KR910004597Y1 - Data communication circuit - Google Patents

Abstract

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Description

Data communication circuit

Figure is a circuit diagram showing the present invention in detail.

The present invention relates to a data communication circuit having a modem connected to an interface of a telephone.

Conventional modems have a simple configuration in which a telephone is connected to a telephone jack.

Therefore, this configuration has a problem that the connection between the telephone dial and the telephone line is integrated, it is troublesome to check the communication destination by turning the telephone dial, the disadvantage of not being able to dial automatically, and the self-checking between the computer systems connected to the modem is impossible. will be.

Also, it is a representative modem integrated circuit used so far, using modem IC of Motorola's MC 6860, which separates data bus and address bus. Requires an external circuit that complicates and clocks, and in terms of itself, the temporal distortion rate in the process of converting the digital pulse of the input data stream into analog tow, and inverting the analog tow signal from the telephone to the digital pulse. It is well known that the data error rate is high since this occurs.

In the present invention, based on the use of an asynchronous communication interface adapter, a CPU and a CPU connected to a telephone via a modem for temporarily storing or retrieving a long and information stored therein as necessary and communicating with an external device are stored. Unlike conventional modem ICs, it consists of a simulation modem that has a program that synchronizes the input data back to the CPU clock to shape the pulse, reducing the external circuit and converting the analog tone signal from the telephone to digital pulse. The data error rate is lowered by reducing the temporal distortion of the process.

In other words, the CPU used in the present invention is a representative case when the serial port (Serial port) is supported, and brand name HD 64180, Z80186 is directly connected, and if there is no serial port, it is a simulation modem using a D / A converter. It can be used by connecting to the transmission / reception data terminals (TXD) and (RXD) of K221 and K222.

The CPU in this design supports the serial port and has five important functional blocks. This function block includes a clock generator, a bus state controller, an interrupt controller, a memory management unit having a program object code, and the like. The input / output function also includes a DMA controller, an asynchronous serial communication interface of two channels, a clock serial input / output port, and a programmable controller. The re-memory timing etc. are provided.

Therefore, the present invention is equipped with the modem brand name K221, the CPU controls the modem's address data terminal (AD _1- AD ₇ ), enable terminal (ALE), control terminal (CS) to enable the modem to read and write data The external clock of the CPU is received from the terminal CLK, and data is received or transmitted from the terminals RXD and TXD.

In addition, the CPU is connected to the telephone line and the telephone line at the same time by the phone data and the dialing data.In the online mode, the CPU receives a control signal that specifies the reception operation of the ASCI channel called a DCD (DATA CARRLER DETEC) signal. In local command mode, the CPU issues a control signal that causes the CPU to dial a signal for transmission, and in the on-line Commcnd Mocd, a request for transmission, called RTS, as a telephone connection switching signal. The control signal is issued.

In particular, the present invention is provided with a relay switch group that allows the telephone line and the telephone line to be connected at the same time can easily induce communication between computers.

Therefore, the present invention is provided with a simulation modem to communicate between computers by the modem, the modem receives a data signal of the transmitting computer and adjusts it to a range that can receive it, and the signal transmitted from the modem It is equipped with a deplex which adjusts the magnitude of the signal so that it can transmit using a telephone line, and it has a relay which responds to the telephone drive signal from its own computer, and a relay which is equivalent to the dial signal. Since it is connected at the same time, it is switched to transmission or response mode. In response mode, it consists of a signal generation circuit during communication so that a signal during communication is transmitted to the CPU.

Referring to the present invention in detail based on the accompanying drawings as follows.

The modem IC 10 of the present invention forms a pulse synchronized with the clock of the CPU while generating a clock signal for synchronizing serial data inputted therein by the clock terminal CLK to the CPU clock again. It has a software program and receives address signal of CPU by its address terminal (AD _0- AD ₇ ), transfers simulated data according to self-programming by CPU during CPU read operation, and enables address latch enable (ALE) from CPU. It has a read terminal (RD) and a write terminal (WR) that read and write the data flow to the CPU according to the signal.

The modem IC 10 is operated by a reset signal RST from the CPU, and receives asynchronous reception data from the CPU from its terminal RXD or transmits asynchronously to the CPU by the chip select signal CS. Transfer data to its terminal TXD.

From the terminals TXD and RXD, a data transmission signal and a reception signal via a telephone are transmitted or received.

For this purpose, the terminal TXA is transmitted to the deplexer 20 and the terminal RXA is connected to the limiter 30.

This deplexer 20 has an inverting amplifier OP ₁ , which allows a feedback resistor R ₃ and a capacitor C ₂ to be connected between its inverting terminal and the output terminal and the terminal of the modem IC 10. The signal from (TXA) is applied to the inverting terminal via the ripple erase capacitor (C ₁ ) and the resistor (R ₁ ), and the non-inverting terminal is grounded, and the inverting amplifier (OP ₁ ) is the resistor (R ₄ ). Via is connected to the hybrid circuit 40 described later.

The limiter 30 is provided with a inverting amplifier (OP _2), the inverting amplifier (OP _2), the feedback resistor (R ₅₎ between its output and inverting input terminal (R ₆₎ and a capacitor (C ₄₎ is connected The capacitor C ₄ is connected in series with a resistor R ₇ having one side grounded.

On the other hand, the inverting terminal on the input side of the inverting amplifier OP ₂ is commonly connected to the hybrid circuit 40 like the doublexer 20 via the resistor R ₈ , the inverting terminal is grounded, and its output terminal is for ripple erasing. The capacitor C ₅ is connected to the data receiving terminal RXA of the modem IC 10.

Therefore, these deplexers 20 and limiters 30 respectively adjust the magnitude of the signals to transmit and receive signals by using a telephone line, and adjust the received signals to a range within which the modem 10 can receive them. It can be seen.

The hybrid circuit 40 is configured to transmit and receive a transmission and reception signal of a telephone with a standing wave of a predetermined level.

That is, the transformer (T ₁ ) is a resistor (R ₉ ) and (at the output terminal for controlling the response mode and the transmission mode of the switch unit 50 and the telephone line connection unit 60 of the telephone control unit described in detail later ( R ₁₀ ) having a secondary coil having two terminals connected by the primary side of which is connected to the input / output common line of the doublexer 20 and the limiter 30 with both ends thereof insulated by a capacitor C ₆ . In addition, in order to have a predetermined level, the common zener diodes ZD ₁ and ZD ₂ are connected in series to the common line so as to be ground-insulated.

The switch unit 50 of the telephone control unit and the switch unit 60 of the telephone line connection unit by the telephone driving switching signal for the telephone transmission mode and response are respectively provided with a dialing signal and a telephone switching connection signal from the CPU (R ₁₁ ) and (R _{12 is} provided separately to the bases of the transistors Q ₁ and Q ₂ to drive them and thus operate relays RY ₁ and RY ₂ to operate.

As shown in the figure, the relay selectively selects the transmission signal and the response signal according to the operation of the modem in the transmission mode and the response mode for the input / output terminal 70 and the telephone line input / output terminal 80, which are telephone standard-mode and jacks. Is applied to the telephone-side selection terminals 3 and 4, respectively.

That is, in the transmission mode, the relay RY ₁ is driven in response to the dial signal from the CPU, and one output terminal of the hybrid circuit 40 is applied to the switch unit 50 contact 9 of the telephone controller, and the telephone line connection is switched from the CPU. Since the relay RY ₂ is driven by a signal, the tangential line 9 is connected to the tangential line 4 so as to be able to communicate with an external device by a telephone line at the same time as dialing, and the tangential line 13 is connected to the tangential line 11. Since it is connected, it is applied to the busy signal generation circuit 9 described in detail later.

In response mode, the relay RY ₂ is activated by the telephone connection switching signal so that the tangential 13 of the telephone line and the input / output terminal 80 passes through the tangential 13 of the switch 60 of the telephone line connection part. The relay RY ₁ is connected to the tangential 9 of the switch 50 of the telephone connection section and the one output terminal of the hybrid circuit 40 while the tangential line 4 is connected to the tangential line 8. The tangent 8 of the switch unit 60 of the telephone line controller is applied to the in-call generation signal circuit 90 described later through the tangent 4.

The signal generation circuit 90 during a call operates in the transmission mode at the CPU or in the response mode at the telephone line input / output terminal 80, so that the diode D ₁ has a predetermined level according to the signal. D ₄₎ provided with a bridge, consisting of the output end of the bridge is through a resistor (R ₁₃₎ and a Zener diode (ZD ₃ consisting of a constant-voltage circuit) and a diode (D ₅₎ is also photo-coupler connected in parallel (PH ₁ ) is installed.

Therefore, when a signal is applied from the switch unit 50, 60 during a call, it is applied to a constant photo coupler PH ₁ , so that the light receiving element generates a busy signal indicating that a certain level of communication is in progress.

Referring to the effect of the present invention configured as described above are as follows.

In the communication mode between the CPUs with the power applied to the circuit, dialing signals and telephones are stored by the system-programmed signals of the CPUs which temporarily store or recall information and the ROM storing their system programming in the transfer mode. When the connection switching signal is transmitted, the relay unit RY ₁₁ of the switch unit 50 of the telephone control unit and the relay RY ₂ of the switch unit 60 of the telephone line connection unit are driven, and the switch units 50 and 60 enter the transmission mode. The control signal and the parallel digital signal, which are switched and output from the CPU, are inputted to the address data terminals AD ₀ -AD ₈ and the respective control terminals RST (CLK) ALE of the modem 10, respectively. ) Starts an operation, and the data inputted to the address data terminals AD ₀ -AD ₇ is analog-converted by the digital-to-analog converter included in the modem IC 10 and then returned to the telephone line. The large signal that can be transmitted is converted and transmitted through the transmission terminal TXA of the modem IC 10. The signal transmitted to the transmission terminal TXA is the capacitor C ₁ and the resistance R of the deflector 20. ₁₎ through the inverting input terminal (the inverting amplifier (OP ₁₎ - is input to) the output terminal of the inverting amplifier (OP ₁₎ is that by the gain control resistor (R ₁₎ is fed back to the input side of the resistance (R ₁₎ The size of the signal is adjusted and input to the hybrid 40, and the signal input to the hybrid 40 is separated and coupled, and the switch unit 60 and the telephone unit 50 of the telephone line connection unit are switched to the transmission mode through the output terminal. The input signal of the telephone is transmitted through the telephone line input terminal 80 through each of the tangential line 8 and the tangential line 13.

At this time, the signal flowing through the switches 50 and 60 passes through the output terminals of the bridges D ₁ -D ₄ of the signal generation circuit 90 and the resistor R ₁₃ , and is a zener diode ZD _3. ) And the diode (D ₃ ) to conduct the photocoupler (PH ₁ ) to give a busy signal.

On the other hand, in response mode, since there is no dialing signal and telephone transmission switching signal from the CPU as opposed to the transmission mode, it is input from the other party through the telephone line input / output terminal 80 of the switch unit 50 of the telephone control unit and the switch unit 60 of the telephone line control unit. When the signal applied from the telephone line input / output terminal 80 is applied to the limiter 30 while the signal is coupled and separated from the transmission of the hybrid 40 through the switch unit 60 of the telephone line controller, the limiter 30 inverting amplifier through a resistor (R ₈₎ input to the signal (OP ₂₎ and the inverting terminal (-) is applied and an inverting amplifier (OP ₂₎ output terminal, the input of which the input signal resistor (R ₈₎ with a feedback resistor to the (R ₅₎ i.e. when adjusted to the magnitude of the signal with the modem IC (10) we can read the input to the receiving terminal (RXA) of the modem IC (10) to control the resistance of the input signal is therein By analog-to-digital converter that converts a digital signal to be dropped it was blown out into the CPU via the data terminal (AD ₀ -AD ₇₎ the digital-converted signal from the modem IC (10) by a control signal from the CPU.

At this time, when a signal is applied from the switch unit 50, 60 during a call, it is applied to the photocoupler PH ₁ through the signal generation circuit 90 during a call as in the case of the transmission. This will generate a busy signal that indicates.

As described above, the present invention enables the telephone to be dialed by the number stored in the CPU itself in the communication between the computers from the above, and the self-switching is performed according to the transmission and response mode, thereby facilitating the communication operation. In addition, the modem IC is equipped with a software program that synchronizes the serial data inputted to the CPU power to form a pulse to build the simulation modem, thereby reducing temporal distortion during data conversion and further improving the modem's data error rate. I lowered it.

Claims (1)

In communicating a data signal between the CPUs via the modem IC 10, the modem IC 10 is configured as a simulation modem for synchronizing the input serial data back to the CPU clock, and the modem IC 10 has its transmission terminal. (TXA) the inverted amplifier (OP ₁ ) for adjusting the transmitted signal to the size of the signal that can be transmitted over the telephone line, a deflector 20 consisting of an input resistor (R ₁ ), an adjustment resistor (R ₁ ), and the modem Inverter amplifier (OP ₂ ) for adjusting the signal in a range that can be received by the IC (10), a limiter (30) consisting of an input resistor (R ₈ ), a control resistor (R ₅ ), and the deflector 20 And a hybrid 40 that separates and transmits and receives a signal from the limiter 30 in an insulated state so as to receive a signal from the limiter 30, and switches the signal from the hybrid 40 by a CPU dialing signal and a telephone connection switching signal. 70 and telephone line input and output terminal (80) To receive a signal from the switch unit 50 of the telephone connection unit and the switch unit 60 of the telephone line connection unit, and the switch unit 50 of the telephone connection unit and the switch unit 60 of the telephone line connection unit to generate a busy signal. Bridge circuit (D ₁ -D ₄ ) A data communication circuit comprising a busy signal generation circuit (90) consisting of a constant voltage element (ZD ₃ ) and a photocoupler (PH ₁ ).