KR920009376B1 - Method for transmitting serially between radio phones - Google Patents

Abstract

The serial inter-communication method for cross protecting in the car phone system comprises the following steps: checking the state of request line (33) after completing the preparation for transmitting the edited information according to the formet of information transmission; executing the information transmission after making the request line to high state if the request line were low state in the first step; checking whether the main apparatus receives the transmitted information exactly in the second step; otherwise re-transmitting the information to the main apparatus; maintaining the request line to low state after sending the ending information to the main apparatus.

Description

Serial communication method between terminals

1 is a system block diagram according to the present invention.

2 is a configuration diagram of the information transmission table.

3 is a diagram illustrating an information transmission table in an embodiment.

4 is a flow chart according to the present invention.

* Explanation of symbols for the main parts of the drawings

10: main unit 20: additional unit

21-2N: 1-N accessory 31: Receive data line

32: Transmission data line 33: Request line

According to the present invention, when a plurality of additional devices are connected to and operated in one main device in a car phone system, confusion can be prevented by increasing the accuracy of information transmission by checking information transmission in serial communication of each additional device. The present invention relates to a serial communication method between terminals.

In the conventional serial communication method between terminals, there is a problem in that information transmission between the main device and the additional device is difficult to verify, and when various additional devices are connected, there is a confusion of information delivery and accurate information cannot be delivered.

Therefore, an object of the present invention is to increase the accuracy of information transmission through serial communication of each additional device when multiple additional devices are connected and operated to one main device to prevent confusion between serial terminals. In providing a communication method.

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

1 is a system block diagram according to the present invention, in which the main unit 10 and the additional unit 20 are connected in parallel to the transmission data line 31, the reception data line 32, and the retraction line 33. do.

In the above configuration, the main unit 10 is composed of a central processing unit 11 and a ROM 12. In the additional unit 20, a plurality of additional units 21-2N include a transmission data line 31 and a reception data line. 32 and parallel to the request line 33, respectively.

2 is a configuration diagram of the information transmission table, in which one piece of information is composed of a total of 10 bits including a start 1 bit 311, an information 8 bit and a stop 1 bit 312. Here, the start 1 bit 311 and the stop 1 bit 312 are automatically transmitted by the internal control of each processor of the accessory unit 20 of FIG.

The information structure of the control byte 313 is a 4-bit content indicating a form for distinguishing the additional device 20, and the 4-bit stores an information code used for determining what information. Examples of the form for distinguishing the additional device unit 20 are as follows.

Control unit: 0000

Interface box: 0001

FAX Modem: 0010

In addition, the type of information can be defined as follows.

Transfer of information from main device to additional device: 0000

Information transfer from auxiliary device to main device: 0001

Received correctly: 0010

If you did not receive the sent message correctly: 0011

When the information is sent: 0100

ㆍ ㆍ

ㆍ ㆍ

ㆍ ㆍ

Looking at the configuration of the header byte 314, 4 bits is a function having a content indicating what function and 4 bits stores a length of information to which information is transmitted.

The length of the information excludes the checksum byte 316 which is the last byte of the format.

An example of the content that indicates what the information is is as follows.

Check the connection status of the device: 0000

key operation information: 0001

display processing information: 0010

swich Processing Information: 0011

The data bytes 315 may set and process various types of information in the main device 10 and the additional device 20.

The checksum byte 316 stores and transmits the sum of the contents of the data bytes 315 in the header byte 314, and transmits the check sum 316 to the main unit. (10) compares the contents received and the contents of the header byte (314) and data bytes (315) at the receiving device with the checksum calculated to determine the status of the reception and request retransmission. Whether the device receives the additional device unit 20 or not. The reason why the control byte 313 is excluded from the checksum is that it is not necessary to receive data later if the main device unit 10 is a type code other than the attached device unit 20.

3 is a block diagram of an information transmission table according to an embodiment of the present invention, and FIG. 4 is a flow chart according to an exemplary embodiment of the present invention, in which an information transmission table is edited and prepared for transmission, and then the state of the request line 33 is checked. Process 1 and, if the request line 33 is low in the first process, a second process of making the request line 33 high and performing information transmission; and information transmitted in the second process A third process of checking whether the data is correctly received by the main unit 10, a fourth process of retransmitting the information to the main unit 10 if the information transmitted in the third process is not correctly received, and the third process. In the process, the transmission telegram was correctly received, and a fifth process of sending the transmission end information to the main device unit 10 consecutively and keeping the regress line 33 low.

Based on the above configuration, an embodiment of the present invention will be described with reference to FIGS. 1-4.

First, it is assumed that the contents of pressing the numeric key ＂1 부가 from the additional device unit 20 to the main device unit 10 are assumed. In step (a), the additional device unit 20 prepares for transmission by editing the information in the information transmission format of FIG. The content edited in the additional device is shown in the table of the embodiment as shown in FIG. 3. The device type is 0000, the transmission information code is 0001, and the function is 0001. The data information length is 0001 Data bytes 315 The upper 1 bit of represents the state of the key, and the remaining 7 bits represent the information of the key '1'. After the editing of the transmission information in step (a) is finished, and in step (b), the additional device unit 20 checks the state of the request line 33 and if the request line 33 is in a high state, the additional device unit 20 If it is determined that a predetermined additional device is transmitting information and waits, and the request line 33 is in a low state, step (c) is performed.

In step (c), the request line 33 is made high for information transmission, and information transmission is performed in step (d). At this time, the main unit 10 stores the received information and calculates a checksum of the header byte 314 and the data byte 315. After performing the information transfer of step (d), in step (e), the checksum value transmitted from the additional device 20 is compared with the checksum value calculated by the main device unit 10 to check whether the information has been received correctly. If it is received, perform step (h). If not, perform step (f).

In step (f), if the information transmission attempt is not finished by checking whether the information transmission attempt is completed, perform step (d) again to retransmit the information, and when the information transmission attempt is finished, cancel the information transmission in step (g) ( Perform step h).

In step (h), transmission end information is continuously sent twice to the main device unit 10, and step (i) is performed. In step (i), the additional device unit 20 sets the request line 316 to a low state and ends the information transmission.

In addition, if there is information to be transmitted from the main device unit 10 to the additional device unit 20, the same method as described above, but can transmit its own information regardless of the state of the request line 33.

As described above, it is possible to connect several additional device units 20 to the main unit unit 10 at the same time and search the request line 33 to determine whether or not to transmit information, thereby preventing confusion of information transmission. Comparing the checksum value with the received checksum value has the advantage of confirming accurate information delivery.

Claims (1)

Serial communication method between the terminals of the car phone system in which the main unit 10 and the additional unit 20 composed of a plurality of additional devices are connected in parallel with the reception data line 31, the transmission data line 32, and the request line 33. In the first step of editing the information according to the information transmission format and preparing for transmission, and then check the state of the request line 33, and if the request line 33 in the first process is the low state A second process of making the request line 33 high and executing information transmission, a third process of checking whether the information transmitted in the second process is correctly received by the main unit 10, and the third process If the information transmitted in the process is not received correctly, the fourth process for retransmitting the information to the main unit 10, and if the information transmitted to the main unit 10 in the third process is correctly received to the main unit 10 Send end information 2 times And a fifth process of continuously sending and maintaining the low line (33) in a low state.

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