DavidStj
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Power on / shutdown RPI time or network

Wed Jun 19, 2019 11:52 am

Hi all,
Kind of new to Raspberry Pi and programing. I have a an issue that I wonder if someone solved. So what i want to do is to power down the Raspberry Pi in a safe way at 09.00 and then power it back on at 23.00. Using cron job i can power it down but is it possible to power up at specific time? I have two Raspberry Pi 3 b+ running and one is only used during night to display my blood glucose. During the day i dont need this to run and the touchscreen to be on. I have a cron job running to turn display to 0 at 09.00 and to 16 at 23.00. But im thinking why not power it of if its not used. Can I set one Raspberry Pi to start another (without wifi power sockets or sockets with timers(thinking this is the only option)?).

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thagrol
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Re: Power on / shutdown RPI time or network

Wed Jun 19, 2019 12:27 pm

There's no sleep mode so no remote wake either.

A shutdown pi with power can be booted by briefly shorting the run header or pulling GPIO 3 to ground. Both of which require external hardware. Be aware that a pi will continue to draw power (though much less) even when the OS is shutdown.

I'd go for a cron job to shut down a 09:00 coupled with a time controled power supply set to switch off at 09:30 and on at 23:00. A simple mains time switch should do that job.
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rpdom
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Re: Power on / shutdown RPI time or network

Wed Jun 19, 2019 12:27 pm

There are HATs and other units that can shut a Pi down and remove power, and start it up again when a button is pressed. But I don't know of any that include a timer option.

The Pi doesn't use a lot of power compared to other computers. A desktop PC in standby or shutdown state uses about the same power as a Pi that is running. A lot of people, like me, leave their Pis running 24x7.

klricks
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Re: Power on / shutdown RPI time or network

Wed Jun 19, 2019 12:34 pm

To turn the RPi back on you will need external hardware such as another RPi or a programmable appliance timer etc.
If using a timer you would set off time to 09:15 (after safe shutdown) then restore power at 23:00.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.

DavidStj
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Re: Power on / shutdown RPI time or network

Wed Jun 19, 2019 1:07 pm

rpdom wrote:
Wed Jun 19, 2019 12:27 pm
There are HATs and other units that can shut a Pi down and remove power, and start it up again when a button is pressed. But I don't know of any that include a timer option.

The Pi doesn't use a lot of power compared to other computers. A desktop PC in standby or shutdown state uses about the same power as a Pi that is running. A lot of people, like me, leave their Pis running 24x7.
Thanks for the answer. Might as well leave it on then. Have many things running on standby so why not this important one.

timrowledge
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Re: Power on / shutdown RPI time or network

Wed Jun 19, 2019 7:35 pm

rpdom wrote:
Wed Jun 19, 2019 12:27 pm
There are HATs and other units that can shut a Pi down and remove power, and start it up again when a button is pressed. But I don't know of any that include a timer option.
At least a couple have RTCs and micro controllers on board. The piups hat appears to be one example. SparkFun etc carry them.
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W. H. Heydt
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Re: Power on / shutdown RPI time or network

Thu Jun 20, 2019 4:42 am

Just another note, given the intended use of the Pi... A Pi is not rated to be a medical device, nor is it rated for any "life safety" application. If it is critical that you continuously monitor blood glucose at night (and, one might presume, set off an alarm if it goes out of a pre-set range), while Pi would *probably* do that reliably, you shouldn't bet your life that it will.

DavidStj
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Re: Power on / shutdown RPI time or network

Thu Jun 20, 2019 7:26 am

W. H. Heydt wrote:
Thu Jun 20, 2019 4:42 am
Just another note, given the intended use of the Pi... A Pi is not rated to be a medical device, nor is it rated for any "life safety" application. If it is critical that you continuously monitor blood glucose at night (and, one might presume, set off an alarm if it goes out of a pre-set range), while Pi would *probably* do that reliably, you shouldn't bet your life that it will.
Thanks! No worries. This is just for display for my convenience. I use other devices for this (that are not FDA approved). But in the community a lot of people use the Pi to distribute insulin. This is how the artificial pancreas started with DIY closed loop. Really cool project! But im not using an insulin pump so right now its not a project for me :) .

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