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I notice that a Pi 3B+ with the offcial touchscreen display will black/power off the display the instant that a shutdown command is issued, but it appears the Pi is still busy doing some things (what?) for up to 10 seconds afterwards, as the green light on the board carries on flashing for a while

Really, I'd like the display to remain on and showing activity (some scrolling text of what is happening, like most other linux devices I'm used to) until finally the screen goes black when it truly is safe to yank the power..

Reason is I'm installing a Pi into an environment where there is a "turn off at night to save the planet" ethos, and they shut down machines and then hard flick a switch that cuts the power. I'm concerned that even if I can get them to hit the "start.. shutdown" option (from what I see they just reach shift end and power the windows PCs off by cutting the AC), they'll then cut the power while the Pi is still flushing something to disk and I'll then get a call saying "uhh.. it won't start up.."

So, is there any way to keep it "on and looking like it's busy" until it truly isn't?

Caius Jard
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  • Raspi-config has an option to disable screen blanking. Menu -> system -> preferences. – Dougie Nov 19 '20 at 22:20
  • I might be being blind but I can't see the option inside raspi-config (I can start it from terminal, sudo raspi-config and I can fin things like display resolution but not blanking) – Caius Jard Nov 19 '20 at 22:42

2 Answers2

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I doubt that what you ask is possible. systemd initiates an orderly shutdown, which is asynchronous.

When the shutdown is complete the Activity LED flashes 10 times.

I include dtparam=act_led_trigger=heartbeat in config.txt as the "heartbeat" makes a good indication that the Pi is running.

Either of these requires the operator to look at the Pi while shutting down.

I suggest you implement a button to shutdown the Pi.
dtoverlay=gpio-shutdown,gpio_pin=21 will perform a safe shutdown when a button (connected to pins 39,40) is pressed. See https://raspberrypi.stackexchange.com/a/77918/8697

NOTE if people just cut power, sooner or later, they will kill the PCs.

Milliways
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I would use either a seperate power supply or a UPS, then sense when the lights go off and then do your orderly shutdown. You can use a small brick or photo sensor to determine when the lights go out. This sensor could also be configured to turn the Pi back on when the lights are turned on. Check the web you probably will find several circuits that will do what you want.

Gil
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