DanITGuyNAH
Posts: 2
Joined: Thu Nov 07, 2019 8:44 pm

PoE hat, Raspberry Pi 4, How to you power on if already connected to PoE

Thu Nov 07, 2019 9:01 pm

Does the PoE Hat respond to wake on LAN or mouse or keyboard after it is shutdown? I can always go in and pull power from the network port and then re-power the port. I was just hoping for some easier way to find and basically power cycle the unit. Because you know some users will go and run a shutdown on it. And some of the ones I am looking to deploy may not be accessible without a ladder. So I am hoping there is a way to turn the device on other than pulling the network cable. Or if I put in one of the power switches using GPIO pins 5&6, because I could run that switch to a location for that purpose.

epoch1970
Posts: 3875
Joined: Thu May 05, 2016 9:33 am
Location: Paris, France

Re: PoE hat, Raspberry Pi 4, How to you power on if already connected to PoE

Fri Nov 08, 2019 4:39 pm

Doesn't the switch have a web interface or something?
"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème." Les Shadoks, J. Rouxel

DanITGuyNAH
Posts: 2
Joined: Thu Nov 07, 2019 8:44 pm

Re: PoE hat, Raspberry Pi 4, How to you power on if already connected to PoE

Tue Nov 12, 2019 10:22 pm

epoch, that is kind of what I am asking. If you install a PoE top hat on a Raspberry PI 3 B+ or 4 and you preform a shutdown after you are done. How do you start it backup again? Unplug the Network cable? Pull power from the PoE port? Or use a switch on GPIO ports 5 &6? Or do they support Wake on LAN protocol? I have pretty much confirmed it doesn't respond to the mouse or keyboard.

Here is my scenario or situation. I am looking at deploying say 50 of these PI's at different locations across possibly multiple states. They will be displaying information at the business location, AD information, Directory of services, etc. I need to shutdown one for a few hours for some reason. How to I power the unit back up and bring it back online? The options I see are: Pull network cable, Pull Power from PoE port, Wake on LAN? install a power switch on GPIO ports 5 & 6 for manual intervention? Which ones will work and which ones are likely not to work.

trejan
Posts: 887
Joined: Tue Jul 02, 2019 2:28 pm

Re: PoE hat, Raspberry Pi 4, How to you power on if already connected to PoE

Tue Nov 12, 2019 10:30 pm

DanITGuyNAH wrote:
Tue Nov 12, 2019 10:22 pm
Pull network cable
Yes.
DanITGuyNAH wrote:
Tue Nov 12, 2019 10:22 pm
Pull Power from PoE port
Yes.
DanITGuyNAH wrote:
Tue Nov 12, 2019 10:22 pm
Wake on LAN?
No. WoL is not supported.
DanITGuyNAH wrote:
Tue Nov 12, 2019 10:22 pm
install a power switch on GPIO ports 5 & 6 for manual intervention?
Only if WAKE_ON_GPIO=1. The Pi 4 originally came with WAKE_ON_GPIO=0 which meant it would completely shutdown the PMIC and you'd have to power cycle or temporarily short the GLOBAL_EN pin to ground to restart the PMIC. They changed the default in later batches so WAKE_ON_GPIO=1 like previous Pi boards and it would wake if you pulled pin 5 low.

See https://www.raspberrypi.org/documentati ... _config.md for more details.

You could fit the momentary switch between GLOBAL_EN and ground which would wake the Pi 4 no matter the state of WAKE_GPIO but this also would immediately restart any currently running Pi if pressed. There wouldn't be a clean shutdown.

Be aware that pin 5 is the I2C clock pin. If you're using I2C on pin 3 + 5 then somebody pressing the button whilst the Pi is on will cause I2C errors.
Last edited by trejan on Tue Nov 12, 2019 10:32 pm, edited 1 time in total.

epoch1970
Posts: 3875
Joined: Thu May 05, 2016 9:33 am
Location: Paris, France

Re: PoE hat, Raspberry Pi 4, How to you power on if already connected to PoE

Tue Nov 12, 2019 10:30 pm

I still don't understand I'm afraid.
A network switch that is capable of distributing power over Ethernet has a web or telnet management interface. Log in to the switch, cycle power on the port the Pi is connected to.

There is no wake on lan on Pi.
"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème." Les Shadoks, J. Rouxel

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