JPS6339784Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to microcomputer application equipment, particularly to an input/output expansion device for a 4-bit microcomputer.

The configuration of conventional examples and their problems The conventional example of a 1-chip microprocessor is
A conventional example of a one-chip microcomputer will be explained with reference to FIG. A 1-chip microprocessor consists of a CPU and one IC.
ROM, RAM, and I/O are composed of separate ICs, such as Intel 8080 and Motorola 6800.
(both product names) etc. The microcomputers are Intel 8048 and Matsushita MN1400 (both product names).
Refers to an IC that consists of a CPU, ROM, RAM, and I/O such as a single IC.

FIG. 1 is a schematic diagram of a one-chip microprocessor 1. As shown in FIG. 2, 3, 4 and 5 are I/Os, 2 and 4 are bus driver ICs with 3-state outputs, and 3 and 5 are data latch ICs. The arrow 6 indicates a bidirectional data bus connecting the 1-chip microprocessor 1 and bus drivers 2, 4 or data latches 3, 5, and the dashed arrow 7 indicates a control bus. (Normally, the output obtained by decoding the output of the control bus is connected to the I/O, but this is omitted in FIG. 1).

For example, to input information from switches 8, 9, and 10, an output to select bus driver 2 is output to the control bus (including the address bus), and the data bus portion of microprocessor 1 is input. , the states of switches 8, 9, and 10, ie, ON-OFF, are input.

Also, to turn on or off the LED of the output of data latch 3, select data latch 3 using the control bus (including the address bus), make the data bus of microprocessor 1 an output, and output the necessary data. In other words, the information commanded by the program of the microprocessor 1 can be held in the latch 3.
For example, to light up the light emitting diode 12 or 14, send a Low signal from the microcomputer to the latch connected to it, the transistor 11 or 13 will turn on, and the light emitting diode 12 or 1 will turn on.
4 Lights up.

For an 8-bit microprocessor, the data bus is usually 8 bits, and the states of 8 switches can be input simultaneously. Although only two latches and two bus drivers are shown in FIG. 1, it is basically possible to connect about ten, and the number of inputs and outputs can be expanded.

However, this type of device requires many parts other than those shown in FIG. 1 around the microprocessor 1, and is not suitable for household equipment or small-sized equipment.

FIG. 2 shows an input expansion method conventionally used in the one-chip computer 15. That is, P00 to P03 are output ports, and P10 to P03 are output ports.
13 is an input port. For example, switch 16
To check whether ~19 is ON, set the output of output port P00 to low level,
The microcomputer 15 simultaneously outputs the outputs of the output ports P01 to P03 to a HIGH level. When the microcomputer 15 outputs the output as described above, the transistor 32 becomes conductive.
Transistors 33-35 become non-conductive. At this time, switch 16 of switches 16 to 18 is ON.
state, transistor 32, switch 1
6, a current flows through the diode 50 and the resistor 36, and a voltage is generated across the resistor 36. Therefore, when input from input ports P10 to P13, input port P10 becomes High level and P11 to P13 become Low level. At this time, switch 20-23
Even if the transistor 33 is turned on, the transistor 33 is turned off, so no current flows through the resistors 36 to 39, so that the input to the input ports P10 to P13 is Low.
In this way, by setting one of P00 to P03 to Low, it is possible to check ON/OFF of four switches at a time.

Next, add a diode 50~ in series with the switch.
I will explain the reason why 65 is added. For example, assume that transistor 32 is conductive. At that time, if switches 16, 20, and 21 are turned on at the same time,
Current flows through resistors 36 and 37, and input port P10
and P11 becomes High, and switches 16 and 17 become high.
It will be detected as ON. That is, this is because current flows through the transistor 32, switch 20, switch 21, and resistor 37. However, by adding the diode 57, the transistor 32
It is possible to prohibit current from flowing from the collector of the transistor 33 to the collector of the transistor 33. Also, the power supply of the microcomputer is 5V, and +B is also
When 5V is connected, the voltage at the input section of P10 to P13 becomes approximately 4.2V, which is the voltage calculated by subtracting the V _CE(S) of the transistor and the drop of the diode, which is sufficiently high to read the input as High.

As explained earlier, output ports P00 to P
Make sure that only one low level is output on 03,
Alternatively, care must be taken in designing the microcomputer program, such as allowing the microcomputer to read the input from the input ports P10 to P13 after outputting to the output ports P00 to P03. This method allows expansion to 16 inputs with 4 inputs and 4 outputs. However, depending on the device, expanding the input/output ports of the microcomputer to the extent shown in FIG. 2 may still be insufficient.

Purpose of the invention This invention improves the conventional drawbacks, expands the input/output ports further, and when expanding, the input switch is not only a momentary switch such as a touch switch, but also an alternate type switch such as a slide switch. The purpose of this invention is to propose an input/output expansion device for a computer that consumes less current even when used.

Structure of the Invention In order to achieve the above object, the present invention is a microcomputer in which the number of input/output ports is limited by the number of pins of the package, and which has multiple output-only ports, multiple input-only ports, and multiple output-only ports. Each output-only port is connected to one data latch less than the number of control-only ports, and is connected to a plurality of first transistors that supply power to the switch matrix. The dedicated port is connected to the plurality of first transistors via a switch and a diode, and the plurality of control dedicated ports are connected to each data latch, one by one, and are connected to the transistors that supply power to the switch matrix. A second transistor provided for supplying is connected to one control-only port, and the second transistor is turned on/off by the output of this one control-only port, This makes it possible to expand the input and output of microcomputers that are limited to connections, and also to save power even when alternate type switches such as slide switches are used as switches in the switch matrix. be.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings. In Fig. 3, 15 is a 1-chip microcomputer, P00~P03, P10~P
13, P20 to P23 are input/output ports, and P
00~P03 are output-only ports, P10~P13
is an input-only port, and P20 to P23 are control-only ports.

P00 is a switch power supply transistor 32,
DO of data latch 40, DO of data latch 41
DO, connected to DO of data latch 42.
Similarly, P01 is connected to D1 of the transistor 33 and data latches 40, 41, 42, and P02 is connected to D2 of the transistor 34 and data latches 40, 41, 42.
, P03 is transistor 35, data latch 4
Connected to D3 of 0, 41, and 42. Also, P
20 is the chip select CS of data latch 40,
P22 is connected to CS of data latch 41, and P23 is connected to CS of data latch 42. P21
is connected to transistor 48. An output O1 corresponding to the D1 input of data latch 40 is connected to transistor 43 via a resistor. That is, when the output O1 becomes Low level, the transistor 43 turns on and the light emitting diode 44 lights up. To turn off this light emitting diode, P0
1 outputs a high level output, then P20
If P20 is set to Low and then P20 is set to High, the output O1 of data latch 40 becomes High, then CS of data latch 40 becomes Low, and P01
The output O1 remains high until the output of O1 goes low. That is, the light emitting diode 44
remains off because the transistor 43 is turned off. Also, as shown in Fig. 4 a to d, P
20, P22, P23, and P21 do not output Low at the same time. However, P00~ of e~h in Figure 4
The level of P03 is only shown for later explanation of what happens when the output of P21 is at low level, and data when P20, P22, and P23 are at low level is not shown.

Similarly, the outputs 00 and 01 of the data latch 41 are the first motor drive circuit 45, and the outputs 02 and 03 are the second motor drive circuit 45.
The motor drive circuit 46 is connected to the motor drive circuit 46 of FIG. If a low level is output to the inputs 00, 02 of the motor drive circuits 45, 46, the motor will rotate forward, and the output will be 01, 0.
If low level is output to 3, the motor will rotate in reverse, and if low level or high level is output to 00, 01 or 02, 03 at the same time,
The configuration is such that the motor is stopped.

Similarly, to change the outputs 00 to 03 of the data latch 42, set the information to be output to P00 to P03, set P23 to Low, and data is set in the data latch 42. In this way, the output side can be expanded and the circuit 47 can be driven.

Next, expansion on the input side will be explained. Of course, the input switch information is 4 bits P10 to P10.
13, the input is checked every 4 bits. To check the switches 16 to 19, output a low level to P21 and turn on the transistor 48.

Next, a low level is outputted to P00, and a high level is outputted to the outputs of P01 to P03. Then, transistor 32 turns on, and one end of the switch has +
A voltage obtained by subtracting the saturation voltage of V _CE of transistors 48 and 32 from B is applied. Therefore switch 16
If is ON, transistor 48,
Transistor 32, switch 16, diode 5
Current flows through the resistor 36 through 0. At that time, P
10 is a high level. That is, on P21
Low, P20, P22, P23 High level, P
After outputting low level to 00 and high level to P01 to P03, inputting P10 to P13,
The microcomputer can input that the switch 16 is in the ON state. Similarly, set P21 to Low and P0
Low level to 1, P00, P02, P03
If high level is output, switches 20 to 23
The microcontroller can read the ON/OFF status. That is, as shown in Figure 4 a, b, and c,
Set P20, P22, P23 to High, set P21 to Low as in d, and sequentially as in e, f, g, h.
If you set it to Low level and input P10 to P13 at a timing like i every time you output Low, you can read whether the switch is ON or OFF.

As is clear from the above description, the transistor 48 is a chip selector of the switch matrix, and by providing this, the switch 16
Even if a thrust switch is used in 31, no unnecessary current is consumed. That is, since P00 to P03 are data buses, data latches 40 and 4
When sending data to 1 and 42, it is not always High. Therefore, transistor 32,3
If emitters 3, 34, and 35 are connected to +B, when sending information to the data latch,
If it is low, the previous transistor is turned on,
If the switch is an alternate switch such as a slide switch, current flows through the resistors 36 to 39. This is an unnecessary current. Especially depending on the microcontroller,
Due to the outflow current of the input port, resistors 36 to 39
If the resistance value cannot be increased, the current loss is particularly large.

According to this embodiment, 4 bits of input and 8 bits of output can be expanded to 12 bits of output and 16 bits of input. However, it is of course possible to extend the input to 8 bits and output to 8 bits to 12 bits for output and 32 bits for input using the same idea. This corresponds to transistors 32 to 35 in FIG.
All you have to do is connect four switches in the same way.

Also, the timing chart in FIG. 4 is a reference diagram for explanation, and the timing chart in FIG.
Send data to each switch 2, then switch 1
6-19, switch 20-23, switch 24-
27. Switches 28 to 31 are set to be ON/OFF, but it is not always necessary to use them in this order. Of course, input and output can be performed as necessary.

Effects of the invention According to the invention, it becomes possible to expand the input and output of a one-chip microprocessor, and
It is also possible to save power in the input section during expansion.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional example to explain input expansion when using a 1-chip microprocessor, and Figure 2 is a configuration diagram of a conventional example to explain input expansion when using a 1-chip microprocessor. 3 is a configuration diagram showing an embodiment of the present invention, and FIG. 4 is a configuration diagram showing an embodiment of the present invention.
It is an example figure which shows the operation timing of a figure. 15...1 chip microcomputer, 16
~31...Switch, 32-35...Transistor, 36-39...Resistor, 40-42...Data latch, 48...Transistor, P00-P03
...Output-only ports, P10-P13...Input-only ports, P20-P23...Control-only ports.

Claims (1)

[Scope of utility model registration request] It is a microcomputer whose number of input/output ports is limited by the number of pins on the package, and it is configured with multiple output-only ports, multiple input-only ports, and multiple control-only ports, and each output-only port is , is connected to one data latch less than the number of control-only ports, and is connected to a plurality of first transistors that supply power to the switch matrix, and the input-only port is connected to one data latch less than the number of control-only ports, and is connected to a plurality of first transistors that supply power to the switch matrix. A plurality of control-only ports are connected to each data latch, one at a time, and a second control port is provided to supply power to a plurality of first transistors that supply power to the switch matrix. An input/output expansion device for a microcomputer, in which a transistor is connected to one control-only port, and the second transistor is turned ON/OFF by the output of this one control-only port.