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Thread: T4.1 ethernet and usb host pin alignments/dimensions

  1. #1
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    T4.1 ethernet and usb host pin alignments/dimensions

    I think I've got this right but just wanted to get a quick review. Here is a drawing I've done. Any correction needed? I'm assuming all the pins are spaced 0.1"/2.54mm. I plan on making a board that would have the MagJack and USB host connectors on it so would solder (or socket) the T4.1 with all it's pins in place.
    Click image for larger version. 

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  2. #2
    Senior Member+ defragster's Avatar
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    Ethernet pins are not 0.1" spacing. Check the Beta T_4.1 thread to see for sure but it uses this :: Header, 3x2, 2mm pitch Digikey 1849-1000-ND

    for ref : oshpark Teensy 4.1 Ethernet

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    I believe the spacing of the pins on the ethernet connector is 2mm, not 2.54mm.

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    Senior Member blackketter's Avatar
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    Yes, the ethernet connector 2mm spacing and is centered between pins 20 and 21. It also has smaller holes, appropriate for the smaller 2mm pins.

    Also, I believe that the vertical (in your drawing) distance between the centers of the USB Host and outside pins is 3mm, not 2.54mm. The pins in that line are offset by 1.27mm as you show.

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    Thanks guys. Very helpful! I looked at the 4.1 beta thread and see discussion about the 2x3 2mm spacing header but nothing about the positioning of that header on the T4.1 (though it's a long thread so I might have missed it). It looks like it is X aligned (X as in my drawing) between pins 20 and 21. Still not sure about the Y alignment. Looking closely at the photo and measuring it, it appears the center line of the top two holes of the 2x3 header is 2.4mm from the line defined by the center points of pins 20 and 21. See updated drawing. I replaced the header with a 2x3 2 mm spaced one. Hoping someone can verify the 2.4 mm spacing as the photo I measured it from is pretty low resolution. I will fix the hole size once I get the spacing correct (though larger holes might save slight misalignment...).
    Click image for larger version. 

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  6. #6
    Senior Member blackketter's Avatar
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    That matches what I've measured with my (cheap) calipers. Here's a high(ish) resolution photo of my beta board front:

    Click image for larger version. 

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  7. #7
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    Thanks! Based on your photo, I think it's 2.5 mm. The ruler is extra helpful. That's into splitting hairs territory but hey, when ya got 'em, split 'em.

  8. #8
    Senior Member PaulStoffregen's Avatar
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    I can confirm the center coordinates for these connectors:

    USB Host: 500, 170

    Ethernet: 600, 475

    These are in mils (1/1000 inch), relative to the bottom left corner of the PCB.

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    Many thanks Paul. Would it be possible to give the dimensions relative to the centre of pin D32 (bottom left hand corner of the Teensy 4.1) as the edge of the board isn't an absolute co-ordinate for those of us making a pcb footprint.
    Also can I assume that the row of pins running from 38 to 27 follow the same convention as the Teensy 4.0. i.e. Vbat, 3.3V GND, Program, On/Off

  10. #10
    @PhilB - just FYI, there's a related thread - https://forum.pjrc.com/threads/60846...Ethernet-board

    plus

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    https://www.mouser.com/ProductDetail...aYqXdbGAlwg%3D

    and

    https://forum.pjrc.com/threads/60846...l=1#post238950

    Are you planning to have the shield match the 18mm width of the Teensy and locate the RJ45 and USB A on the same side/in the same plane as the on-board micro USB?
    Is that even remotely possible (willing to sacrifice pins)?

    Asking for the friend of a friend

  11. #11
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    board

    Quote Originally Posted by b2020 View Post
    @PhilB - just FYI, there's a related thread - https://forum.pjrc.com/threads/60846...Ethernet-board

    plus

    Name:  0820-1X1T-00-F_SPL.jpg
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    https://www.mouser.com/ProductDetail...aYqXdbGAlwg%3D

    and

    https://forum.pjrc.com/threads/60846...l=1#post238950

    Are you planning to have the shield match the 18mm width of the Teensy and locate the RJ45 and USB A on the same side/in the same plane as the on-board micro USB?
    Is that even remotely possible (willing to sacrifice pins)?

    Asking for the friend of a friend


    If you get to the board stage, I'd be getting a couple of them,

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    Hmmm, interesting idea. I'm currently working on a CNC breakout board for grblHAL (32bit ARM version of the now-long-in-the-tooth grbl that runs on plain old arduinos). It does have an ethernet jack on it. Current status is I have first PCBs back, soldering on components (taking a break to catch up on email and such).

    But the various comments made me go look at the idea of daughterboard for the 4.1 that supports both USB and ethernet jacks. Mechanical support is a concern - stress from two wires plugged in could easily overwhelm the 11 pins, even if soldered. The width issue is another one but moving the jacks forward or back might allow a slim fit.

    Another thing I'm worried about is interference between the T4.1 and magjack. The literature is full of warnings about not running traces under the magjack. A bit of standoff might mitigate any problems. Worth trying.

    I took a shot at a layout but am not happy with it. Needs some rework. Will probably have some time in the next couple of days - rain is predicted and the "honey-do" list is mostly outside...

  13. #13
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    Quote Originally Posted by b2020 View Post
    @PhilB - just FYI, there's a related thread - https://forum.pjrc.com/threads/60846...Ethernet-board

    plus

    Name:  0820-1X1T-00-F_SPL.jpg
Views: 746
Size:  5.2 KB
    https://www.mouser.com/ProductDetail...aYqXdbGAlwg%3D

    and

    https://forum.pjrc.com/threads/60846...l=1#post238950

    Are you planning to have the shield match the 18mm width of the Teensy and locate the RJ45 and USB A on the same side/in the same plane as the on-board micro USB?
    Is that even remotely possible (willing to sacrifice pins)?

    Asking for the friend of a friend
    By the way, the datasheet on that makes me think it's a passive RJ45, no magnetics. I might go spelunking mouser/digikey...

  14. #14
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    I found one that might work. The Bel 530-0821-1X1T-36-F

    Did a quick layout but there are issues using it for a daughter card atop the T4.1:
    - it needs to be a bit wider than the T4.1 (850 vs 700 mils). It might be possible to squeeze another 50 mils or so...
    - if the jack is mounted forward of the USB and 6 pin ethernet connectors (to the left in the 4.1 card view), the card needs to be high enough above the T4.1 to provide clearance to a plug in the microUSB connector. - probably 300 mils or more. Not sure how sturdy that would be.
    - if the jack is mounted behind (to the right of) the connectors it forces the card to be wider because you don't want to route signals under the magjack. (might not be true with this connector because the USB receptacle is at the bottom of the stack - anyone have thoughts on that?)

    Anyway, this was a good exercise for me as I am thinking about adding it as a version of my T4.1 grblHAL breakout board to allow a USB based pendant for CNC control. I have an eagle lib device is anyone is interested.
    Click image for larger version. 

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    Last edited by PhilB; 05-31-2020 at 03:59 AM.

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