Background
I'm trying to control some motors by raspberry pi zero w.
I did, but the PWM produced by Software was unstable. So I decided to use arduino uno with zero.
(Zero is required because I should install some software in it)
It worked by serial communication, But the size of arduino uno is big to me. So I want to use arduino nano instead of uno.
Problem
raspberry pi zero w model has no usb port. How to make zero (serial) communicate with nano?