JPH11187141A - Semiconductor integrated circuit for communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To integrate an FSK modulation circuit and a DTMF demodulation circuit on the same substrate at a terminal adapter. SOLUTION: Once FSK data has been inputted from an ISDN telephone line 1, a control circuit 5 switches the movable terminals of first to third selector circuits 9 to 11 to the side of an FSK modulation circuit 8. The FSK data are inputted to the FSK modulation circuit 8 and based on these data, signals are converted to FSK modulated signals and impressed to an analog telephone set 2. When originating a telephone call, the control circuit 5 switches the first to third selector circuits 9 to 11 to the side of a DTMF detection circuit 7 so that the data of digitized DTMF signals can be inputted to the control circuit 5. Afterwards, the control circuit 5 sends the DTMF data to an ISDN telephone line 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor integrated circuit for communication used in a terminal adapter connected between an ISDN digital telephone line and an analog telephone.

[0002]

2. Description of the Related Art At present, call information and communication information (for example, digital data called ISDN) are used as telephone lines.
Digital telephone lines (used for computers and facsimile machines) are widely used. On the other hand, as telephones, analog telephones, which have been well known, have been widely used. However, since the data format is different between the ISDN line and the analog telephone, it is not possible to directly connect the ISDN line and the analog telephone. Therefore, FIG.
As shown in the figure, the ISDN line 1 and the analog telephone 2
A terminal adapter is connected between the terminal and the adapter 3. The adapter 3 converts the digital signal from the ISDN into a two-wire signal so that the analog telephone can receive the signal, and converts the two-wire analog signal from the analog telephone into an ISDN line. Is converted to digital data conforming to the standard. In other words, by connecting the terminal adapter 3, even if an ISDN telephone line is used, a pseudo two-wire telephone line is connected to the telephone line from the viewpoint of the telephone. It will be possible to connect.

On the other hand, a service called a calling telephone number notification service has been started in Japan. In this service, information such as the telephone number and name of the caller is transmitted to the telephone terminal device by an FSK modulation signal. By demodulating the FSK-modulated signal on the telephone terminal side, information such as the telephone number and name of the caller can be known, and the callee can select whether or not to answer the call after confirming the information. So it will be possible to prevent prank calls.

[0004]

The terminal adapter has a DTMF detection circuit that detects a DTMF dial signal from an analog telephone and converts the signal into digital data to be output to the ISDN telephone line 1. In addition, the outgoing telephone number notification service uses the ISDN telephone line 1
An FSK modulation circuit for generating an FSK modulation signal in accordance with data input from the FSK is provided, and this is achieved by transmitting the FSK modulation signal to an analog telephone.

As described above, the DT in the terminal adapter
Since the MF data transmission and the outgoing telephone number notification service are completely different functions, each function is conventionally mounted on two separate semiconductor integrated circuits. Therefore, there is a problem that a large number of semiconductor chips are required. Also,
When trying to realize the DTMF detection circuit and the FSK modulation circuit on one semiconductor integrated circuit board by transmitting and receiving data by independent dedicated external terminals respectively,
There is a problem that external terminals are increased.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a terminal adapter connected between a digital telephone line and an analog telephone detects a DTMF signal transmitted from the analog telephone and outputs DTMF data.
An MF detection circuit for generating an FSK modulation signal based on digital data input via the digital line, and outputting the FSK modulation signal to the analog telephone;
And a modulation circuit, wherein the DTMF detection circuit and the FSK modulation circuit are integrated on the same semiconductor substrate.

Further, the semiconductor integrated circuit includes a first terminal and a first selection circuit for switching data input / output to / from the first terminal to the DTMF detection circuit or FSK modulation circuit for inputting / outputting the data. Features. Further, the semiconductor integrated circuit includes a second terminal, and a second selection circuit that switches a clock input to the second terminal to the DTMF detection circuit or the FSK modulation circuit and transmits the clock.

Still further, the DTMF detection circuit has a DTMF detection circuit.
When detection of the MF signal is completed, a DTMF detection signal is output,
Alternatively, the FSK modulation circuit outputs an FSK input enable signal when the data can be input, and the semiconductor integrated circuit includes a third terminal, a DTMF
A detection signal or an FSK input enable signal is switched and output from the third terminal.

According to the present invention, since an external terminal for outputting DTMF data and an external terminal for inputting FSK data are also used, they can be integrated on the same integrated circuit substrate without increasing the number of terminals. be able to.

[0010]

FIG. 1 is a diagram showing an embodiment of the present invention. Reference numeral 4 denotes an ISDN telephone line and DTMF data;
An ISDN interface for transmitting and receiving SK data and voice data; 5, a control circuit for transmitting and receiving DTMF data, FSK data and voice data; 6, a communication semiconductor integrated circuit integrated on the same semiconductor substrate;
7 is a control circuit for detecting a DTMF signal and transmitting DTMF data
The DTMF detection circuit 8 transmits to the F
FSK modulation circuit for modulating SK data into FSK signal, 9
Is a first selection circuit whose movable terminal switches according to the transfer of DTMF data or FSK data, 10 is a second selection circuit for transmitting a clock signal of the control circuit 5 to the DTMF detection circuit 7 or the FSK modulation circuit 8, and 11 is DTMF detection A third selection circuit that outputs one of the detection signal of the circuit 7 and the input enable signal of the FSK modulation circuit 8 to the control circuit 5; 12 is an analog interface for transmitting and receiving the DTMF signal, the FSK modulation signal, and the voice signal to and from the analog telephone 2; Reference numeral 13 denotes a conversion circuit for A / D and D / A conversion of the audio signal and the audio data, respectively. In FIG. 1, the same circuits as those in the conventional example of FIG. 2 are denoted by the same reference numerals. Generally, the analog interface 12 is the analog telephone 2
In the present invention, the analog telephone 2 and the analog interface 12 are provided in order to simplify the description.
Are described separately.

In FIG. 1, the analog telephone 2
When no TMF signal is output and no FSK data is input from the ISDN telephone line 1, the first to third selection circuits 9 to 11 are switched to the terminal a (FSK modulation circuit side) as shown in the figure. I have. That is, in the standby state, the FSK signal waits, and only when the DTMF signal is input, the state is switched to the wait state for the DTMF signal.

First, the operation when the calling telephone number notification service is performed in the standby state will be described. FSK data is transferred from the exchange. FSK data is IS
It is input from the DN telephone line 1 to the control circuit 5 via the ISDN interface 4. The control circuit 5 detects that the FSK data has been input, and detects one switching signal DTMF / FSK.
Is output. In response to the switching signal DTMF / FSK of “1”, the first to third selection circuits 9 to 10 continue the state shown in FIG.
The K modulation circuit 8 is enabled, and the DTMF detection circuit 7 is disabled. FSK modulation circuit 8
Outputs an input enable signal FSK-READY when it is in a state of waiting for data. The input enable signal FSK-READY is input to the control circuit 5 via the third selection circuit 11, and the control circuit 5 recognizes the standby state of the FSK modulation circuit 8.

Subsequently, the control circuit 5 transmits the FSK data FSK-DA
Clock CL synchronized with TA and FSK data FSK-DATA
And send. The FSK data FSK-DATA and the clock CL are input to the FSK modulation circuit 8 via the first and second selection circuits 9 and 10. The FSK modulation circuit uses FSK data FSK-
A different frequency is switched according to the value of FSK data based on DATA, and an FSK modulation signal is modulated and output. The FSK modulated signal is transmitted to an analog telephone via the analog interface 12. When the FSK modulation is completed, the input enable signal FSK-READY from the FSK modulation circuit 8 is returned again.
Is output to the control circuit 5 via the third selection circuit 11. The control circuit 5 outputs the next FSK data according to the input enable signal FSK-READY. The FSK modulated signals sequentially output in this manner are output to the analog telephone 2 by the FS
K demodulation is performed, and information such as the telephone number and name of the caller can be obtained.

Next, an operation when a DTMF signal is received from the analog telephone 2 in the standby state will be described. In order to make a call on the analog telephone 2, the receiver is first picked up. Therefore, a hook signal HOOK indicating that the receiver is picked up is output from the analog telephone 2 and is directly input to the control circuit 5 via the analog interface 12. As a result, the control circuit 5 starts to use the DTMF
Recognizing that a signal is input, the control signal outputs a switching signal DTMF / FSK of 0. Switching signal DTMF / FSK becomes 0
, The terminals of the first to third selection circuits 9 to 11 are switched to the b side, and the first to third selection circuits 9 to 11
This means that the mode has been switched to the MF detection circuit 7 side.

During this time, the DTMF signal is input to the DTMF detection circuit 7 via the analog interface 12. The DTMF detection circuit 7 detects the type of the DTMF signal and outputs digital data according to the detected type. When the DTMF signal is detected, the DTMF detection circuit 7
Outputs a detection signal DTMF-ON to the control circuit 5. In response to the detection signal DTMF-ON, the control circuit 5 sets the clock CL to the second
The signal is input to the DTMF detection circuit 7 via the selection circuit 10. Then, the DTMF data DTMF is synchronized with the clock CL.
-DATA is output from the DTMF detection circuit 7 and transferred to the control circuit 5 via the first selection circuit 9. As a result, DT
The transfer of the MF data DTMF-DATA is transferred in synchronization with the operation of the control circuit 5. The control circuit 5 is DTMF data DTMF-DAT
A is transmitted to the ISDN telephone line 1 via the ISDN interface 4.

In FIG. 1, the number of the first control circuit 9 is described as one, but this is applied when the data transmission is a serial system. In the case of a multi-bit parallel system, it is preferable to prepare a plurality of first selection circuits 9 corresponding to the number of bits. In FIG. 1, the ISDN telephone line 1 is in the standby state.
Is set to wait for FSK data from the analog telephone 2 in the standby state.
Wait for a signal and set it to ISDN telephone circuit line 1 to F
Only when SK data is input, a state where FSK data is waited may be set.

Incidentally, the call signal is transmitted and received as follows. Call data from ISDN telephone line 1 is ISD
Input to the control circuit 5 via the N interface 4;
The data is decoded by the control circuit 5. After the decoded digital data is converted into an analog signal by the conversion circuit 13, it is input to the analog telephone 2 via the analog interface 12 as a call signal. On the other hand, a call signal from the analog telephone 2 is input to the conversion circuit 13 via the analog interface 12 and is converted into a digital signal. The converted digital data is encoded by the control circuit 5 into a form corresponding to the ISDN telephone line, and then transmitted to the ISDN telephone line 1 via the ISDN interface 4 as call data.

[0018]

According to the present invention, an external terminal for outputting DTMF data and an external terminal for inputting FSK data are also used, so that the number of terminals does not increase and the same terminals can be mounted on the same integrated circuit substrate. Can be integrated. In addition, the terminal for the clock and the terminal for other signals can also be shared. In particular, since the FSK modulation circuit and the DTMF detection circuit do not operate at the same time, no problem occurs even if the FSK modulation unit and the DTMF detection circuit are integrated on the same semiconductor substrate.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ISDN telephone line 2 Analog telephone 3 Terminal adapter 4 ISDN interface 5 Control circuit 6 Communication semiconductor integrated circuit 7 DTMF detection circuit 8 FSK modulation circuit 9-11 The 1st-3rd selection circuit 12 Analog interface 13 Conversion circuit

Claims (4)

[Claims] 1. A terminal adapter connected between a digital telephone line and an analog telephone, comprising: a DTMF detection circuit for detecting a DTMF signal transmitted from the analog telephone and outputting DTMF data; An FSK modulation circuit that generates an FSK modulation signal based on digital data input through the FSK modulation circuit and outputs the FSK modulation signal to the analog telephone. The DTMF detection circuit and the FSK modulation circuit are integrated on the same semiconductor substrate. A semiconductor integrated circuit for communication, characterized in that it is made into an integrated circuit. 2. The semiconductor integrated circuit according to claim 1, further comprising: a first terminal; and a first selection circuit that switches data input / output to / from the first terminal to the DTMF detection circuit or FSK modulation circuit to input / output data. The communication semiconductor integrated circuit according to claim 1, wherein: 3. The semiconductor integrated circuit according to claim 2, further comprising a second terminal, and a second terminal for switching a clock input to the second terminal to the DTMF detection circuit or the FSK modulation circuit for transmission.
The communication semiconductor integrated circuit according to claim 2, further comprising a selection circuit. 4. The DTMF detection circuit outputs a DTMF detection signal when the detection of the DTMF signal is completed, or the FSK modulation circuit outputs an FSK input enable signal when the data is ready to be input. 4. The communication semiconductor integrated circuit according to claim 3, wherein the semiconductor integrated circuit switches between a third terminal and a DTMF detection signal or an FSK input enable signal and outputs the signal from the third terminal.