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