Adding a Serial Port to the Raspberry Pi Zero

The Raspberry Pi Zero lacks a USB hub and only comes with a single Micro USB port which means you have to be careful with the limited available port. Adding a USB to serial converter is a good way of accessing the Pi Zero without having to plug a keyboard and HDMI connector and it frees the Micro USB port.

There are many flavors of USB to RS232 adapters and one of them is CH340 eBay which is affordable. Another adapter I like is the CP2102 you can find them on eBay. This are just recommendations in the end it’s your choice as to the one you choose.

How I wire my Pi Zero

  • The Raspberry Pi can be powered from the same 5V pin coming from the USB to RS232 adapter, I rather have the Zero use a dedicated PSU for stable power.

Wiring the Pi Zero

Use the MicroSD slot as a reference point. On the Pi Zero you will make use of the following pins:

  • pin 6 is ground(GND)
  • pin 8 is transmit(TXD)
  • pin 10 is receive(RXD)


Wiring the USB to RS232

There might be a slight difference with your USB to RS232 adapter but I am certain it will be the same as below. Make sure to match wiring with those of the Pi Zero.


On the terminal client of your choice use the COM port assigned to the USB adapter and baud rate of 115200.


If you don’t see any output in the console make sure the TXD and RXD pins are in the correct position, otherwise swap them.