FTDI makes a variety of products that allows microcontrollers to connect to USB by using the much less sophisticated serial protocol. Most well known is probably the USB converter cable.
| Pin | Color | Signal | In/Out | |
|---|---|---|---|---|
 |
1 | Black | GND | - |
| 2 | Brown | CTS | In | |
| 3 | Red | VCC | Out | |
| 4 | Orange | TXD | Out | |
| 5 | Yellow | RXD | In | |
| 6 | Green | RTS | Out |