I have a USB to Serial TTL PL2303HX (Prolific chipset) that I would like to connect to my Pi. My Pi model is 2011.12.

The USB to Serial adapter has 5 PINs labeled as follows:

  • 3V3
  • TXD
  • RXD
  • GND
  • +5V

I received 4 cables with the USB to Serial Adapter (4 female-female dupont connectors).

I've seen various diagrams of the GPIO, but I'm not sure which PINS on the GPIO go to the PINs on the adapter.

Question: Which PINs on the GPIO need to be wired to which PINs on the USB adapter?


3 Answers 3


You only need to connect GND, RXD, TXD

GND => PIN 6

RXD => PIN 8

TXD => PIN 10


In addition to John La Rooy's answer, I've also connected VCC (i.e., +5V) to PIN 2. Thus, my Pi receives enough power from my computer to boot from a USB key.

  • 2
    Technically - Your Pi will only receive 500ma of power as per USB specification. Some motherboards allow short bursts of more power but it could reset the power and cause the Pi to reset. A nice idea but it can have long term problems.
    – Piotr Kula
    Nov 8, 2013 at 10:20

I can tell you the WRONG way. I did as above but also connected the 3v3 pin on the prolific dongle to the 3v3 pin on the pi and apparently it fried the pi. Not sure why. I wish someone would give an explanation.

  • 2
    You might bet better answers if you post this as a separate question.
    – bobstro
    Sep 25, 2015 at 20:12
  • IF valid, I think this warning should be included in the accepted answer. Jul 4, 2017 at 11:02

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