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eagle help

Vertex78Vertex78 Posts: 51
edited 2008-01-10 03:49 in General Discussion
When I choose an the 7404 hex inverter from the library and place it in a schematic it only gives me each of the inverter gates but not the power and ground. How do I get these put into the schematic?

Comments

  • James LongJames Long Posts: 1,181
    edited 2008-01-10 02:35
    Vertex78 said...
    When I choose an the 7404 hex inverter from the library and place it in a schematic it only gives me each of the inverter gates but not the power and ground. How do I get these put into the schematic?
    If your power and ground lines are named correctly (whatever the library is looking for) it will automatically be connected.

    This is a problem with the library. There is no standardization of the different ones, so you have to open the library and check to see what the part is looking for.

    Also be careful to check the pins to make sure they are laid out right. I have found parts that are wrong. Unfortunately for me...it was when·I went to assemble the board. I don't trust any part I didn't draw myself....I always double check now.

    James L


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    James L

    Partner/Designer
    Lil Brother LLC (SMT Assembly Services)
  • MarkSMarkS Posts: 342
    edited 2008-01-10 03:23
    Click on the 'Invoke' tool (bottom right tool, below 'Miter' and right of 'Split') and then click on one of the gates in the schematic. This will bring up a dialog box with several choices. You want the one that says "PWRN". Click on it and then press OK. You can now place the power gate anywhere on the schematic. This is also useful with multi-gate logic chips, where you want to use gates 1 and 3, for instance. The first gate placed will always be gate one and Eagle increments the gates by one with each click. Using the 'Invoke' tool allows you to use only the gates you'll need, which can sometimes be critical in tight PCB placements.

    Post Edited (MarkS) : 1/10/2008 3:28:31 AM GMT
  • James LongJames Long Posts: 1,181
    edited 2008-01-10 03:27
    MarkS said...
    Click on the invoke tool (bottom right tool, below 'miter' and right of 'split') and then click on one of the gates in the schematic. This will bring up a dialog box with several choices. You want the one that says "PWRN". Click on it and then press OK. You can now place the power gate anywhere on the schematic.
    Mark,

    Did I misunderstand the question?

    If I did ....I'm sorry.·· I know some chips in the library·have hidden power and ground pins.

    I didn't know of the method Mark mentions.

    James L

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    James L

    Partner/Designer
    Lil Brother LLC (SMT Assembly Services)
  • MarkSMarkS Posts: 342
    edited 2008-01-10 03:35
    James Long said...
    MarkS said...

    Click on the invoke tool (bottom right tool, below 'miter' and right of 'split') and then click on one of the gates in the schematic. This will bring up a dialog box with several choices. You want the one that says "PWRN". Click on it and then press OK. You can now place the power gate anywhere on the schematic.
    Mark,


    Did I misunderstand the question?



    If I did ....I'm sorry. I know some chips in the library have hidden power and ground pins.



    I didn't know of the method Mark mentions.



    James L

    I don't think you misunderstood the question, and you are partially correct. However, Eagle does not check the libraries, so using your method would force the designer to rely solely on the skill of the library's creator. This could also be a problem if the library used 'Vcc' for power and the chip requires 3.3v and the PCB designer designates 'Vcc' to be 5v. Eagle would create a net in the PCB editor automatically and the error might go unnoticed. Remember that Eagle is basically dumb. It only does checking by comparing strings. If you have the hot leg of a 120v AC circuit designated as 'Vcc' (you'd be pretty stupid to do so, but for the sake of argument...), Eagle will cheerfully create nets to any IC with a 'Vcc' pin.

    Post Edited (MarkS) : 1/10/2008 3:53:13 AM GMT
  • James LongJames Long Posts: 1,181
    edited 2008-01-10 03:45
    Mark,



    All valid points.

    I learned something from this thread. Didn't know you could place the hidden pins.



    James L

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    James L

    Partner/Designer
    Lil Brother LLC (SMT Assembly Services)
  • MarkSMarkS Posts: 342
    edited 2008-01-10 03:49
    Glad to help! You would not believe how long it took me to figure that out.
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