JPS63219054A - Microcomputer device - Google Patents

Abstract

PURPOSE:To change a state programmable by setting in an EPROM circuit control data controlling optional switching and always setting an E<2>PROM circuit in a read state besides when control data is written at the charge time of a power source. CONSTITUTION:Data on a pullup resistance is written in the E<2>PROM circuit. If the power source is charged in the titled device, a reset signal is outputted. With the reset signal, the output of an FF is set through an OR circuit in a control circuit 3, and the E<2>PROM circuit 2 comes to the read state. Since the address line of the circuit 2 is connected with the power source, the E<2> PROM circuit 2 in which data on the pullup resistance 5 is written is selected. Data is given to the pullup resistance circuit 5 through a latch circuit 4 and the presence and absence of the resistance is decided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microcomputer device having option switching.

[Conventional technology]

As a conventional microcomputer device, for example, a pull-up resistor using mask switching will be explained. Fourth
The figure is a circuit diagram of a pull-up resistor whose presence or absence is determined by depression implantation. In the figure, 10 is a first N-type MO3) transistor whose source is connected to the power supply and its drain and gate are connected to the same terminal, and 1) is a first N-type MO3) transistor whose drain is connected to the drain and gate of the first N-type MO3) transistor 10. 12 is the drain and gate of the first N-type MO3) transistor 10 and the drain of the second N-type MO3) transistor 1); An inverter 13 has a gate connected to the output of the inverter 12, a source connected to the power supply, and a drain connected to the terminal 14 of the microcomputer.
This is a P-type MO3) transistor that serves as a pull amplifier resistor.

Next, the operation will be explained. 1st by wafer process
If depletion is implanted only into the N-type MO3) transistor 10, the transistor 10 becomes a depletion type transistor and is always in an ON state. Therefore, the input of the inverter 12 becomes "H" level, and the gate of the P-type MOS transistor 13 becomes "L" level, so 13 becomes O
It becomes N state and operates as a pull amplifier resistor.

Furthermore, if depletion is injected into only the second N-type MO3) transistor 1), then 1) becomes a depression-type transistor, so the input of the inverter 12 becomes "L" level, and the gate of the P-type MOS transistor 13 becomes It becomes "H" level, 4 becomes OFF state, and there is no pull amplifier resistor.

[Problem that the invention seeks to solve]

Since the conventional pull-up resistor circuit is configured as described above, the presence or absence of the pull-up resistor is determined during the wafer process, and there is a problem in that the presence or absence of the pull-up resistor cannot be changed once the product is manufactured.

This invention was made to solve the above-mentioned problems, and aims to provide a microcomputer device that can programmably change the presence or absence of a pull-up resistor regardless of the wafer process.

[Means for solving problems]

The microcomputer device according to the present invention has an E"PR for writing data for controlling option switching.
The device is equipped with an OM circuit, a control circuit that keeps the E''PROM circuit in a read state at all times except when data is written when the power is turned on, and means for latching the output of the E''PROM circuit.

[Effect]

The microcomputer device in this invention is E”
The control data that controls option switching is set in the PROM circuit, and the E"PROM circuit is always in the read state when the power is turned on, except when writing the control data, so options such as the presence or absence of a pull-up resistor can be changed. Switching can be determined programmably.

〔Example〕

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

FIG. 1 is a block diagram showing one embodiment of the present invention,
For the purpose of the invention, write the data of the pull-up resistor.
Regarding the PROM circuit, only circuits related to reading and writing are shown. In the figure, 1 is a CPU, which generates various signals. 2 is an E" PROM circuit in which data about the pull amplifier resistance is stored, and whether the write or read state is determined depending on the state of the write signal terminal (in this example, reading is performed at the "H level, and writing is performed at the "L" level). Yes, the address line is connected to the power supply.

3 is a control circuit that provides a write signal to the E"PROM circuit 2. Also, 4 is a latch circuit;
The contents of the ROM circuit 2 are always output as they are except in the writing state, and in the writing state, the data before being rewritten is latched. Reference numeral 5 denotes a pull-up resistor circuit, the presence or absence of which is determined by the output of the latch circuit 4.

FIG. 2 is a diagram showing the internal configuration of the control circuit 3. In the figure, 6 is a decoder for decoding the address of the E2PROM circuit 2. 7 is started by the output of the decoder 6, and the E2PROM- It is a timer that measures the writing time of @path 2. 9 is an OR circuit to which the signal output when the timer 7 finishes measuring and the reset signal are input. 8 is the reset input from which the output of the decoder 6 is input. The outputs of the OR circuits are respectively connected to set inputs, and the output is a write signal of a set/reset flip-flop.

Next, the operation will be explained.

Suppose that data regarding the pull-up resistor has been written in the PROM circuit 2. If the microcomputer device is now powered on, a reset signal is output (see Figure 3).The above reset signal is, for example, This can be realized with an external resistor, an integrator circuit of a capacitor, and an inverter circuit.The output of the set-reset flip-flop 8 is set through the OR circuit 9 by the above reset signal, and E
The 2FROM circuit enters the read state. Since the address line of E"PROM circuit 2 is connected to the power supply, the E"FROM in which data regarding the pull-up resistor is written is connected to the power supply.
Circuit 2 is selected and provides data to the pull-amp resistor circuit through latch circuit 4 to determine the presence or absence of the pull-up resistor.

Next, the operation of writing data regarding the pull amplifier resistor into the E'' FROM circuit 2 will be explained.

The address and data are output from the CPUI, the address is decoded by the decoder 6, and the center reset flip-flop 8 is reset, thereby E' FROM
The circuit 2 enters a writing state and writing is performed. At this time, the write signal causes the latch circuit 4 to
The output of the FROM circuit 2 is held, and the pull-up resistor circuit 5 maintains its previous state even during writing. Further, the timer 7 measures the write time based on the output of the decoder 6, and when the write time is completed, the set/reset flip-flop 8 is set through the OR circuit 9 and returns to the read state, and the latch circuit releases the latch and changes the state of the pull-up resistor circuit 5. change.

As described above, by writing data to the E"FROM circuit 2, the state of the pull amplifier resistor can be determined programmably, and even when the power is turned off, the previous state remains E"FRO.
It is held by M2 and remains in the previous state the next time the power is turned on.

In the above embodiment, the control circuit is composed of a set/reset flip-flop 8, an OR circuit 9, a decoder 6, and a timer 7, but other circuits may be used.

Further, although the above embodiments have been described using pull amplifier resistors, any type of mask switching that has conventionally been performed may be used, and the same effects as in the above embodiments can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, in a microcomputer, the option switching circuit, which was conventionally performed by mask switching, is configured to determine the state by writing data to the E"FROM circuit, so the state can be changed programmably. This has the effect of making it possible.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a microcomputer device according to an embodiment of the present invention, Fig. 2 is a block diagram showing the internal configuration of the control circuit in Fig. 1, and Fig. 3 shows the relationship between power supply voltage and reset signal. The waveform diagram in FIG. 4 is a diagram showing a conventional pull-up resistor circuit. 2 is an E2PROM circuit, 4 is a latch circuit, 3 is a control circuit, 6 is a decoder, 7 is a timer, 8 is a set/reset flip-flop, and 9 is an OR circuit.

Claims (1)

[Claims] (1) In a microcomputer device that has some kind of option switching, an E^ that stores data that controls the above option switching.
A microcontroller comprising: a 2PROM circuit; a control circuit that keeps the E^2PROM circuit in a read state at all times except when writing data in a power-on state; and means for latching the output of the E^2PROM circuit. computer equipment.