Schorschi
Posts: 245
Joined: Thu Nov 22, 2012 9:38 pm

PEN and RUN Pins, Proper Use?

Sun May 05, 2019 11:25 pm

Do I have this right:

PEN when shorted to GND will wake up Pi that is in a halt (or former shutdown state)?
RUN when shorted to GND does a safe reset of the Pi? Safe as in SD card corruption is not an issue?

Read quite a bit of information on this, and the many different references, none seems official. Moreover, why the heck are these locations not pinned via a proper header? It seems their proper use should be encouraged, not discouraged since no header in place?

Last, can't a GND pin next to them not be added in Pi 4 design? Would seem to be a logical and straight forward thing to do?

User avatar
Imperf3kt
Posts: 4018
Joined: Tue Jun 20, 2017 12:16 am
Location: Australia

Re: PEN and RUN Pins, Proper Use?

Mon May 06, 2019 12:08 am

The PEN connection wasn't exposed until the Pi3b+
Prior to that model, there was a ground connection in its place.

The next (or later) model Pi is unlikely to revert this change.
55:55:44:44:4C
52:4C:52:42:41

Rose coloured glasses are difficult to see through.

User avatar
Milliways
Posts: 579
Joined: Fri Apr 25, 2014 12:18 am
Location: Sydney, Australia

Re: PEN and RUN Pins, Proper Use?

Mon May 06, 2019 4:24 am

Schorschi wrote:
Sun May 05, 2019 11:25 pm
Do I have this right:

PEN when shorted to GND will wake up Pi that is in a halt (or former shutdown state)?
RUN when shorted to GND does a safe reset of the Pi? Safe as in SD card corruption is not an issue?

Read quite a bit of information on this, and the many different references, none seems official. Moreover, why the heck are these locations not pinned via a proper header? It seems their proper use should be encouraged, not discouraged since no header in place?

Last, can't a GND pin next to them not be added in Pi 4 design? Would seem to be a logical and straight forward thing to do?
RUN is actually the SOC Reset pin. It DOES NOT perform a safe shutdown, but can be used to restart the Pi after shutdown.

PEN is the Power ENable pin of the regulator chip - it can be used to put the Pi into a low power state after shutdown; NOTHING to do with wake up - except the Pi will boot when power is applied. The only useful purpose is with external circuitry e.g. solar power etc.

Return to “General discussion”