I am designing PCB. I am making this schematic with RP2040. Since I have no experience with PCB design, I want to ask some questions. 1-) RP2040 don't have AGND or CGND pin . Can I still use CGND for this photo. If I can, I will use CGND polygon , little square left bottom side ( Rest will be GND polygon.) Is it correct?

enter image description here

2-) For this photo, Is it enough for safety? Should I use ferrite bead(s) or 1nF/2kV is enough?

enter image description here

3-) This is off topic but for crystals, what is the best footprint for crystal when you don't have the correct name of it? I found some but as I am beginner, I don't know if I select correct (I calculate the capacitors.) Thank you.

  • 1
    \$\begingroup\$ The capacitor is for EMC, not safety. It goes to chassis gnd. If it is for a hobbyist project and you’re not concerned about EMC, then leave it off. The best crystal is the one you can buy that meets the specs. Go to lcsc or digikey a find the ones that meet the requirements and have large stock - that suggests they’re popular. \$\endgroup\$
    – Kartman
    Oct 28, 2021 at 12:29
  • \$\begingroup\$ Why do you think the magjack needs another 1nF capacitor as it already has a built in 1nF capacitor for you? \$\endgroup\$
    – Justme
    Oct 28, 2021 at 12:40
  • \$\begingroup\$ Thank you @Kartman. I am gonna buy one. If this project will work all day. Will it be a problem? \$\endgroup\$ Oct 28, 2021 at 12:45
  • \$\begingroup\$ @Justme I didn't know. I saw a person who connected GND to AGND with ferrite bead 120 ohms \$\endgroup\$ Oct 28, 2021 at 12:46


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