JPH03250264A - Automatic wiring method considering wiring rule - Google Patents

Abstract

PURPOSE:To prevent wiring rule error by preparing wiring rule countermeasure information corresponding to error contents after automatically extracting a net with high possibility to generate the wiring rule error, and automatically executing wiring while keeping this countermeasure information. CONSTITUTION:Signal point information for one net is taken out of a design information file 1 and this signal point information is divided for the unit of a connection block at a wiring rule consideration block 4. Then, it is decided whether the wiring rule countermeasure is required or not according to the distance of each connection block and the information of a wiring rule file 2, and when the countermeasure is required, the wiring rule countermeasure information is prepared and outputted to a wiring rule countermeasure information file 6. By using the information of this wiring rule countermeasure information file 6, a print pattern is decided by a print pattern decision block 5 and outputted to a wiring pattern file 7. Thus, by controlling a wiring length by automatic wiring, the print pattern can be obtained not to be the wiring rule error.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printed circuit board design system, and particularly to an automatic wiring method for preventing wiring rule errors.

[Conventional technology]

As parts mounted on printed circuit boards become faster and more densely packed, it is necessary to strictly adhere to wiring rules such as net wiring length restrictions in order to ensure stable operation of devices. On the other hand, in the design work of printed circuit boards, especially in the design of printed patterns for large-scale logic devices, it is essential to use an automatic wiring program due to the design time and man-hours.

For this reason, consideration of wiring rules in automatic wiring programs is important. As an automatic wiring method that takes the wiring length into consideration, there is known a ``printed board wiring method'' described in Japanese Patent Laid-Open No. 63-31192.

[Problem to be solved by the invention]

The automatic wiring method according to the conventional technology calculates the slope between two signal points to be wired, groups signal points with similar slopes, and allocates each group to each layer to reduce detours of each net. be. However, this method does not take into account the ease with which wiring rule errors occur (the margin of wiring length relative to the constraint length in wiring rules), and it does not take into account the minimum wiring length as a constraint in wiring rules. There are other problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic wiring method that takes wiring rules into consideration and facilitates the design of printed patterns for printed circuit boards that operate at high speeds and shortens the development period.

[Means to solve the problem]

In order to achieve the above objective, an automatic wiring program using a computer that creates wiring pattern information from a design information file storing net information reads the net information from the above design information file and calculates the shortest distance between each signal point of the net. , a first step of estimating the print pattern length based on the shortest distance, preset average detour information of the print pattern, and average shortening information of the print pattern due to branching; The second step is to determine whether or not the constraint length determined by the wiring rule is satisfied, and if the constraint length determined by the wiring rule is not satisfied, determine whether branching is possible or not, and the minimum and maximum values of the wiring length constraints of the printed pattern. The process consists of a third step of deciding, and a fourth step of deciding the route of the printed pattern while observing the branchability and wiring length constraints determined in the third step, and the above steps are executed in order. be.

[Effect]

The causes of a wiring rule error after running the automatic wiring program are the following two items.

<Causes of wiring rule errors> ■ The printed pattern takes a detour and becomes longer than the shortest distance between signal points.

■ Due to the branching of the printed pattern, the length of the printed pattern according to the wiring rules becomes shorter than the shortest distance between signal points.

Both of the causes of the two items are related to the wiring length of the printed pattern, and by controlling this wiring length by automatic wiring, it is possible to obtain a printed pattern that does not cause wiring rule errors.

〔Example〕

An embodiment of the present invention will be specifically described below with reference to FIGS. 1 to 6.

FIG. 1 is a block diagram of an automatic wiring computer system according to the present invention. The design information file l is a file on a magnetic disk that stores net information (coordinates of signal points, pin specifications, etc.), which is a collection of signal points (component pins, etc.) to be connected on a printed circuit board. Wiring rule file 2
is a file that stores information on constrained wiring lengths based on wiring rules, the average detour rate of printed patterns, and the average shortened length due to branching of wiring patterns. The automatic wiring system 3 is a program that determines a print pattern based on the network information of the design information file 1. The wiring rule consideration block 4 is a block that creates wiring rule countermeasure information for each net. The print pattern determination block 5 inputs the design information file 1.

This block determines the print pattern for each net. The wiring rule countermeasure information file 6 is a file that stores distribution, s, and i rule countermeasure information, such as whether branching is possible or not, and constrained wiring length for each net. The wiring pattern file 7 is a file that stores determined print pattern information (lines, pads, etc.).

Here, the wiring rule countermeasure information file 6 is created on a magnetic disk or on the main memory of a processing device (not shown).

The automatic wiring system 3 first extracts signal point information for one net from the design information file 1. Next, the extracted signal point information is divided into connection section units in the wiring rule consideration block 4, and it is determined whether or not wiring rule measures are necessary based on the distance of each connection section and the information in the layout 1 AM rule file 2. If so, wiring rule countermeasure information is created and output to the wiring rule countermeasure information file 6. Next, print pattern determination block 5
Then, a print pattern is determined using the information in the wiring rule countermeasure information file 6 and outputted to the wiring pattern file 7.

FIG. 2 is a processing flow of the wiring rule consideration block 4 and print pattern determination block 5 in FIG. Here, steps 1 to 3 are processing of the wiring rule consideration block, and step 4 is processing of the print pattern determination block.

FIG. 3 is a diagram showing a general network configuration on a printed circuit board stored in the design information file 1 of FIG. 1. The net is composed of source pin 8 (hereinafter referred to as S pin) which is a signal source, sink pin 9 and 10 (hereinafter referred to as pin) which is a load, and termination resistor pin 11 (hereinafter referred to as T pin). The net information includes the X and Y coordinates of the signal point and the source/sink/terminal resistance classification (pin specifications).

The operation of the present invention will be described in detail below, taking the net shown in FIG. 3 as an example and following the processing flow shown in FIG.

(1) Step 1 Niblint pattern length estimation Read signal point information constituting a net for one net from the design information file 1 shown in FIG. It is assumed that the signal points for one net read here are as shown in FIG. In fast logic, source.

Serial wiring (-written) is done in the order of sink and terminating resistor. For this reason, if the pin specifications are the same, it is necessary to determine the connection order, and this connection order is determined so that the overall printed pattern length is shortened.

In the case of FIG. 3, the order is sink pin 9→10, and the sink pin 9 will be called the 1st pin and the sink pin 10 will be called the 2nd pin. Next, find the shortest wiring length between each signal point as a perpendicular distance. Here, the perpendicular distance is defined as the distance between the pins 13 and 12 of one component in the X direction and the Y direction, as shown in FIG.
(coordinate difference). In the example shown in Figure 3, between S pin 8 and 1 pin 9, between 1 pin 9 and 2 pin 10.
Between, calculate the right angle distance between 2 pin 10 and T pin 11,
respectively fl sx+ t fl XlK1 Q +c
This is expressed as zT and is taken as the shortest wiring length.

Next, the print pattern length between each signal point is estimated using the following formula based on the average detour rate and the average shortened length due to branching of the wiring pattern.

Estimated print pattern length (wax) = Shortest wiring length x Average detour rate Estimated print pattern length (win) = Shortest wiring length - Average shortened length Here, what is the average detour rate? Detour rate = Print pattern length of connection section ÷ Connection section This is the shortest wiring length and can be easily determined from past automatic wiring results, and is set in advance in the automatic wiring system. Furthermore, when the wiring pattern branches, as shown in FIG. 5, the length of the printed pattern between the source 14 and the sink 15 is physically Q+ΔL, but becomes short to Q in terms of wiring rules. The average of this shortened ΔL is called the average shortened length, and this value can also be easily determined from past automatic wiring results and is set in advance in the system. It was obtained as described above. Estimated print pattern length (-
ax) to Q'SK"l, u::xz, QHIT
The estimated print pattern length (min) is Qsxl, R
Let x+xz, QK*r.

(2) Step 2: Step 1 to determine whether wiring regulation measures are necessary
Estimated print pattern length (max, win
) is compared with the constraint length on the wiring rules defined in the wiring rule file 2 shown in FIG. 1 to determine whether or not measures against the wiring rules are necessary. Details are shown below.

Among the wiring rule constraints for printed circuit boards, the following two items must be observed in automatic wiring.

■ Load spacing: Print pattern length between sink and sink ≧ Constraint length L1 ■ Net length: Print pattern length between source and final sink ≦ Constraint length L
2. Load spacing means, when there are multiple loads on the net, to provide a certain amount of time, or a certain distance, between one load and the next load in order to avoid the influence of signal waveform distortion caused by the previous load. In the example of FIG. 3, the load spacing is a constraint between K□ pin 9 and 2 pins 10,
The net length is a constraint between the S pin 8 and the two pins 10. Applying the above-mentioned wiring rule constraints to the example shown in FIG.

(Bago+Pa;÷2)>When the constraint length L2 or Pato<constraint length, it is determined that the wiring rule constraint is required.

Here, the constraint length is about 40 to 50 m1+, and the constraint length L2 is about 200 to 300 mm.

(3) Step 3: Creation of wiring rule countermeasure information To create wiring rule countermeasure information, prepare for load spacing, then prepare for net length, and finally allocate to connection sections.

(i) Countermeasure information creation case A for load spacing: Estimated print pattern length (win) + average shortened length ≧ constraint length L1. Branching not possible.

There is no wiring length restriction.

Case B: Estimated print pattern length (win) + average shortening and constraint length L1. Branching not possible.

Minimum wiring length 2 constraint length L1. Maximum wiring length: No length restrictions.

(ii) Create countermeasure information for net length branch possible, minimum wiring length = no restriction, maximum wiring length = restriction length L2.

(iii) Assignment of constraint information to connection sections.Whether or not the constraints on net length and load spacing can be divided for each connection section so as not to contradict each other.

Assign the wiring length.

For example, when the net shown in FIG. 3 does not satisfy both the net length and load spacing, the constraints are as shown in FIG. 6. This will be explained in detail below using the example shown in FIG.

The restriction between K1 pin 9 and 2 pin 10 cannot be branched.

Minimum wiring length = constraint length, which is uniquely determined. Regarding the maximum wiring length, it is not necessary between K□ pin 9 and 2 pins 10, but it is necessary to determine the maximum wiring length between S pin 8 and 2 pins 10 because there is a restriction on the maximum wiring length. Wire length = minimum wire length α.

This α is a margin value, and is usually 5IIl! It is about 1.

Next, the connection between the S pin 8 and the two pins 10 will be described. It is possible to branch between these signal points, but it is not possible to branch between K1 pin 9 and 2 pin 10.
It is contradictory that it is possible to branch between.

Therefore, it is not possible to branch between the S pin 8 and the two pins 10.

The constraint between S pin 8 and 2 pins 10 is 2 between K1 pin 9 and
Since the distance between pins 10 is determined as described above, S pin 8
All you have to do is decide on 1 bin and 9 intervals.

The constraints between S pin 8 and shrimp 29 are: branching is not allowed, minimum wiring length = no constraint length, maximum wiring length = constraint length L2 - constraint length L1
−α. The branching availability, minimum wiring length, and maximum wiring length thus determined are output to the wiring rule countermeasure information file 6 of FIG.

(4) Step 4 Print pattern determination Read the branchability and wiring length constraints from the wiring rule countermeasure information file 6 shown in FIG. 1, and determine the print pattern according to the following.

Case A: Case 6 without countermeasure information A well-known automatic wiring algorithm (maze method).

The print pattern is determined using a line segment search method, etc.

Case B: Branching is not possible and there are no wiring length restrictions.

A known automatic wiring algorithm is used to determine a print pattern that does not allow branching.

Case C: No minimum wiring length restriction, maximum wiring length restriction.

After determining the printed pattern route using a well-known automatic wiring algorithm, it is checked whether the wiring length is within the maximum wiring length, and if it is, the route is deleted and a route that satisfies the maximum wiring length is found. Repeat the process until.

Case C: Minimum wiring length constraint.

The publicly known automatic wiring algorithm “Special Publication No. 63-131
77: Determine the printed pattern using the detour wiring shown in "Printed board wiring method".

The print pattern determined as described above is output to the wiring pattern file 7 shown in FIG.

As described above, according to this embodiment, a print pattern can be determined taking into consideration the net length and load spacing, which are the wiring rules to be followed in an automatic wiring system.

〔Effect of the invention〕

As explained above, according to the present invention, after automatically extracting nets with a high possibility of a wiring rule error occurring, wiring rule countermeasure information corresponding to the error content is created, and automatic wiring is performed while following this countermeasure information. This can prevent wiring rule errors. This makes it easy to design printed patterns for printed circuit boards that require high-speed operation.
This has a great effect on shortening the development period.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an automatic wiring computer system that takes into account wiring rules, which is an embodiment of the present invention. FIG. Figure 4 is a diagram that explains the perpendicular distance, Figure 5 is a diagram that explains how the printed pattern length is shortened by branching the wiring pattern, and Figure 6 is a diagram that shows an example of the net in Figure 3. FIG. 7 is a diagram illustrating an example when two pieces of wiring rule countermeasure information are given. 1...Design information file, 2...Wiring rule file, 3...Automatic wiring system, 4...Wiring rule consideration block, 5...Print pattern determination block. 6...Wiring rule countermeasure information file, 7-.Wiring pattern file, 8...Signal point (source pin), 9...Signal point (sink pin), 10...Signal point (sink pin), 11.Signal point (terminal resistor pin), 12... signal point (component pin), 13... signal point (component pin). 14...Signal point (source pin). 15...Signal point (sink pin). 16...Signal point (terminal resistor pin). Arithmetic 2 Diagram wa wa jima square right angle distance = 1χ 1 pi

Claims (1)

[Claims] In an automatic wiring program using a computer that creates wiring pattern information from a design information file that stores net information, the net information is read from the design information file, the shortest distance between each signal point of the net is calculated, and the shortest distance and the preset distance are calculated. A first step of estimating the print pattern length based on the average detour information of the print pattern and the average shortening information of the print pattern due to branching, and whether the estimated print pattern length satisfies the constraint length of the wiring rule. ,
The second step is to determine if the constraint length determined by the wiring rules is not satisfied, and the third step is to decide whether or not to branch, and to determine the minimum and maximum values of the wiring length constraints of the printed pattern.
The fourth step is to determine the route of the printed pattern while observing the branchability and wiring length constraints determined by the above-mentioned step and the third step.
An automatic wiring method comprising the following steps, and characterized in that wiring rule errors are prevented by executing the above steps in order.