JPH02205354A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To set the port modes of input/output ports simply while stably operating a device by setting the storage content of a nonvolatile storage cell. CONSTITUTION:A circuit including a nonvolatile semiconductor storage cell such as an EPROM 11 is also used in addition to a conventional register as a circuit in which the directions of the input and output of input/output ports are set and stored. Consequently, when the input/output ports are employed only as either one of an input port or an output port, the port is set continuously as the input port or the output port at ail times during the effective period of the storage content of the EPROM 11 on setting at a time. Accordingly, the setting of port modes not influenced by the interruption of a power supply and the electrical noises of the inside of the circuit can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor integrated circuit device, and particularly to an improvement in a port mode setting mechanism of an input/output port thereof.

[Conventional technology]

FIG. 2 shows the configuration of a conventional input/output port circuit.

In the figure, 1 is a port terminal, and 2 and 3 are an input buffer and an output buffer sofa, respectively. Each buffer is used when operating as an input port or an output port. 4 is a circuit block indicating a port mode register, 5 is a control signal consisting of a write signal WR and a decoder output output at the time of port access in this example, and 6 is a data bus.

Next, the operation will be explained. In this conventional example, either the input buffer sofa 2 or the output buffer 3 is operated, and the other is left in a floating state, so that only the function of either the input port or the output port functions properly. It is. As mentioned above, the port mode setting is to select and set the port function, and the port mode register is to memorize the setting contents in the circuit and hold it for the required period. .

In other words, the information regarding the port mode setting is ``Low'' or ``H''.
tgh" signal on the data bus 6 and then generates the write control signal 5 to write to the port mode register 4. Depending on the data in the port mode register 4, either the input buffer 2 or the output buffer sofa 3 is written. For example, if the former is operated, it will operate as an input port, and if the latter is operated, it will operate as an output port.

[Problem to be solved by the invention]

However, according to the conventional setting method, for example, when the power is turned off and then turned on again, the port mode register 4
Since the remaining data contents are undefined, it is necessary to set them again. In addition to power interruption, there is also a possibility that the data contents of the port mode register 4 may be changed due to some electrical noise generated within the semiconductor integrated circuit.

For this reason, even if the port is an input/output port, the above-mentioned problem always occurs even when the port is used as an input-only port, making it difficult to use.

The present invention has been made in order to solve the problems of the conventional devices as described above, and aims to provide a semiconductor integrated circuit device that can simplify the port mode setting of input/output ports and operate stably. purpose.

[Means to solve the problem]

The semiconductor integrated circuit device according to the present invention uses, in addition to conventional registers, a circuit including a non-volatile semiconductor memory element such as an EPROM as a circuit for setting and storing input and output directions of input/output ports. This is what I did.

[Effect]

In the present invention, since the apparatus is configured as described above,
When an input/output port is used only as either an input port or an output port, the - degree setting will ensure that the port function settings remain stable for as long as the memory contents of the nonvolatile memory element are valid. be able to.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a semiconductor integrated circuit device according to an embodiment of the present invention, in which input/output ports are connected to ports by both a port mode register and an input port exclusive mode setting circuit including a newly added nonvolatile memory element. This shows what allows the mode to be set.

In the figure, the same reference numerals as in FIG. 1 indicate the same or corresponding parts. 11 is a non-volatile memory element ~ this is E
P ROM (Electrically Progr.
12 is a write transistor;
13 is a read transistor, and 14 and 15 are a write signal and a read signal, respectively. Further, 16 is a high voltage power supply for writing, 17 is a power supply for reading, 18 is an inverter circuit, 1
9 is a NAND circuit.

Next, the operation will be explained. First, when EFROM 11 is not used, when port 1 is accessed and EPROM II and read transistor 13 are accessed with the decode output and read signal 15, EFROM 1 becomes conductive and the gate input of inverter 18 becomes 'Low'.
Therefore, by setting one input of the NAND circuit 19 to the old gh level, it can be used in the same manner as the conventional one by keeping the other parts the same as in the conventional one.

On the other hand, in order to realize the operation according to the present invention, first, the EFR
To write to OMI 1, access port 1 and set the decode output to /i (high) level (however, to control writing, set the decode output to “High” level, which is close to the write voltage).
gh" level) and write signal 14
．． EPROMI with write power supply 16 as write mode
Write to 1.

After performing this write, when the port is accessed and the decode output and read signal 15 are set to ')Ihigh' level to set the read mode, the gate input of the inverter 18 becomes 'High' level because EPROM II is non-conductive this time, and therefore the NAND One input of circuit 19 is 1o11
s level, and the output of the NAND circuit 19 becomes '1 (
This input/output port is set as an input port.
As long as the stored contents of I1 are valid, this port continues to be set as an input port. This makes it possible to set a port mode that is not affected by power interruption or electrical noise inside the circuit.

Note that in the above embodiment, EFRO is used as the nonvolatile memory element.
Although the description has been made using M, other nonvolatile memory elements may be used and the same effects as in the above embodiments can be achieved.

Further, in the above embodiment, only the case where the input port is set has been described, but the case where the output port is set can be similarly implemented.

〔Effect of the invention〕

As described above, according to the present invention, by setting the memory contents of the nonvolatile memory element, ports that can be used for either input or output can be used only for one of them. Set the mode register once,
If no changes are made thereafter, a semiconductor integrated circuit device that is extremely easy to use can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a conventional example. In the figure, 1 is a port terminal, 2 is an input buffer, and 3 is a port terminal.
is an output buffer, 4 is a port mode register, 5 is a port mode register control signal, 6 is a data bus, 11 is an EPROM, 12 is a writing transistor, 13 is a reading transistor, 14 is a writing signal, 15 is for reading 16 is a high-voltage power supply for writing, 17 is a power supply for reading, 18 is an inverter circuit, and 19 is a NAND circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a semiconductor integrated circuit device having an input/output port that can be used for both input and output, the above is implemented using a port mode register that stores data to set the input and output modes, and a nonvolatile memory element. A semiconductor integrated circuit device characterized in that a mode setting circuit for preferentially setting a port mode is formed on the same semiconductor chip.