JPH0440127A - Data transmitter - Google Patents

Abstract

PURPOSE:To transmit a data between a transmitter and a receiver by connecting only an information line for transmitting the data by providing a clock generating means to generate a clock for fetching the data while shifting the phase of the clock for establishing the synchronization of the receiver. CONSTITUTION:The data transmitted from a transmitter 1 through an information line 3 to a receiver 2 is inputted both a reception circuit 4 and a synchronization establishing circuit 6 in the receiver 2. The synchronization establishing circuit 6 establishes synchronization between the transmitter 1 and the receiver 2 and generates the clock synchronized to the transmitter 1 by detecting a synchronizing flag out of the received data and controlling the clock in the receiver 2. In that case, by using the clock shifting the phase to the clock for establishing synchronization and the clock for fetching the data of the receiver, the point of fetching the data is defined as the stable period of the data when establishing synchronization, and the correct data transmission is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data transmission device for transmitting data between a transmitter and a receiver.

Conventional technology Conventionally, a method for establishing synchronized timing between a transmitter and a receiver in a data transmission system is described, for example, on page 25 of "Data Communication" (Data Communication Educational Research Kinsen, Kyoritsu Publishing Co., Ltd.). , the configuration shown in FIG. 4.9(a) is known. The configuration will be briefly explained below with reference to FIG.

In FIG. 2, 7 is a transmitter that transmits data, 8 is a receiver that receives data transmitted by transmitter 7, 9 is an information line for transmitting data, and 10 is a link between transmitter 7 and receiver 8. This is a synchronous timing line that transmits synchronous timing. With this configuration, data transmitted from the transmitter 7 through the information line 9 is transferred to the receiver 8 from the transmitter 7 through the synchronization timing line 10.
It can be imported based on the synchronization timing transmitted by the host.

Problems to be Solved by the Invention However, in the conventional data transmission device configured as described above, in addition to the information line for transmitting data, a separate timing line for synchronization is required for transmitting synchronization timing, which increases the cost accordingly. was connected to. Another possible method is to eliminate the synchronization timing line used to transmit synchronization timing and establish synchronization between the transmitter and receiver by detecting a synchronization flag in the data to be transmitted. Since the clock for data acquisition and the clock for data acquisition are common, when synchronization is established, the data acquisition point may not always be in a stable period of data, as shown in Figure 3, and correct data reception cannot be performed. There was a problem that this could occur.

The present invention provides that, in the conventional digital data transmission device as described above, in addition to the information line for transmitting data, a synchronization timing line for transmitting synchronization timing is required separately, which leads to an increase in cost. In order to eliminate the synchronization timing line, the method of establishing synchronization between the transmitter and receiver by detecting the synchronization flag in the data uses the same clock for establishing synchronization of the receiver and the clock for data acquisition. In view of the problem that when establishing synchronization, the data import point is not always in a stable period of data, and correct data transmission may not be possible, we established synchronization without a synchronization timing line and imported the data. This is a period when data is stable, and the purpose is to ensure correct data transmission.

Means for Solving the Problems To achieve this object, the present invention provides a data transmission device that establishes synchronization between a transmitter and a receiver by detecting a synchronization flag in transmitted data. The apparatus is equipped with a clock generation means for generating a data acquisition clock with the phase of the establishment clock shifted, and is configured to transmit data between the transmitter and the receiver by connecting only an information line for transmitting data. There is.

The present invention provides a data transmission device which is established by detecting a synchronization flag in data to be transmitted, and which has the above configuration.
By using clocks with different phases for the receiver's synchronization establishment clock and data acquisition clock, when synchronization is established, the data acquisition point is set as the data stable period, and correct data transmission can be performed. It has been made possible.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a data transmission device according to the present invention.

In Fig. 1, 1 is a transmitter that transmits data, 2 is a receiver that receives data transmitted by transmitter 1, 3 is an information line for transmitting data, and 4 is a receiver that receives sent data. 5 is a delay circuit for shifting the phase of the clock; 6 detects a synchronization flag from the sent data and controls the clock in receiver 2 to synchronize between transmitter 1 and receiver 2; This is a synchronization establishment circuit that establishes.

With this configuration, data sent from the transmitter 1 to the receiver 2 through the information line 3 is input to both the receiving circuit 4 and the synchronization establishment circuit 6 in the receiver 2. The synchronization establishment circuit 6 detects a synchronization flag from the received data, controls the clock in the receiver 2 to establish synchronization between the transmitter 1 and the receiver 2, and outputs the clock synchronized with the transmitter 1. generate. However, if this clock is used to capture the data sent by the receiving circuit 4, the data capture point may not always be in a stable data period, so the delay circuit 5 uses the clock generated by the synchronization establishment circuit 6. Capture data using a delayed clock.

As mentioned above, in a data transmission device that establishes synchronization by detecting a synchronization flag in the data to be transmitted, it is possible to use a clock whose phase is shifted between the receiver's synchronization establishment clock and data acquisition clock. So, when synchronization is established,
The data capture point is used as a data stability period to ensure correct data transmission.

Effects of the Invention As described above, the present invention provides a data transmission device that establishes synchronization between a transmitter and a receiver by detecting a synchronization flag in transmitted data, in which the phase of the synchronization establishment clock of the receiver is shifted. It is equipped with a clock generation means that generates a clock for data acquisition, and is configured to perform data transmission between the transmitter and receiver by connecting only the information line that transmits data, so synchronization can be established without a synchronization timing line. , and the data import point is the data stability period,
It becomes possible to perform correct data transmission.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a data transmission device according to an embodiment of the present invention, FIG. 2 is a block diagram of the configuration of a conventional data transmission device, and FIG. 5 is a timing chart showing a shrinkage point. 1... Transmitter, 2... Receiver, 3... Information line, 4
...Reception circuit, 5.Delay circuit, 6.Synchronization establishment circuit.

Claims (1)

[Claims] In a data transmission device that establishes synchronization between a transmitter and a receiver by detecting a synchronization flag in data to be transmitted, there is provided a clock generation means that generates a clock for data acquisition by shifting the phase of a clock for establishing synchronization of the receiver. What is claimed is: 1. A data transmission device characterized in that data transmission is performed between a transmitter and a receiver by connecting only an information line for transmitting data.