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Thread: Schematic question

  1. #1

    Schematic question

    Every time I'm making a custom board based on the PJRC schematics, I'm initially puzzled by the many unconnected "stubs" in the drawing (see enclosed image). They all look intentional, but they serve no purpose? Anyone know why they're there?

    Click image for larger version. 

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    Last edited by jensa; 02-03-2022 at 02:20 PM. Reason: No image uploaded?

  2. #2
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    Guessing: test points ??

  3. #3
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    I think so - the underside of each board has a number of small round pads, presumably for a bed-of-nails test fixture.

  4. #4
    Sounds obvious when you type it out? Makes perfect sense. Thanks!

  5. #5
    Senior Member PaulStoffregen's Avatar
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    I've added test point diagrams to the Teensy 4.0 and Teensy 4.1 pages.

  6. #6
    Cool. Now that I know why they're there - they are obviously a good reference when making custom boards for where you might want to have test points yourself. It's really nice to have them in the schematic, I just couldn't figure it out by myself. I'll publish my Kicad files on github for others to us after I've tested the boards, as I've done for T3.6 and T3.2.

  7. #7
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    Quote Originally Posted by jensa View Post
    I'll publish my Kicad files on github for others to us after I've tested the boards, as I've done for T3.6 and T3.2.
    Looking forward to this! I don't know if I will succeed in soldering a BGA though

  8. #8
    @Srx Shouldn't be hard if you have a hot-plate. Does not need to be big either. I used the MiniWare MHP30 (https://www.youtube.com/watch?v=JKlTd1B6Au8). It's tiny, but perfect for doing stuff like this & reflowing IC's.

    This reminded me that I had not published the files since they had a bug with the USB switch, but I guess I should just document that bug so here they are https://forum.pjrc.com/threads/70319...547#post306547
    Last edited by jensa; 05-23-2022 at 11:03 AM.

  9. #9
    Senior Member PaulStoffregen's Avatar
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    I've added a link to your github project page.

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