Add some protection to USB <-> uP like [PGB1010603MR](https://www.mouser.com/ProductDetail/Littelfuse/PGB1010603MR?qs=gu7KAQ731URLg4GSnNNN7Q%3D%3D). See reference forum: [VUSB circuit](https://www.element14.com/community/thread/28401/l/can-someone-explain-how-this-v-usb-circuit-works). Others links: - [USBLC6-2](http://www.farnell.com/datasheets/1690354.pdf?COM=Arduino) - [CG0603MLC](https://www.mouser.com/ProductDetail/Bourns/CG0603MLC-05E?qs=%2Fha2pyFadujvz5NXVTcV%2FWR6cySD%252Bi8y6HhU%2FSe4KlP%2FXyUwNhFf7Q%3D%3D): 5 V protection.
Add some protection to USB <-> uP like PGB1010603MR.
See reference forum: VUSB circuit.
Others links: