JPS6158074A - Microcomputer - Google Patents

Abstract

PURPOSE:To restrain an increase of a chip size, to select data or a circuit and to facilitate the occurrence of a switch control signal by incorporating a port control circuit other than an input/output port and carrying out a simple program. CONSTITUTION:A port selection signal generating circuit 1 generates a signal to access an optional port used by data of I/OBUS 8-1 inside. A port control signal generating circuit 2 accessed by the port selection signal makes a port control signal from the input data using the existing instruction. The port control signal selects either of a gate or circuit, and A or B of input of a switch circuit 4 and outputs as C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a microcomputer, which facilitates the generation of control signals for selecting and switching gates or circuits using existing instructions. Regarding port control circuits.

Conventional configurations and their problems As microcomputer systems have improved and become more dependent on them, the functions required of the microcomputers themselves have also increased. In particular, as the signal processing inside microcomputers becomes increasingly complex, control signals are required to control each process. However, in order to generate control signals for selecting and switching gates or circuits inside a microcomputer, it is necessary to add a complex circuit inside the chip or to apply the control signals to peripheral ports from the outside. You need to add a special boat. For this reason, there were disadvantages such as the internal hardware becoming complicated and the total area increasing.

Purpose of the Invention The present invention has been made in order to eliminate the many drawbacks of the conventional microcomputers mentioned above. It minimizes the increase in chip area by adding very little hardware, and allows generation of control signals for selecting and switching gates or circuits.

DESCRIPTION OF THE INVENTION The present invention is a microcomputer having a boat control circuit and a function of generating control signals for selecting and switching gates or circuits when executing instructions.

DESCRIPTION OF EMBODIMENTS The present invention will now be described with reference to the drawings. The drawing shows a device comprising a port selection signal generation circuit section 1 and a port control circuit 3 incorporating a port control signal generation circuit section. This port 3, -) generates a signal to access F. The port control signal generation circuit 2 accessed by this port selection signal generates a port control signal from the input data using existing instructions. It is possible to create control signals as desired using simple software. This port control circuit 3
The boat control signal generated by the gate or circuit selects either the input A or B of the switching circuit 4 and outputs it as C. In the figure, 5 is a port selection signal line, 6 is a port control signal line, and 7 is a port selection signal line.
, 8 are gate input terminals, and 9 is a gate output terminal. Further, in this port control circuit 3, system control signals such as a signal for using the port as an output (port output enable signal) and a signal for operating other systems (clock) control this circuit.

Effects of the Invention As is clear from the above explanation, the microcomputer of the present invention has a built-in port control circuit separate from the original input/output ports, and by executing a simple program using existing instructions, the chip size can be reduced. It is possible to minimize the increase in gate or circuit selection and to easily generate control signals for switching.

[Brief explanation of drawings]

The figure is a circuit diagram of a main part of a microcomputer equipped with a port control circuit according to an embodiment of the invention. 1... Port selection signal generation circuit, 2...
・Port control signal generation circuit, 3...port control circuit, 4...gate selection circuit, 5...port selection signal, 6...port control l signal, 7゜8...Gate input terminal, 9...Gate output terminal.

Claims (1)

[Claims] A microcomputer that has a port control circuit and has the function of generating control signals for selecting and switching gates or circuits when executing instructions.