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	blubbi	2010-06-08 , 10:32
	Posts: 288 \| Thanked: 113 times \| Joined on Dec 2009 @ Germany	#21

Mmmh, all I came up without having a clue if there is a special mechanism is the following:

Code:

f = open('/sys/class/i2c-adapter/i2c-2/2-0029/lux')
while True:
    value = f.read()
    print value
    f.seek(0)

This, wrapped in a own thread, could to the trick, but does anyone have a smarter, less CPU-hogging and faster way to get the latest value?

Cheers Bjoern

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	thp	2010-06-08 , 10:44
	Posts: 1,391 \| Thanked: 4,272 times \| Joined on Sep 2007 @ Vienna, Austria	#22

Originally Posted by blubbi

Mmmh, all I came up without having a clue if there is a special mechanism is the following:
Code:
f = open('/sys/class/i2c-adapter/i2c-2/2-0029/lux')
while True:
    value = f.read()
    print value
    f.seek(0)
This, wrapped in a own thread, could to the trick, but does anyone have a smarter, less CPU-hogging and faster way to get the latest value?

You can keep the file open and get notified in your main loop when its contents change, as in this script:

http://talk.maemo.org/showthread.php?t=54695

The interesting bits here are the call to "gobject.io_add_watch" and the "on_state_changed" callback. You don't even need to have a separate thread for it, simply start a GLib main loop (e.g. call gtk.main()) and the mainloop will call your callback when the file has changed (just waiting while it's not changing).