Extra bypass caps on ethernet traces on Smoothieboard?

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John deGlavina

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Jun 10, 2020, 6:47:33 PM6/10/20
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I'm just curious why some extra bypass caps were added to the Smoothieboard design on the Ethernet traces? Was there some additional noise coming in from the stepper drivers? Specifically C49, C52-C57.
smoothie_bypass_caps.PNG

Logxen

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Jun 17, 2020, 1:30:26 PM6/17/20
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We followed the schematic used on the lpcexpresso board that the project originally used back when we were breadboarding. here’s a link to that for reference: https://www.embeddedartists.com/wp-content/uploads/2018/07/LPCXpressoLPC1769revB.pdf

the biggest oddity on smoothie v1’s ethernet is actually IC7 which was added to solve a weird timing issue we had.

John deGlavina

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Jun 17, 2020, 3:16:24 PM6/17/20
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I see - that makes sense. 

IC7 is an inverter, right? Were the timing issues related to booting up? I've quickly learned the the LAN8720 is weird in that it it has dual function pins that have different purposes depending on the state it's in - boot vs running. 

John deGlavina

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Jun 17, 2020, 3:16:40 PM6/17/20
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Also, thanks for explaining. I appreciate it.

On Wednesday, June 17, 2020 at 1:30:26 PM UTC-4 Logxen wrote:
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