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Inbetween the Display port, and the Activity LED on my Raspbery Pi 2, There are 2 holes boxed off, labled with: "Run".

enter image description here

What are those pins? What do they do? Is it a reset?

17

Short answer: It is a reset.

Here is why:

From the ARM information center - Cortex-A7 MPCore Technical Reference Manual

Run mode

This is the normal mode of operation where all of the processor functionality is available. The Cortex-A7 MPCore processor uses gated clocks and gates to disable inputs to unused functional blocks. Only the logic in use to perform an operation consumes any dynamic power.

Basically, the BCM2835/BCM2836 runs normally when this RUN pin to the IC is held to a logical HIGH.

From the Raspberry Pi Foundation's website - Released RPi Model B Schematics

It might be a bit difficult to see, but off to the left of this schematic is the wiring for P6, which you see as RUN when you look at the physical board.

During normal operation (leaving that connection open), PIN D15 (RUN) to the BCM IC (IC2) is held to a logical HIGH by R15 (pull-up resistor). When the P6 connection is closed, that same pin is pulled to a logical LOW (electricity likes to take the path of least resistance), effectively clearing that state to IC2 and resetting your system.

7

I found that it can be used to restart the RPi after it has been shutdown with "sudo shutdown -h now" command. By grounding and then releasing the RPi will run.

  • 2
    Now this is a practical use. – CousinCocaine Mar 13 '18 at 10:21
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If you have halted the Pi it will "reset", and thus reboot. I would suggest you refrain from connecting them on a running Pi, as this risks SD corruption.

  • so you're saying don't use it as a way to boot the PI? Or like emergency use only? – j0h Apr 4 '15 at 23:22
  • I use it often. If I want to change the environment, I will shut down the Pi normally. Rather than cycling the power to reboot I bridge the Run pins. I have occasionally used it to recover from a Pi lockup - this is risky, but less so than removing power. You could use it, in conjunction with other software/hardware, to make a proper power button. – Milliways Apr 5 '15 at 0:01
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    @Milliways, why is it less risky than shutting off the power? – hat Dec 13 '17 at 11:01
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Yes, if you connect the two pads with a piece of wire the Pi will reset.

  • 1
    Run=Reset oh ok (LOL) – j0h Apr 4 '15 at 15:27
  • RUN when high. (It's held high by default.) Stop running when pulled low. This makes the signal an effective /RESET (pull low to reset), but the way the chip works, that's not quite its intended function—just how it happens to be implemented on the Pi. – Joseph Carter Oct 27 '18 at 17:06

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