JPS6376623A - Crc generating circuit - Google Patents

Abstract

PURPOSE:To attain data transmission with higher quality by preserving the quality of transmitted data and updating CRC data when new data are added to a transmitting data column and a relaying transmission is executed. CONSTITUTION:When new data are added and a CRC generation is executed, the received data inputted from a data input terminal 1 and new data inputted from a new data input terminal 2 are added by an MOD 2 adder 15 and inputted to an MOD 2 adder 13. The data are fed back to a CRC arithmetic part and CRC operation is executed. A gate 14 controls, by the signal inputted from an information/CRC changing-over terminal 4, whether or not the CRC operation is executed. The arithmetic result at the CRC arithmetic part is outputted to a delaying device 10 and the result to add the CRC of the received data and MOD2 with an MOD2 adder 16 is inputted to a selecting device 6. The selecting device 6 changes over the new information inputted from the new data input terminal 2 and the CRC and outputs them to a data output terminal 3, by the input signal of an information/CRC changing-over terminal 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J This invention relates to error detection when data is transmitted while adding new data during relay.

[Prior art] The 4s2 diagram shows the conventional CRC (Cyclic Redundant
(1) is a data input terminal, (2) is a new data input terminal, (3) is a data output terminal, (4) is an information/CRC9J replacement terminal, (5) ) and (6] are selectors, (7) to (lO) are delay devices, (11) to (13) are M
OD 2 adder, (14) #f gate, (17) is a data addition/non-addition switching terminal.

Next, the operation will be explained. Whether or not to add new data to the received data is selected by the selector (5) depending on the input signal of the data addition/non-addition switching terminal (17). In addition, the CRC main component includes delay devices (7) to (10)%M
Consists of OD2 adders (11) to (13), gates (14), and selectors (6), and always selects information at the information/CRC switching terminal (4) when no CRC calculation is performed. Input the signal. When performing a CRC calculation on additional data, first input a signal for selecting information to the information/CRC switching terminal (4), and then the selector (6) selects the new data input from the new data input terminal (3). The data is output as is to the data output terminal (3). During that time, the CRC calculation circuit performs CRC calculation on the new data.
After information output information/CRC (CRC on 71I replacement terminal (4)
By inputting a signal for selecting , the CRC calculation result is output to the data output terminal (3).

[Problem that the invention seeks to solve]

Conventional CRC calculation circuits are configured as described above, so when new data is added during relay in data transmission, a CRC calculation is performed on the new data and a CRC error occurs in the data received by the repeater. However, there was a problem in that it was not possible to transmit this information.

This invention was made to solve the above-mentioned problems, and when relaying data transmission, by performing a CRC check on the received data after the relay, it is also possible to perform a CRC check on the data before the relay. The object of the present invention is to obtain a CRC calculation circuit that can perform simultaneous operations.

[Means for Solving Problems J] In data transmission, when data is added during relay, the CRC generation circuit according to the present invention generates a C
Generates RC, and also generates CRC for received data.
The value added at OD2 is added to the transmitted data as the CRC of the repeater output.

[Effect]

The CRC generation circuit in this invention performs a C
Since RC generation is performed, when relay data is received, not only errors in the data after relay but also errors in the data received by the repeater are saved as they are, so errors before and after relay can be detected by a CRC check.

[Embodiment J Hereinafter, one embodiment of the present invention will be described with reference to the drawings. 1st
In the figure, %(1) is a data input terminal, into which data received by the repeater is input. (2) is a new data input terminal, into which information to be transmitted after relaying is input. (5) is a selector which selects whether or not to add new data to the received data by switching the data addition/non-addition switching terminal (17). (7) to (10) are delay devices, (11) to
(13) is a MOD2 adder, (14) is a gate, (15
) and (16) are MOD2 adders (7) to (16)
The CRC generation section is configured by: Switch (6) is a selector, which performs information/CRC switching of data output from the data output terminal (3) by switching 9J of the signal input to the information/CRC4y'J switching terminal (4).

Next, the operation will be explained. Whether or not to add new data to the received data is selected by the selector (5) based on the input signal of the data addition/non-addition switching terminal (17). A selector (6) determines whether information or CRC is output from the data output terminal (3) based on the input signal of the information/CRC switching terminal (4). If CRC generation is not performed, always select information.

When adding new data and generating a CRC, MOD2 converts the received data input from the data input terminal (1) and the new data input from the new data input terminal (2).
Add by adder (15), MOD2 adder (13)
Enter. The data is transmitted to delay devices (7) to (10), M
The signal is fed back to the CRC calculation unit composed of OD2 adders (11) and (12), and subjected to CRC calculation. Game) (14)
This controls whether or not to perform I/iCRC calculations.
It is controlled by the signal input from the information/CRC switching terminal (4). The calculation result in the CRC calculation section is sent to a delay device (lO
), and the MOD2 adder (16) adds the received data CRC and MOD2 to the selector (6).
]. The selector (6) is the information/CRC switching terminal (
In response to the input signal 4), the new information inputted from the new data input terminal (2) and the CRC are switched and outputted to the data output terminal (3).

This circuit performs a CRC operation on the new data and received data added MOD2, and then performs a CRC operation on the received data.
Since the CRC of the transmitted data is generated by adding RCt-MOD2, errors in the received data are added to the new data by performing CRC calculation and CRC, and the signal output from the repeater is not received. However, by checking the CRC, it is possible to detect errors in the data before it is relayed.

[Effects of the Invention] As described above, according to the present invention, the MOD2 adder, delay device, gate, and selector are configured so that the CRC error before data relay can be stored, so that a small amount of circuitry is required in addition to the conventional circuit. By simply adding , higher quality data transmission can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a CRC generation circuit according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional CRC generation circuit. In the figure, (1) #: Il' data input terminal, (2
) is the new data input terminal, (3) is the data output terminal, (4
) are information/CRC switching terminals, (5) and (6) are selectors, (7) to (10) are delay devices, (11) to (13)
RM OD 2 adder, (14) is a gate, (15) and (16) are MOD 2 adders, (17) //'i data addition/non-addition switching terminal. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A CRC generation circuit that updates CRC data while preserving the quality of the transmitted data when adding new data to a transmission data string and relaying it.