KR19990021022A - Device and method for automatic detection of communication speed in serial communication - Google Patents

Abstract

The present invention relates to an apparatus and method for automatically detecting a communication speed in serial (RS-232C) communication, and automatically detects a transmission speed of data according to time at both terminals communicating with RS-232C, and sets a suitable communication speed thereto. An object of the present invention is to provide an apparatus and method for automatically detecting a communication speed in RS-232C communication that enables efficient communication.

According to the apparatus and method for automatically detecting the communication speed in RS-232C communication according to the present invention, unlike the conventional method of setting the same communication speed between the personal computer and the application device before starting data communication using software or a slide switch, etc. By determining the inactive state through the received signal and automatically determining the communication speed by detecting the length of the start bit received thereafter, it is possible to efficiently change the communication speed according to the variable amount of transmission data to enable efficient memory use. It can improve the price competitiveness and the satisfaction of serial (RS-232C) communication users.

Description

Device and method for automatic detection of communication speed in serial communication

The present invention relates to an apparatus and method for automatically detecting a communication speed in serial communication, and automatically detects a transmission speed of data according to time at both terminals communicating with RS-232C, and sets an appropriate communication speed to enable efficient communication. An object of the present invention is to provide an apparatus and method for automatically detecting a communication speed in serial communication.

As the demand for personal computers increases explosively, the demand for communication between each personal computer and a large computer is expanding. In particular, due to the advantages of low capital, easy access to external I / O devices, advancement to a local area network (LAN), and communication speed and wide degree of freedom of data, network configuration through communication between personal computers is difficult. It is commonly used to improve resource sharing and reliability. However, for the network configuration, in addition to the format of data to be exchanged, information about control information and timing information depending on hardware must be set in advance, which is called a protocol.

The protocol can be largely divided into a serial communication method and a parallel communication method. The serial communication method is a communication method for transmitting data applied in parallel from the main bus to the outside using a single data signal line, and applying data input in series from the outside to the main bus in parallel. RS-232C, RS- 422, RS-423 and X.21 have been adopted as standards. In addition, the parallel communication method is a communication method for transmitting or receiving data using a plurality of data signal lines, and the data communication speed increases in proportion to the number of data signal lines compared to the serial communication method, but the price increases. Have

Meanwhile, the serial communication method is classified into a synchronous communication method and an asynchronous communication method according to a method of securing synchronization required for both terminals communicating data, and the former transfers a synchronization signal between both terminals. In the latter method, the start bit and the stop bit are used for data transmission.

Hereinafter, RS-232C, which is an asynchronous serial communication device that is most commonly used in personal computers, will be described with reference to FIG. 1.

The RS-232C asynchronous serial communication apparatus according to the prior art receives an address, an enable signal and an input / output command signal RD / WR from the central processing unit 1 inside the computer as shown in FIG. By using an address decoder 2 for outputting a control signal for controlling, a clock generator 4 for generating and outputting a clock to be used for data transmission, and a clock signal input from the clock generator 4 A communication speed control unit 5 converts and outputs a clock suitable for a set communication speed and a control signal from the address decoder 2, and receives a clock signal from the communication speed control unit 5 to transmit and receive a signal. A parallel-to-serial conversion unit for outputting a control signal indicating a and converting the data inputted in parallel from the central processing unit 1 into a serial format suitable for a prescribed format ( 6) an interrupt / enable control unit 3 which receives the transmission and reception status signals and the synchronization control signal from the parallel-serial conversion unit 6 and outputs an interrupt to the central processing unit 1, and the parallel- It is comprised by the level converter 7 which converts the serial data input from the serial converter 6 into the signal system used by an external interface.

Hereinafter, the operation of RS-232C, an asynchronous serial communication device, will be described.

The central processing unit 1 controls the RS-232C interface and transfers data to be transmitted to the outside via a data bus. The parallel-to-serial converter 6 receives data in parallel from the central processing unit 1 via a bus and converts the data into serial data for serial communication, and transmits data according to the data format shown in FIG. 2. Will be constructed. The signal configured as described above is a digital signal represented by '0' or '1' as shown in FIG. 3 and is a TTL level signal having 0 Volts or 5 Volts. The level converter 7 receiving the TTL level signal converts a digital signal of '0' and '1' having a TTL level into a signal of + V volts and -V volts for transmission via a cable. Here, V volt is a value existing within a level of 3 volts or more and 15 volts or less.

However, in the conventional asynchronous serial communication apparatus configured as described above, the same communication speed must be set between the personal computer and the application device before starting data communication using software or a slide switch. In addition, since the amount of data to be transmitted varies with time, a method of presetting a communication speed as described above should use excessive memory and is not preferable for efficient communication because it does not actively operate over time. not.

Accordingly, an object of the present invention is to solve such a problem, it is possible to efficiently communicate by detecting the transmission speed of the data in time to both terminals to communicate with RS-232C by setting the appropriate communication speed accordingly The present invention provides an apparatus and method for automatically detecting a communication speed in serial communication.

1 is a structural diagram of a serial data conversion device according to the prior art,

2 is a block diagram of an automatic communication speed detection apparatus in RS-232C communication according to the present invention;

3 is a data format of RS-232C communication;

4 is a flowchart illustrating an operation of an inactivity detection unit according to the present invention;

5 is a flowchart illustrating an operation of a communication speed determining unit according to the present invention.

<Description of the code | symbol about the principal part of drawing>

1: central control unit 2: address decoding unit

3: Interrupt / Enable Controller 4: Clock Generator

5: communication speed control 6: parallel-serial converter

7: level converting unit 10: inactivity detecting unit

11: inactive start determining unit 12: inactive counter

13: counter comparing unit 20: communication speed determining unit

21: Start signal determination section 22: Start counter section

23: communication speed detection unit 30: communication speed setting unit

Apparatus and method for automatically detecting a communication speed in serial communication according to the present invention for achieving the above object is different from the conventional method of setting the communication speed of the same terminal in advance, through the received signal to determine the inactive state, and then received The communication speed can be automatically determined by detecting the length of the start bit.

In the serial communication according to the present invention, as shown in FIG. 2, the automatic communication speed detecting apparatus includes an inactivity detecting unit 10 that detects an inactive state by receiving data received from the outside and generates an active / inactive signal, and the inactive. A communication speed determining unit 20 enabled by an active / inactive signal from the detector 10 and measuring a length of a start bit of data received from the outside to output a communication speed, and the communication speed determining unit 20 And a communication speed setting section 30 for changing a setting value using a communication speed input from the same and generating a clock equal to this communication speed.

The inactivity detection unit 10 receives an incoming data from the outside and detects a '1' level indicating a state of inactivity, and the inactivity start determination unit 11 output signal indicating the start of inactivity. It is enabled by the, and the counting value output from the inactive counter 12 and the inactive counter 12 for performing the counting using the clock output from the clock generator 4 of FIG. And a counter comparator 13 for outputting a signal indicating an inactive state at the same time as the value.

The communication speed determination unit 20 receives a signal indicating that the state of inactivity is output from the inactivity detection unit 10 and determines a start signal for generating a signal indicating the start of a start signal by receiving data received from the outside. A start counter 22 that is enabled by the unit 21, a signal applied from the start signal determiner 21, and counts using a clock of the clock generator 4, and the start counter unit And a communication speed detection unit 23 for detecting a communication speed using the counting value output from the 22 and outputting the communication speed to the communication speed setting unit 30.

Hereinafter, the operation of the automatic communication speed detection apparatus in RS-232C communication according to the present invention configured as described above will be described in detail with reference to FIGS.

In the RS-232C communication, the format of data includes a start bit 40 indicating the start of one data transmission unit, a data bit 50 to be transmitted, and an error in transmission data, as shown in FIG. 3. Parity bit (parity bit) (60) and a stop bit (70) indicating the completion of one data transmission unit.

First, the start bit 40 is information indicating the start of one data transmission unit when data is transmitted after the inactive state is completed, and has a '0' level to distinguish it from an inactive state having a '1' level. Subsequently, data to be transmitted is often transmitted in units of 8 bits, and in the present invention, in order to distinguish the start bit 40 from the first bit, the first bit of the 8 data bits is changed to data having a '1' level. Use the data start code. The parity bit 60 is combined with the data bit 50 consisting of 8 bits so that the '1' level is odd or even, thereby being used for received data error detection. Finally, the stop bit 70 used is composed of 1 bit or 2 bits, indicating completion of one data transmission unit, and having a '1' level.

The inactivity start determination unit 11 receives the data received in the data format configured as described above and checks whether a '1' level indicating an inactivity state is started. In the inactivity counter determination unit 12, the inactivity start determination unit ( It is enabled by '1' level detected in 11) and starts counting. Subsequently, the counter comparator 13 receives the counted value and compares the counted value with a predetermined time indicating an inactive state to determine whether the '1' level is due to an inactive state or an arbitrary data to determine an inactive state. . Here, the predetermined time indicating the inactive state may be set to the time required to transmit one data transmission unit at the lowest communication speed supported by RS-232C, and may be changed by a clock input from an external source. to be.

Since the signal input after the inactive state by the data format is the start signal 40, the start signal determination unit 21 is enabled by the signal output from the inactivity detection unit 10, and ' The start signal is detected by detecting the 0 'level. The start counter unit 22 starts counting from the start point of the start bit, stops counting when the start bit is completed, and outputs a counting value to the communication speed detector 23. The communication speed detector 23 receiving the counting value detects a communication speed corresponding to the counting value and outputs the communication speed to the communication speed setting unit 30.

The operation of the automatic communication speed detecting apparatus in RS-232C communication according to the present invention is shown systematically in the flowcharts of FIGS. 4 and 5.

Hereinafter, a method of automatically detecting a communication speed in RS-232C communication according to the present invention will be described.

In the RS-232C communication according to the present invention, the automatic communication speed detection method includes an inactive detection step of detecting an inactive state by receiving data received from the outside and generating an active and inactive signal, and from the inactive detection step to an active and inactive signal. Enabled by the communication speed determination step of outputting the communication speed by measuring the length of the start bit of the data received from the outside, and by changing the setting value using the communication speed input from the communication speed determination step, the same clock It consists of a communication speed setting step of generating.

The inactivity detection step is enabled by an inactivity start determination step of detecting a '1' level indicating that an inactive state is received by receiving data received from the outside, and enabled by an output signal indicating the start of inactivity in the inactivity start determination step. An inactive counting step of performing counting using an input clock, and a counter comparison step of outputting a signal indicating that the inactive state when the counting value output from the inactive counting step becomes equal to the embedded value.

The communication speed determining step may include: a start signal determining step of receiving a signal indicating an inactive state output from the inactive detection step and receiving data received from an external source and generating a signal indicating the start of a start signal; The communication speed setting step is performed by detecting a communication speed using a counting value which is enabled by a signal applied from a signal determination step and counts using a clock input from an external source, and a counting value output from the start counting step. It consists of a communication speed detection step to output.

Hereinafter, a procedure of an automatic communication speed detection method in RS-232C communication according to the present invention configured as described above will be described in detail with reference to FIGS. 3 to 5.

The inactivity start determination step receives the data received in the data format configured as described above and checks whether a '1' level indicating an inactive state is started; in the inactivity counting step, a '1' level detected in the inactivity start determination step Enabled by to perform counting. Subsequently, the counter comparison step receives the counted value and compares the counted value with a predetermined value indicating the inactive state to determine whether the '1' level is due to the inactive state. Here, the constant value indicating the inactive state is the same as described above.

Since the signal input after the inactive state by the data format is the start signal 40, the start signal determination step is enabled by the signal output in the inactive detection step, and detects the '0' level of the received signal. To detect the start signal. In the start counting step, counting starts from a time point at which the start bit 40 starts, counting stops at a time point when the start bit 40 is completed, and outputs a counting value to the communication speed detection step. In the communication speed detecting step of receiving the counting value, a communication speed corresponding to the counting value is detected and outputted to the communication speed setting step.

According to the apparatus and method for automatically detecting the communication speed in serial (RS-232C) communication according to the present invention described above, the communication speed of the data is automatically detected by both terminals communicating in the serial (RS-232C) and suitable for this. In order to solve the inconvenience, it is necessary to set the same communication speed between the personal computer and the application device before starting data communication using software or slide switch. It can be changed, enabling efficient memory usage, improving price competitiveness and user satisfaction of RS-232C communication.

Claims (7)

An apparatus for automatically detecting a communication speed in serial communication, An inactivity detector configured to receive data received from the outside and detect an inactive state to generate an active / inactive signal; A communication speed determining unit which is enabled by an active / inactive signal from the inactive detection unit and measures a length of a start bit of data received from the outside to output a communication speed; And a communication speed setting unit for changing a setting value using a communication speed input from the communication speed determining unit to generate a clock equal to the communication speed. The method of claim 1, wherein the inactivity detection unit An inactivity start determination unit which receives the received data from the outside and detects a '1' level indicating an inactivity state; An inactivity counter unit enabled by the output signal indicating the start of inactivity in the inactivity start determination unit, and performing counting using a clock output from the clock generator; And a counter comparator for outputting a signal indicating that the signal is inactive when the counted value output from the inactive counter becomes equal to the embedded value. The method of claim 1, wherein the communication speed determination unit A start signal determination unit configured to receive a signal indicating an inactive state output from the inactivity detection unit and to receive data received from an external source and to generate a signal indicating the start of a start signal; A start counter unit enabled by a signal applied from the start signal determination unit and counting using a clock of the clock generation unit; And a communication speed detecting unit for detecting a communication speed by using a counting value output from the start counter unit and outputting the communication speed to the communication speed setting unit. An apparatus for automatically detecting a communication speed in RS-232C communication, And a data start encoding device for encoding the first bit of the data bits to be distinguished from the level of the start bit. In the method of automatically detecting the communication speed in serial communication, An inactivity detection step of detecting an inactive state by receiving data received from the outside and generating active and inactive signals; A communication speed determination step enabled by the inactivation and inactivation signals from the inactivity detection step, and measuring a length of a start bit of data received from the outside to output a communication speed; And a communication speed setting step of generating a same clock by changing a setting value using the communication speed input from the communication speed determining step. The method of claim 6, wherein the inactive detection step An inactivity start determination step of receiving the received data from the outside and detecting a level indicating an inactivity state; An inactive counting step that is enabled by an output signal indicating the start of the inactive in the inactive start determination step and performs counting using a clock input from the outside; And a counter comparing step of outputting a signal indicating that the counting value output from the inactive counting step is inactive when the counting value outputted from the inactive counting step becomes equal to a built-in value. The method of claim 5, wherein the determining of the communication speed A start signal determination step of receiving a signal indicating an inactive state output from the inactivity detection step and receiving data received from the outside and generating a signal indicating the start of a start signal; A start counting step enabled by a signal applied from the start signal determining step and counting using a clock input from an external device; And a communication speed detecting step of detecting a communication speed using the counting value output from the start counting step and outputting the communication speed setting step.