osquillar
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Boot up time in compute module

Wed Jan 13, 2016 11:55 am

Hi all, I have had a great experience with the Raspi B+ but I can not use for industrial applications that is switching ON and OFF many times and that needs a fast boot time.
I see that the the Compute Module has a Flash Eeprom instead an SD and is a good point for this module.
Can anyone tell me which is the clasical boot up time until I can run the application software?

Thanks in advance.
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RaTTuS
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Re: Boot up time in compute module

Wed Jan 13, 2016 12:02 pm

depends on what you need to be running -
if you want the full linux stack of goodies then the same times are a Pi B+
if you go for less or bare metal then < seconds
if you are having power re-applied very fast then - you will be better off making the carrier board have a battery backup system and keep running inteligently
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rzusman
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Re: Boot up time in compute module

Wed Jan 13, 2016 6:14 pm

I am designing an embedded controller with the Compute Module.

With a small OS (I'm playing with Minibian right now), boot times are under 10 seconds.

The big issue is not boot time, though - it's shutdown time! You need to solve the shutdown-and-save-state issue if you plan on flipping the power off and on randomly!

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jackokring
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Re: Boot up time in compute module

Wed Jan 13, 2016 8:24 pm

You need to 'cron' a 'sync' (with a still in 'cron' check for long 'sync' > 'cron' interval) to achieve a stable-ish shutdown. Another option is a brown out capacitor circuit to keep the pi running a few seconds while it detects and saves.

Or maybe start up using a micro controller init sequence, and run it when the pi is up.
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rzusman
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Re: Boot up time in compute module

Wed Jan 13, 2016 9:25 pm

Oh, I've figured out how to do it!

I'm using 50F of capacitance to give me 100W•S of power to allow the Pi to shutdown gracefully during a power fail. I just mentioned it to bring it to the OP's attention.

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