JPH0512455A - Option setting circuit - Google Patents

Abstract

PURPOSE:To improve reliability for setting options by connecting output signals from a noise filter to plural latch clocks to latch plural data from a non-volatile memory for storing option data. CONSTITUTION:An output signal 8 of a digital filter 7 to define a reset terminal 1 for system of a microcomputer as an input and to define a system clock 6 of the microcomputer as the filtering clock of the filter is connected to the latch clock inputs of plural latches 3 for holding the data from plural outputs 4 of a non-volatile memory 2 for option digital storage. While using this clock 6, the noise loaded on a signal 9 from the reset terminal 1 for system of the microcomputer is removed by the digital filter 7 and according to the filter output 8 loading no noise, the data from the output 4 having the contents of the previously digitally written non-volatile memory 2 for option digital storage are held in the latch 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-chip microcomputer with a built-in non-volatile memory, in which the reliability of option setting such as pull-up and pull-down inside the microcomputer can be improved by the data of the non-volatile memory. It is about circuits.

[0002]

2. Description of the Related Art A conventional microcomputer option setting circuit will be described below with reference to FIG.

Conventionally, a plurality of data outputs 4 from an option data storage memory 2 in which data for setting options such as pull-up and pull-down in a microcomputer are stored are reset by inputting them to a reset terminal 1. A signal 9 generates a latch signal of a plurality of data holding latches 3 for holding the data of a plurality of data outputs 4 from the option data storage memory 2, and the latch signals from the plurality of data holding latches 3 are generated. The output signal 5 was used to set options inside the microcomputer.

[0004]

As shown in FIG. 2, the option setting is executed by a plurality of data holding latches 3 having the reset terminal 1 as a latch signal. Therefore, if some noise is applied to the reset terminal 1, the output of the data holding latch 3 changes, and as a result, the option setting causes a malfunction. Therefore, there is a problem that reliability is lowered.

An object of the present invention is to provide an option setting circuit capable of improving the reliability of option setting with a simple structure.

[0006]

In order to solve the above-mentioned problems, an option setting circuit of the present invention is a one-chip microcomputer with a built-in non-volatile memory.
Using the clock as a filtering clock, the output signal from the noise filter that removes noise from the reset pin is used as the latch clock for multiple latches that latch multiple output data from the nonvolatile memory for storing option data. By connecting, the reliability of option setting is improved.

[0007]

With this configuration, even if noise occurs on the reset terminal of the microcomputer system, the noise does not directly go to the option setting output, and the reliability of option setting can be improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, and the construction and operation will be described.

The output signal 8 of the digital filter 7 having the system reset terminal 1 of the microcomputer as an input and the system clock 6 of the microcomputer as a filtering clock of the filter is stored in the nonvolatile memory 2 for storing the option data. It is configured to be connected to the latch clock inputs of a plurality of latches 3 which hold the data of a plurality of outputs 4. The outputs 5 of the plurality of latches 3 are pulled up, pulled down, and
It is a control signal for setting various options.

In operation, the system clock 6 of the microcomputer is always input, and the noise carried on the signal 9 from the system reset terminal 1 of the microcomputer is removed by the digital filter 7 by using this clock. The non-loaded filter output 8 holds the data from the output 4 of the contents of the non-volatile memory for storing option data 2 in which the data is written in advance in the latch 3.

In the option setting circuit configured as described above, even if the system reset terminal 1 is noisy,
Since the clock of the latch that holds the data does not have noise, the output 5 of the latch 3 does not malfunction,
The reliability can be improved.

[0012]

As is apparent from the above description, according to the present invention, even if the system reset terminal 1 is noisy, the clock of the latch for holding the data is not noisy and the present digital filter is used. This is an extremely effective invention because it can improve the reliability of the microcomputer system with a simple circuit configuration because it is easy to use technology to make it a semiconductor.

[Brief description of drawings]

FIG. 1 is a block diagram of an option setting circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional option setting circuit.

[Explanation of symbols]

1 Reset terminal 2 Non-volatile memory for storing option data 3 Latch 4 Output of contents of non-volatile memory for storing option data 5 Latch output 6 Microcomputer system clock 7 Digital filter 8 Digital filter output 9 Reset signal

Claims (1)

Claims: 1. In a one-chip microcomputer with a built-in non-volatile memory, the output signal from a noise filter that removes noise at the reset terminal using the system clock of the microcomputer as a filtering clock is used as option data. An option setting circuit characterized by being connected to a latch clock of a plurality of latches for latching a plurality of output data from a non-volatile memory for storage.