Buy usb to 5v ttl converter usb adapter cables.
Usb to ttl converter cable.
The i o pins of this cable are configured to operate at 3 3v specifically with a raspberry pi with each serial pin broken apart.
The power pin provides the 5v 500ma direct from the usb port and the rx tx pins are 3 3v level for interfacing with the most common 3 3v logic level chipsets.
Hiletgo ft232rl ftdi mini usb to ttl serial converter adapter module 3 3v 5 5v ft232r breakout ft232rl usb to serial mini usb to ttl adapter board for arduino 4 2 out of 5 stars 384 5 99.
Dtech ftdi usb to ttl serial 3 3v adapter cable 6 pin 0 1 inch pitch female socket header uart ic ft232rl chip windows 10 8 7 linux 6ft black 5 0 out of 5 stars 7 13 49 13.
Usb to ttl serial 3 3v uart converter cable with ftdi chip terminated by 6 way header works with galileo gen2 boards beaglebone black minnowboard max and more 4 4 out of 5 stars 49 15 59 15.
Inside the big usb plug is a usb serial conversion chip and at the end of the 36 cable are four wire red power black ground white rx into usb port and green tx out of the usb port.
This is a usb to ttl serial cable which allows for a simple way to connect ttl interface devices to usb.