travisfarmer
Posts: 47
Joined: Sun Jan 07, 2018 9:33 pm
Location: Maine, USA
Contact: Website

hardware gpio shutdown signalling

Wed Sep 05, 2018 7:51 am

I stumbled upon this: https://www.raspberrypi.org/forums/view ... 5#p1233749

i don't post much in this forum as i can easily be considered a Rpi beginner, though i am far more experienced with an Arduino.

in any case, i am planning on using a Rpi 3 as a GPS plotter using OpenPlotter (http://www.sailoog.com/openplotter). if i have gpio_poweroff, and gpio_shutdown understood correctly, i would like to use an Arduino to handle sending the safe shutdown signal to the gpio_shutdown pin, and once power to the Arduino is removed, i will use a set of supercaps to enable the arduino to be powered long enough to wait for the gpio_poweroff signal from the Rpi, and then remove power from the Rpi, and also sever the connection from the supercaps to the Arduino.
I will draw up a Eagle schematic once i am sure i have the understanding of the gpio_poweroff and gpio_shutdown signals correct.
so, the question: can i use both gpio_poweroff and gpio_shutdown, on separate pins, in the above described manner? in other words, does gpio_shutdown function as an input signal to trigger a safe shutdown? and does gpio_poweroff function as an output signal for when the safe shutdown is complete, and is ready for power to be removed?

I am still waiting for my HDMI screen for my Rpi to show up, so it is rather inconvenient to test my plan at the moment.

i thank you all in advance for any help. :D

~Travis
Most of my electronics/programming experience is in Arduino, but i am learning Rpi to broaden my projects capabilities.

gordon77
Posts: 4115
Joined: Sun Aug 05, 2012 3:12 pm

Re: hardware gpio shutdown signalling

Fri Sep 07, 2018 8:20 am

does gpio_shutdown function as an input signal to trigger a safe shutdown? YES

does gpio_poweroff function as an output signal for when the safe shutdown is complete, and is ready for power to be removed? YES

eg. adding the following to /boot/config.txt

dtoverlay=gpio-shutdown,gpio_pin=7
dtoverlay=gpio-poweroff,gpiopin=27,active_low=1

will cause GPIO7 (pin 26) going LOW to do a shutdown, and GPIO27 (pin13) will indicate the pi is running when HIGH.

travisfarmer
Posts: 47
Joined: Sun Jan 07, 2018 9:33 pm
Location: Maine, USA
Contact: Website

Re: hardware gpio shutdown signalling

Sat Sep 08, 2018 11:34 am

Thank you gordon77!

apparently i don't get email notifications, so i didn't know there was a response until i checked just now.

~Travis
Most of my electronics/programming experience is in Arduino, but i am learning Rpi to broaden my projects capabilities.

klricks
Posts: 6543
Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA
Contact: Website

Re: hardware gpio shutdown signalling

Sat Sep 08, 2018 12:57 pm

travisfarmer wrote:
Sat Sep 08, 2018 11:34 am
Thank you gordon77!

apparently i don't get email notifications, so i didn't know there was a response until i checked just now.

~Travis
email notifications must be enabled in your user control panel.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

travisfarmer
Posts: 47
Joined: Sun Jan 07, 2018 9:33 pm
Location: Maine, USA
Contact: Website

Re: hardware gpio shutdown signalling

Sat Sep 08, 2018 1:05 pm

klricks wrote: email notifications must be enabled in your user control panel.
lol, i checked that already, but apparently i neglected to set up automatic subscriptions to posts/replies. :oops:
Thanks klricks.

~Travis
Most of my electronics/programming experience is in Arduino, but i am learning Rpi to broaden my projects capabilities.

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