JPH0570189B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a ROM constant development device for a one-chip microcomputer, and more specifically, to a ROM constant development device that is performed by changing the constants of an externally attached rewritable ROM. Regarding improvement technology.

<Prior art> For example, microcomputers are increasingly being used to control automobile engines (fuel supply amount, ignition timing control, etc.), but in order to improve the reliability of control programs stored in ROM, There is a tendency to use non-rewritable ROM (mask ROM), but due to the consolidation of circuits, such ROM
One-chip microcomputers that have built-in memory, RAM, and I/O are increasingly being used (see Japanese Patent Laid-Open No. 60-244650, etc.).

<Problems to be Solved by the Invention> By the way, when developing a control program using a one-chip microcomputer with such a built-in non-rewritable ROM, as shown in FIG. A dedicated development board 2 is provided that allows the use of the
By changing the constants of ROM1, we were able to develop the final specifications of the ROM to be built into the one-chip microcontroller 3.

That is, during mass production, a one-chip microcomputer 3 is mounted on a mass-production type board 4 as shown in FIG. The program is executed, but during development, as shown in FIG. In order to recover ports lost due to access, external latch circuits 5a and 5b are mounted together with external ROM 1 on the same board 2 as one-chip microcomputer 3.

In this way, during development and mass production, there will be differences in the circuits of the boards on which the one-chip microcontroller 3 is mounted, and the layout of the mounting boards will be different. Even if the failure resistance and noise resistance are evaluated, it does not mean that the evaluation of the mass-produced board 4 shown in Figure 4 has been performed correctly, and the final evaluation needs to be performed again with the mass-produced board. There was a problem.

The present invention was created in view of the above problems, and reduces development costs and evaluation man-hours by using a common board for development that changes ROM constants and mass production that uses non-rewritable ROM. The purpose is to

<Means for solving the problem> Therefore, in the present invention, a development board on which a rewritable external ROM is mounted is connected to a mass-produced board on which a one-chip microcontroller with a non-rewritable ROM built into one chip is mounted. The external ROM of the development board is configured so that it can be accessed by the one-chip microcomputer, and the external ROM is configured to be accessible by the one-chip microcomputer. A circuit is installed on the development board to restore the ports of the one-chip microcontroller that were lost during the process and return them to the mass-produced board. The mass-produced board is provided with a switching means for switching between the use of the ROM, and when developing ROM constants, the development board is connected to the mass-produced board, the one-chip microcontroller accesses the external ROM, and the recovery port from the development board is connected to the mass-produced board. A ROM constant development device for a one-chip microcomputer was constructed using the following.

<Function> According to the ROM constant development device having such a configuration,
When changing the ROM constants for development, connect the development board to a mass-produced board on which a one-chip microcontroller is mounted. Then, by switching the switching means provided on the mass-produced board, the ports of the one-chip microcomputer are not used directly, but the ports returned from the development board are used. Then, the circuit installed on the development board enables the one-chip microcontroller on the mass-produced board to access the rewritable external ROM, and the ports lost due to access to the external ROM are replaced by the development board. It will be revived and returned to mass-produced boards for use.

That is, the external ROM required for developing ROM constants and the peripheral circuitry required for accessing the external ROM are provided on the development board, and the development board is connected to the mass-produced board. By returning the port to the mass-produced board, it is now possible to use the mass-produced board as is for development by changing the external ROM constants.

<Example> An embodiment of the present invention will be described below.

In FIG. 1, a one-chip microcomputer 12 is mounted on a mass-produced board 11. This one-chip microcomputer 12 includes CPU, RAM, ROM, I/
The ROM is a non-rewritable mask ROM.

The signal line 13 connected to each port of the one-chip microcomputer 12 is divided into two parts in the middle and extended on the mass-produced board 11, one of which is connected to the board 1.
Flat cable terminal 14 provided at one end
(Note that this terminal 14 may be a simple through hole.), and the other terminal is connected to a switching terminal portion 16 which is connected and disconnected by a switching jumper wire 15 as a switching means. When the mass production type board 11 is used for mass production, the ports of the one-chip microcomputer 12 are directly used by the switching jumper wires 15 without using the flat cable terminals 14. Therefore, during mass production, the flat cable terminal 14 and the switching jumper wire 15 are
etc. are unnecessary.

By the way, during development until the final specifications of the non-rewritable ROM built into the one-chip microcomputer 12 are determined, a rewritable ROM is externally attached, and this external ROM is used in the one-chip microcomputer 1.
Since it is necessary to determine the optimum constant by changing the constant while accessing the
A development board (sub board) 18 on which ROM) 17a and 17b are mounted is prepared, and this development board 18
By electrically connecting the PCB and the mass-produced board 11 via the flat cable 19 connected to the flat cable terminal 14, the one-chip microcontroller 12 can read the EPROMs 17a and 17b of the development board 18.
has been made accessible.

The development board 18 includes a flat cable 1.
A flat cable terminal 20 similar to the terminal 14 to which the other end of the flat cable 9 is connected is provided. The extended signal line is connected to the gate array 21 mounted on the development board 18, and the port (output channel) of the gate array 21 and the switching terminal section 16 on the mass production board 11 side are also connected to the terminal 20, It is connected via a flat cable 19 and terminal 14.

When the gate array 21 uses EPROMs 17a and 17b mounted on the same substrate 18,
When using only one chip microcontroller 12 (during mass production)
It emulates the same functions as the
Lost due to external attachment of a and 17b (external
The emulation port 22 of the one-chip microcomputer 12 (used for accessing the ROM) is output.

That is, by connecting the ports of the one-chip microcomputer 12 to the gate array 21, the external EPROMs 17a and 17 are mounted on the development board 18.
b and make EPROM accessible.
This is to restore the ports of the one-chip microcomputer 12 that were lost due to access by 17a and 17b and return them to the mass-produced board 11.

Therefore, when the mass production board 11 and the development board 18 are connected with the flat cable 19, the switching jumper wire 15 does not directly use the port of the one-chip microcomputer 12, but connects the gate of the development board 18. The emulation port 22 returned from the array 21 is switched to be used, and the EPROM 17a, 17 is connected to the one-chip microcomputer 12 via the switching terminal section 16 with the same function as in mass production using only the one-chip microcomputer 12.
EPROM17a, 17b while accessing
Change the constants and proceed with development.

As described above, according to this embodiment, the mass-produced substrate 11
By connecting the development board 18 to the
Since EPROM17a and 17b can be accessed,
The board on which the one-chip microcomputer 12 is mounted can be used in common during development and mass production, reducing development costs. Furthermore, since the configuration is such that signals are exchanged between the mass-produced board 11 and the development board 18 during development, it is inferior to the case where only the mass-produced board 11 is used in terms of resistance to radio interference and noise. This is obvious, so if there is no problem in evaluating radio interference resistance etc. during development when the development board 18 is connected, it can be assumed that there is no problem with the mass production board 11 alone during mass production. There is no need to perform evaluations separately during mass production and during mass production, reducing man-hours.

FIG. 2 shows the circuit configuration of the gate array 21 shown in FIG. 1.

Here, the gate array 21 includes ports of the one-chip microcomputer 12 and EPROMs 17a and 17b.
Address latch circuit 23 for use as an address/data line for DATA access
An emulation circuit 24 (latch circuit) for emulating each port of the one-chip microcomputer 12 is also provided. The emulation circuit 24 includes the shift register circuit 2
5. Consists of an inverter circuit 26, a buffer circuit 27, and an emulation circuit 24.
The emulation port 22 is designed to function in substantially the same way as the port of the one-chip microcomputer 12.

The configuration of the gate array 21 shown in FIG. 2 includes the external latch circuits 5a and 5b shown in FIG. 3, and conventionally, the structure of the gate array 21 shown in FIG. The external ROM and external latch circuit 5a, which were mounted for development purposes on the mass-produced board 2 on which the one-chip microcomputer 3 is mounted,
5b (gate array 21) is mounted on the development board 18 in this embodiment, and the port is mounted on the mass production board 1 again.
1 side so that even if the development board 18 is connected, it can function in the same way as in mass production.

<Effects of the Invention> As explained above, according to the present invention, a rewritable external ROM on a development board and a one-chip microcontroller can be accessed with the same functions, and the lost port can be accessed. A circuit is provided to restore the 1-chip microcontroller and return it to the mass-produced board, and the development board is connected to the mass-produced board on which the one-chip microcontroller is mounted, so that the ports returned from the development board are used during development. As a result, the board on which the one-chip microcontroller is mounted is the same during development and mass production, which has the effect of reducing development costs and making it easier to evaluate radio interference resistance, etc., thereby reducing man-hours.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a system during development of ROM constants showing one embodiment of the present invention, FIG. 2 is a circuit diagram showing the circuit configuration of a gate array in the same embodiment, and FIG.
The figure is a block diagram showing a board during conventional ROM constant development, and FIG. 4 is a block diagram showing a board during conventional mass production. 11...Mass production type board, 12...One-chip microcomputer, 15...Switching jumper wire, 17a, 17b
...EPROM, 18... Development board, 19... Flat cable, 21... Gate array.

Claims (1)

[Claims] 1 Connect a development board on which a rewritable external ROM is mounted to a mass-produced board on which a one-chip microcontroller with a non-rewritable ROM built into one chip is installed, and connect the external ROM of the development board to the one-chip microcontroller. The device is configured to be accessible by a chip microcomputer, and enables the one-chip microcomputer to access the external ROM, and also restores a port of the one-chip microcomputer that was lost for accessing the external ROM. A circuit to be returned to the mass production board is installed on the development board, and a switching means for switching between direct use of the one-chip microcontroller port and use of the recovery port returned from the development board is provided on the mass production board. The one-chip device is characterized in that when developing ROM constants, the development board is connected to the mass-produced board, the one-chip microcontroller accesses the external ROM, and a recovery port from the development board is used. Microcomputer ROM constant development device.