JPS6033326B2 - Receiving distortion adjustment method for asynchronous system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a reception distortion adjustment method for an asynchronous system, in particular, a method for adjusting reception distortion in an asynchronous signal reception distribution process used in terminal devices such as telex. The present invention relates to an adjustment method that performs adjustment by making sampling points variable.

FIG. 1 shows a conventional control block diagram of a portion related to reception.

In the figure, numeral 1 is a bell conversion circuit, 2 is a receiving circuit, 3 is a microprocessor, and 4 is an output device. For example, the level conversion circuit 1 has a bias value of about 1 hA for a current loop interface of 20 to 23 hA of a telex line, and uses elements such as a polarized mercury relay and a photocoupler to mark the state when current is flowing. (Logically 1", also called stop condition), and when there is no current, it is judged as a space state (logically 0", also called start gutter condition), and this is transmitted to the receiving circuit 2.

The receiving circuit 2 is matched to a logic level appropriate to the microprocessor 3 to which it is connected. The microprocessor 3 receives and distributes the asynchronous serial reception signal from the reception circuit 2 into parallel information, and also controls the output to an output device 4 such as a printer or paper tape punch. The reception and distribution of the microprocessor 3 is performed by program processing. That is, the timing of a plurality of reception samplings given for one bit length is obtained, for example, by interrupt processing using a hard timer, and sampling is performed at the timing that is the midpoint of the one bit length. In subscriber lines such as telex, distortion occurs in the signal waveform, and the degree of this distortion varies greatly depending on the type of line, distance, repeaters, etc. Therefore, at present, the distortion is corrected by changing the bias value in the bell conversion circuit 1, for example. This adjustment method was effective when a polarized mercury relay was used, but when a photocoupler was used, the degree of distortion correction was small with respect to changes in the bias value, and the effect was low. Furthermore, in the receiving circuit 2, if the distortion is corrected using a logic signal, the circuit scale is large, and if correction is attempted to be performed using an integrating circuit consisting of a capacitor or a resistor, it is susceptible to temperature fluctuations and secular fluctuations. FIG. 2 is an example of a time chart showing reception and distribution processing that is generally performed in a subordinate system.

The start-stop synchronization signal AS has two states: mark state M and space state S.
value is taken, and the start bit (ST
(denoted as bit), the first bit, and the second bit. In addition, the figure shows the clock CLK as ``16'' per 1 bit length. This value is the most common, and it may take other values such as "32", "64", and "8", all of which operate in the same way.
The larger the value, the smaller the error and the stronger the reception distortion. The midpoint sampling SPT in this example is "8", "24", "40",
...and the first ST bit is "8", but the subsequent bits are every "16".

The start/stop synchronization signal AS has a number of code bits such as ``5'', ``6'', ``7'', and ``8'' depending on the device, the start bit is uniformly assigned 1 bit, and the stop bit (not shown) is assigned depending on the device. "1", "1.5"
, "2" bits. ST
In the bit midpoint sampling SPT, the asynchronous signal AS
Check the space status S of . If the mark state is M, this is considered an erroneous operation and the reception distribution operation is stopped. In addition,
Confirmation of the space state S may be performed in synchronization with each clock CLK up to the midpoint sampling SPT. SUMMARY OF THE INVENTION The present invention aims to correct the distortion that occurs in the line section during asynchronous reception and distribution, and provides a reliable method with simple adjustment operations. FIG. 3 is a time chart illustrating an embodiment of the present invention, and FIG. 3A is a space state S.
When there is a strain in the direction in which the space state S is extended, FIG. 3B shows a case in which there is a strain in the direction in which the space state S is contracted.

First, FIG. 3A will be explained. The start-stop synchronization signal AS should originally be shown as a dotted line, but it is changed to 2 as shown as a solid line.
The case of 0% elongation is shown. When testing line distortion,
In the test equipment on the sending side, the ST bit is generally set to 130% distortion or -30% distortion based on the allowable distortion distribution, and when this distorted code is received, the degree of distortion is determined based on whether or not an error has occurred. Adjustments are being made as necessary. In this example, 13
During the 0% distortion test, the start-stop synchronization signal AS becomes as shown by a dotted line with 50% distortion, and the conventional midpoint sampling SPT
If "8", "24", "40", etc. are used in the clock CLK, it is a typographical error. Therefore, in the present invention, the midpoint sampling SPT is "10" and "26" at the clock CLK.
, "42", etc., the ST bit is changed from "8" to "10", and thereafter it is set every "16" as before. In this way, reception distortion can be adjusted by changing the mid-point sampling SPT of the ST bits. The width of this change is subject to ±30% distortion of the ST bit, and may be determined according to the presence or absence of typographical errors. The value of this ±30% strain does not need to be uniform at all, and may be set to various values. FIG. 3B shows a case where, contrary to the case of FIG. 3A, the start-stop synchronization signal AS has been reduced by 25% as shown by the solid line instead of the dotted line. Times are expressed as 30% strain. At this time as well, the conventional midpoint sampling SPT is broken. CL
If K is "8", "24", "40", etc., it is a typo. Therefore, in the present invention, the midpoint sampling SPT is "7", "23", "39", . . . by the clock CLK. ．． ．． and S
The T bit is changed from "8" to "7", and thereafter it is changed every "16" as in the subordinate function. In this way, reception distortion can be adjusted by changing the midpoint sampling SPT of the GT bits. Fourth
The figure is a block diagram showing the configuration of the present invention, and 5 is a switch section.

The switch unit 5 may be a small dip switch, a short terminal by soldering, a combination of a terminal board and a short pin, a digital switch, etc., and provides a clock for the ST bit of the midpoint sampling SPT to the microprocessor 3. It is sufficient if the number of CLKs can be specified.
As in this example, when 1 bit length is set to "16" by clock CLK, for example, "6", "7", "8", "9", "
10" can be specified. The designation in the switch section 5 is switched to prevent typographical errors from occurring during line testing. FIG. 5 is a diagram showing a part of the operational flow of reception distribution processing in the present invention.

That is, the number of clocks until sampling the data midpoint is set. In the above description, since the microprocessor 3 is used, the process is shown in the form of program processing, but the process is not limited to program processing and may be performed by wired logic control consisting of counters, shift registers, and the like.

The point is that the difference from the slave is that the number of clocks for sampling the center point of the ST bit is variable. In addition, when a non-volatile memo IJ is included in the device control, a predetermined code string, for example 130
Check the presence or absence of typos when receiving % distortion and when receiving -30% distortion, set the number of clocks CLK of the ST bit so that the midpoint sampling SPT is such that no typos occur, and store this in a non-volatile manner. You can write raw memos and memorize them regardless of whether the enemy's power is turned on or off. In this way, the switch section 5 shown in FIG. 4 does not need to have the role of specifying the midpoint sampling SPT, and can be used to specify to the program that distortion adjustment is to be performed in the line test. becomes. With this configuration, the operator can automate distortion adjustment by simply specifying the adjustment mode. It is also possible to output the degree of distortion to a printer or the like to inform the operator of the line status. Further, when a mercury relay is used in the level conversion circuit 1, the impression time and recovery time are different due to the characteristics of the element, and as a result, distortion appears in ten directions or in one direction. In such a case, the present invention can be applied to shift the midpoint sampling in advance for the distortion that can be grasped in advance based on the element characteristics, and it is also possible to design the device to have no apparent distortion. Furthermore, there is a device in which the reception distribution circuit is a peripheral BI of the microprocessor 3, such as the PuPD8251 manufactured by NEC Corporation.

In the case of this element, the stop bit length and the number of 1-bit length clock CLKs can be specified by the microprocessor 3 in a programmable manner with respect to start-stop synchronization. The present invention is applied to the element, and the midpoint sampling S of the ST bit is sent from the microprocessor 3 as specified information.
By including the number of PTs, it becomes equipped with a distortion adjustment function, and the ease of use is improved. As described above, according to the present invention, the number of clocks CLK of the midpoint sampling SPT of the start bit (ST bit) of the asynchronous signal AS is made variable according to the designation of the switch, thereby correcting reception distortion.

For this reason, in the adjustment operation, it is not only necessary to simply change the switch so that there is no typo in the predetermined distortion code, but also the distortion can be adjusted reliably. Also, if you have non-volatile memory, instead of following the switch designation and making it variable directly,
When a predetermined distortion code is received in the adjustment mode, the midpoint sampling SPT of the stop bit is automatically switched to avoid errors, and the value of the clock CLK based on this result is stored, and the mode is specified by a switch. can do. Furthermore, an existing asynchronous programmable LSI can be provided with a distortion adjustment function by incorporating the start bit midpoint sampling SPT as a parameter.

[Brief explanation of drawings]

FIG. 1 is an example of a conventional control block diagram of a portion related to reception, and FIG. 2 is a time chart showing conventional reception distribution processing. FIG. 3 shows a time chart for explaining the embodiment of the present invention, and FIG. 3A shows the case where the space condition is extended.
Figure B shows the case where the space condition is reduced. FIG. 4 shows the configuration of one embodiment to which the present invention is applied, and FIG. 5 shows a flow chart showing one embodiment of the present invention. In the figure, 1 is a bell conversion circuit, 2 is a receiving circuit, 3 is a microprocessor, and 4
5 represents an output device, and 5 represents a switch section. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. In asynchronous reception distribution processing with a start bit, a single fixed count value is counted from then on using the midpoint sampling point of the start bit as a reference, and each subsequent data bit is extracted. In the reception distribution processing circuit of the synchronous system, the timing at which the midpoint of the start bit should be sampled is set in advance according to the system in accordance with the measurement results for the system in question. A reception distortion adjustment method for an asynchronous system, characterized in that the reception distribution processing circuit performs the midpoint sampling.