Board DRC - Supposed to Generate Errors/Warnings on Unrouted Nets?

On 09/10/10 20:56, Michael Sansom wrote:

I just noticed that I have two unrouted nets on my board layout (i.e.

the ratsnets lines are visible but no copper tracks connect) and the DRC

isn't generating any errors/warning.  Is this correct?  What am I doing

wrong, I've never seen a DRC that wouldn't flag unrouted signals.

If the DRC were to warn about unrouted signals, it would ave to

run a complete RATSNEST (including processing all polygons) every

time the DRC is run. Clearly this is not desirable.

Klaus Schmidinger

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Klaus Schmidinger                       Phone: +49-8635-6989-10

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Klaus Schmidinger wrote on Mon, 13 September 2010 03:38

On 09/10/10 20:56, Michael Sansom wrote:

I just noticed that I have two unrouted nets on my board layout

(i.e.

the ratsnets lines are visible but no copper tracks connect) and

the DRC

isn't generating any errors/warning.  Is this correct?  What am I

doing

wrong, I've never seen a DRC that wouldn't flag unrouted signals.

 

If the DRC were to warn about unrouted signals, it would ave to

run a complete RATSNEST (including processing all polygons) every

time the DRC is run. Clearly this is not desirable.

I'm not sure it's so clear.

I think that there are actually two usage cases for the DRC:

a quick test at design test to make sure that the just placed features

don't create design rule issues

a complete test a design review time to ensure that the board that is

manufactured meets the intended design criteria

There may be more usage cases.

What I would like to see is the ability to configure the DRC engine to turn

on and off a bunch of different checks.  So for the first case above I

would care about things like clearances and trace widths, etc but not

things like off-angle, text and mask clearances, ...  And because I do that

so often it would save me a huge amount of time.

However, for the second case I definitely want to know if there is a signal

not routed--that board isn't going to be manufactured to the intention of

the schematic.  And if this takes 3 minutes I don't really care--thorough

is good in this case.  And it should also run the ERC as well since this is

pertinent information.  Think of a board design review--any information

that you'd want to see there should be in the report.

Maybe you could pass a DRC configuration name to the command and it would

run with those settings.  Then we could have numerous different levels of

DRC checking.  And there should be a switch to run on all layers no matter

what is displayed.

Altium has a similar feature where they have a configuration window where

you can turn off individual checks in both their online DRC and the batch

DRC.  That's sort of the idea but why not make it more generic so that the

user can just create a configuration and run it--no need to limit to 2.

The other big shortcoming of the DRC is that there is no reporting facility

other than on-screen display.  A typical design review process would be to

attach the DRC report from the CAD tool for a record of any issues that the

CAD tool had flagged (preferably none).  It should show the name of the

design, the timestamp of when the test was run, and a list of all the

errors and warnings (approved or otherwise).

It would be good for the CAM processor to create its own report as well

since that is as much of the design process as anything else--any error or

warning there could mean the board won't work too.

Cheers,

James.

--

James Morrison  ~~~  Stratford Digital

Specializing in CadSoft EAGLE

• Online Sales to North America

• Electronic Design Services

• EAGLE Enterprise Toolkit

--

Web access to CadSoft support forums at www.eaglecentral.ca.  Where the CadSoft EAGLE community meets.

On 9/13/2010 5:19 PM, James Morrison wrote:

Klaus Schmidinger wrote on Mon, 13 September 2010 03:38

>> On 09/10/10 20:56, Michael Sansom wrote:

>> > I just noticed that I have two unrouted nets on my board layout

>> > (i.e.

>> > the ratsnets lines are visible but no copper tracks connect) and

>> > the DRC

>> > isn't generating any errors/warning. Is this correct? What am I

>> > doing

>> > wrong, I've never seen a DRC that wouldn't flag unrouted signals.

>>

>> If the DRC were to warn about unrouted signals, it would ave to

>> run a complete RATSNEST (including processing all polygons) every

>> time the DRC is run. Clearly this is not desirable.

>

>

I'm not sure it's so clear.

>

I think that there are actually two usage cases for the DRC:

>

>

a quick test at design test to make sure that the just placed features

don't create design rule issues

a complete test a design review time to ensure that the board that is

manufactured meets the intended design criteria

>

>

There may be more usage cases.

>

What I would like to see is the ability to configure the DRC engine to turn

on and off a bunch of different checks. So for the first case above I

would care about things like clearances and trace widths, etc but not

things like off-angle, text and mask clearances, ... And because I do that

so often it would save me a huge amount of time.

>

However, for the second case I definitely want to know if there is a signal

not routed--that board isn't going to be manufactured to the intention of

the schematic. And if this takes 3 minutes I don't really care--thorough

is good in this case. And it should also run the ERC as well since this is

pertinent information. Think of a board design review--any information

that you'd want to see there should be in the report.

>

Maybe you could pass a DRC configuration name to the command and it would

run with those settings. Then we could have numerous different levels of

DRC checking. And there should be a switch to run on all layers no matter

what is displayed.

>

Altium has a similar feature where they have a configuration window where

you can turn off individual checks in both their online DRC and the batch

DRC. That's sort of the idea but why not make it more generic so that the

user can just create a configuration and run it--no need to limit to 2.

>

The other big shortcoming of the DRC is that there is no reporting facility

other than on-screen display. A typical design review process would be to

attach the DRC report from the CAD tool for a record of any issues that the

CAD tool had flagged (preferably none). It should show the name of the

design, the timestamp of when the test was run, and a list of all the

errors and warnings (approved or otherwise).

>

It would be good for the CAM processor to create its own report as well

since that is as much of the design process as anything else--any error or

warning there could mean the board won't work too.

>

Cheers,

>

James.

>

I would vote for real time flagging of clearance and width issues rather

than running DRC on small areas.

And to not lose sight of my main point, DRC report, when there are no

errors found, should at least mention that RATS has not been run since

the last change and that some layers were not checked.

On 9/13/2010 5:19 PM, James Morrison wrote:

Klaus Schmidinger wrote on Mon, 13 September 2010 03:38

>> On 09/10/10 20:56, Michael Sansom wrote:

>> > I just noticed that I have two unrouted nets on my board layout

>> > (i.e.

>> > the ratsnets lines are visible but no copper tracks connect) and

>> > the DRC

>> > isn't generating any errors/warning. Is this correct? What am I

>> > doing

>> > wrong, I've never seen a DRC that wouldn't flag unrouted signals.

>>

>> If the DRC were to warn about unrouted signals, it would ave to

>> run a complete RATSNEST (including processing all polygons) every

>> time the DRC is run. Clearly this is not desirable.

>

>

I'm not sure it's so clear.

>

I think that there are actually two usage cases for the DRC:

>

>

a quick test at design test to make sure that the just placed features

don't create design rule issues

a complete test a design review time to ensure that the board that is

manufactured meets the intended design criteria

>

>

There may be more usage cases.

>

What I would like to see is the ability to configure the DRC engine to turn

on and off a bunch of different checks. So for the first case above I

would care about things like clearances and trace widths, etc but not

things like off-angle, text and mask clearances, ... And because I do that

so often it would save me a huge amount of time.

>

However, for the second case I definitely want to know if there is a signal

not routed--that board isn't going to be manufactured to the intention of

the schematic. And if this takes 3 minutes I don't really care--thorough

is good in this case. And it should also run the ERC as well since this is

pertinent information. Think of a board design review--any information

that you'd want to see there should be in the report.

>

Maybe you could pass a DRC configuration name to the command and it would

run with those settings. Then we could have numerous different levels of

DRC checking. And there should be a switch to run on all layers no matter

what is displayed.

>

Altium has a similar feature where they have a configuration window where

you can turn off individual checks in both their online DRC and the batch

DRC. That's sort of the idea but why not make it more generic so that the

user can just create a configuration and run it--no need to limit to 2.

>

The other big shortcoming of the DRC is that there is no reporting facility

other than on-screen display. A typical design review process would be to

attach the DRC report from the CAD tool for a record of any issues that the

CAD tool had flagged (preferably none). It should show the name of the

design, the timestamp of when the test was run, and a list of all the

errors and warnings (approved or otherwise).

>

It would be good for the CAM processor to create its own report as well

since that is as much of the design process as anything else--any error or

warning there could mean the board won't work too.

>

Cheers,

>

James.

>

I would vote for real time flagging of clearance and width issues rather

than running DRC on small areas.

And to not lose sight of my main point, DRC report, when there are no

errors found, should at least mention that RATS has not been run since

the last change and that some layers were not checked.

"Gary Gofstein" <nospam@use.forum.net> wrote in message

news:i6onrq$sor$1@cheetah.cadsoft.de...

I would vote for real time flagging of clearance and width issues rather

than running DRC on small areas.

That would be very nice.

And to not lose sight of my main point, DRC report, when there are no

errors found, should at least mention that RATS has not been run since the

last change and that some layers were not checked.

Amen! Good summary.