KR900006975B1 - Method of detecting data transmission speed in data terminal equipment - Google Patents

Abstract

The method for detecting the data transmission speed with some command input comprises steps; (a) initialising data I/O port; (b) transmitting the low width of start bit corresponding to A or a command to the MODEM; (c) determining the transmission speed of the A or a and setting start, data, no parity, and stop bits of the data format to buffer register; (d) checking and transmitting the data bit at serial receiving port; (e) storing the received character and setting the start, data even parity, and stop bits to the buffer resistor; (f) checking high state of the serial receiving port to check T or t; and (g) determining the data pattern for transmission speed corresponding transmission to stored A or a or T or t value.

Description

Automatic detection method of data transmission speed

Figure 1 illustrates a conventional data path selection embodiment.

2 is a circuit diagram according to the present invention.

3 is an automatic protection mode flow chart according to the present invention.

4 is a data mode flow chart according to the present invention.

5 is a transmission data format waveform diagram of the letter A or a according to the present invention.

6 is an A, T or a, t command combination table according to the present invention.

* Explanation of symbols for main parts of the drawings

10: RS-232C Concentrator 20: Micom

30: modem 40: DAA

The present invention relates to a method for detecting a transmission rate during data transmission in a connection between a modem and a personal computer (hereinafter referred to as a "PC"). In particular, the present invention can automatically detect a transmission speed when a predetermined command is sequentially inputted. The present invention relates to an automatic detection method of a data transmission rate.

In the conventional modem, the data transmission speed is detected by resetting the system according to the transmission mode after the system is reset, and when the key is pressed, the input key is interpreted and the transmission speed is determined accordingly. This has been handled by Mycom's software. The data path has been selected using a two input one output (2/1) multiplexer (MUX) as shown in FIG. 1, and each mode is the same as (1a)-(1d) in FIG. That is, (1a) is an automatic bow mode example, (1b) is a command mode, (1c) is a check mode, and (1d) is a data mode.

In the auto bow mode of (1a), the data bit transmitted from the terminal (DTE) connected to the RS-232C large connector (CE) is returned to the terminal (DTE) through the receiving terminal (Rx). Detect.

The command mode of (1b) returns the characters entered from the microcomputer (μ-com) through the RS-232C connector (CE) to the terminal (DTE) and the transmitter (Tx) of the RS-232C large decker (CE) to the microcomputer. In the meantime, the terminal DTE performs the command based on the character combination and sends a response.

In the check mode of (1c), the modem MODEM is used to detect the state of the received data (RxD) received when the modem attempts to connect with the other modem (MODEM), and the receive data (RxD) through the input port C7 of the microcomputer. The signal is detected.

The data mode of (1d) sends data sent from the terminal (DTE) or the microcomputer to the modem and simultaneously monitors the data from the microcomputer and monitors the data received by the modem to the terminal (DTE) or the microcomputer. send. Here, the reason why the microcomputer monitors the data transmitted to the modem is to check and execute when the user wants to switch from the data mode to the command mode. The reason the microcomputer monitors the data received from the modem. Is for checking whether the received data is a logic " 0 " for more than a predetermined time. If the modem has a long space disconnect and a logic “0” is received for a predetermined time or more, the modem is disconnected.

As described above, there is a problem in that the transmission speed is always known after resetting the system, and the system configuration itself is complicated because a separate multiplexer must be used when selecting a data path.

Accordingly, an object of the present invention is to provide a method for automatically detecting a data transmission speed simultaneously with a predetermined command input.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram according to the present invention, which is connected to a RS-232C connector 10 connected to a terminal (not shown) and the RS-232C connector 10 to match a transmission level of an RS-232C method. NAND gate 21 for receiving line receiving data at a voltage of ± 12 V, and the RS-232C connector 10 connected to the NAND gate 21 to transmit TTL level (5V). The controller 22 receives the command and the information transmitted / received through the inverter 22 and the NAND gate 21 and the inverter 22, and analyzes in advance by a program to generate a control signal for selecting a data path, and then, in the preset table. In comparison, the microcomputer 20 automatically determines the transmission speed, and modulates the digital information to be transmitted according to the transmission speed set by the microcom 20, outputs the analog signal, demodulates the received signal, and converts the received signal into a digital signal. 20) mouth on Is doedo reuk treatment is associated with a digital signal and Alas and modem 30 to the modem logs the signal, the antenna (Co) comprises a DAA (40) forming the matching of the data transmission and the modem 30.

3 is a flowchart of an auto baud mode according to the present invention, and FIG. 4 is a flowchart of a data mode according to the present invention.

5 is a waveform diagram of a data transmission format of "A" and "a" characters according to the present invention, and FIG. 6 is a table of A, T or a, t command combinations according to the present invention.

Therefore, a specific embodiment of the present invention will be described in detail with reference to FIGS. 2-6 again. When the output of the terminal or personal computer is passed through the inverter 22 which is a line driver through the RS-232C connector 10, It is driven and converted into a TTL level signal, which is input to the serial receiving port A5 of the data micom 10, and this signal is output to the output port of the microcomputer 20 according to the data path selection by the program processing of the microcomputer 20. Output via B0) or serial transfer port (B3).

The output source signal is modulated by the modem 30 by the output only (B0) and input to the transmission (TxD) of the modem 30 only, and the signal output to the serial transmission port B3 is NAND, which is a line receiver. It is input to the RS-232C connector 10 through the gate 21. On the other hand, the reception terminal RxA of the modem 30 modulates the signal received from the DAA 40 by the modem 30 and outputs it through the output terminal RxD. The output terminal RxD of the modem 30 receives the output source signal from the input / output port A4 of the microcomputer 20 and controls the RS-232C level through the NAND gate 2l through the serial transmission port B3. It becomes (± 12V) and is input to RS-232C connector (10).

The signal received from the RS-232C connector 10 is sent to a terminal and a personal computer.

The automatic detection of data rate will be described in detail with reference to FIG. At the same time the system is powered on, the microcomputer 20 initializes the input / output port in step 3a. When the terminal inputs the command "A" or "a" in the terminal, the microcomputer 20 is driven to the TTL level through the RS-232C large decker 10 and the inverter 22 and the microcomputer 20 is input to the serial receiving port A5. At this time, if the input waveform signal is input to the serial receiving port A5 by the mark MARK and the space SPACE having a predetermined width as shown in FIG. 5, the microcomputer 20 checks in step 3b to determine whether the signal is "low". Search. Here, the "low" state checks the start bit "low" state in the data format of FIG. 5, when it is "low" in step (3b), the serial transmission port B3 is set to "low" in step (3c), ( In step 3d), the internal counter of the microcomputer 20 is increased to measure the "low" width of the start bit. When the "low" width is counted in step (3d), and the "high" state is reached in the fifth bit, the serial reception port A5 checks whether "high" in step (3e).

When "high" in the process (3e) outputs "high" to the serial transmission port (B3) of the microcomputer 20 in the process (3f) to the TTL level at the NAND gate 21 to the RS-232C level of ± 12 After conversion, it is sent to the terminal through the RS-232C connector (10). Subsequently, in step 39, the terminal may detect the transmission speed by comparing the count value with a reference table value. When the transmission speed is determined as a desired start bit, the bit pattern following the start bit is 1000... If "0" after "1" is regarded as a new start bit, the following all bits are set to 1 start bit, 6 data bits, no paRity, and 1 stop bit. To the buffer of the register of the internal UART (synchronous / asynchronous transceiver). In step 3h, when the data bit " low " width is checked as shown in FIG. 5, when it is " low ", " low " is sent to the serial transmission port B3 in step 3i and the RS-232C connector 10 When the terminal recognizes the signal and transmits the signal "high" when the signal is not "low" in the process (3h) through the serial transmission port B3 in the process (3j), the terminal recognizes the signal by the microcom (3k) process. 30) Check if all characters of “A” have been received from the status register of the UART (synchronous / asynchronous transceiver).

Here, when one character is received, it is checked from hex data 41H and 61H whether one character input in the process (31) is "A" or "a". Here, it is determined that "A" is 41H and "a" is "61H", and "A" or "a" is stored in the predetermined memory area (3m). When the UART (synchronous / asynchronous transceiver) inside the microcomputer 20 is used, the read value is different according to the received data, so the value is stored in a predetermined RAM in the microcomputer 20, and (3n). Stores UART as 1 start bit, 7 data bit, Even parity bit, 1 stop bit, and reads the next character "t" or "T". Check whether the port A5 is "high", and when it is "high", output "high" to the serial transmission port B3 in the process (3p) and transmit it to the terminal through the RS-232C connector 10, and ( When the serial receiving port (A5) is "low" in the process 3o) After outputting "low" to the serial transmission port (B3) (3R), check whether all 1 characters are received. If it is not checked by checking whether the received data is "T" or "t" in step 3s), return to the previous step (3b). In the case of "T" or "t", it is combined with the previous letter "A" or "a" as shown in the table of FIG.

For example, if the first value is 30H and a parity error, the terminal data transmission format is 1 start bit, 7 data bits, odd parity bit, and 1 stop bit. As described above, when the command "AT" is inputted, the transmission speed can be automatically detected, and the command mode, which has been complicatedly performed in the multiplexer (MUX) in FIG. 1, is not shown in FIG. The process may be performed from (3b), and the check mode only needs to detect the state of the input / output port A4 of the microcomputer 20. The data mode is performed as shown in FIG. 4 and the microcomputer 20 outputs "low" to the output port B0 when the serial receiving port A5 is "low" in the process (4a). When "high" in (4a), "high" is output to the output port B0 in (4c). According to the process (4b, 4c), check whether one character is received in the process (4d) and check whether it should enter the command mode in the process (4e). When entering and not receiving a single character in the above (4d, 4e) process or entering the command mode (4f), the input and output port (A4) of the microcomputer 20 is monitored to check "high".

When the input / output port A4 is “high”, the NAND gate 21 outputs “high” to the serial transmission port B3 in step 49, and outputs “low” in the process of “low” (4h). After converting to TTL and output to the terminal through the RS-232C connector (10). If the input / output port A4 is " low " for more than 1.6 in step (4h), it checks this in step (4i), disconnects the modem 30, and returns to step (4a) if it is within 1.6 seconds. In FIG. 2, the RS-232C connector 10, the line receiver and driver inverter 22, and the NAND gate 21 are 300, 1200, 2400 bps external connection type modems, but the built-in modem (Built- in Type Modem) can be replaced by a communication controller (eg "i8250") with one chip UART / BRG.

As described above, if only two keys of "A", "T" or "a", "t" are input in order without resetting the system to detect the transmission speed, the transmission speed and parity can be known automatically. have.

Claims (1)

A method for automatically detecting a data transmission speed of a modem terminal, comprising: a first step (3a) of initializing a data input / output port for transmitting data to the modem, and reading the input / output port from the first step (3a) or A or a The second time (3b-3d) of checking and counting the "low" width of the start bit for the command, and the "start" of the "low" of the second step (3b-3d) end " Checks the status "high" and transmits to the terminal and determines the transmission rate for A or a by the counting value and synchronizes 1 start, 6 data, no parity, and 1 stop bit of the data format for the counted A or a. Step 3 (3e-3g) setting in the asynchronous transmit / receive buffer register. A fourth step (3h-3k) of checking the status of the data bit in the serial receiving port reading the command from the third step (3e-3g) and transmitting it to the terminal and checking whether all characters have been received; When one character is received from the fourth step (3h-3k), it checks and stores whether it is "A" or "a", and again, 1 start, 7 data, even parity 1 stop bit in the synchronous / asynchronous transmission / reception buffer register. In order to recognize the T or t from the fifth step (31-3m) and the fifth step (31-3m) to set the "high" state of the serial receiving input port is sent to the terminal and received one character Is stored in the sixth step (3o-3R) to check the value, the seventh step (3s) to check whether T or t from the sixth step (3o-3R), and the fifth step (31-3m) Data pattern of the corresponding baud rate with or without parity from the value of "A" or "a" and the value of the letter "T" or "t" in the seventh step (3s) How the automatic sensing of the data transmission rate, characterized by made of an step 8 (3t) of determining.

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