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 Jumpers - and how to short them 

Last post Mon, Jan 21 2013 5:23 AM by mcatramb91. 6 replies.
Started by TH Designs 18 Jan 2013 06:11 AM. Topic has 6 replies and 1451 views
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  • Fri, Jan 18 2013 6:11 AM

    • TH Designs
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    Jumpers - and how to short them Reply

    A lot of times, especially for prototype circuits, I'll have to include a jumper in a trace. This jumper would have two through hole pads separated by 0.1" and tied together with a copper trace that could be cut  during circuit debug / development. Coming from layout, I had a symbol with the two pads and used the "detail" obstacle to create the copper trace between the pads. This worked very well and dod not give me any errors.

    That same symbol, now converted to 16.6, gives me DRC's as it sees the trace between the two pads as a short. I sould mention that the schematic symbol is simply two opposing pins with circles and a line between them "symbolizing" the short, there is no real wire connection between the two pins on the schematic. (thus the DRC).

    I was wondering how to approach this in 16.6. Could I edit the symbol and put the trace on some alternate layer / class like board geo or pkg goe and then include that class in the gerber generation? I have tried a few things but have had no success, looking for ideas or how thers may have approaced a similar situation.

      


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  • Fri, Jan 18 2013 6:27 AM

    • fxffxf
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    Re: Jumpers - and how to short them Reply

    You could try using the jumper feature. The easiest place I found that describes the feature is the Whats Net in Release 16.3. You can get to that by going to Cadence Help, Whats new for 16.6, then Whats new Older Release. I pasted the doc below.

     

    Jumpers

    The use of a wire jumper is sometimes necessary on single-layer PCBs to continue the route over a group of signals; hence the term jumper.

    This release offers the following methodology to support jumpers in the Etch Edit environment:

    1.
    Create a package symbol that must consist of two vias.
     
    ParagraphBullet
    Enable Jumper option in Design Parameter -- Design form (Drawing Type section). of the package symbol drawing.
    2.
    Assign the JUMPER_LIST property to the board. This is a drawing level property.
     
    ParagraphBullet
    The value of the JUMPER_LIST property is a string of valid jumper symbol names.
    3.
    When in Add Connect, right-click and choose Add Jumper to add jumper symbol while routing.
    Note: The pop-up menu lists the jumper names stored as drawing properties. Ones that are grayed out either do not exist as a symbol or are not in PSMPATH.

     

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  • Fri, Jan 18 2013 11:06 AM

    • TH Designs
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    Re: Jumpers - and how to short them Reply
    fxffxf:

    You could try using the jumper feature. The easiest place I found that describes the feature is the Whats Net in Release 16.3. You can get to that by going to Cadence Help, Whats new for 16.6, then Whats new Older Release. I pasted the doc below.

    Jumpers

    The use of a wire jumper is sometimes necessary on single-layer PCBs to continue the route over a group of signals; hence the term jumper.

    This release offers the following methodology to support jumpers in the Etch Edit environment:

    1.
    Create a package symbol that must consist of two vias.
    ParagraphBullet
    Enable Jumper option in Design Parameter -- Design form (Drawing Type section). of the package symbol drawing.
    2.
    Assign the JUMPER_LIST property to the board. This is a drawing level property.
    ParagraphBullet
    The value of the JUMPER_LIST property is a string of valid jumper symbol names.
    3.
    When in Add Connect, right-click and choose Add Jumper to add jumper symbol while routing.
    Note: The pop-up menu lists the jumper names stored as drawing properties. Ones that are grayed out either do not exist as a symbol or are not in PSMPATH.


    This only seems to apply to a jumper used when routing a single sided board. When you have to "jump" over a trace, or group of traces as you manually route. You would route up to the group, then select add jumper, and then pick up on the other side of the group.

    I'm looking to use a library symbol that has two pins shorted which can be cut if needed during development. For now I will just short the two pins together on the schematic so the netlist has the two pins electrically connected while I work on a scheme similar to what I had done in Layout.

    The first picture is the schematic as drawn and goes with the snapshot of the board layout in the first post. The second picture is what I'm doing in the schematic to make it work while I work on a more elegant solution.

    Tom


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  • Fri, Jan 18 2013 11:10 AM

    • TH Designs
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    Re: Jumpers - and how to short them Reply
    Second picture (can't put two in one reply???)
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  • Fri, Jan 18 2013 11:16 AM

    • fxffxf
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    Re: Jumpers - and how to short them Reply

    It can be used to jump over traces since the trace that connects the 2 pins of the jumper is on a virtual layer and you can run traces that  fits between the 2 pins of the jumper symbol.

    • Post Points: 5
  • Fri, Jan 18 2013 8:26 PM

    • ScottCad
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    Re: Jumpers - and how to short them Reply

    Tom Allegro doesnt handle this very well. It is expecting to see one pin per net. Only way I know to do it is create a 2 pin symbol in capture that looks like a standard jumper and then short those two pins out with a wire in capture. Over on the board side you should be able to route those two pads on your jumper part together. Not ideal but the netlist will match the schematic.

    Only other way as you suggested is to use an alternate class layer and put a line between the 2 jumper pins/pads but chances are it might be easy to foregt to turn that layer on in the gerber creation, so no short..

     Thanks Scott

     

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  • Mon, Jan 21 2013 5:23 AM

    • mcatramb91
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    Re: Jumpers - and how to short them Reply

    What I have done in the past is to create a special symbol which has overlapping pads to form the short and to suppress the Pin to Pin DRC by added Symbol Drawing property "NODRC_SYM_SAME_PIN"

    Here is a summary of the steps:

    1. Create a two pin symbol using rectangular (or oval) padstacks with an offset to make the pads touch (overlap) to create the short.
    2. In the DRA Symbol, Pin 2 should be rotated by 180 degrees compared to Pin 1 with the center route point still clear to route to the pin.  Make sure the overlap zone is not near the center point (origin point) of the padstack so it doesn’t cause an issue when routing a trace to the pins.
    3. Add the Symbol Drawing Property "NODRC_SYM_SAME_PIN" (In DRA Symbol) using Edit > Property
            a. Change Find By Name in Find Filter to DRAWING then click the More Button.
            b. Select Drawing Select then Apply
            c. Select the property NODRC_SYM_SAME_PIN from the left pane to add it to the right pane then select Apply.
    4. Save off the .dra symbol and you are good to go.

    Hope this helps,
    Mike Catrambone

    • Post Points: 5
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Started by TH Designs at 18 Jan 2013 06:11 AM. Topic has 6 replies.