JPS60128717A - Integrated circuit device - Google Patents

Abstract

PURPOSE:To charge easily the function of an input/output circuit on demand by generating a switching control signal in accordance with a switching command and providing a switch circuit which selects one of plural operating functions of the input/output circuit and switches the function to the selected function. CONSTITUTION:When a high-level output setting signal (b) and a latch control signal (c) are supplied to an output control circuit 16 from a CPU circuit through a data bus line, a latch circuit 15 outputs a high-level switching control signal (d). Therefore, a latch circuit 14 is turned on, and a pull-up resistance 12 is connected to an open drain output circuit. That is, the function switching instruction of the output circuit is given to a program of the CPU circuit to control turning-on/off of the switch circuit 14 of the output control circuit 16, thus switching the function of the output circuit from the open drain output function to the pull-up resistance output function or from the pull-up resistance output function to the open drain output function.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an integrated circuit device, and more particularly to an integrated circuit device improved so that the operating functions of an input/output circuit can be selectively switched.

[Technical Background of the Invention and Problems Therewith] As is well known, integrated circuit devices used in, for example, microcomputers are manufactured according to the functions of input/output circuits using mask options. For example, as an output circuit, an output MO3-F as shown in Fig. 1(a) is used.
An output circuit with a pull-up resistor consisting of an ET (MO8 field effect transistor) 11 and a pull-up resistor 12, and an output MO8-FET 11 as shown in FIG. 1(b).
However, in general, integrated circuit devices are manufactured separately for the two types of output circuits, depending on whether or not a mask option process is provided for the resistor R1 in the masking process for the open-train output circuit. has been done.

However, manufacturing integrated circuit devices for each input/output circuit function as described above requires replacing the integrated circuit device itself when it is desired to change the function of the input/output circuit in a circuit using this device. In other words, the integrated circuit device described above cannot cope with changes in software, and requires modification of hardware. Furthermore, it is not possible to change the function of the input/output circuit during program execution. For this reason, there has been a strong desire for an integrated circuit device in which the functions of input/output circuits can be easily changed as necessary.

[Objective of the Invention] This invention has been made in consideration of the above-mentioned circumstances, and it is an object of the present invention to provide an extremely good integrated circuit device in which the functions of input/output circuits can be easily changed as necessary. With the goal.

[Summary of the Invention] That is, an integrated circuit device according to the present invention includes a switching control signal generating means that generates a switching control signal in response to a switching command, and a switching control signal generating means that generates a switching control signal in response to a switching command, and a switching control signal generating means that generates a switching control signal from a plurality of operating functions of an input/output circuit in response to the switching control signal. It is characterized by comprising a switch circuit that selects and switches one.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

FIG. 2 shows its configuration, and shows an output circuit having a pull-up resistor output function and an open train output function in a one-chip microcomputer integrated circuit device. That is, this output circuit outputs the switching signal in response to the output signal @a.
In an open drain output circuit in which the O8-FET 11 is connected to the output terminal 13, the pull-up resistor 12 is connected to the output terminal 13 via a switch circuit 14.

Here, the switch circuit 14 is composed of a transmission gate made of, for example, a MO8-FET for switching, and the output of the latch circuit 15 is supplied to its control input terminal. When the output of the circuit 15 is at H (high) level, it is in an on state, and when it is at an L (low) level, it is in an off state.

The latch circuit 15 constitutes an output control circuit 16 together with the switch circuit 14, and is connected to a data bus connected to the output end of an internal central control circuit (CPU) (not shown).
An output setting signal S and a latch control 1-roll signal C are inputted from the line. Then, the value of the output setting signal S when the latch control 1-roll signal C is supplied is stored, the state is held until the next latch control signal C is supplied, and the stored value is applied to the switching control signal. It is outputted to the switch circuit 14 as @d.

The operation of the above configuration will be described below.

First, when the CPU circuit sends an H level output setting signal and a latch control signal to the output control circuit 16 via the data bus line, the latch circuit 15 of the output control circuit 16 controls the H level switching control. Outputs the signal S d. Therefore, the switch circuit 14 is turned on and the pull-up resistor 12 is connected to the open drain output circuit, so that this output circuit has a pull-up resistor output (geometry).

Conversely, when the CPU circuit supplies the L level output setting signal and latch control signal C to the output control circuit 1G, the latch circuit 15 of the output control circuit 16
Outputs L level switching control signal d. Therefore, the switch circuit 14 is set to the OFF state and the pull-up resistor 12 is disconnected from the output terminal 13, so that this output circuit has an open-drain output function.

In other words, the integrated circuit device described above controls the switch circuit 14 of the output control circuit 16 on and off by giving an output circuit function switching command to the CPU circuit program, and switches the output circuit to an open drain output function. This allows switching from the output function to the pull-up resistor output function, or from the pull-up resistor output function to the open drain output function.

Therefore, in the integrated circuit device configured as described above, the function of the output circuit can be easily selected and switched by changing the software. There is also no need to replace the integrated circuit device itself. Furthermore, this integrated circuit device can also change the function of the output circuit during program execution.

Incidentally, in order to have an E/E type output function and an open drain output function as an output circuit of the integrated circuit device, it may be configured as shown in FIG. That is,
This output circuit has first and second output M which respectively performs switching output in accordance with two output signals al and a2.
For an E/E type output circuit consisting of an O8-FET 17.18 and a bias resistor 19, the switch circuit 14
is interposed in the output line of the output signal a1, and by controlling the switch circuit 14 on and off as described above, the E/E type output function and the oven drain output function can be selectively switched. It was made so that it could be done.

Further, in the above embodiment, the integrated circuit device of a one-chip microcomputer has been described, but if the integrated circuit device does not have the above data bus line, the above output setting signals and latch controller 1 to roll signal C can be input from the outside. It may also be supplied.

Furthermore, the present invention can also be applied to input circuits, and can be implemented with various modifications without departing from the gist of the invention.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide an extremely good integrated circuit device in which the functions of the input/output circuit can be easily changed as necessary.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for explaining an output circuit of a conventional integrated circuit device, FIG. 2 is a circuit diagram showing an embodiment of an integrated circuit device according to the present invention, and FIG. 3 is a circuit diagram for explaining an output circuit of a conventional integrated circuit device. It is a circuit diagram showing an example of. 11.17.18... MO8-FET for output, 12.
...Pull-up resistor, 13...Output terminal, 14...
Switch circuit, 15... Latch circuit, 16... Output control circuit, a... Output target (word, b... Output setting signal, d... Latch control I-roll signal.

Claims (1)

[Claims] A switching control signal generation means for generating a switching control signal in response to a switching command, and a switch circuit for selecting and switching one of a plurality of operating functions of the input/output circuit in response to the switching control signal. An integrated circuit device characterized by: