lakmalp
Posts: 6
Joined: Thu Jul 04, 2013 4:57 pm

Minimum peripherals to run a PI

Thu Jul 04, 2013 5:06 pm

Hi,

This is my first post and I am slowly learning Raspberry PI system. :)

I have a requirement to generate an audio signal at a predefined time intervals. If I create the java program and configure to run it as required, can I run the PI with just the Audio Out jack and SD card connected? (No keyboard, no monitor, etc... - but the audio jack and SD card)

Lakmal

fredoll
Posts: 228
Joined: Thu Jan 10, 2013 10:30 am

Re: Minimum peripherals to run a PI

Thu Jul 04, 2013 5:40 pm

yes

pbrwr
Posts: 22
Joined: Tue Sep 04, 2012 9:03 pm
Location: The Netherlands

Re: Minimum peripherals to run a PI

Fri Jul 05, 2013 10:46 am

Keep in mind the Pi has no internal clock. If you want to make things happen at a specific time (let's say at 3 pm), you also need a network connection, so the Pi can sync it's timekeeping to an external timesource.

Pieter

hldswrth
Posts: 108
Joined: Mon Sep 10, 2012 4:14 pm

Re: Minimum peripherals to run a PI

Fri Jul 05, 2013 11:55 am

The pi does have an internal clock (or at least, an internal counter) its just not battery-backed, so it has no concept of the current time on its own. Once the time has been set manually or via a network connection the Pi can maintain the current time, however you're right, if the Pi is rebooted with only an SD card and sound cable it won't know the current time after a reboot. If the requirement is periodic rather than at specific times that would not be an issue.

lakmalp
Posts: 6
Joined: Thu Jul 04, 2013 4:57 pm

Re: Minimum peripherals to run a PI

Fri Jul 05, 2013 12:02 pm

As pointed out by Pieter, I may have to use either a network connection or RTC module. And, in my case RTC module would be the ideal solution since network connection may not be available where the Pi will be installed.

Thank you all for your valuable input. (Y)

ghp
Posts: 1409
Joined: Wed Jun 12, 2013 12:41 pm
Location: Stuttgart Germany
Contact: Website

Re: Minimum peripherals to run a PI

Fri Jul 05, 2013 12:17 pm

... it might be that you need a power supply, too.

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Jim Manley
Posts: 1600
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Location: SillyCon Valley, California, and Powell, Wyoming, USA, plus The Universe
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Re: Minimum peripherals to run a PI

Fri Jul 05, 2013 12:46 pm

Most Pii seem to consistently run about half a second fast per hour, or 12 seconds per day. It's a pretty simple matter to measure a particular Pi's rate of offset over whatever the maximum service interval is estimated to be (how long between opportunities to check for and correct problems), and use a script that applies that offset periodically in the opposite direction. Even the atomic clocks used by GPS, Network Time Protocol (NTP), and the standards bureaus have to institute a "leap second" periodically to account for an offset that accumulates from miniscule errors over a period of years. The number of atomic oscillations being counted doesn't precisely align with the number that's actually needed to maintain a 100% accurate rate, plus the rotation of the Earth about its axis and its orbit around the Sun are slowing down almost imperceptibly over time.
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