I'm still waiting to sort getting a Pi Zero, but a thought has just occured to me.

The Pi Zero has 4 pins which are AFAIK something to do with video:

enter image description here

So I have two questions:

  • What is the pinout for this?

  • Does it include an audio output?

The reason I am guessing this functions the same way as the RCA jack on the B+/2B, which I think includes stereo audio and a composite video connection (2 pins for audio, 1 pin for video, and 1 ground). In which case if I was to get a Zero, could I use this as a audio (and video) output via connection to a RCA or similar cable?

N.B. This question is similar in the audio respect but more specific than this one

2 Answers 2


No, those pins have nothing to do with audio.

The upper two pins are to reset the Pi and are labeled "Run". While we have no schematics of the Pi Zero available yet, we can deduce this from former models of the Pi. According to this article it's a two pin header. The circuit with two clamp diodes, a pull-up resistor, and capacitor connected (at least that's what we know about the model B, Rev 2.1).

The lower two pins are dedicated to composite video out.

Note that in both cases the circular pads are ground and the rectangular pads are the respective signals - reset, and composite video out.


Just like @Ghanima said, the top two, labeled "RUN" are the reset pins, if you wire them together it will hard reset your Pi.

Now, as for the bottom two pins, the square one is TX (signal) and the circular one is ground.

If you have an old RCA cable you can strip the wire and solder the two wires directly onto the two pins like so:

enter image description here

and use RCA video out only. NOTE: There is no composite audio out on the Pi Zero without something fancy, like Hi-Fi Pi.

Image source: Element14

  • Hi Patrick, are you sure about that square pad being GND? I have no Pi available right now, but from the pictures (especially the PCB's bottom side it seems that the circulars are connected to the GND-plane, while the rectangular have some longer traces going "somewhere". Could you please check - to have one of our answers fixed accordingly? Thanks.
    – Ghanima
    Commented Dec 17, 2015 at 9:14
  • 1
    @Ghanima when my Pi Zero arrives, which will hopefully be today or tomorrow, I will check. Commented Dec 17, 2015 at 20:33
  • 2
    @Ghanima Yep, the circular one is ground, I will edit my answer. Commented Dec 19, 2015 at 0:47
  • 2
    A square pad on a row of PWB pins/pads that otherwise are round is one way of indicating "Pin 1" in the copper without any silk-screen (writing) on the PWB! Checkout the 40-pin GPIO connector on any RPi and you will see that Pin 1 (the end 3.3V pin) has a square pad - Q.E.D.
    – SlySven
    Commented Feb 19, 2016 at 5:47

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.