JPH0832631A - Non-data part detection device for serial communication - Google Patents

Abstract

PURPOSE:To detect the non-data part of a serial data signal generated based on a transmission clock signal. CONSTITUTION:An edge detection circuit 23a detects the edge of the serial data signal from an inputted Manchester code. A counter circuit 23b outputs a clock signal for serial data signal reproduction. A phase comparison circuit 23c outputs an equality signal when edge detection timing by the edge detection circuit 23a is equal to the output timing of the clock signal from the counter circuit 23b. A non-data part judgement circuit 24 outputs a non-data detection signal and gives the notice of the invalidity of the serial data signal when an equality signal from the phase comparison circuit 23c is not inputted for three consecutive times at the output timing of the clock signal from the counter circuit 23b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial communication non-data section detecting device for detecting a non-data section based on an input of a serial data signal.

[0002]

2. Description of the Related Art Conventionally, when transmitting serial data, the serial data having a data start portion added to the head is modulated into a serial data signal and transmitted. Then, when the serial data obtained by demodulating the serial data signal is the data start portion, the receiving side inputs the subsequent serial data as true data.

As a method of demodulating the serial data signal and detecting the data start portion as described above, for example, a high level data link control procedure (HDLC) (JIS)
X5104). In this high-level data link control procedure, for example, “1” is continuously transmitted in synchronization with the transmission clock signal during non-communication, and when serial data is transmitted, the serial start data is added to the serial data added at the beginning. The data signal is modulated and transmitted. Therefore, on the receiving side, when the serial data obtained by demodulating the input serial data signal changes from the data pattern during non-communication, it is determined whether or not it is the data start portion. The subsequent serial data is input as data.

By the way, when, for example, electrical noise occurs during non-communication, the transmission timing of the serial data signal deviates from the transmission clock signal and the data pattern during non-communication is different from the data start portion in the non-data portion. It can change. In such a case, when the serial data changes, the receiving side determines whether the changed pattern is the data start part or the non-data part, and when it is the non-data part, invalidates the serial data to be input subsequently. I am trying to change. Therefore, serial data can be reliably communicated regardless of the influence of electrical noise.

[0005]

However, in the above-mentioned conventional example, when the serial data obtained by demodulating the input serial data signal changes from the data pattern during non-communication, the data pattern is not Since it is a configuration for determining whether each is a data part or not, there is a problem that the configuration for determining is complicated and processing time is required. In particular, in the case of a small-scale communication system that alternately transmits and receives with an unspecified number of communication partners in a short time, there are disadvantages that the cost is great and the communication efficiency is extremely low.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a non-data part detecting device for serial communication capable of detecting a non-data part of input serial data with a simple structure. It is in.

[0007]

A non-data part detecting device for serial communication according to the present invention comprises a clock signal reproducing circuit for reproducing a clock signal based on an input of a serial data signal generated based on a transmission clock signal. A reproduction determination circuit for determining whether or not the reproduction of the serial data signal based on the clock signal from the clock signal reproduction circuit is provided, and when the determination by the reproduction determination circuit is no for a predetermined number of times continuously, The serial data signal is provided with a non-data part determination circuit which determines that the serial data signal is invalid.

In the above structure, the non-data portion judging circuit is constituted so as to judge that the inputted serial data signal is invalid when the judgment by the reproducing judging circuit is no succession three times in a row. May be.

[0009]

In the case of the non-data part detecting device for serial communication according to claim 1, the clock signal reproducing circuit is:
The transmission clock signal is reproduced based on the input serial data signal. Then, the reproduction determination circuit determines whether reproduction of the serial data signal based on the reproduced clock signal is appropriate. Now, if the serial data signal is affected by electrical noise, for example, reproduction of the serial data signal based on the clock signal becomes impossible. In such a case, the non-data part determination circuit determines that the input serial data signal is invalid because the determination by the reproduction determination circuit is no more than a predetermined number of times in succession. As a result, a wrong serial data signal will not be input.

In the non-data section detecting device for serial communication according to the second aspect, the serial data signal is valid when the determination of the serial data signal based on the clock signal fails once or twice in succession. Most likely there is. Therefore, the data determination circuit determines that the input serial data signal is invalid when the determination by the reproduction determination circuit is no succession three times in a row. It does not inadvertently invalidate the data signal.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a toll road toll collection system will be described below. FIG. 2 shows the appearance of the gate provided on the toll road. In FIG. 2, the toll road 1 is provided with a plurality of lanes, and a gate 2 is installed so as to straddle the toll road 1. The gate 2 is provided with an antenna unit 3 as a plurality of fixed stations, and a microwave communication area from the antenna unit 3 (a region indicated by a chain double-dashed line in the figure) is set for each lane. There is. In this case, each communication area is set so as to cross the toll road and is set so that a part of the adjacent communication areas overlap each other. This is to enable communication even when the vehicle 4 as a moving body traveling on the toll road 1 travels across the lane.

FIG. 3 schematically shows the overall structure. In FIG. 3, each antenna unit 3 is connected to the controller 5. The controller 5 controls transmission / reception of the antenna unit 3 and exchanges communication data with the host computer 6.

The vehicle 4 is equipped with a tag unit 7 (see FIG. 4) as a mobile station so that the tag unit 7 and the antenna unit 3 communicate with each other when the vehicle 4 enters the communication area. It has become.

FIG. 4 schematically shows the entire electrical structure. That is, in the antenna unit 3, the modulation circuit 8 modulates the oscillation signal of the predetermined frequency given from the oscillator 9 with the interrogation signal given from the controller 5, and outputs it to the antenna 11 via the circulator 10. The mixer 12 modulates the reception signal input from the antenna 11 through the circulator 10 by combining it with the carrier signal from the oscillator 9, and supplies the modulated signal to the reception circuit 13. The receiving circuit 13 obtains a response signal corresponding to the interrogation signal by demodulating the combined signal supplied from the mixer 12, and
The response signal is output to the controller 5.

In the controller 5, the unit control circuit 14 is connected to the modulation circuit 8 and the reception circuit 13 of each antenna unit 3, outputs the interrogation signal to the modulation circuit 8 at a predetermined timing, and outputs the interrogation signal from the reception circuit 13. It is designed to input a response signal. The unit control circuit 14 is also connected to the host computer 6 via the interface circuit 15.

Here, the unit control circuit 14 is integrally formed with a non-data part detecting device 16, and the non-data part detecting device 16 detects the non-data part of the response signal input from the antenna unit 3. I have to.

On the other hand, in the tag unit 7, when the control circuit 17 inputs the inquiry signal received from the antenna 19 through the receiving circuit 18, the identification code, the paid fee, etc. stored in the data memory 20 according to the inquiry signal. Is output to the antenna 19 through the transmission circuit 21 as a response signal. Then, the battery 22 supplies power to each circuit forming the tag unit 7.

The control circuit 17 is integrally formed with a non-data part detecting device 16. The non-data part detecting device 16 detects the non-data part of the interrogation signal input from the receiving circuit 17. ing.

FIG. 1 shows a non-data section detecting device 16 which is integrally formed with the unit control circuit 14 of the controller 5 and the tag unit 7. In this FIG.
The non-data part detection device 16 is mainly composed of the digital PLL circuit 23. This digital PLL circuit 23
Is composed of an edge detection circuit 23a, a counter circuit 23b, and a phase comparison circuit 23c. The edge detection circuit 23a inputs a serial data signal composed of Manchester code, for example, and outputs an edge detection signal to the phase comparison circuit 23c when an edge of the input serial data signal is detected. The counter circuit 23b is
A clock signal is output every time a clock having a predetermined cycle is counted a predetermined number of times. The phase comparison circuit 23c determines whether or not the phases of the two signals match with each other based on the edge detection signal from the edge detection circuit 23a and the clock signal from the counter circuit 23b, and both of them match within a predetermined allowable range. If so, the coincidence signal is output and a correction signal for correcting the deviation amount is output to the counter circuit 23b.

Here, the counter circuit 23b corrects the output timing of the clock signal based on the correction signal from the phase comparison circuit 23c so as to match the output timing of the edge detection signal from the edge detection circuit 23a. Therefore, when the output timing of the clock signal from the counter circuit 23b deviates from the regular timing, the output timing is automatically corrected to the regular timing.

The non-data part determination circuit 24 is a digital PL.
A clock signal and a coincidence signal are inputted from the L circuit 23, and a non-data part detection signal is outputted when the coincidence signal is not inputted three times in succession at the input timing of the clock signal. There is. In this case, the unit control circuit 14 of the controller 5 and the control circuit 17 of the tag unit 7 invalidate the input serial data signal when the non-data part detection signal is input from the non-data part detection device 16. Has become.

Next, the operation of the above configuration will be described. The unit control circuit 14 of the controller 5 converts the interrogation signal from the Manchester code into a serial data signal and outputs the interrogation signal to each antenna unit 3 in a predetermined cycle. Then, the modulation circuit 8 of the antenna unit 3 modulates the carrier signal supplied from the oscillator 9 with the serial data signal composed of the Manchester code supplied from the controller 5, and transmits from the antenna 11 toward each communication area.

In this case, each antenna unit 3 is not modulated by the modulation circuit 8 while the interrogation signal is not given from the host computer 6, so that the carrier signal from the oscillator 9 is not modulated. It is transmitted from the antenna 11 as it is into the corresponding communication area. Then, when the antenna unit 3 is activated, the host computer 6 transmits an interrogation signal as a carrier signal.

Now, when the vehicle 4 has not entered the communication area, the antenna unit 3 does not communicate with the tag unit 7 mounted on the vehicle 4. Therefore, the unit control circuit 14 of the controller 5 outputs the interrogation signal to the next antenna unit 3 after a predetermined time elapses, so that the antenna unit 3 operates in a time division manner.

When the vehicle 4 enters the communication area, the tag unit 7 receives the inquiry signal transmitted from the antenna unit 3 and transmits a response signal, so that the communication between the antenna unit 3 and the tag unit 7 is performed. Is done.

The communication between the antenna unit 3 and the tag unit 7 as described above is performed as follows. That is, the host computer 6 continues to transmit the serial data signal composed of the Manchester code indicating "1" to the predetermined antenna unit 3 in the non-communication state.

As a result, during non-communication, the antenna unit 3 transmits a serial data signal consisting of Manchester code indicating "1", so that the non-data portion detecting device 16 integrated with the control circuit 17 of the tag unit 7 is provided.
Inputs a serial data signal composed of Manchester code received by the antenna 19.

At this time, the edge detection circuit 23a of the non-data part detection device 16 outputs an edge detection signal to the phase comparison circuit 23c when the edge of the input serial data signal composed of the Manchester code is detected. As a result, when the edge of the serial data signal composed of the Manchester code is within a predetermined deviation amount from the output timing of the clock signal from the counter circuit 23b, the phase comparison circuit 23c outputs the coincidence signal as shown in FIG. Judgment circuit 2
4 and the correction signal indicating the shift amount are output to the counter circuit 23b, so that the output timing of the clock signal from the counter circuit 23b can be matched with the edge of the serial data signal composed of the Manchester code. In this case, when the serial data signal based on the clock signal can be reproduced, the non-data part detection device 16 does not output the non-data part detection signal. Therefore, the control circuit 17 of the tag unit 7 uses the Manchester code serial data. The signal can be regenerated based on the clock signal from the non-data part detection device 16.

When the communication timing comes, the antenna unit 3 modulates the serial data (inquiry signal) having the data start portion added to the head thereof into a serial data signal and transmits the serial data signal.

Now, the control circuit 17 of the tag unit 7 is
When the data start portion is detected by demodulating the serial data signal including the Manchester code received from the antenna unit 3 into serial data, the inquiry signal following the data start portion is input and the response signal corresponding to the inquiry signal is input. Is converted into a serial data signal composed of Manchester code and output to the transmission circuit 21. As a result, the carrier signal transmitted from the antenna unit 3 is modulated by the response signal and returned.

On the other hand, since the antenna unit 3 receives the serial data signal (response signal) composed of the Manchester code transmitted from the tag unit 7, the response signal is demodulated by the receiving circuit 13 and sent to the controller 5. In this case, when the serial data signal can be reproduced based on the clock signal, the non-data part detection device 1
Since the non-data part detection signal is not output from 6, the unit control circuit 14 of the controller 5 outputs the serial data signal composed of the Manchester code to the non-data part detection device 16
A response signal can be obtained by reproducing based on the clock signal from.

In the communication as described above, the identification code set in the tag unit 7 is confirmed, and when the identification code is legitimate, only the paid toll stored in the tag unit 7 is paid. Fees will be collected by reducing the amount.

When the transmission signal is affected by electrical noise during non-communication, the edge of the serial data signal indicating non-communication may be largely deviated from the normal timing. In such a case, the non-data part detection device 16
Attempts to invalidate the serial data signal input as follows.

That is, in the non-data part detecting device 16,
Since the phase comparison circuit 23c does not output the coincidence signal when the edge detection signal from the edge detection circuit 23a and the output timing of the clock signal from the counter circuit 23b are significantly deviated, the non-data part determination circuit 24 is provided.
When the coincidence signal from the phase comparison circuit 23c is not input three times in succession at the output timing of the clock signal from the counter circuit 23b, it is determined to be the non-data portion and the non-data portion detection signal is output. To do. As a result, the unit control circuit 14 of the controller 5 or the control circuit 17 of the tag unit 7 determines that the input serial data signal is not valid and invalidates the input serial data signal.

According to the above configuration, the non-data part detecting device 16 has the edge of the input serial data signal composed of the Manchester code and the output timing of the clock signal reproduced from the serial data signal, which are consecutive three times. When they do not match, the input serial data signal is judged to be invalid and is notified so that data link control is performed to detect the non-data part of the input serial data signal. Unlike the conventional example using the procedure, the cost can be significantly reduced and the processing time can be significantly reduced. In this case, the conventional digital PLL circuit 2
Since it can be implemented only by adding the non-data part determination circuit 24 to 3, the circuit configuration does not become complicated.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows. FM0 and FM1 may be adopted as the standard of the serial data signal. The information of the conveyed object may be transmitted by communication with the tag unit mounted on the automatic guided vehicle. The present invention may be applied to an automatic ticket gate in a doorway of a station or a ski resort, and the validity of traffic may be determined by communication with a tag unit carried by a person.

[Brief description of drawings]

FIG. 1 is a block diagram showing a non-data part detection device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a gate straddling a road.

FIG. 3 is a schematic diagram showing the overall configuration.

FIG. 4 is a schematic diagram showing the overall electrical configuration.

FIG. 5 is a diagram showing a serial data signal composed of Manchester code.

FIG. 6 is a diagram corresponding to FIG. 5 showing abnormal communication.

[Explanation of symbols]

16 is a non-data part detection device, 23 is a digital PLL circuit, 23a is an edge detection circuit (clock signal reproduction circuit), 23b is a counter circuit (clock signal reproduction circuit), 23c is a phase comparison circuit (reproduction determination circuit), and 24 is It is a non-data part determination circuit.

Claims (2)

[Claims] 1. A clock signal regenerating circuit for regenerating a clock signal based on an input of a serial data signal generated based on a transmission clock signal, and a serial data signal based on the clock signal from the clock signal regenerating circuit. A reproduction determination circuit that determines whether reproduction is appropriate, and a non-data section determination circuit that determines that the input serial data signal is invalid when the determination by the reproduction determination circuit is no for a predetermined number of consecutive times A serial communication non-data part detection device characterized by the above. 2. The non-data section determination circuit is configured to determine that the input serial data signal is invalid when the determination by the reproduction determination circuit is no succession three times in a row. The non-data part detecting device for serial communication according to claim 1, wherein