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Snap to Trace End and Snap to pad

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14 comments

  • Gerald Thompson

    It would seem most logical if when a track is drawn to a pad it just always snaps to the centre of the pad if that is necessary.  Why go anywhere else?  Or else just leave it alone - ie. if it's anywhere in the pad then leave it alone and don't add dangles...  Seems like there is something unnecessary going on to cause these problems... :(

    I tried out another PCB program and this stuff just never happened. 

    Seems unique to DS.

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  • Darren Conway

    Hi

    Right now I am struggling to insert a via in a track to connect the track to the ground plane using the "Add Unrouted Connection".

    I have deleted the section of track I wanted to insert the via into. 

    I then used the "Add Unrouted Connection" to connect the via to the two track ends.  No problem.

    Trying to complete the connection when there are a lot of other features nearby was finicky.  Using "N" got me to the thin line but when I finished laying the track the thin line remained, indicating to me that the track was there but did not replace the thin line.

    I am able to use the "Add Unrouted Connection" feature but it would be so much easier if the there was a snap feature.

    Most of my dangling tracks occur when I try and clean up after shifting a component.   The hardest ones to find are very short tracks within a pad area.  I can't find a way of turning off the pad displays to see the tracks.

    A feature to delete all dangling tracks would be helpful.

    I am currently working my way through the error report.  A lot of my errors are because I missed the connection point of the pad when routing or editing tracks.

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  • Gerald Thompson

    " delete all dangling tracks"   Makes perfect sense...  In fact (cleaning up after the mess) should just not be necessary...  :)

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  • Darren Conway

    Agreed. 

    Having a snap feature that would allow sensible routing to pads with sub-grid x,y locations would avoid the need for working with very fine grids.  It is super annoying to have tiny lengths of track within a pad. 

    Can't see them.  Hard to find.  Hard to fix.

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  • Darren Conway

    So after using the "Add Unrouted Connection" for a bit, I found that it works but has some nasty behaviours.

    If it is used to manually route two pads that are not perfectly aligned in the X or Y axis, it will create a very short track centered on one pad. This means the track is not centred when it lands on the pad. 

     

    It would be a big improvement if that first track segment defaulted to the edge of the pad as illustrated in the exaggerated drawing below.

    I found an annoying behaviour when setting this up.  If I click on the edge of the pad, the track jumps to the centre of the pad as seen below.

    I then have to manually edit the track to get it right. 

    I have a good reason to lay that first track to the edge of a pad.  If I want to connect a  1mm track to a .5mm wide rect pad, that can be done with a short thin track to the pad edge, then the wide track from then on.  This is illustrated below where the short track from the pad centre to the edge allows a fat track, wider than the pad, without overshoot out the other side of the pad.

    A track segment ending at the pad edge would be a lot easier to find and edit.

    Other things that annoy me:

    There doesn't appear to be an option for tracks to snap to 45degree increments.

    The "Add Unrouted Connection" won't connect to an existing track corner to create a T or Y.  I get around this by deleting a track segment.  The "Add Unrouted Connection" will then connect to the hanging track end.  I then redraw the deleted segment. 

    In summary I have found a few behaviours of "Add Unrouted Connection" greatly increase the time to manually lay and then edit tracks.  The unwanted creation of dangling tracks and the creation of very short, almost invisible tracks on pads are very frustrating and greatly increase work. 

    Other than that, I have found the software easy to learn and use.

     

     

     

     

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  • Boss .

    Just saw this post.

    Not sure I follow all the points, but I find the placing of tracks snaps nicely to the centre of pads.

    Here is a quick test circuit with a 0.1" pitch component 'on grid' and smd 'off grid'

    The smap to grid is a sensible setting - never go to fine which approaches gridless and I believe may cause dangling tracks as you can create extremely small stubs.

    In the image I just clicked on the airwire and routed the track to the smd which connects to centre of the pad.

    Are you doing anything differently?

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  • Boss .

    Looking back over this discussion, do not use fine grids, choose and use something appropriate to the task.
    I tend to set the grid at the component pitch and snap at half or a quarter grid.

    I also change the settings if I swap from from a through hole design or an SMD area, but as shown in previous post you can leave the grid 'course' and still track to a fine pad.

    I see a commonent on 45 degree tracks, if that relates to the 45 degree examples as I posted previously, this is "Segment Mode" and discussed here.  https://designspark.zendesk.com/hc/en-us/articles/211645369-How-do-I-place-tracks-on-my-PCB-with-different-features- 

    Try to post single topics to allow easier understanding and post them in "Discussions", many users have a short cut directly there -   I do :)   , so may not see "New feature requests".

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  • Gerald Thompson

    Your example does not have any tracks running between pads.  I think I've mentioned before that to run a track at an even distance between two pads on a component you often need a finer snap setting - or else you get something like this. ( Grid set to 0.1" with quarter grid snap mode.)

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  • Darren Conway

    Hi

    I am very fussy on PCB design.  The following images shows tracks I routed on the left.  Autoroute to the right.

    The autoroute might be electrically correct and in compliance with the rules, but from my point of view, unacceptable. 

    I note there is a  report on dangling tracks.  It would be really helpful if there was a report that listed the individual track segments in order from the shortest to the longest.  This would be a big help to clean up a layout.

    Dazz

     

     

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  • Boss .

    @Gerald, Sorry didn't see any mention of tracks between pads, I thought the snap to pin centre was the issue.

    The issue you describe is off grid pads. As shown below with a grid matching the pad pitch and a snap to grid of a half the track placement is not possible. Using a finer grid can work but the best cure is to align the grid to the pads.

     

    The grid is aligned with the System Origin point. So to align the grid with the pads, click on a pad to highlight, right click and select "Origin --> Set System Origin at item"

     

    The grid will now be aligned.
    Here I have 100 thou grid and snap to grid of a half. You can now place tracks between the pads and as shown as your routing approaches the fine pitch SMD with off grid pads the track snaps to the pad centre.

     

    Routing the other tracks gives the same result.

    In Summary. Use a course grid and match it to the component pad pitch so all components are ‘on grid’ at the start of your design.
    At any time you change grid, just realign as required with the System Origin, but avoid fine grids unless they are essential for the task.

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  • Darren Conway

    Hi

    20 years ago nearly every component I used fitted on a 0.1" grid.   I only used SMDs for special applications (RF).  I routed on a 25mil grid and auto-routing provided a reasonable layout.

    Now I find that pin(pad) pitches are both metric and imperial and SMDs don't ft on any grid.  The EDA models for the same package (eg. 0805) are subtly different from different suppliers with slightly different pitches.     Autorouting no longer produces an acceptable solution (example posted above). 

    The boards I have been designing have a mix of connectors, passives and semiconductors with imperial and metric pitches.   They will not fit on any grid.  I have quickly found that off-grid tracks and pads are now the norm.

    The problems I am having are:

    the creation of dangling tracks that are often hidden inside pads and are difficult to detect

    the creation of ultra-short track segments where they are not wanted (eg. inside pads or at track segment junctions).

    The absence of features to prevent these problems. 

    For example, I want to be able to string a pad to a junction as illustrated below.   Without the feature to string between a pad and a off-grid  track segment junction I have to go through a whole load of key strokes, including manually finding and entering the coordinates of the track segment junction, to make a a simple connection between a pad and a track junction. 

    What should take a few seconds takes me a minute or two.  It doesn't take long for that to add a whole lot of time and effort to the design.

     

    Another example is shown below from a board that features imperial 0.1" pitch connectors and metric 2mm pitch connectors on a metric grid.  The routine task of running a track off-grid between pads again takes a whole lot of key strokes to centre the track.  There are no tools to aid this (eg. the ruler does not show the x,y coords of the points being measured).  I end up writing details down on paper.  Again something that should take seconds takes a minute or two.

    My re-entry to PCB design has been an infuriating experience because of the absence of a few simple tools to make manual off-grid design easier.  These include:

    • A tool to snap tracks through the centre of two identified features (eg, tracks, pads, copper)
    • Enhancing the string tool to allow a link to the junction of track segments as illustrated above.
    • Adding display of the x,y coordinates measured by the ruler tool.
    • Adding display of the x,y coords of the mid way point measured by the ruler tool
    • A report that allows easy finding of ultra-short track segments.
    • A Delete All Dangling Tracks feature.
    • An option that prevents creation of a track segment that ends within a pad.  Enabling this setting would snap a segment to the pad centre and then snap to the edge of the pad. This would fix some problems with auto-routing as well.  

    This last point is illustrated below.  This feature should allow the user to override the pad edge snap on a pad-by-pad basis.  In my experience, it is uncommon to want/need to have a track segment within a pad.

     

    On the whole I have found DS-PCB to be a good application.  If I could still work to a 0.1" grid, it would be fantastic.  I have quickly found that modern SMDs won't fit any grid.  That makes manual editing off-grid a normal requirement.  At present it takes me way too many key strokes and too much time to do simple changes.  As I see it, the addition of a small number of tools would greatly enhance the usability of DS-PCB to manually route and edit off-grid tracks. 

     

     

     

     

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  • Gerald Thompson

    Thanks - changing the grid reference makes sense.  But as above looks like some components might still have issues? 

    For example try routing a DsuB board mounted connector!  The distance between pins is .109 inches or 2.7686 mm.  Once I twigged though, I set the grid size to this odd distance.

    Be nice if this could somehow be avoided some other way like auto-guiding the track when drawing between adjacent pads on a component - but that might be getting a bit fancy?  :)

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  • Boss .
    • A tool to snap tracks through the centre of two identified features (eg, tracks, pads, copper)
      That would be nice.
    • Enhancing the string tool to allow a link to the junction of track segments as illustrated above.
      I'll examine this later.

    • Adding display of the x,y coordinates measured by the ruler tool.
      This is available if you are not snapping to the component or grid and use the "Report" button.

    • Adding display of the x,y coords of the mid way point measured by the ruler tool

    • A report that allows easy finding of ultra-short track segments.

    • A Delete All Dangling Tracks feature.
      Agree, I requested this with support, delete all dangling tracks within a pad.

    • An option that prevents creation of a track segment that ends within a pad.  Enabling this setting would snap a segment to the pad centre and then snap to the edge of the pad. This would fix some problems with auto-routing as well.
      I don't see this as an issue as a track is copper as is the pad, so the Gerber files will be identical. Also as the CAD system supports a Photoplotter the track end is semicircular and has to end within the pad to avoid backoff errors.
      The autorouter pad entry is a separate issue which I have discussed with support and relates to 'side pad' entry issues. Turning the side pad entry off can actually give better results especially with selective autorouting of tracks. I tend not to use the autorouter but it can be 'helped' if you fanout the pads with short stubs which I tend to do when manually routing.

    Have you invetigated "Sketch Track", that was new to V6 or 7 I think and once you get used to it offers some nice features. Lots in Help.

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  • Darren Conway

    Hi

    • Adding display of the x,y coordinates measured by the ruler tool.
      This is available if you are not snapping to the component or grid and use the "Report" button.

    The Reports done give me the info is a format I can use.  With DSPCB I find that I am routinely writing down x,y coords, or typing them into the manual coords feature.  Other CAD programs I have used include a scratch pad feature that acts like a pad of paper from where x,y coords can be stored on a table and dragged to other places, like manual x,y entry.  One click and drag then dumps the x,y coord into the manual x,y entry field.

     

    • Adding display of the x,y coords of the mid way point measured by the ruler tool.

    Other CAD programs (non-PCB)I use all include this and a whole lot more.   Running track(s) between other objects is so routine in PCBs,it should be very easy to do.

    • A report that allows easy finding of ultra-short track segments.
      If there are tracks that are 0.2mm long (say), that probably indicates a problem with the layout.
    • A Delete All Dangling Tracks feature.
      Agree, I requested this with support, delete all dangling tracks within a pad.

    • An option that prevents creation of a track segment that ends within a pad.  Enabling this setting would snap a segment to the pad centre and then snap to the edge of the pad. This would fix some problems with auto-routing as well.
      I don't see this as an issue as a track is copper as is the pad, so the Gerber files will be identical. Also as the CAD system supports a Photoplotter the track end is semicircular and has to end within the pad to avoid backoff errors.
      The autorouter pad entry is a separate issue which I have discussed with support and relates to 'side pad' entry issues. Turning the side pad entry off can actually give better results especially with selective autorouting of tracks. I tend not to use the autorouter but it can be 'helped' if you fanout the pads with short stubs which I tend to do when manually routing.

    A feature that snapped a track to the pad centre, then offered a snap point on the edge of the pad at 45degree angles(or whatever was in the Tech file) from the pad centre would prevent a lot of problems with dangling tracks and very short tracks.

    Have you invetigated "Sketch Track", that was new to V6 or 7 I think and once you get used to it offers some nice features. Lots in Help.

    I have now. I   like it.

    My problem is that I have used other CAD programs (non PCB) that include features that would make DSPCB so much easier to use. 

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