JPH03139034A - Skew correction communication system - Google Patents

Abstract

PURPOSE:To automatize skew correction by measuring a skew between a timing signal and a data signal in advance to store skew correction value and eliminating the skew of both signals based on the correction value at communication. CONSTITUTION:A skew control adaptor 1 uses a switching section 14 to transfer a communication timing signal ST and a transmission data signal SD sent from a data termination equipment 2 to a skew measuring section 11 to measure a skew between both the signals and it is stored in a storage section 12. Simultaneously, the signal ST is selected by switching sections 16, 17 to loop back the signal as a reception timing signal RT and a reception data signal RD. The skew control addition circuit 4 of a terminator 2 transfers the two signals RT, RD to a skew measurement section 22 via a switching section 25 and the skew of both signals is measured and stored in a storage section 23. Thus, while referencing to a skew correction value stored in the storage section 23, the phase correction is applied by the skew correction section 24 and the result is sent to a transmission/reception control section 25 in the terminator 2.

Description

[Detailed Description of the Invention] [Summary] Data circuit termination equipment (DCE) and data termination equipment (DT
E) Regarding the skew correction communication method in intercommunication, the transmission timing signal ST sent from the data termination equipment (DTE) is intended to automatically correct the skew between the timing signal and the data signal.
and a mechanism that measures and corrects the skew between the data signal SD and the transmitted data signal SD, and a mechanism that measures and corrects the skew between the ST and SD signals sent from the DTE to the data line termination equipment (DCE) through the skew correction section, or performs skew measurement. A switching mechanism selects whether to measure the skew between both signals through the CS, and whether the CS sends the reception timing signal RT and reception data RD from the DCE to the DTE as they are, or the ST sent from the DTE as a skew measurement signal. A skew control adapter equipped with a switching mechanism that selects whether to return the data and send it to the DTE as RT or RD.
a mechanism provided on the side and generating a signal for skew measurement;
A mechanism that measures and corrects the skew between the reception timing signal RT sent from the skew control adapter and the transmission data signal RD, and a skew correction unit that corrects the skew of the RT and RD signals using the control signal CH sent from the host. A switching mechanism that selects whether to send the signal to the host through the CH or to measure the skew of both signals through the skew measurement section;
It is equipped with a switching mechanism that selects whether to send the transmission timing signal ST and transmission data SD to the DCE as they are to the DCE, or to send the skew measurement signal to the DCE as ST and SD. is configured to correct the phase difference between ST and SD or RT and RD using a skew correction signal held in a skew control adapter and an additional skew control circuit, respectively.

[Industrial Field of Application] The present invention relates to a skew correction communication system in communication between a data line terminating equipment (DCE) and a data terminating equipment (DTE).

BACKGROUND OF THE INVENTION With the recent growth of a highly information-oriented society, data communication systems are being widely introduced. For this reason, there has been a demand for DCEs and DTEs, which were conventionally placed together with host computers in computer centers, to be placed separately on the basement and office floors of intelligent buildings, for example.

The present invention has been made in view of such problems, and has the object of providing a skew correction communication method that can automatically correct the skew between a timing signal and a data signal. It has been the target.

[Prior Art] As a result, there has been a demand for an extension of the cable length, but existing systems cannot be operated under conditions that exceed the margin that has been taken into account in advance at the design stage. In other words, the host and DTE DC remain the same as the conventional I/D system.
If E is placed apart, a phenomenon (referred to as skew) occurs in which a phase shift occurs between the timing signal and the data signal.

[Problem to be solved by the invention] Therefore, if operation is required under conditions that exceed the margins that have been considered in advance at the design stage, it is necessary to redesign a new system to satisfy these conditions again. was there.

[Means for Solving the Problems] FIG. 1 is a block diagram of the principle of the present invention. In the figure,
1 is a mechanism that measures and corrects the skew between the transmission timing signal ST sent from the data termination equipment (DTE) 2 and the transmission data signal SD, and the ST and SD signals are controlled by the control signal CS sent from the DTE 2. is sent to the data circuit terminating equipment (DCE) 3 through the skew correction section, or the skew between both signals is sent to the data line termination equipment (DCE) 3 through the skew measurement section.
2. A switching mechanism for selecting whether to send the reception timing signal RT and reception data RD from the DCE3 to the DTE2 as they are, or send them as a skew measurement signal using the CS. This is a skew control adapter equipped with a switching mechanism that selects whether to return the ST sent from the DCEB and send it to the DTE2 as RT or RD.
It is located on the side.

4 is a device that generates signals for skew measurement (core and reception timing signal R sent from the skew control adapter 1).
A mechanism that measures and corrects the skew between T and the transmitted data signal RD, and a control signal C' sent from the host.
A switching mechanism that selects whether to send the RT and RD signals to the host through the skew correction unit or to measure the skew of both signals through the skew measurement unit by H, and a transmission timing signal ST and transmission data SD to the DCE 3 by CH. An additional skew control circuit equipped with a switching mechanism that selects whether to send the skew measurement signal to the DCE3 as is or to send the skew measurement signal to the DCE3 as ST or SD.
It is located on the side.

Reference numeral 5 denotes a transmission/reception control section having an interface function provided between the host and the additional circuit 4 for skew control. The output of the DCE 3 is connected to a communication line 6.

[Effect] (at initial setting) Initial settings are performed when the system is started up.

At this time, the skew control adapter 1 and the skew control additional circuit 4 are set to the skew measurement mode according to an instruction from the host (not shown). The skew control additional circuit 4 on the DTE 2 side applies a signal expressed by a step function for skew measurement to the timing signal ST and data signal SD, and sends them to the DCE 3. On the skew control adapter 1 side, the two ST SD signals sent from the DTE 2 are transferred to the skew measurement section, the skew between the two signals is measured, and the value is held in the storage section.

In addition, on the skew control adapter 1 side, the timing signal ST is simultaneously connected to the timing signal RT and the data signal RD.
Return as Additional circuit 4 for skew control on DTE2 side
Then, the two signals RT and RD are transferred to the skew measurement section, the skew of both signals is measured, and the values are held in the storage section.

(During normal operation) In normal communication between the DTE 2 and DCE 3, the reception timing and reception data sent from the skew control adapter 1 are held in the storage section in the skew control additional circuit 4 on the DTE 2 side. The phase is corrected while referring to the skew complementary phase value, and the signal is sent to the transmission/reception control section 5 in the DTE 2.

On the other hand, the reception timing signal ST and reception data SD sent from the DTE 2 are phase-corrected while referring to the skew correction value held in the storage section in the skew control adapter 1 on the DCEB side, and sent to the DCE 3.

As described above, according to the present invention, since the skew between DTE2 and DCE3 is obtained in advance at the initial setting stage, in the subsequent normal DTE-DCEC connection, this DTE-DC
There is no need to be aware of queues between communications between ECs, and any operation mode can be realized as long as conditions other than skew, such as attenuation of signals on cables, are satisfied.

Therefore, according to the present invention, the skew between the timing signal and the data signal can be automatically corrected.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a diagram showing the main part of an embodiment of the present invention.

In the figure, 11. 1 is a skew measurement unit that measures the skew between the transmission timing signal ST and the transmission data signal SD sent from the DTE 2; 12 is a storage unit that holds the measurement results; and 13 is the storage unit that receives the ST multiplied signal and the SD multiplied signal. This is a skew correction unit that performs skew correction using the skew correction value held in 12. The ST multiplied signal and the SD multiplied signal DCE3 corrected by the skew correction section 13 are sent.

Reference numeral 14 denotes a skew correction unit 13 which converts the ST and SD signals by the control signal CS sent from the skew control additional circuit 4.
A switching section 15 selects whether to send the CS signal to the data line termination equipment (DCE) 3 through the skew measurement section 11 or to measure the skew between the two signals through the skew measurement section 11. It is. 16.1.7 uses the CS signal to send the reception timing signal RT and reception data RD from DCE3 to DTE2 as they are, or returns the ST sent from DTE2 as a skew ΔP1 regular signal and sends it to DTE2 as RT and RD. This is a switching section that selects either.

21 is a skew measurement clock generation unit that generates a skew measurement signal; 22 is a reception timing signal RT and a transmission data signal RD sent from the skew control adapter 1;
23 is a storage unit that holds the measurement results; 24 is a skew correction unit that receives the RT multiplied signal and the RD multiplied signal and performs skew correction using the skew correction value held in the storage unit 23; Department.

25 is R by the control signal CH sent from the host.
A switching unit selects whether to send the T and RD signals to the host through the skew compensator 1E unit 24 or to measure the skew of both signals through the skew measuring unit 22; 26 is a control unit that receives a control signal CH from the host; The output is sent to the skew control adapter 1 as a CS signal. 27.2
8 sends the transmission timing signal ST and transmission data SD to the DCE 3 as they are to the DCE 3 by the CH double signal, or
This is a switching unit that selects whether to send the skew measurement signal to the DCE 3 as ST or SD. The triangles in the figure are drivers or receivers.

In the circuit configured as described above, at the time of initial setting, the skew control adapter 1 and the skew control additional circuit 4 are set to the skew all constant mode according to an instruction from the host. In the skew control additional circuit 4 on the DTE2 side,
The switching sections 27 and 28 select the output of the skew measurement clock generation section 21 based on the control signal CH. A step signal is inputted from the skew lp1 regular clock generation section 21 and sent to the DCE3.

On the skew control adapter 1 side, the switching section] 4 is set to DTE.
The two signals ST and SD sent from 2 are transferred to the skew ΔIII constant section 11, the skew between the two signals is measured, and the value is held in the storage section 12. Also, on the skew control adapter 1 side, the timing signal ST
is selected by the switching units 16 and 17 to output the timing signal RT.
, and is returned as a data signal RD. In the skew control additional circuit 4 on the DTE 2 side, the switching unit 25 transfers the two signals RT and RD to the skew measuring unit 22, measures the skew of both signals, and stores the values in the storage unit 23. put.

During normal operation, in communication between the DTE 2 and DCEB, the reception timing and reception data sent from the skew control adapter 1 are stored in the storage section 23 in the skew control additional circuit 4 on the DTE 2 side. The phase is corrected by the skew correction unit 24 while referring to the value,
It is sent to the transmission/reception control section 5 in the DTE 2.

On the other hand, the reception timing signal ST and reception data SD sent from the DTE 2 are phase-corrected by the skew correction unit 13 while referring to the skew correction value held in the storage unit 12 in the skew control adapter 1 on the DCEB side. , sent to DCE3.

FIG. 3 is a diagram showing a detailed configuration example of the skew control adapter 1. Components that are the same as those in FIG. 2 are designated by the same reference numerals. The embodiment shown in the figure has V, 35 between the DTE and DCE.
The configuration of a skew control adapter when using an interface is shown. The control signal from the host for switching between skew measurement mode and skew correction mode is E
It is sent from the DTE 2 to the skew control adapter 1 on the R and R8 lines.

In this example, turning on R8 when ER is off switches to skew measurement mode, and turning on R8 when ER is on switches to skew correction mode (normal communication mode).
The switching is performed so that the value is set to . The mechanism for detecting timing and data skew is as follows.

An N-stage shift register (here, N-8) 30 takes in the measurement signal on the data line, and an M-stage shift register (here, M-4) 30 takes in the measurement signal on the timing line.
1 and an arithmetic unit 34 for encoding the output values of each of the N-stage flip-flops (FF) using an encoder 32 and comparing them with a preset value (4 in this case) 33, and holding the output of this arithmetic unit 34. A clock control unit 36 for supplying the necessary timing signals to each of these parts, and a final FF of the M-stage shift register 31. A control mechanism is provided that stops the shift clock supplied to the N-stage shift register 30 when detected.

One AND gate 37 is assigned to each of the N stages of shift registers 30, and gate control is performed so that the outputs of all FFs are manually input to the encoder 32 in the SCUBA constant mode. On the other hand, in the skew correction mode, the switching unit 38 switches so that only the FF of the decoded number held in the register 35 is gated.

Further, the switching unit 39 uses the change point of the timing signal detected in the final FF of the M-stage shift register 3 as a clock stop signal to the clock control unit 36;
Performs control to switch whether to output the timing signal as is. Therefore, the output of the OR gate 40 has no meaning in the skew measurement mode, and in the skew correction mode, a signal with no skew is obtained for the output timing signal. However, in this embodiment, the resolution for determining and correcting the skew δ1 depends on the number of shift registers in each logic and the frequency of the clock added thereto.
By making both of these values sufficiently large, it becomes possible to correct the skew with high accuracy.

In the above-mentioned embodiment, the skew control adapter] was described in detail, but the configuration of the skew control additional circuit 4 is exactly the same, so a description thereof will be omitted.

[Effects of the Invention] As described in detail above, according to the present invention, the skew between the timing signal and the data signal is measured in advance, the skew correction value is stored, and the skew correction value is used during actual communication. The skew between the timing signal and the data signal can be automatically corrected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of main parts of an embodiment of the present invention, and FIG. 3 is a diagram showing a detailed configuration example of a skew control adapter. In Fig. 1, 1 is a skew control adapter, and 2 is a DTE. 3 is DCE. 4 is an additional circuit for skew control, 5 is a transmission/reception control section, and 6 is a communication line.

Claims (1)

[Claims] A mechanism for measuring and correcting the skew between a transmission timing signal ST sent from a data termination equipment (DTE) (2) and a transmission data signal SD; Control signal CS causes ST and SD signals to pass through a skew correction unit to a data line termination equipment (DCE) (3).
) or to measure the skew between the two signals through the skew measuring section;
A switching mechanism that selects whether to send T and received data RD to DTE (2) as is, or to return ST sent from DTE (2) as a skew measurement signal and send it to DTE (2) as RT and RD. A skew control adapter (1) equipped with a skew control adapter (1) is provided on the DCE (3) side, a mechanism for generating a signal for skew measurement, and a reception timing signal RT sent from the skew control adapter (1).
A mechanism for measuring and correcting the skew between the data signal RD and the transmission data signal RD;
A switching mechanism that selects whether to measure the skew of both signals through the skew measurement section, and a switching mechanism that selects whether to measure the skew of both signals through the skew measurement section, and whether to send the transmission timing signal ST and transmission data SD to the DCE (3) as they are to the DCE (3) or to send the skew measurement signal to the DCE (3) by CH. ST,
It is equipped with a switching mechanism that selects whether to send it as SD to DCE (3), and in normal communication between DTE (2) and DCE (3),
A skew correction method configured to correct the phase difference between ST and SD or RT and RD using skew correction signals held in a skew control adapter (1) and an additional skew control circuit (4), respectively.