what consideration should I have for the USB section. How do correctly the usb traces? What means this curves?

This is my reference schematic and due board.

enter image description here


  • \$\begingroup\$ I wouldn't use that board as an example of how to do USB properly. It's a real mess. There are many documents online that will give you a straightforward explanation of the requirements, search for something like "USB2.0 PCB layout design guide". \$\endgroup\$ – Wossname Jun 24 at 13:40
  • \$\begingroup\$ What are the chips the 2 sets of USB are going to? Their datasheet will give recommendations regarding length of signals, termination resistors, etc. \$\endgroup\$ – CrossRoads Jun 24 at 15:16
  • \$\begingroup\$ ATMEGA16U2-MU ATSAM3X8EA-AU \$\endgroup\$ – asterix Jun 24 at 19:49
  • \$\begingroup\$ The following design guidelines should be met: Serial resistors on USB Data lines must have 22 Ohms value (+/- 5%). Traces from the input USB receptacle (or from the cable connection in the case of a tethered device) to the USB microcontroller pads should be as short as possible, and follow differential traces routing rules (same length, as near as possible and avoid vias accumulation). • Voltage transient / ESD suppressors may also be used to prevent USB pads to be damaged by external disturbances. Ucap capacitor should be 1μF (+/- 10%) for correct operation. \$\endgroup\$ – asterix Jun 24 at 19:53

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