apparat
Posts: 6
Joined: Sat Apr 28, 2018 10:34 pm

Pi rejects to reboot and always needs 3-30s cooldown

Thu Sep 19, 2019 1:05 am

My Pi4 does not reboot; neither soft nor hard.
It is necessary to let the Pi "cool down" by switching off the supply voltage for at least 3 seconds until it boots again fine.
If powered up immediatly after switching off, the green LED flashes once and nothing more happens.
I tried different images, sd cards etc, same behavior, even without any attached peripherals, without ethernet, monitor and usb devices,. just power supply.
It is 100% reproducable, the required cooldown time varies, but it is never below 3 seconds, sometimes up to 30 seconds (couldn't figure out what causes the variance).

What could cause this behaviour? Which element on the PI has a state when not supplied with power? A capacitor that is discharging? A fuse that is cooling down below a certain temperature threshold?

Edit: The power supply is connected to the mentioned Pi4 and two more Pi3s. Only the PI4 is affected by the problem - it doesn't matter if the other PI3s are running or not - and the PI3s are also not affected and just operate normally if i reboot the PI4 - so I don't think it is the power supply that is responsible for the required cooldown time interval.
Edit2: Voltages are: 3.3v and 4.9v
Edit3: Problem persists even without any SD Card: The green LED flashes to indicate that no SD Card was found only after waiting for the required time, otherwise it just flashes once.

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rpdom
Posts: 16376
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Pi rejects to reboot and always needs 3-30s cooldown

Thu Sep 19, 2019 6:23 am

Are you switching off at the wall socket, or unplugging the power supply from the Pi?

The PSU will have capacitors that hold a voltage for a few seconds and that may be enough to confuse the power management chip on the Pi.

Generally with any electronic equipment you should always completely remove the power for about 10 seconds, just to make sure everything on the board has discharged, before powering back on again.

If you want to do a quick restart you can do a shutdown/poweroff command and either briefly join pins 5 and 6 on the GPIO header, or join the RUN holes (on those Pi that have them) to restart.

mattmiller
Posts: 2188
Joined: Thu Feb 05, 2015 11:25 pm

Re: Pi rejects to reboot and always needs 3-30s cooldown

Thu Sep 19, 2019 6:47 am

I just tried my Pi4 - I pulled the power lead out of the socket on the Pi and put it back in as fast as I could and it rebooted fine

Did it again - fine

But having said that - I normally do
Generally with any electronic equipment you should always completely remove the power for about 10 seconds, just to make sure everything on the board has discharged, before powering back on again.

alphanumeric
Posts: 2391
Joined: Tue Jan 19, 2016 2:17 pm
Location: Sydney, Nova Scotia, Canada

Re: Pi rejects to reboot and always needs 3-30s cooldown

Thu Sep 19, 2019 11:32 am

Reboot from the shut down menu? I'm not 100% sure what you mean by soft and hard reboot.

With the factory shipped firmware, grounding GPIO 3 will not make a Pi 4 boot up after doing a shut down from Raspbian. You have to power cycle it.
With the updated eeprom boot firmware that functionality will work.

apparat
Posts: 6
Joined: Sat Apr 28, 2018 10:34 pm

Re: Pi rejects to reboot and always needs 3-30s cooldown

Thu Sep 19, 2019 3:19 pm

rpdom wrote:
Thu Sep 19, 2019 6:23 am
Are you switching off at the wall socket, or unplugging the power supply from the Pi?
Unplugging the Power Supply from the Pi (Mechanical switch between PSU and USB 5V) (Hard Reset)

Code: Select all

# reboot
# reboot -f 
# shutdown -r now
doesn't work (Soft Reset).
It shuts down flawlessly, stops all daemons, syncs the file system but does not boot up again.
Of course, it is less of an issue to wait for 5 seconds when turning off the power before turing it on again, but being unable to reboot
in software is.
With the updated eeprom boot firmware that functionality will work.
I think I already updated it, but I will check again.

alphanumeric
Posts: 2391
Joined: Tue Jan 19, 2016 2:17 pm
Location: Sydney, Nova Scotia, Canada

Re: Pi rejects to reboot and always needs 3-30s cooldown

Thu Sep 19, 2019 7:19 pm

I've updated my eeprom, sudo reboot and selecting reboot from the shutdown menu works for me. Just a FYI post

EDIT: If I shut down, and unplug my power supply, I have to wait for the Pi's Power LED to fade to black, before plugging it back in. If I don't it won't boot up. It does take a couple of seconds,

apparat
Posts: 6
Joined: Sat Apr 28, 2018 10:34 pm

Re: Pi rejects to reboot and always needs 3-30s cooldown

Sun Sep 22, 2019 2:13 am

I just tried my Pi4 - I pulled the power lead out of the socket on the Pi and put it back in as fast as I could and it rebooted fine
I've updated my eeprom, sudo reboot and selecting reboot from the shutdown menu works for me. Just a FYI post
Thanks to mattmiller and alphanumeric for trying that out.

I recently noticed that my USB ports are not working at all - no 5V and lsusb shows only one entry.
Maybe I was too incautious and there is/was something on the pcb causing a short circuit.
I cannot find anything on the board that may have caused this, but it's very unlikely that the pi had left the factory damaged, is it?

My hope to be able to fix it is vanishing, but at least I want to find out the cause of the problem.
I really wonder what happens during the "cooldown" interval.

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