JP3024597B2 - CPU device and method of using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CPU device capable of writing a program or the like into a boot ROM by an operation of its own CPU.

[0002]

2. Description of the Related Art CPs comprising an electronic circuit using a CPU
The U device is operated by a program written in the ROM.
You can determine its function.

[0003] For this reason, by mounting ROMs in which different types of programs are written in a CPU device in which the same board is incorporated in the same housing, the products can be shipped as products having different specifications, and the cost of production and inventory management can be reduced. Can be reduced.

In this case, in order to obtain a product having desired specifications at the time of shipment, as shown in FIG.
M2 is replaced by a ROM 2 'in which a necessary program is written, or a ROM writing device 7 is externally connected via a interface 6, 6' to a CPU device 5 incorporating a rewritable internal ROM 4 as shown in FIG. Then, the writing control circuit 8 writes necessary programs and necessary data into the internal ROM 4 to carry out the processing.

[0005]

The method of replacing the ROM shown in FIG. 5 requires a complicated operation such as disassembly of the housing, since the mounting position of the internal ROM 2 is the board in the housing. Thus, there is a problem that the cost increases because the socket needs to be used.

In the method using an external ROM writing device 7 shown in FIG. 6 , a chip select signal, a read / write signal, an address signal and a data signal supplied from the outside to the internal ROM 4 are transmitted from the CPU 9 of the CPU device. Since the write control circuit 8 must be separated from the write control circuit 8, the write control circuit 8 becomes complicated and the cost increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a CPU device capable of easily writing a program or the like into an internal ROM without making the CPU device complicated and costly.

[0008]

(1) A CPU device provided by the present invention has a CPU and a rewritable internal ROM in which a function program for determining a function of the device is written.
A communication controller and a communication interface for communicating with a network device that transmits the function program, an external ROM interface for connecting an external ROM, and a start for designating whether to start the CPU from the internal ROM or the external ROM When the selection switch and the boot selection switch specify the internal ROM, the internal ROM is allocated in the boot address space of the CPU, and when the boot selection switch specifies the external ROM, the external ROM is allocated in the boot address space of the CPU. And a main body having a ROM control circuit for arranging the internal ROM in another address space, and a write program for receiving a function program from a network device via the communication controller and the communication interface and writing the program to the internal ROM. , The external ROM interface Through the face, characterized by comprising an external ROM which is detachably connected to the body.

[0009]

[0010]

(2) In the configuration of the above (1), the start selection switch connects the external ROM interface to the external RO.
It is possible to automatically detect whether or not M is connected, and switch to designation of external ROM startup when connected, and switch to designation of internal ROM startup when not connected. This can be configured, for example, by using a connector for connecting an external ROM board to an external ROM interface as a switch.

Thus, it is not necessary to arrange a mechanical switch in the CPU device, and it is not necessary to manually operate the start selection switch, so that the cost can be reduced.

[0013]

(3) The CPU device of the above (1) is used as follows. That is, when writing the function program to the internal ROM, the start selection switch is set to the external ROM.
And by connecting the external ROM to the main body of the CPU device via the external ROM interface, the CPU can be started with the external ROM writing program.
increase. This external ROM has a device for writing to the internal ROM.
Function program is not stored. That is, launch
Communication program and communication interface
Function program from a network device via the
The RAM is received and written to the internal ROM. At the time of normal use thereafter, the start selection switch is switched to the designation of the internal ROM, the external ROM is removed, and the internal ROM is removed.
Is started and the CPU device is operated with the function.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment of the present invention shown in FIG. 1, reference numeral 10 denotes a CPU device, and a main body 10a is provided with a CP.
U11, internal ROM 12, start selection switch 13, RO
M control circuit 14, external ROM interface 15, communication
Communication controller 21 and communication interface 22
You. Reference numeral 16 denotes an external ROM board on which an external ROM 17 is assembled.
And the external ROM interface 15 via the connector.
The external ROM 17 is attached to the CPU 11
Address bus and data bus. Communication interface
Interface 22 is connected to the network
The connected communication terminal device 23 is connected to the network.
Received a functional program from another computer
You.

The CPU device 10 stores a program written in the internal ROM 12 or the external ROM 17 into the CPU 1.
1 operates by executing. The internal ROM 12
A rewritable ROM, for example, a flash memory is used, and a function program for determining the function of the apparatus and data related thereto are written. Start selection switch 13
Indicates that the CPU 11 is started up by the internal ROM 12 and the external ROM 1
7 is specified, for example, as shown in FIG.
As shown in (a), a circuit is used in which a BOOT terminal 13b pulled up by a resistor 13a is grounded by a dip switch 13c.

The external ROM 17 stores the communication controller
Via the network 21 and the communication interface 22.
Function programs and related data from network devices
And store the write program to be written to the internal ROM
I have.

The ROM control circuit 14 switches the arrangement of the internal ROM 12 and the external ROM 17 in the address space of the CPU 11 as shown in FIGS. In FIGS. 2 (a) and 2 (b),
The chip select signal CS1 has the smallest address CP
U designates an address area to be activated, and the chip select signal CS2 designates an address area following this.
The chip select signals CS1 and CS2 are transferred to the internal ROM 12
By changing the address to the external ROM 17, thereby changing the address assignment.

The ROM control circuit 14 is provided, for example, in FIG.
It is configured as shown in (a). In FIG. 3A, 18
Is a decoder which decodes the upper address signals A14, A15, A16 output from the CPU 11 to generate chip select signals CS1, CS2,. This chip select signal CS
1, CS2 are multiplexers 19, controlled by the boot signals “H” and “L” output from the start selection switch 13.
19, and are output to the ROMs 12 and 17 as shown in the logical diagram of FIG. In addition, CPU
If the decoder 11 directly outputs the chip select signals CS1 and CS2, the decoder 18 need not be provided.

The operation of the CPU device 10 having the above-described configuration will be described separately for writing a functional program or the like into the internal ROM 12 and the subsequent normal operation.

To write the function program or the like, the start selection switch 13 is switched to the designation of the external ROM (by turning on the dip switch 13c in FIG. 3 (a) to set the boot signal to "L"). External ROM
It is started by turning on the power of the CPU device 10 after mounting the board 16.

At this time, the ROM control circuit 14
As shown in (a), the external ROM 17 is arranged in the start address space, and the internal ROM 12 is arranged in the subsequent address space. Therefore, the CPU 11 first reads the external ROM 17 and operates according to the write program. This writing program is a communication interface
Function program and the like via the
The data is written to a predetermined address of the OM 12, and in the case of a flash memory, non-volatile storage is performed by a normal writing operation similar to writing to a RAM. Also,
The write address of the internal ROM 12 is shifted so that the address arrangement of the internal ROM 12 becomes a correct address at the time of the normal operation because the address arrangement of the internal ROM 12 is changed at the time of the writing of the functional program and at the time of the normal operation as shown in FIGS. Value is used. Which of multiple function programs to write
Indicates a dedicated writing program for each function program.
Prepare the external ROM 17 that you have memorized, select this
This is performed by inserting it into the OM interface 15 or the like.

After the writing of the function program into the internal ROM 12 is completed, the external ROM board 16 is removed, and the startup selection switch 13 is switched to the internal ROM 12, so that normal operation can be performed.

The normal operation used only by the main body 10a is R
The OM control circuit 14 controls the internal ROM 12 as shown in FIG.
Are arranged in the start address space. When the power is turned on, the CPU 11 first reads the internal ROM 12, and the written functional program starts. Thereby, the CPU device 10 operates with a predetermined function.

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

In the first embodiment, the selection of the ROM to be started is performed by the start selection switch 13 using the dip switch 13c. However, the selection is automatically performed depending on whether or not the external ROM board 16 is mounted. be able to.

FIG. 4 shows this as a second embodiment.
You.

In this configuration, the boot signal input terminal 24 of the ROM control circuit 14 is pulled up by a resistor 25, and this terminal 24 is grounded by a ground circuit 26 provided on the external ROM board 16 via the external ROM interface 15. It was made. In this configuration, the external ROM board 16
Into the external ROM interface 15 and connect
When the terminal 24 is grounded and the boot signal goes to “L” level, and the external ROM board 16 is removed, the boot signal at the terminal 24 goes to “H” level. 14 can be switched between "H" and "L". This second
In the second embodiment, it is not necessary to provide the dip switch 13c used only at the time of shipment, and the operation of switching the dip switch 13c is not required, so that the cost can be reduced.

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

According to the present invention, a ROM control circuit for switching the address arrangement between an internal ROM and an external ROM is provided.
M, a function program and its related
Write program to receive serial data and write it to internal ROM
Since the RAM has been stored , the external RO
M to connect to a network such as a host computer.
Function program received from the network device
M can be written . Therefore, it is not necessary to replace a ROM, which requires a lot of man-hours, or to use an external ROM writing device for complicating the inside of the CPU device, and it is particularly necessary to supply hardware of the same configuration as a variety of products. Reduction becomes possible.

[Brief description of the drawings]

FIG. 1 shows a function program for writing, etc.
FIG. 1 is a circuit diagram showing a first embodiment of the present invention in which a signal is received through an interface .

FIG. 2 is a diagram showing an address space to which an internal ROM and an external ROM are allocated in the embodiment of FIG. 1 when the internal ROM is written (a) and during normal use (b), respectively.

FIG. 3 is a diagram showing a specific example of the ROM control circuit of FIG. 1;

FIG. 4 External ROM to external ROM interface
The figure which shows the modification of embodiment of FIG. 1 which selects a starting ROM automatically according to the presence or absence of board insertion.

FIG. 5 is an explanatory diagram of a conventional example in which an internal ROM is replaced.

FIG. 6 is an explanatory diagram of a conventional example in which a write control circuit is provided in a CPU device and an internal ROM is rewritten by an external write device.

DESCRIPTION OF SYMBOLS 10 CPU device 11 CPU 12 Internal ROM 13 Start-up selection switch 13a Resistance 13b BOOT terminal pulled up 13c Dip switch 14 ROM control circuit 15 External ROM interface 16 External ROM board 17 External ROM 18 Decoder 19 Multiplexer 21 Communication Controller 22 Communication interface 23 Communication terminal device connected to network 24 Boot signal input terminal 25 Resistance 26 Grounding circuit 27 Network 28 Network device such as host computer CS1, CS2 Chip select signal

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-68928 (JP, A) JP-A-3-294923 (JP, A) JP-A-5-204654 (JP, A) JP-A-7- 146837 (JP, A) JP-A-8-179996 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 9/06 G06F 15/78

Claims (3)

(57) [Claims] 1. A CPU, a rewritable internal ROM in which a function program for determining a function of the apparatus is written,
A communication controller and a communication interface for communicating with the network device transmitting the function program; an external ROM interface for connecting an external ROM; and a start selection switch for specifying whether to start the CPU from the internal ROM or the external ROM. When the startup selection switch specifies the internal ROM, the internal ROM is
A ROM control circuit for arranging the external ROM in the start address space of the CPU and arranging the internal ROM in the other address space when the start select switch designates the external ROM; An external ROM detachably connected to the main body via the external ROM interface, storing a writing program for receiving a function program from a network device via the communication controller and the communication interface and writing the program into an internal ROM. C characterized by comprising:
PU device. 2. A boot selection switch automatically detects whether or not an external ROM is connected to an external ROM interface. When the external ROM interface is connected, the switch is switched to a specification of external ROM boot. 2. The CPU device according to claim 1, wherein the CPU device is switched to designation. 3. A CPU, a rewritable internal ROM in which a function program for determining a function of the apparatus is written,
A communication controller and a communication interface for communicating with a network device transmitting the function program; an external ROM interface for connecting an external ROM; and a start selection switch for specifying whether to start the CPU from the internal ROM or the external ROM. When the startup selection switch specifies the internal ROM, the internal ROM is
A ROM control circuit for arranging the external ROM in the start address space of the CPU and arranging the internal ROM in the other address space when the start select switch designates the external ROM. The main unit that has received the function program from the network device via the communication controller and communication interface
External ROM storing a write program to be written to M
Is connected via the external ROM interface, and at the same time, the start selection switch is switched to the designation of the external ROM start, and the CPU is started by the writing program of the external ROM. After the above writing, the external ROM is removed from the main body, and the start selection switch is switched to the designation of the internal ROM, and
A method of using a CPU device, wherein the CPU is started by a functional program written in an internal ROM.