JP2523190Y2 - Key input switching circuit for telephone IC - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a key input switching circuit of a telephone IC using a keyboard.

(B) Conventional technology Normally, pulse dial and tone dial ICs are
A keyboard having numeric keys and function keys is connected, and a key scan input circuit for inputting key operations of the keyboard is provided. For example, when a 5 × 5 matrix keyboard is used for the key scan input circuit, five drive terminals for outputting a selection signal and an input terminal for inputting information on an operated key are provided. Are required.

When such a telephone IC is controlled by a microcomputer, the microcomputer scans the keyboard and transmits the resulting key data to the telephone IC.
The external terminals of the IC are connected to the input / output terminals of the microcomputer. Alternatively, a telephone IC provided with a dedicated interface circuit is used to receive key data from a microcomputer.

(C) Problems to be Solved by the Invention Conventionally, when a system for controlling a telephone IC by a microcomputer is adopted, a method of connecting the external terminal for key scanning of the telephone IC to the input / output terminal of the microcomputer. In such a case, the input / output terminals of the microcomputer are occupied for key scanning, and the terminal utilization efficiency of the microcomputer is disadvantageously deteriorated.

Also, in order to provide a dedicated interface circuit for receiving data from the microcomputer in the telephone IC, it is necessary to provide an input terminal dedicated to the interface in the telephone IC, so that the number of terminals of the telephone IC increases. Was.

(D) Means for Solving the Problems The present invention has been made in view of the above-mentioned points, and a key code of a key operated by performing a key scan of key switches arranged in a matrix is provided. A key input switching circuit of a telephone IC having a key scan input circuit for outputting, and a telephone function circuit for performing an operation indicated by a key code output by the key scan input circuit, wherein arbitrary data is transmitted from an external control device. An input circuit for receiving a key input signal to the key scan input circuit and a switching circuit for selectively connecting a signal line to be externally applied to the interface to an external terminal; By providing an external terminal to which a signal for controlling switching of the switching circuit is applied, input of key scan is performed. The power terminal and the microcomputer interface terminal are shared.

(E) Function According to the above means, when the keyboard is directly connected to the telephone IC, the switching circuit connects the input terminal to the key input signal line of the key scan input circuit and connects the microcomputer. Since the switching circuit connects the input terminal to the input signal line of the interface circuit, the input terminal can be shared by the input terminal of the key scan and the interface terminal of the microcomputer.

(F) Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention.
(1) is a key scan input circuit, (2) is a telephone function circuit, (3) is a data bus, (4) is an interface circuit, (5), (6) and (7) are switching circuits, and S / K is switching control. Terminal.

As the key scan input circuit (1), a 5 × 8 matrix keyboard (not shown) can be used, and a key scan signal line for sequentially driving the rows of the keyboard is connected to terminals R _{1 to} R ₅ . key operation information from the columns present 5 of the key input signal line 8 to be input is connected to the terminal C ₁ -C _5. Further, the remaining three key input signal lines are connected to the outputs of the switching circuits (5), (6) and (7), respectively. The key code of the key switch operated on the keyboard by the key scan input circuit (1) is supplied to the telephone function circuit (2) via the data bus (3). The telephone function circuit (2) operates according to the input key code. For example, if the key code is a numeric key, the telephone function circuit (2) transmits a pulse of the number or a tone corresponding to the number to the telephone line, and if the key is a function key, operates to realize the function. Interface circuit (4)
Comprises a shift register (8) and a latch circuit (9) for holding data input to the shift register (8). The data input D of the shift register (8) is connected to the other output of the switching circuit (5), and the clock input CL of the shift register (8) is connected to the other output of the switching circuit (6). The control signal of the switching control terminal S / K is applied to the reset input R of (8) via the inverter (10). The other output of the switching circuit (7) is connected to the latch control input L of the latch circuit (9). The output of the latch circuit (9) is connected to the data bus (3), and the data held in the latch circuit (9) is supplied to the telephone function circuit (2) via the data bus (3).

The inputs of the switching circuits (5), (6) and (7) are connected to input terminals DA / C ₆ , CLK / C ₇ and STB / C ₈ , respectively, and are controlled by a control signal applied to a switching control terminal S / K. Switching is controlled. The control signal applied to the switching control terminal S / K is also applied to the key scan input circuit (1).

In FIG. 1, when the switching control terminal S / K is at the ground voltage level “L”, the switching circuits (5) and (6)
(7) selectively connects the input terminals DA / C ₆ , CLK / C ₇ , and STB / C ₈ to the key input signal lines of the key scan input circuit (1), respectively. The key scan input circuit (1) Perform a scan operation. At this time, the shift register (8) is in a reset state by the output of the inverter (10), and the operation of the interface circuit (4) is prohibited. Accordingly, in this state, key scan input circuit closing information is input from the C input terminal for each row of the keyboard ₁ -C ₅ and the input terminal _{DA / C 6, CLK / C} 7, STB / C 8 key switch ( 1) is applied.

On the other hand, when a signal of the power supply voltage level “H” is applied to the switching control terminal S / K, the switching circuits (5), (6), (7)
Connects the input terminals DA / C ₆ , CLK / C ₇ , and STB / C ₈ to the data input D of the shift register (8), the clock input CL, and the latch input L of the latch circuit (9). At this time, the reset of the shift register (8) is released, and the operation of the key scan input circuit (1) is prohibited. In this state, the data applied to the input terminal DA / C ₆ is sequentially shifted to the shift register (8) by the synchronous clock applied to the input terminal CLK / C _7, and when the transfer of the predetermined bit data is completed, the input terminal STB / by a signal applied to C _8, the data shifted into the shift register (8) is held in the latch circuit (9).

Next, FIGS. 2 and 3 show examples of use of the telephone IC having the configuration shown in FIG.

FIG. 2 shows a case in which a 5 × 5 keyboard (11) is used, and the keyboard (11) is connected to the terminal R ₁ of the telephone IC (12).
Is connected to a to R ₅ and the terminal C ₁ -C ₅ are connected to the terminals R ₁ to R ₅ and the terminal C ₁ -C ₅ a microcomputer (13). The output of a power supply circuit (14) for obtaining a DC voltage from an AC power supply of 100V AC is applied to the switching control terminal S / K. In this example, when the power supply AC100V is supplied,
Keyboard (11) by microcomputer (13)
Key scan, and the data is used for telephone IC (12)
Input terminal DA / C ₆ , CLK / C ₇ , STB / C ₈
When V is cut off, only the telephone IC (12) is operated by the voltage obtained from the telephone line, and the telephone IC (12)
Key scanning of the keyboard (11).

Of course, using a 5x8 keyboard, the microcomputer scans the keys and performs input terminal DA /
_{C 6, CLK / C 7,} STB / C 8 telephone for IC data through the (12)
It can also be used to send to.

Fig. 3 shows a 5 × 8 keyboard (15) for direct telephone use
This is the case where key scanning is performed by the IC (12) and the microcomputer is not used. In this case, terminal R ₁
To R _5, the terminal C ₁ -C ₅ and the input terminal _{DA / C 6, CLK / C} 7, STB / C 8
Are all connected to the keyboard (15) and switch control terminals
S / K is grounded.

(G) Effect of the present invention As described above, according to the present invention, the input terminal can be shared by the input terminal of the keyboard and the input terminal of the interface of the microcomputer, so that a single telephone IC can be shared by various telephone systems. Another advantage is that the function of the telephone IC is greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 and 3 show examples of use of a telephone IC having the circuit shown in FIG. (1) key scan input circuit, (2) telephone function circuit, (3) data bus, (4) interface circuit, (5) (6) (7) switching circuit,
(8) ... shift register, (9) ... latch circuit.

Claims (1)

(57) [Scope of request for utility model registration] 1. A key scan input circuit for outputting a key code of a key operated by performing a key scan of a key switch arranged in a matrix, and an operation specified by the key code output by the key scan input circuit. For telephones with telephone function circuits
A key input switching circuit of an IC, an interface circuit for receiving arbitrary data from an external control device, an arbitrary signal line for applying a key input signal to the key scan input circuit, and an externally applied signal to the interface A switching circuit for selectively connecting a signal line to be connected to an external terminal; and an external terminal to which a signal for controlling switching of the switching circuit is applied. circuit.