JPH05342377A - Microcomputer - Google Patents

Abstract

PURPOSE:To easily develop a program to be stored by providing a single-chip microcomputer with the function which emulates its own operation. CONSTITUTION:With respect to single-chip microcomputers provided with a means (mode A) which switches a part of input/output terminals to an internal bus and an address data bus connected to an external memory and a means (mode B) which allows terminals switched by the mode A to function as normal input/output terminals and switches a part of the other input/output terminals to the internal bus, internal busses 14 of two single-chip microcomputers 11 and 12 switched to the mode A and the mode B respectively are connected, and a general PROM 13 is connected to an address data bus 15 on the mode A side, thereby equivalently emulating the operation of one single-chip microcomputers for the normal use.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcomputer, and more particularly to a single chip microcomputer containing a ROM.

[0002]

2. Description of the Related Art Conventionally, in developing a built-in program, a single-chip microcomputer actually tests or debugs the program on a development device.
Rewritable ROM (Read Only Memory) P
A single-chip microcomputer replaced with a (programmable) ROM is used, or an in-circuit emulator (hereinafter, ICE) that emulates the operation of the single-chip microcomputer is used.

In the PROM version of a single-chip microcomputer, a program for execution is written in a PROM by a PROM writer, and the single-chip microcomputer is mounted on a development apparatus to execute the program.
If there is an error, the single-chip microcomputer is removed from the development device, the modified program is written, and the program is re-executed to perform debugging.

When using ICE, instead of a single-chip microcomputer, an ICE probe is mounted and a program is loaded from a host computer and executed. When there is an error, the program is debugged by using the debugger to modify and re-execute the program.

[0005]

Conventionally, there is a case where a single-chip microcomputer incorporating a PROM is not prepared, and a jig is used when a general ROM writer is used for writing a program in the PROM. Often needed. Further, if the ICE is very expensive and the electrical characteristics at the terminal level are different from those of an actual single-chip microcomputer, if a single-chip microcomputer containing a ROM in which a program after debugging is written is operated on the development device. , There may be problems such as not working as expected.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned drawbacks, to provide a microcomputer which does not require a special jig, is inexpensive, and operates as expected.

[0007]

The microcomputer of the present invention has a structure in which a part of input / output terminals is switched to an internal data bus or an address data bus connected to an external memory (A mode) and a terminal switched in A mode. Has a function (B mode) of switching a part of the other input / output terminals to the internal bus by connecting the external memory to the address data bus on the A mode side. It is characterized by emulating the operation of a single-chip microcomputer in normal use.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an embodiment of the present invention, which emulates a single-chip microcomputer in normal use by using a single-chip microcomputer and a general-purpose PROM.

In FIG. 1, in this embodiment, a single-chip microcomputer 11 switched to A mode.
And the internal bus 14 is connected to the single chip microcomputer 12 switched to the B mode. Where A
In the mode, a part of the input / output terminals has means for switching to the internal bus and the address data bus connected to the external memory. In the B mode, the terminals switching in the A mode function as normal input / output terminals, and other terminals. It has means for switching a part of the input / output terminals to the internal bus.

The A-mode single-chip microcomputer 11 has a general-purpose PROM in which a program is written.
The memory 13 is connected by the address data bus 15.

Single-chip microcomputer 11
Has ports A, B, C, D, the other single-chip microcomputer 12 has ports A, C, D, and the outside has ports A, B, CD.

With this, the operation of the single-chip microcomputer at the time of normal use can be emulated, and the program is debugged by vapor deposition on the development device. The program is modified by rewriting with a PROM writer.

FIG. 2 is a block diagram for emulating a single-chip microcomputer and a single-chip microcomputer in normal use by using a ROM emulator according to another embodiment of the present invention.

In FIG. 2, this embodiment is based on the general-purpose P of FIG.
ROM emulator probe 2 instead of ROM 13
3 is connected and used. Further, a ROM emulator is provided outside the probe 23. Other configurations are the same as those in FIG.

The program is loaded from the host computer into the ROM emulator 26 and executed. The program is modified by the debugger.

[0016]

As described above, in the single-chip microcomputer of the present invention, a part of the input / output terminals is switched to the internal bus and the address data bus connected to the external memory (A mode) and the A mode. The terminal functions as a normal input / output terminal, and a part of the other input / output terminals has a means (B mode) for switching to the internal bus. , It is not necessary to select a single-chip microcomputer compatible with the PROM version.
An expensive IC that does not require a jig for writing to ROM
Since an inexpensive ROM emulator can be used instead of E, the development cost can be reduced, and since the emulation is performed by the actual single-chip microcomputer, the electrical characteristics of the I / O port are the same as in normal use. Even when a single-chip microcomputer incorporating a ROM in which a program after debugging has been written is operated on the development device, there is an effect that abnormal operation due to electrical characteristics does not occur.

[Brief description of drawings]

FIG. 1 is a block diagram for emulating the operation of a single-chip microcomputer during normal use by using a single-chip microcomputer and a general-purpose PROM according to an embodiment of the present invention.

FIG. 2 is a block diagram for emulating the operation of a single-chip microcomputer during normal use by using a single-chip microcomputer and a ROM emulator according to another embodiment of the present invention.

[Explanation of symbols]

11, 21 A-mode single-chip microcomputer computer 12, 22 B-mode single-chip microcomputer 13 General-purpose PROM with built-in program 14, 24 Internal bus 15, 25 Address data bus 23 ROM emulator probe 26 ROM emulator

Claims (2)

[Claims] 1. An A mode in which a part of the input / output terminals is switched to an internal data bus and an address data bus connected to an external memory, and a terminal switched in the A mode functions as a normal input / output terminal, and other input / output terminals. B mode in which some of the terminals are switched to the internal bus, and the A mode and the B mode
The internal buses of the two single-chip microcomputers switched to the mode are connected to each other, and the external memory is connected to the address data bus on the A mode side, equivalently emulating the operation of the single-chip microcomputer during normal use. A microcomputer characterized by being able to do so. 2. The external memory is a ROM via a plug.
The microcomputer according to claim 1, which is an emulator.