JPH08102990A - Sound output device - Google Patents

Abstract

PURPOSE: To provide a sound output device with less number of externally mounted components in which sound volume adjustment of a speaker is easily made. CONSTITUTION: Plural resistor groups 5-1 to 5-4 to adjust a sound volume of a speaker 17 and plural transmission gates 7-1 to 7-4 to selectively short-circuit each of the resistor groups are provided inside a microcomputer. Then a control signal obtained by the decoding result of program data is latched by a latch circuit group 8 to control number of series connection of the resistor groups 5-1 to 5-4. Thus, number of externally mounted components for the microcomputer is reduced to reduce the cost and the operation by the user is facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio output device suitable for controlling the volume of sound emitted from a speaker by using an integrated circuit.

[0002]

2. Description of the Related Art Currently, a microcomputer for emitting a musical scale (melody, buzzer, etc.) from a speaker is on sale, and this microcomputer is constructed as follows. That is, a scale generation source capable of generating frequency signals corresponding to a plurality of scales is built in the microcomputer, a frequency signal of a predetermined scale selected according to a program is taken out from an output terminal, and this frequency signal is externally output. The sound emission operation is realized by giving it to the speaker through the resistance of. By the way, in the case of performing so-called volume adjustment such that the volume of the speaker is further increased or decreased from the current volume, a gap between the output terminal of the microcomputer that outputs the frequency signal and the terminal of the speaker that gives the frequency signal is used. , A plurality of resistors are connected in series as a load, and a load of the speaker is made variable by short-circuiting a predetermined resistor among the plurality of resistors, thereby adjusting the volume of the sound emitted from the speaker. Has been realized. As a specific method, a mechanical switch or a switching transistor is provided for each of a plurality of resistors externally connected to the microcomputer, and the mechanical switch is opened / closed or the switching transistor is turned on / off by a user's operation. I was dealing with it by changing the number of series.

[0003]

However, the number of external elements of the microcomputer is very large, which causes a problem of cost increase. Further, the user must voluntarily operate the individual mechanical switches or generate the signals for the on / off control of the switching transistors, which causes a problem that the operation becomes complicated.

Therefore, according to the present invention, the number of external parts is small,
Moreover, it is an object of the present invention to provide an audio output device in which the volume of a speaker can be easily adjusted.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is characterized by a scale capable of selectively generating frequency signals corresponding to a plurality of scales. A generation source and a scale setting circuit for instructing one kind of scale and causing the scale generation source to output a frequency signal corresponding to a predetermined one kind of scale set in the scale generation source, and the scale generation A switching transistor that is switched by a frequency signal output from the source,
A plurality of resistance groups connected in series to the switching transistor, a plurality of short-circuits that are respectively connected in parallel to each of the plurality of resistance groups, and selectively short-circuit each of the resistance groups;
A holding circuit that holds a control signal for selectively connecting or disconnecting the plurality of short-circuit circuits is provided inside the microcomputer, and one end of the plurality of resistor groups on the side not connected to the switching transistor is the microcomputer. Sound is emitted from the speaker by connecting to an external speaker, holding the control signal obtained by decoding the program in the microcomputer in the holding circuit, and controlling connection and disconnection of the short circuit. The point is to adjust the volume.

[0006]

According to the present invention, a plurality of resistor groups for adjusting the volume of the speaker and a plurality of short-circuit circuits for selectively short-circuiting each of these resistor groups are provided inside the microcomputer, and the program data is stored. By holding the control signal obtained from the decoding result of the above in the holding circuit, the number of resistors in series is controlled. As a result, the external parts of the microcomputer can be reduced, the cost can be reduced, and the operation by the user becomes easy.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a diagram showing an audio output device of the present invention. FIG.
In (1) to (1-n) are scale generation sources, a plurality of T flip-flops (not shown) connected in series are provided inside, and the reference clock RCK is divided. The structure is such that a frequency signal can be generated from a predetermined number of T flip-flops. In other words, each scale source (1-1) to (1-n) is 12
A frequency signal corresponding to sound can be selectively generated. (2-1) to (2-n) are scale setting circuits, which are setting signals for setting any scale of 12 tones to the scale generation sources (1-1) to (1-n), respectively. Is output. That is, the setting signals applied from the scale setting circuits (2-1) to (2-n) to the scale generation sources (1-1) to (1-n) are the scale generation sources (1-1) to (1). -N) This signal is for controlling from which stage of the plurality of T flip-flops incorporated inside the T flip-flop the frequency signal is generated. Specifically, the scale generation sources (1-1) to (1-n)
In each of the above, there is provided a multi-bit preset register for setting a plurality of T flip-flops connected in series in accordance with each scale, and an arbitrary T flip-flop is set and the reference clock RCK is set. By dividing the frequency, a frequency signal corresponding to a desired scale can be obtained from the T flip-flop at the final stage. In particular, the preset register receives the instruction of the scale to be output, preset data corresponding to the scale is preset each time, and by the trigger signal created based on the output obtained from the T flip-flop at the final stage, The preset data is applied from the preset register to the T flip-flop. (3-1) to (3-n)
Is an AND gate, one input terminal is connected to the output of the final stage of the output T flip-flop of each of the scale generation sources (1-1) to (1-n), and the other input terminal is
A selection signal is applied which indicates which of the AND gates (3-1) to (3-n) is to be opened. Here, the setting signal output from the scale setting circuits (2-1) to (2-n) and the selection signal controlling the opening and closing of the AND gates (3-1) to (3-n) operate the microcomputer. Let R
It is assumed that the predetermined state is determined based on the result of decoding the program read from the OM. In addition, (4-
1) to (4-n) are N-channel MOS transistors, and each gate has AND gates (3-1) to (3).
-N) is connected to the output terminal and the source is grounded. Further, (5-1) to (5-4) are resistors connected in series, one end of which is connected to the drain of the N-channel type MOS transistor (4-1) and the other end of which is an output terminal (6). Connected with. (7-1) to (7-4)
Is a transmission gate (short circuit), and the individual transmission gates (7-1) to (7-4) are connected in parallel with the resistors (5-1) to (5-4), respectively. (8) is a latch circuit group (holding circuit), which is composed of four latch circuits (9-1) to (9-4). The L (latch) terminals of the latch circuits (9-1) to (9-4) are each connected to a 4-bit data bus, and C (clock)
The terminals are commonly connected to the output terminal of the AND gate (10), and the Q (output) terminals are connected to the control terminals of the transmission gates (7-1) to (7-4), respectively.
The same structure is used for N-channel MOS transistor (4-
2) It is also provided for (4-3), but since the connection relationship is the same, its explanation is omitted. The above configuration is provided inside the microcomputer.

Further, as an external configuration of the microcomputer, a diode (1) is provided between the power supply V and the output terminal (6).
5) and the coil (16) are connected in series, and the coil (1
A speaker (17) is connected to 6) in a state capable of emitting sound. FIG. 2 is a diagram showing a configuration for creating latch data (control signal) for the latch circuit groups (8), (13) and (14) inside the microcomputer. In FIG.
Reference numeral (18) is a ROM in which program data for controlling the microcomputer is stored.
(19) is an instruction decoder, ROM
The program data read from (18) is decoded. Reference numeral (20) is a RAM in which various data calculated in the microcomputer are written or read. (21) is an ALU that performs a logical operation
And the output A of the instruction decoder (19)
Calculation for taking in the data read from the RAM (20) via the data bus (22) and generating a control signal for turning on any of the transmission gates (5-1) to (5-4) based on The processing is performed, and the result is written again in the RAM (20) via the data bus (22).

The operation of FIGS. 1 and 2 will be described below. First, consider a case where sound is emitted from the speaker (17) using only the frequency signal of the scale generation source (1-1). In this case, the frequency signal selected by the output of the scale setting circuit (2-1) is output via the AND gate (3-1),
The N-channel MOS transistor (4-1) is being switched. Here, the volume of the speaker (17) is determined by the number of resistors (5-1) to (5-4) in series, which are its load. That is, as the number of resistors increases, the load increases and the volume decreases, and as the number of resistors decreases, the load decreases and the volume increases. Therefore, when the user operates a volume adjusting key (not shown) in order to obtain a predetermined volume, an interrupt signal for instructing volume change (high or low) is generated at the same time when this key is operated. This interrupt signal causes RO
M (18) jumps from the currently read address to this interrupt address and reads the program data stored at this interrupt address. The instruction decoder (19) generates a decoding signal A as a result of decoding the program data read from the ROM (18) at this time. On the basis of the decoded signal A, the RAM (20) reads out the control data from the address in which the 4-bit control data that currently sets the transmission gates (5-1) to (5-4) in a predetermined open / close state is stored. , ALU (2
1) The arithmetic processing for changing the volume is internally performed, and the changed control data is again written in the read address of the RAM (20). Furthermore, the changed control data is stored in RAM (2
0) read from the latch circuit group (8) (13) (1
4). On the other hand, from the instruction decoder (19), in addition to the decoded signal A, a decoded signal B indicating which of the AND gates (10), (11) and (12) is to be opened, and which latch circuit group (8) (13)
A decoded signal C is generated which instructs the timing generation circuit (23) whether to apply the clock signal to (14). In the case of the operation of this embodiment, only the input of the AND gate (10) becomes high level, new control data of 4 bits is latched in the latch circuit group (8), and the transmission gates (5-1) to (5-). 4) the open / closed state is changed, and as a result, the number of resistors (5-1) to (5-4) in series is changed and the volume of the speaker (17) is changed.

Although the above description is an example of using only the frequency signals of a single scale generation source, a plurality of N channel type MOS transistors corresponding to the frequency scale signals of different scale generation sources are used. Switching at the same time,
A chord may be emitted from the speaker (17). In this case, AND gates (3-1) to (3-
It suffices to open a predetermined plurality of n). Also,
This can be realized by repeating the above-mentioned rewriting operation of the RAM (20) for a latch circuit group that needs rewriting of control data and causing the latch circuit group to sequentially latch.

In this embodiment, the number of resistors connected in series between the drain of the N-channel type MOS transistor and the output terminal is four, but the number of resistors is not limited to four.
As described above, the external parts of the microcomputer can be reduced, and as a result, the cost can be reduced. Also, the operation by the user becomes easy.

[0012]

According to the present invention, a plurality of resistor groups for adjusting the volume of a speaker and a plurality of short-circuit circuits for selectively short-circuiting each of these resistor groups are provided inside a microcomputer. By holding the control signal obtained from the result of decoding the program data in the holding circuit, the number of resistors in series is controlled. As a result, the number of external components of the microcomputer can be reduced, the cost can be reduced, and further, the operation by the user can be facilitated.

[Brief description of drawings]

FIG. 1 is a diagram showing an audio output device of the present invention.

FIG. 2 is a diagram for realizing the volume adjustment of the present invention.

[Explanation of symbols]

(1-1) to (1-n) Scale generation source (2-1) to (2-n) Scale setting circuit (4-1) to (4-n) N-channel MOS transistor (5-1) to (5-4) Resistor (6) Output terminal (7-1) to (7-4) Transmission gate (8) (13) (14) Latch circuit group

Claims (2)

[Claims] 1. A scale generation source capable of selectively generating frequency signals corresponding to a plurality of scales and one kind of scale, and a predetermined one kind of scale set in the scale generation source is specified. A scale setting circuit that outputs a corresponding frequency signal from the scale generation source, a switching transistor that is switched by the frequency signal output from the scale generation source, a plurality of resistance groups connected in series to the switching transistor, and A plurality of short-circuits that are individually connected in parallel to each other in the plurality of resistance groups and that selectively short-circuit each of the resistance groups; and a holding circuit that holds a control signal for selectively connecting or disconnecting the plurality of short-circuit circuits. Is provided inside the microcomputer, and one end of the plurality of resistor groups that is not connected to the switching transistor is connected to the microcomputer. Sound is emitted from the speaker by connecting to an external speaker, holding the control signal obtained by decoding the program in the microcomputer in the holding circuit, and controlling connection and disconnection of the short circuit. An audio output device for adjusting the volume of sound output. 2. The program for generating the control signal is read from a program memory provided inside or outside the microcomputer by an interrupt signal for adjusting the volume from the speaker. The audio output device described.