JP2000181609A - Operation switch identification circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation switch identification circuit capable of identifying an operation switch with one A/D port for a microcomputer. SOLUTION: A voltage division circuit which divides a power supply voltage VDD applied to a microcomputer 1 by such a manner that a switch S4 is turned on in a voltage division ratio being different according to the on-off of key switches S1 and S2 and the switching of a changeover switch S3 consists of a common resistance RA and resistances R1 to R3, and a devided voltage is applied to the A/D port of the microcomputer 1. When the switch S3 and the switches S1 and S2 operated based on the devided voltage are identified, the switching position of the switch S3 is identified just after the voltage VDD is inputted to the microcomputer 1 according to the on of the switch S4, the switches S1 and S2 are identified by being operated after identifying the switching position of the switch S3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation switch identification circuit for identifying an operated switch in a microcomputer using an A / D terminal of the microcomputer.

[0002]

2. Description of the Related Art As shown in FIG.
/ D port a _1, definitive when the key switch S ₂ to the ON state, the power supply voltage V through the power switch S ₄
To determine that the key switch S ₂ is set to the ON state by applying a common resistor R _A and dividing the divided voltage by the resistor R ₂ to _DD, to perform an operation to correspond to the key switch S ₂ ing.

Similarly, the key switch S₁To the on state
Power switch S₄Supply voltage V through
_DDIs the common resistance R_AAnd resistance R₁Apply divided voltage with
Key switch S₁Has been turned on
Key switch S ₁Perform the operation corresponding to
I'm making it.

[0004] In this way A / D port _{a 1,} and subjected to determination of the input by turning on the key switch, as shown in the flowchart of FIG. 6, the voltage of the A / D port _{a 1} is _{V D D} × R ₂ / (R _A + R ₂ ) (step S2
0), the key switch S ₂ is determined to have been turned on by the operation to correspond to the key switch S ₂ ON (step S2
1), the voltage of the A / D port a ₁ is V _DD × R ₁ / (R _A
+ R ₁ ) (step S22), the key switch S
₁ it is determined that has been turned on, it causes the operation to correspond to S ₁ ON (step S23).

On the other hand, A / D of microcomputer 1A
Port a₂And the changeover switch S ₃Turned on
Power switch S₄Supply voltage V through
_DDIs the resistance R_BAnd resistance R₃And the divided voltage
Switch S by applying₃Is contact A
Or switch B is contacted, and the switch
Switch S₃The circuit corresponds to the contact that
The destination of the worn device (hereinafter simply referred to as destination)
Action is performed.

[0006] Thus, and subjected to determination of the destination in the A / D port a _2, as shown in the flowchart of FIG. 7, when the common contact of the switch S ₃ is brought into contact with the contact point A, i.e. A / when the voltage of the D port _{a 2} is _{V DD} (step S30), it is determined that the destination a, is the operation of the destination a (step S31), when the common contact of the switch _{S 3} is brought into contact with the contact B , that is, the voltage of the a / D port _{a 2} is _{V DD × R 3 / (R} B +
In the case of R ₃ ) (step S32), it is determined that the destination is B, and the operation of the destination B is performed (step S33).

[0007]

However, in the above-described conventional operation switch identification circuit, two A / D ports are required for determining key switch input and one for destination determination, that is, two A / D ports are required. There is a problem that the number of ports becomes insufficient and a microcomputer having many A / D ports must be used.

However, there is usually a problem that a microcomputer having many A / D ports is expensive.

The present invention relates to a microcomputer A / D.
It is an object of the present invention to provide an operation switch identification circuit that can identify an operation switch with one port.

[0010]

An operation switch identification circuit according to the present invention divides a power supply voltage of a microcomputer at different voltage division ratios by turning on / off each key switch and switching a changeover switch, thereby dividing the divided voltage. A is applied to the A / D port of the microcomputer, and A
An operation switch identification circuit that identifies a key switch operated based on the divided voltage applied to the / D port and a switch operated by a switching operation, identifies a switching position of the switch immediately after power-on, and performs switching. The key switch operated after the switch switching position is identified is identified.

According to the operation switch identification circuit of the present invention, the switching position of the changeover switch is identified immediately after the power is turned on, and the key switch operated after the identification of the changeover position of the changeover switch is identified. In addition, the A / D port for determining the divided voltage is changed, and the A / D port for identifying the switching position of the switch and for identifying the operated key switch can be shared.
The number of / D ports can be reduced by one.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An operation switch identification circuit according to the present invention will be described below based on an embodiment.

FIG. 1 is a block diagram showing a configuration of an operation switch identification circuit according to an embodiment of the present invention.

[0014] Operation switch identification circuit according to an embodiment of the present invention, the key switch identified and the operation of the destination by the changeover switch operated by a voltage applied to the A / D port a ₁ of the microcomputer 1 Identification of

The power supply voltage V _DD applied through the switch S ₄ is divided by a common resistor _RA and a resistor R ₂ which divide the voltage by turning on the key switch S ₂ , and the power supply voltage V _DD
Common resistance R for dividing the by-on of the key switch S ₁
Divided by the _A and the resistor _{R 1,} to apply the divided voltage to the A / D port a1. Here, the key switches S ₁ and S
_A switch ₂ is turned on only during the pressing period.

The power supply voltage V _DD applied via the switch S ₄ is changed to a common resistor _RA , a changeover switch S ₃ and a resistor R
3 is applied to the series circuit of the, a voltage of the common terminal of the switch S ₃ to the A / D port a1. here,
When switching the common contact of the changeover switch S ₃ to one of the contacts A or B is a changeover switch which is kept in that state, not be switched by the user after normally switched in correspondence with the destination . Bit A common contact when the changeover switch S ₃ is directed A
In the case of destination B, the common contact is brought into contact with contact B. In FIG. 1, for example, the destination is set to B.

The operation of the operation switch identification circuit according to the embodiment of the present invention will be described with reference to the flowcharts of FIGS. 2, 3 and 4.

[0018] determining when the power switch S ₄ to the ON state, as shown in FIG. 2, the destination is checked voltage of the A / D port a _1. A / D port voltage _{a 1} is V
When _DD (step S1) (common contact of the changeover switch _{S 3} is in a state in contact with the contact point _{A), V DD}
× When _{R 1 / (R A + R} 1) ( Step S2) (common contact of the changeover switch _{S 3} is in contact with the contact point A, and is when the key switch _{S 1} is turned _{on), V DD} × R
_{2 / (R A + R 2} ) when (Step S3) (common contact of the changeover switch _{S 3} is in contact with the contact point A, and is when the key switch _{S 2} is turned _{on), V DD} × _R K /
When the _(R A ₊ R _K) (is when the common contact of the changeover switch S ₃ is in contact with the contact point A, and the key switch S ₁ and the key switch S ₂ is turned on), destination determines that the destination A A corresponding to A (step S
5).

A / D port a₁Voltage is V_DD× R₃/
(R_A+ R₃) (Step S6) (switch
Switch S₃In the state where the common contact of
), V_DD× R_L/ (R_A+ R_L) When (step
S7) (Changeover switch S₃Common contact to contact B
Touch and key switch S₁Is turned on.
), V_DD× R_M/ (R_A+ R_M) (Step S8)
(Changeover switch S₃Contacts the contact B,
And key switch S₂Is turned on), V
_DD× R_N/ (R_A+ R_N) (Step S9)
(Changeover switch S₃Contacts the contact B,
And key switch S₁And S₂Is turned on.
) Is an operation that is determined to be destination B and corresponds to destination B.
Is performed (step S10). Works.

Here, R _K = R ₁ × R ₂ / (R ₁ +
R ₂ ) _RL = R ₁ × R ₃ / (R ₁ + R ₃ ) _RM = R ₂ × R ₃ / (R ₂ + R ₃ ) _RN = R ₁ × R ₂ × R ₃ / (R ₁ × R ₂ + R ₁ × R ₃ +
R ₂ × R ₃ ).

[0021] If the key switch S ₁ and the key switch S ₂ while turning on the power switch S ₄ and the ON state also considered, the determination value of the number of A / D ports a ₁ voltage is increased. In other words, usually, the power switch state but after turning ON the power switch S ₄ is to press the key switch S ₁ and the key switch S _2, the key switch S ₁ and the key switch S ₂ is pressed for some reason It is also considered if it is ON the S _4. Naturally, it is necessary to determine the resistance values of the resistors R _A , R ₁ , R ₂ , and R ₃ so that these determination values do not become the same.

Next, the key switch input is determined. Figure
2 is determined as destination A, the flowchart of FIG.
Move to A / D Auto a₁Voltage is V_DD× R₁/ (R
_A+ R₁), (Step S51), the key switch
S₁Is turned on, and the key switch S₁
Is turned on (step S5).
2), A / D port a₁Voltage is V_DD× R₂/ (R_A
+ R₂) (Step S53), the key switch S₂
Is turned on, and the key switch S ₂But
Key switch S₂Is on
The operation at the time of being turned on is performed (step S54).

When the destination B is determined in FIG.
Move to flowchart, A / D port a₁Voltage is V
_DD× R_L/ (R_A+ R_L) (Step S6)
1), key switch S₁Is determined to have been turned on.
And key switch S₁The operation when is turned on.
(Step S62), A / D port a₁Voltage is V
_DD× R _M/ (R_A+ R_M) (Step S6)
3), key switch S₂Is determined to have been turned on.
And key switch S₂The operation when is turned on.
(Step S64).

As described above, the destination determination is made by the power switch S.
_By performing the determination immediately after turning on the switch 4 and determining the input of the key switch after the destination is determined, the number of A / D ports conventionally used two can be reduced to one.

In the above-described operation switch identification circuit according to the embodiment of the present invention, the destination is divided into two and the number of key switches is set to two. can do.

[0026]

As described above, according to the operation switch identification circuit of the present invention, the required number of A / D ports is one.
Can be reduced. As a result, the range of choice of microcomputer is expanded, and a cheaper microcomputer can be used.

Further, according to the operation switch identification circuit of the present invention, the number of wirings to the microcomputer is reduced by one, which is advantageous in designing a wiring pattern of a printed board.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an operation switch identification circuit of the present invention.

FIG. 2 is a flowchart for explaining a destination identification operation in the operation switch identification circuit of the present invention.

FIG. 3 is a flowchart for explaining an operation key switch identification operation in the operation switch identification circuit of the present invention.

FIG. 4 is a flowchart for explaining an operation key switch identification operation in the operation switch identification circuit of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional operation switch identification circuit.

FIG. 6 is a flowchart for explaining an operation key switch identification operation in a conventional operation switch identification circuit.

FIG. 7 is a flowchart for explaining a destination identification operation in a conventional operation switch identification circuit.

[Explanation of symbols]

Reference Signs List 1 microcomputer S ₁ and S ₂ key switch S ₃ changeover switch S ₄ power switch R _A common resistance R _1, R ₂ and R ₃ resistance a ₁ and a ₂ A / D port

Claims (1)

[Claims] 1. A power supply voltage of a microcomputer is divided at different voltage dividing ratios by turning on / off each key switch and switching of a changeover switch, and the divided voltage is applied to an A / D port of the microcomputer. D
An operation switch identification circuit for identifying the key switch operated based on the divided voltage applied to the port and the changeover switch operated for changeover, identifies a changeover position of the changeover switch immediately after turning on the power, and An operation switch identification circuit for identifying a key switch operated after identifying a switching position.