JPS62112449A - Signal transmitter - Google Patents

Abstract

PURPOSE:To attain digital transmission through a transmission line insulated by a transformer by connecting an encoding circuit for converting an NRZI code into a bipolar code in series to a pulse transformer for outputting only a differential component of an output signal outputted from the encoding circuit. CONSTITUTION:The encoding circuit 2 is constituted of a shift register 21, a clock generator 22, an exclusive OR gate circuit 23, an inversion gate circuit 24, a J-K flip-flop 25 obtained by pulling up J and K terminals, negative AND gate circuits 26, 27, and transistors 28, 29 for driving a pulse transformer. A driving signal inputted to the primary side of the pulse transformer becomes a bipolar code and a signal applied between the secondary side terminals 303 and 304 of the pulse transformer is converted a into similar code and sent to the transmission line. Consequently, an NRZI code outputted by a microcomputer LSI is converted into a bipolar code and sent to the transmission line insulated by the transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a signal transmitter used for digital transmission.

Conventional technology Conventionally, when this type of signal transmitter performs digital transmission using a microcomputer IJS that can directly input and output NRZI codes, conventionally, for example, the signal transmitter was Interface circuit tt based on R3422 standard The microcomputer T
It was installed between the input/output terminal of the JS engineer and the transmission line to transmit the NRZI code as is.

Problems to be Solved by the Invention In such a conventional configuration, the transmission line is not electrically insulated from the microcomputer LSI, so it is easily affected by the ground potential, and it is also susceptible to large common-mode noise, resulting in transmission errors. It was easy to happen.

On the other hand, the transformer insulation method, which electrically isolates the transmitting/receiving station and the transmission line using a pulse transformer, is known as an insulation method that is resistant to common-mode noise and is suitable for long-distance, high-speed transmission without being affected by ground potential. Since the transformer does not pass DC signals, a bipolar code is suitable for the drive signal, or an NRZI code containing a DC component cannot drive the pulse transformer.

Means for Solving the Problems The present invention provides an encoding circuit that converts the NRZI code outputted from the microcomputer LSI into a bipolar code and outputs the bipolar code between the microcomputer LSI that directly inputs and outputs the NRZI code and the transmission line. and a pulse transformer that electrically insulates the encoding circuit and the transmission line and outputs only the differential component of the output signal of the encoding circuit to the transmission line is connected in series, and the two of the encoding circuits are connected in series. The connection point between the output terminal of the pulse transformer and the winding terminal of the primary winding of the pulse transformer is connected to a decoding circuit, the bipolar code is converted to an NR2 code, and the output thereof is input to the microcomputer LSI. A block diagram of the configuration of the signal transmitter of the present invention is shown in FIG.

In the figure, (1) is a microcomputer LSI, (
2) is an encoding circuit, (3) is a decoding circuit, (4) is a pulse transformer, and (5) is a transmission line.

The configuration of the signal transmitter of the present invention will be explained.

Microcomputer L 5I (1) 41, N R
Z code output terminal 101, NRZX code input terminal 102
has. The encoding circuit (2) encodes and compares the NRZI code inputted from the input terminal 201 with a bipolar code, and obtains the differential signal from the differential output terminals '202 and 203.

The pulse transformer (4) has primary side terminals 301 and 302
and has secondary side terminals 303 and 304, and has a primary side and a
The next side is electrically isolated and only differential signals are passed between them, so common mode signals are removed. It is connected to the communication partner station via a transmission line (5). The decoding circuit (3) has differential input terminals 501, 5O2 and an output terminal 5()3,
The bipolar code inputted from the differential input terminals 501 and 502 is decoded into an NR2 code, and the output is sent to the output terminal 5.
Obtained from 03.

The microcomputer LSI100NRZI code output terminal 101 is connected to the input terminal 201 of the encoding circuit (2), and the differential output terminals 202 and 203 of the encoding circuit (2) are the primary side terminals 301 and 302 of the pulse transformer (4).
2 are connected. Secondary terminals 303 and 304 of the pulse transformer (4) are connected to the transmission line (5). The primary side terminals 301 and 302 of the pulse transformer (4) are also the differential input terminals 501 and 502 of the decoding circuit (3).
It is also connected to the output terminal 50 of the decoding circuit (3).
3 is connected to the NRZI code input terminal 102 of the microcomputer LSI (1).

The operation of the signal transmitter of the present invention will be explained.

First, the NRZI code output from the microcomputer LSI (11) that directly inputs and outputs the NRZI code is converted into a bipolar code by the encoding circuit (2), drives the pulse transformer (4), and is output to the transmission line (5). Ru.

Next, the bipolar code output on the transmission line (5) is input to the decoding circuit (3) through the pulse transformer (4), where it is converted into an NRZI code and sent to the microcomputer LS.
It is input to I(1).

As described above, according to the present invention, it becomes possible to digitally transmit the NRZI code via the microcomputer LSI (1) that directly inputs and outputs it or via a transformer-insulated transmission line.

Embodiment Fig. 2 is a circuit diagram of an embodiment of the signal transmitter of the present invention, and Fig. 3 is a circuit diagram of an embodiment of the signal transmitter of the present invention.
FIG. 4 shows operation timing diagrams of the main parts.

In the figure, the same symbols as in Fig. 1 indicate the same circuits, the same parts,
shows.

The configuration of each circuit of the present invention will be explained.

The encoding circuit (2) includes a shift register at+, a clock generator, an exclusive OR gate circuit, and an inverting gate circuit c.
24, :r, pulled up 6 children. r -K flip-flop (c), negative AND gate circuit (to), @, transistor for driving pulse transformer (to), 0! It consists of a circuit consisting of J. The pulse transformer (4) is provided with a center point tap terminal 305 on the negative winding for pull-up. In addition, the decoding f[Z circuit (3) is a voltage comparator (51),
(52), constant voltage source that generates electricity 8EE (53),
Exclusive OR gate circuit (54)1. I pulled up TKJko. It consists of a circuit consisting of 70 flip tabs (55) on the T- side.

The input terminal 201 of the encoding circuit (2) connected to the output terminal 1o1 of the microcomputer LSI (1) is condensed to the shift register Qυ and the exclusive OR gate circuit,
The output terminal of the shift register Qυ is connected to the exclusive OR gate, and the clock generator is connected to the shift register (2υ).

The output terminal of the exclusive OR gate @ is connected to the flip-flop (G) and the inverting gate circuit 241 at T-, and the Q, Q terminal of the output of the flip-flop circuit (C) and the inverting gate circuit ( Connect the output terminals of 2) to the negative AND gate circuit (T) and @, respectively, and connect the output of the negative AND gate circuit to the base of the transistor (to) and the base of the device, and connect the emitters to each other and ground. do. Differential output terminal 20 of both collectors
2, 203 is the negative side terminal 30 of the pulse transformer (4)
1, 302, and pulls up the center tap terminal 305 of the negative winding.

On the other hand, the differential output terminal 202 of the transistor (goods) and the negative side terminal 3 of the pulse transformer (4) are connected to the negative input terminals 502 and 501 of the electronic comparators (51) and (52), respectively.
01, and the differential output terminal 203 of the transistor (to) and the negative side terminal 302 of the pulse transformer (4).
Connect the connection point with the power supply (
53).

The output terminals of the voltage comparators (51) and (52) are connected to the input terminal of the exclusive OR gate circuit (54), and the output terminal is connected to the input terminal of the exclusive OR gate circuit (54).
Connect the flip-flop (55) to T-, and connect the output terminal 1
The output terminal 503 of the decoding circuit (3) is connected to the input terminal 102 of the microcomputer I, S (1).

The operation of one embodiment of the signal transmitter of the present invention will be explained.

In FIG. 2, when the output of the NRZI code output terminal 101 of the microcomputer LSI (1) is as shown in FIG. Figure 3 (b
) signal.

When the communication speed is I bits per second and the duty ratio of the pulses forming the bipolar code is 50%, the value of T is set to 1/2x second. The signal shown in FIG. 3(&)(b) is input to the exclusive OR gate circuit (c) to obtain the output shown in FIG. 3(Q). I pulled up the terminal on J. The flip-flop (c) at r- is triggered at the falling edge of the human input signal in Fig. 3 (Q) and the output is inverted, so the output is inverted, so the output is inverted.
The positive output shown in d) and the inverted output shown in FIG. 3(e) are obtained. The signal of FIG. 3(0) is also input to the inverting gate circuit (2) to obtain the inverted output of FIG. 3(f).

Figure 3 (dL(f) signal is a negative logic gate circuit (to)
The output shown in Figure 3 (g) is obtained, and the output shown in Figure 3 (e) is obtained.
), (f) are input to the negative OR gate circuit (3) to obtain the output shown in FIG. 3(h). Transistor (to)
is turned on in response to the pulse of the signal shown in FIG. 3(g), and a current flows from the center tap terminal 305 of the pulse transformer (4) to one primary side terminal 301, and the transistor (to)
flows a current from the ONL center tap terminal 305 to the other primary side terminal 302 in response to the pulse of the signal shown in FIG. 3(h), so the drive signal input to the primary side of the pulse transformer is ultimately It becomes a bipolar code as shown in Figure 3 (1),
Similarly, the signal between the secondary side terminals 303 and 304 of the pulse transformer becomes as shown in FIG. 3(1), and this is also a signal on the transmission line.

On the other hand, if the signal on the transmission line (5) is the bipolar code shown in Fig. 4 (j), this signal is transmitted through the pulse transformer (
4) through the input terminal 501゜50 of the decoding circuit (3)
A differential signal as shown in FIG. 4(j) is applied between the two terminals. In addition, since the center tap terminal 305 is pull-amplified, the input terminal 5
An in-phase component of V is given between 01 and 502, and the voltage waveform of the input terminal 501 is as shown in FIG.
The voltage waveform of is shown in FIG. 4 (1). Here, the voltage comparator (
When the voltage E generated by the constant voltage source (53) connected to the positive input terminal of (52) is greater than O and less than 7, the output of one voltage comparator (51) is as shown in FIG. n
), and the output of the other voltage comparator (52) is as shown in FIG. 4(n). These signals in FIG. 4 (, n) and (→) are input to the exclusive OR gate circuit (54), and the signals in FIG. 4 (0) are input.
Get the output of le. Flip-flop (55) is the fourth
A trigger is activated at the rising edge of the signal shown in FIG. 4 (0), the output is reversed, and the signal shown in FIG. 4 (p) is output. This figure 4 (
1)) The bipolar code in Fig. 4 (j) is NR.
It is decoded into ZI code and is sent to microcomputer L.
It is input manually to the NRZI code input terminal 102 of S I ftl.

As described above, according to the embodiment of the present invention, the NRZ code output from the microcomputer TJSI is converted into a bipolar code and sent out to a transformer-insulated transmission line, and the bipolar code on the transformer-insulated transmission line is The code is converted into an NRZI code and sent to the microcomputer LSi.

Note that the delay circuit constituted by the shift register (2I1) and the clock generator 0 of the encoding circuit (2) according to the embodiment of the present invention can also be realized by a CRM path, a delay element, or the like.

Effects of the Invention According to the configuration of the present invention, the microcomputer TJS directly inputs and outputs NR and Z codes.
The ZI code is converted into a bipolar code by the encoding circuit, which drives a pulse transformer and sent out to the transmission line, and the bipolar code on the transmission line is taken in by the decoding circuit via the pulse transformer and converted to the NRZI code. It will be input to the microcomputer LS King. As a result, the 71' black combination L S I
Due to the transformer insulation method, digital communication can be performed using the microcomputer LSI and an uninterrupted transmission line, and the common mode noise C1 is strong, there is no influence from the ground potential, and long-distance, high-speed digital transmission is possible. etc., etc., etc.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a circuit of an embodiment of the signal transmitter of the present invention, Fig. 2 is a circuit diagram of an embodiment of the block circuit of the invention, and Figs. The timing diagram of the block circuit operation is shown below. 1: Microcomputer] + [Coni 2: i-encoding circuit 3: decoding circuit 4: pulse transformer 5:
Transmission line 21: Shift register 22: Clock generator 23154: Exclusive OR gate 24: Inverting gate circuit 25.558 J-K 7 lip flop 96, 277 Negative AND gate circuit 28.29:)
Langista → 1 can of mango 9 Figure 3 Figure 4

Claims (1)

[Claims] The NRZ output from the microcomputer LSI is connected between the transmission line and the microcomputer LSI that directly inputs and outputs NRZI (non-return-to-zero-inpart) codes.
an encoding circuit that converts an I code into a bipolar code and outputs it, electrically insulating the encoding circuit and the transmission line, and outputting only the differential component of the output signal of the encoding circuit to the transmission line. Pulse transformers are connected in series, and a point where the two output terminals of the encoding circuit and the winding terminal of the primary winding of the pulse transformer are connected is connected to a decoding circuit, and the bipolar code is converted to an NRZI code. A signal transmitter configured to input the output to the microcomputer LSI.