JP2000358081A - Data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute fast data transmission by providing a delay means for providing a specific delay time to a data signal transmitted through one of two signal conductors when a delay time exists in the timing of sending a data signal to the two signal conductors, so as to reduce the influence of the difference of the delay time. SOLUTION: It is supposed that a delay time exists in timing for carrying data signals SIG 0 and SIG 1 to a signal conductor 31 and 32 by a data transmission logical part 41. Then, the maximum delay time of the timing of sending the signal SIG 0 to the conductor 31 by the part 41 is set to be TA, the minimum delay time of the timing of sending the signal SIG 1 to the conductor 32 by the part 41 is set to be TB, and a delay means 42 providing the signal SIG 1 transmitted through the 32 with the delay time T of a degree which can be given by an expression; T=(TA-TB)/2. Thus, fast data transmission is realized by reducing the influence of the difference of the delaying time generated at each transmission signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission apparatus for transmitting data between communication apparatuses via a bus including a plurality of signal lines.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing a configuration example of a conventional data transmission device. In FIG. 5, the communication devices 10 and 20 communicate via a bus 30. The bus 30 includes two signal lines 31 and 32. The data transmission logic units 11 and 21 are provided in the communication devices 10 and 20. The data transmission logic units 11 and 21 perform logical processing for data transfer. For example, when transmitting a data signal from the communication device 10 to the communication device 20, the data transmission logic unit 11 transmits the data signals SIG0, SIG0,
Send SIG1. The data transmission logic unit 21 receives and processes the received data signals SIG0 and SIG1. The data transmission logic units 11 and 21 are composed of custom ICs.

[0003] Problems of such a data transmission device will be described below. Data signal S output by data transmission logic units 11 and 21
IG0 and SIG1 may be signals that should be output simultaneously. However, the delay times of transmitting the data signals SIG0 and SIG1 may be different due to the following reasons.・ Circuit design for reducing simultaneous switching noise in ICs constituting data transmission logic units 11 and 21 ・ Difference in lead wires of ICs for transferring data signals SIG0 and SIG1 ・ Difference in layout of chips in IC ・ IC Of internal device characteristics

The data signals SIG0 and SIG1 which should originally change at the same time due to such a situation.
May change at different times.

As a physical layer device for transmitting data from the data transmission logic units 11 and 21, a single-ended device such as a TTL (transistor, transistor, logic) is widely used. TTL
Ideally, the transition time when the output changes from H (high level) to L (low level) is equal to the transition time when the output changes from L to H. However, the two transition times described above are not equal due to the characteristics of the internal circuit of the device, transmission conditions in an actual application, and the like. 2
The difference between the two transition times is the difference between the delay times of the signals. If a differential output device is used, two transition times are used, so that the problem can be solved. However, disadvantages arise in that the number of signal lines increases and an expensive device must be used.

As described above, when designing a data transmission apparatus, it is necessary to determine the output timing of signals and the like in consideration of the difference in delay time between signals. This has been a hindrance in improving the data transfer speed.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and a delay means for giving a delay time of (maximum delay time difference of a transmission signal) / 2 to a transmission signal is provided by a signal line. It is an object of the present invention to realize a data transmission device capable of performing high-speed data transmission by reducing the influence of a delay time difference generated for each transmission signal.

[0008]

SUMMARY OF THE INVENTION The present invention is a data transmission device having the following configuration.

(1) In a data transmission device for transmitting a data signal from a communication device on the transmission side to a communication device on the reception side via a bus composed of a plurality of signal lines, a data transmission device is provided in the communication device and logically transmits data. A data transmission logic unit that performs processing and sends a data signal to the signal line; and a delay time exists when the data transmission logic unit sends a data signal to the signal line A and the signal line B. A data transmission device comprising a delay means for giving a data signal transmitted on a signal line B a delay time T of the degree given by the following equation. T = (T _A −T _B ) / 2, where T _A is the maximum delay time when the data transmission logic unit sends out the data signal to the signal line A, and T _{B is the} data transmission logic unit sends the data signal to the signal line B. , The minimum delay time of the transmission timing, T _A > T _B

(2) A data signal and a strobe signal are transmitted from a transmitting communication device to a receiving communication device via a bus composed of a plurality of signal lines, and the receiving communication device transmits the data signal at the timing of the strobe signal. In the data transmission device to take in, a data transmission logic unit provided in the communication device for performing a logical process for data transmission and transmitting a data signal and a strobe signal to the signal line; A delay means for providing the strobe signal with a delay time T given by the following equation when the data signal and the strobe signal are transmitted on the signal line D at a delay time. Data transmission device. _{T = (T C -T D)} / 2 However, T _C: data transmission logic timing the maximum delay time for transmitting the data signal to the signal line C, T _D: data transmission logic strobe signals to the signal lines D , The minimum delay time of the timing for sending out, T _C > T _D

(3) The data transmission device according to (1), wherein the delay means is constituted by a pattern of a printed circuit board having a pattern length corresponding to a delay time T.

(4) The data transmission device according to (1), wherein the delay means is constituted by a pattern of a printed circuit board having a folded shape.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention. 1 that are the same as those in FIG. 5 are given the same reference numerals. FIG.
The communication devices 40 and 50 are provided with data transmission logic units 41 and 51, respectively. Data transmission logic 41, 51
Performs logical processing for data transfer. The data transmission logics 41 and 51 may be the same or different. The delay units 42 and 52 give a delay time to the transmission signal on the signal line 32. The delay units 42 and 52 are composed of, for example, an active delay line, an LC filter connecting a coil and a capacitor, and the like.

The operation of the apparatus shown in FIG. 1 will be described. Communication device 4
A case where a data signal is transmitted from 0 to the communication device 50 is taken as an example.
I will. The data transmission logic 41 is connected to the signal lines 31 and 32.
Data signals SIG0 and SIG1
It is assumed that the delay time exists. Data transmission logic 4
1 is the time when the data signal SIG0 is transmitted to the signal line 31.
The maximum delay time of _AAnd Data transmission logic 4
1 is the time when the data signal SIG1 is transmitted to the signal line 32.
The minimum delay time of_BAnd Where T_A> T_BWhen
The delay means 42 outputs the data signal S transmitted on the signal line 32.
Give IG1 a delay time T of the degree given by
You. T = (T_A-T_B) / 2

[0015] In formula (T _A -T _B) is the average value of the delay time difference between the data signal of the signal line 31 and 32. Delay time difference is in a distribution close to the normal distribution from 0 to (T _A -T _B). The mean value (T _A -T _B) / 2 most prone delay time difference stochastically the delay time difference. The delay means 42 gives an average value of the delay time difference to the data signal. For this reason,
The probability of giving the optimum delay time difference is the highest.

The communication device 50 is also provided with a delay means 52 similar to the delay means 42. Since the communication device 40 transmits data while the communication device 50 receives data,
The delay unit 52 differs from the delay unit 42 in that the terminal on the communication device side is an output terminal.

FIG. 2 is a block diagram showing another embodiment of the present invention. In this embodiment, a data signal is transmitted to a signal line 31 and a strobe signal is transmitted to a signal line 32. The communication device on the receiving side captures the data signal at the timing of the strobe signal. There is a delay time at the timing at which the data transmission logic sends the data signal and the strobe signal to the signal lines C and D, respectively. The delay time of the data signal may be different from the delay time of the strobe signal. This is the transition time required for the signal to change from L to H and H
One reason is that the transition time required to change from L to L is different. The delay means 43 gives the strobe signal a delay time T of a degree given by the following equation. _{T = (T C -T D)} / 2 However, T _C: data transmission logic timing the maximum delay time for transmitting the data signal to the signal line C, T _D: data transmission logic strobe signals to the signal lines D , T _C > T _D, whereby the effect of the difference between the two transition times is reduced, and the receiving-side communication device can take in the data signal at the optimal timing.

FIG. 3 is a diagram showing a configuration example of the delay means. In FIG. 3, a printed circuit board 60 has a linear pattern 61 and a folded pattern 62 formed thereon. The signal SIG0 is transmitted in the pattern 61 and the pattern 6 is transmitted.
2, the signal SIG1 is transmitted. By making the pattern length of the pattern 62 longer than the pattern length of the pattern 61, the signal SIG1 has a delay time. In addition,
The delay time may be provided by a pattern having a pattern length according to the delay time, not limited to the folded pattern.

FIG. 4 is a diagram showing another embodiment of the present invention. In this embodiment, two communication units 70 and 80 are connected via repeaters 90 and 100. The two communication units 70 and 80 are connected by signal lines 110 and 111. The delay means 91 and 101 are
Alternatively, the configuration is the same as that of the delay unit 43. According to the embodiment of FIG. 4, a plurality of communication units can be interconnected without making a major modification to an existing communication device, and diversification of the system can be realized. Also, since many communication devices can be connected to one system, total cost can be reduced.

Although the embodiment has been described in connection with the case where two signal lines are provided, the present invention is not limited to this, and three or more signal lines may be provided.

[0021]

According to the present invention, the following effects can be obtained.

According to the first aspect of the present invention, a delay means for giving a delay time of (maximum delay time difference of transmission signal) / 2 to the transmission signal is provided in the signal line, so that the delay time difference generated for each transmission signal is reduced. The effect can be reduced and high-speed data transmission can be realized.

According to the second aspect of the present invention, the influence of the difference between the transition time required for the transmission signal to change from L to H and the transition time required for the transmission signal to change from H to L is reduced. A data signal can be captured at an optimal timing. Further, since the influence of the difference between the two transition times can be eliminated without using a device having a differential output, high-speed data transmission can be realized without increasing the cost.

According to the third and fourth aspects of the present invention, the delay means is constituted by the pattern of the printed circuit board.
There is almost no need for parts for the delay means.

As described above, according to the present invention, it is possible to realize a data transmission device capable of performing high-speed data transmission by reducing the influence of the difference in delay time generated for each transmission signal.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration example of a delay unit;

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration example of a conventional data transmission device.

[Explanation of symbols]

 31, 32 signal line 40, 50 communication device 41, 51 data transmission logic unit 42, 43, 52, 53 delay means 60 printed circuit board 61, 62 pattern

Claims (4)

[Claims] 1. A data transmission device for transmitting a data signal from a communication device on a transmission side to a communication device on a reception side via a bus composed of a plurality of signal lines. And a data transmission logic unit for transmitting a data signal to the signal line, and a signal when the data transmission logic unit transmits a data signal to the signal lines A and B when there is a delay time. A data transmission device, comprising: delay means for giving a data signal transmitted on a line B a delay time T of a degree given by the following equation. T = (T _A −T _B ) / 2, where T _A is the maximum delay time when the data transmission logic unit sends out the data signal to the signal line A, and T _{B is the} data transmission logic unit sends the data signal to the signal line B. , The minimum delay time of the transmission timing, T _A > T _B 2. A data signal and a strobe signal are transmitted from a transmitting communication device to a receiving communication device via a bus including a plurality of signal lines, and the receiving communication device takes in the data signal at the timing of the strobe signal. In the data transmission device, a data transmission logic unit is provided in the communication device, performs a logical process for data transmission, and sends a data signal and a strobe signal to the signal line. And delay means for providing the strobe signal with a delay time T given by the following equation when a delay time is present at the timing of transmitting the data signal and the strobe signal on the line D, respectively. Data transmission equipment. _{T = (T C -T D)} / 2 However, T _C: data transmission logic timing the maximum delay time for transmitting the data signal to the signal line C, T _D: data transmission logic strobe signals to the signal lines D , The minimum delay time of the timing for sending out, T _C > T _D 3. The data transmission apparatus according to claim 1, wherein said delay means is constituted by a pattern of a printed circuit board having a pattern length corresponding to a delay time T. 4. The data transmission apparatus according to claim 1, wherein said delay means is constituted by a pattern of a printed circuit board having a folded shape.