terminal 24a of the extension connector 24 as shown in FIG. The terminal 24a is pulled up.

In the switching circuit 25, as shown in FIG. 2, the terminal 24a of the expansion connector 24 is grounded through the resistor 25a, the voltage of the terminal 24a is inverted by the inverter 25b, and the inverted voltage is applied to each switch SW2. In addition to the above, the voltage of the terminal 24a is applied to each switch SW1.

When the normal cable 13 is connected to the extension connector 24, the terminal 24a is opened or grounded, the voltage inverted by the inverter 25b becomes high level, and each switch SW2 is turned on. In this case, the expansion connector 24 is connected to the normal input terminal group 21a of the microprocessor 21 via the switching circuit 25. Further, the normal cable 13 is connected to the serial port of the personal computer 12. As a result, the serial port of the personal computer 12 is connected to the normal input terminal group 21 of the microprocessor 21 through the normal cable 13, the expansion connector 24, and the switching circuit 25.
connected to a. At this time, the personal computer 1
Normal data communication is performed between the microprocessor 2 and the microprocessor 21 of the electronic device 11.

Further, the dedicated cable 14 is connected to the extension connector 2
4 is connected, the terminal 24a is pulled up and each switch SW1 is turned on. In this case, the expansion connector 2
4 is a microprocessor 21 via a switching circuit 25.
Connected to the test terminal group 21b. Also, the dedicated cable 14 is connected to the parallel port of the personal computer 12. This allows the personal computer 1
The parallel port 2 is connected to the test terminal group 21b of the microprocessor 21 through the dedicated cable 14, the expansion connector 24, and the switching circuit 25. At this time, the personal computer 12 can control the microprocessor 21 through the test terminal group 21b as described later.

FIG. 3 shows the configuration of the microprocessor 21. The microprocessor 21 includes a main logic circuit 21c for executing various programs and the like, and a test logic unit for testing the operation of the main logic circuit 21c. The test logic unit includes a test access port TAP and a boundary scan register.

The boundary scan register includes a main logic circuit 21c and each cell 21e inserted between each terminal 21d, and a register 21f. Each cell 21
e is a register, which is serially connected to each other together with the register 21f.

The test access port TAP corresponds to the test clock terminal TCK, the test mode select terminal TMS, the test reset terminal TRST, etc., and is an input / output terminal for communicating between the test logic unit and the outside. Also, the operation of the test logic unit is enabled or disabled according to the signal level of the test reset terminal TRST. Specifically, when the signal of the test reset terminal TRST becomes high level, the signal shift between each cell 21e and the register 21f of the boundary scan register is permitted,
When the signal of the test reset terminal TRST becomes low level,
A signal shift between each cell 21e of the boundary scan register and the register 21f is prohibited.

On the other hand, the test reset terminal TRST is connected to the terminal 24a of the expansion connector 24 described above.
Therefore, when the normal cable 13 is connected to the expansion connector 24 and the terminal 24a is opened or grounded, the signal of the test reset terminal TRST becomes low level, and the operation of the test logic unit becomes invalid. Further, when the dedicated cable 14 is connected to the expansion connector 24 and the terminal 24a is pulled up, the signal of the test reset terminal TRST becomes high level, and the operation of the test logic unit becomes valid.

Therefore, when the exclusive cable 14 is connected to the expansion connector 24 and the terminal 24a of the expansion connector 24 is pulled up, the test terminal group 21b of the microprocessor 21 is connected to the expansion connector 24 and the exclusive cable 1.
4, the signal of the test reset terminal TRST becomes high level, and the operation of the test logic unit of the microprocessor 21 becomes effective.

The test logic unit of the microprocessor 21 as described above is for observing and controlling the input / output signal of each terminal 21d of the main logic circuit 21c, and originally, for testing the operation of the main logic circuit 21c. It is provided.

Now, when the personal computer 12 is connected to the test terminal group 21b of the test logic unit of the microprocessor 21 through the expansion connector 24 and the dedicated cable 14, the personal computer 1
2 can observe and control the input / output signal of each terminal 21d of the main logic circuit 21c through the test terminal group 21b. Therefore, the personal computer 12 can control the operation and the input / output signal of the main logic circuit 21c of the microprocessor 21 by executing the control program built in the personal computer 12, and the contents stored in the flash memory 22 can be stored. It can be rewritten.

Therefore, in the present embodiment, a control program for rewriting the contents stored in the flash memory 22,
And a program to be stored in the flash memory 22 (boot program, self-check inspection program,
(Operating system, application program, etc.) is stored in the hard disk of the personal computer 12 in advance, the control program is executed by the personal computer 12, and the microprocessor 2
The program to be stored in the flash memory 22 is transferred from the personal computer 12 to the microprocessor 21 while controlling the operation and the input / output signal of the first main logic circuit 21c, and the program is stored in the flash memory 22. The process of rewriting the flash memory 22 will be described below with reference to the flowchart shown in FIG.

First, the personal computer 12 is connected to the test terminal group 21b of the microprocessor 21 through the dedicated cable 14. Then, an input operation of the personal computer 12 activates a control program for rewriting the flash memory 22 in the hard disk (step S101).

Next, when the rewriting of the flash memory 22 is instructed by the input operation of the personal computer 12 (step S102), the personal computer 1
2 controls the main logic circuit 21c through the test terminal group 21b of the microprocessor 21,
Erase a block of the flash memory 22 (step S
103), the program to be written to this block is read from the hard disk, this program is written to the block (step S104), the program is read from the block, and the read program is compared with the original program (step S105). ), And confirm that the writing was done normally.

After this, the personal computer 12
It is determined whether or not the rewriting of the flash memory 22 is completed (step S106). If the rewriting is not completed (“No” in step S106), the process returns to step S103 to rewrite the next block. Also,
If the rewriting is completed (“Yes” in step S106).
s "), the personal computer 12 sets the protection of the flash memory 22 by controlling the main logic circuit 21c through the test terminal group 21b (step S107), and then ends the processing of FIG.

As described above, in this embodiment, a control program for rewriting the stored contents of the flash memory 22,
Also, a program to be stored in the flash memory 22 is stored in advance in the hard disk of the personal computer 12, and the personal computer 12 is connected to the test terminal group 2 of the microprocessor 21 through the dedicated cable 14.
1b, the personal computer 12 controls the main logic circuit 21c through the test terminal group 21b, and the program to be stored in the flash memory 22 is sent from the personal computer 12 to the microprocessor 2
1 and transfer this program to flash memory 22
I remember it. Therefore, the boot program in the flash memory 22 is erased carelessly, and the electronic device 11
The flash memory 22 can be rewritten under the control of the personal computer 12 even when the flash memory 22 cannot be activated by itself. In addition, general normal cable 1
In place of 3, the personal computer 12 is connected to the test terminal group 21b of the test logic unit of the microprocessor 21 only by connecting the dedicated cable 14 to the expansion connector 24, and the operation of the test logic unit is enabled. Control of the microprocessor 21 by 12 may be enabled. Furthermore, since the extension connector 24 is used both for connecting the normal cable 13 and the dedicated cable 14, the dedicated cable 14 does not require a dedicated connector, and the size and cost of the device are not increased. Moreover, the expansion connector 24
As the above, a terminal having a small number of terminals can be applied, and the number of signal lines of the dedicated cable 14 can be small.

The present invention is not limited to the above embodiment, but can be variously modified. For example,
The electronic device may be of any type as long as it has a flash memory, an expansion connector, and a test terminal group for testing the operation of the microprocessor. In addition, it is possible to store a control program for controlling the electronic device through the test terminal group and a program to be stored in the flash memory, and execute the control program to control the electronic device through the test terminal group. Even the above device can be applied in place of the personal computer. Further, although the switching connection between the normal cable 13 and the dedicated cable 14 is automatically performed by the switching circuit 25, a switch for manually performing this switching connection may be provided.

[0035]

As described above, according to the present invention, in the electronic equipment, the expansion connector is usually used for inputting / outputting various data, and the expansion connector is connected to the external equipment by switching the switching means. It is diverted to connect between test terminal groups. When the external device is connected to the test terminal group through the expansion connector of the electronic device, the external device controls the operation of the electronic device and rewrites the content stored in the flash memory of the electronic device. Therefore, the flash memory of the electronic device can be rewritten through the existing general connector of the electronic device. Further, since the electronic device is controlled through the test terminal group without using a boot program for booting in the flash memory or a program such as an operating system, even if the program in the flash memory is accidentally erased, It is possible to reliably rewrite the flash memory.

Further, even in the case where the board needs to be replaced conventionally in order to destroy the program in the flash memory, find a bug in the program, or change the specification, the application of the present invention allows the personal computer to be connected to the cable. It is possible to connect to the expansion connector through and rewrite the stored contents of the flash memory by the personal computer.

Furthermore, according to the present invention, the connection of the expansion connector in the electronic device is switched and the purpose of the expansion connector is changed only by generating a signal from a preset terminal of the expansion connector. be able to. Further, since the expansion connector is used for both the connection of the normal cable and the connection of the exclusive cable, the exclusive connector is not required for the exclusive cable, and the device does not become large and the cost does not increase.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a rewriting system of the present invention.

FIG. 2 is a diagram schematically showing an extension connector and a switching circuit of an electronic device in the system of FIG.

3 is a block diagram showing a configuration of a microprocessor of an electronic device in the system of FIG.

FIG. 4 is a flowchart showing a processing procedure by the system of FIG.

[Explanation of symbols]

11 electronic devices 12 personal computer 13 normal cable 14 dedicated cable 21 microprocessors 21a Normal input terminal group 21b Test terminal group 22 Flash memory 23 RAM 24 Expansion connector 25 Switching circuit

Claims (3)

[Claims] 1. An electronic device including a flash memory, an expansion connector for inputting / outputting various data, and a test terminal group connected to an external device for receiving an operation test by the external device. An electronic device, comprising switching means for switching the connection of the expansion connector in, and changing the use of the expansion connector from input / output of various data to connection between an external device and a test terminal group. 2. The switching means switches the connection of the expansion connector in the electronic device in response to a signal from a preset terminal of the expansion connector.
Electronic device described in. 3. An electronic device including a flash memory, an expansion connector for inputting / outputting various data, and a test terminal group connected to the external device for receiving an operation test by the external device, and a flash memory of the electronic device. In a flash memory rewriting system including an external device that rewrites the stored contents of the electronic device, the electronic device switches the connection of the expansion connector in the electronic device to switch various data input / outputs between the external device and the test terminal group. The external device controls the operation of the electronic device when the external device is connected to the test terminal group through the expansion connector of the electronic device.
A flash memory rewriting system, characterized in that the stored contents of the flash memory of the electronic device are rewritten.