JPH01191916A - System resetting control circuit - Google Patents

Abstract

PURPOSE:To perform the different processes at initialization by using a means which distinguishes a case where a system is initialized by the signal produced automatically in an internal circuit from another case where the system is initialized by an external request. CONSTITUTION:A microcomputer 23 contains a microprocessor 10, an input/ output part 11, a ROM 12 and a RAM 13. Then the microcomputer 23 is connected to an external input/output part 24 via the part 11 and to an external resetting generating circuit 22 via a system resetting input terminal 21 respectively. Furthermore a circuit 14 is added to automatically produce a system resetting signal via an internal circuit of the processor 10 according to the state of the processor 10, together with a flag generating circuit 15, a flag generating circuit 16 which latches the external resetting signal produced from the circuit 22 and decides this signal via the software, etc. Then the processor 10 is initialized into a prescribed state through an output terminal 20 of an OR 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit system for initializing a microprocessor and a microcomputer.

[Conventional technology]

As shown in Figure 2, the conventional method for initializing a microprocessor or microcomputer is to input an external input signal for initialization, and when the power is turned on and a certain state is reached. This was a method in which the internally automatically generated signals were combined using OR logic to initialize the internal circuit.

[Problem to be solved by the invention]

However, the conventional methods described above are either forced to work from the outside during the initialization of the microprocessor or microcomputer itself, or the system using it, or are they worked automatically internally when the power is turned on, etc. It is said that when a system is created using a microprocessor or microcomputer, and a program is used to make the system perform the desired function, the initialization of the system due to these multiple factors becomes the same. There was a problem. In other words, depending on the application of the system, system initialization involves inputting a signal from the outside to the system reset input of a microprocessor or microcomputer, and initialization by a signal automatically generated internally depending on the power supply status, etc. Although there are many cases in which different processing is desired in normal program processing, it is impossible to do so because it is not possible to distinguish between them.

The present invention is intended to solve these problems, and its purpose is to provide a microprocessor system that can be used to initialize a system using a signal automatically generated by an internal circuit in a system using a microcomputer. To provide a microprocessor or microcomputer that provides means for distinguishing between the case where the system is initialized by a request from an external signal and the case where the system is initialized by a request from an external signal, and which can be determined by software and perform different processing in those cases. It is in.

[Means to solve the problem]

The microprocessor or microcomputer of the present invention includes: a) a microprocessor in which a CPU is integrated into one chip;
In a microcomputer that has ROM, RAM, and input/output functions in one chip in addition to the PU, b) a circuit using an external input terminal (system reset input terminal) for initializing the internal circuit (hardware), and c) a source At startup or under certain conditions of the internal circuit (for example, when CPU runaway is detected),
A circuit (internal reset circuit) that automatically initializes the internal circuit (hardware), and d) Whether the initialization was caused by the system reset input or by the internal reset circuit. The present invention is characterized in that it includes at least a flag that allows identification of whether it is caused by both.

[For production]

According to the above configuration of the present invention, in the system using the microprocessor or microcomputer,
Provides a means to distinguish between cases in which the system is initialized by a signal automatically generated by an internal circuit and cases in which the system is initialized by an external request, and software determines the difference between the cases. It can be applied to enable further processing.

〔Example〕

FIG. 1 is a block diagram of an embodiment of the present invention. 1st
In the figure, 23 is a microcomputer. 10
is a microprocessor, which is the central processing part of a microcomputer. The microcomputer is 10
microprocessor, 11 input/output units, and 12 R
It is composed of OPvl and 13 RAMs. In addition, the microcomputer has 11 input/output sections, 24 external input/output terminals, 21 system reset input terminals, and 22 input/output terminals.
Connected to external reset generation circuit.

16 is a circuit for latching an external reset signal generated by an external reset generating circuit and generating a flag for determination by software; 19 is a terminal through which the flag is connected to the inside of the microprocessor. 15 is
A circuit latches a reset signal generated in an internal circuit and generates a flag for determination by software, and 18 is a terminal through which the flag is connected to the inside of the microprocessor.

Reference numeral 17 denotes an OR which receives a system reset signal generated internally or externally, and its output is led into the processor through a 2° terminal, and the processor is initialized to a predetermined state.

Reference numeral 14 denotes a circuit for automatically generating a system reset signal by the internal circuit of the processor depending on the state of the processor.

〔Effect of the invention〕

As described above, according to the present invention, for the initialization of a system using a microprocessor or microcomputer,
Separate flags correspond to requests from the outside and automatic factors from the inside, so by determining this in software, a system using a microprocessor or microcomputer can handle requests from the outside. It has the advantage that the system can be initialized to a certain state upon request, and also that the system can be initialized to a different state upon a change in the internal state of the microprocessor.

Also, by using these effects, the signal from the external reset input terminal can be made equivalent to the interrupt signal with the highest priority in the microprocessor, and can be used for interrupt control in systems using microprocessors or microcomputers. It also has the effect of expanding the circuit.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention. FIG. 2 is a conventional configuration diagram. 10... Microprocessor section 11... Input/output section 12... ROM 13... RAM 14... Internal state detection and reset generation circuit 15...
・Internal reset flag generation, erase circuit 16...External reset flag generation, erase circuit 17...OR circuit 18...terminal 19...terminal 20...terminal 21...terminal 22...・External reset generation circuit 23...Microcomputer 24...External input/output section and above Applicant: Seiko Epson Corporation

Claims (1)

[Claims] (1) a) In a microprocessor in which the CPU is integrated into one chip, and in a microcomputer in which ROM, RAM, and input/output functions are integrated into one chip in addition to the CPU, b) External input terminal for initializing the internal circuit (hardware) c) When the power is turned on or under certain conditions of the internal circuit (for example, when CPU runaway is detected), the internal circuit (hardware) automatically resets. (internal reset circuit); and d) It is possible to identify whether the initial naturalization was caused by the system reset input, the internal reset circuit, or both. , a system reset control circuit comprising at least a flag that can be reset after determination by software, and having a system reset with different functions.