Author Topic: Caffeine will keep your PC from locking, starting screensavers or going to sleep  (Read 1396 times)

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Software Santa

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Caffeine will keep your PC from locking, starting screensavers, or going to sleep.

Macintosh Users have a Program like this ... with the same name: Caffeine


If you have problems with your PC locking or going to sleep, caffeine will keep it awake. It works by simulating a keypress once every 59 seconds, so your machine thinks you're still working at the keyboard, so won't lock the screen or activate the screensaver.

The icon is shown above - it's the leftmost one in the task tray, and this is all you see. Double-clicking the icon empties the coffee pot (that's what the icon is) and temporarily disables the program. Double-clicking it again refills the pot, and will keep your machine awake.

By default the app starts enabled, and works every 59 seconds. There are some command line switches you can use to alter this behavior:

  • xx - where xx is a number which sets the number of seconds between simulated keypresses. This must be the first text on the commandline
  • -startoff - application starts disabled.
  • -exitafter:xx - application will terminate after xx minutes
  • -activefor:xx - application will become inactive after xx minutes
  • -inactivefor:xx - application will become active after xx minutes
  • -appexit - terminates current running instance of application
  • -appon - makes the current running instance of the application active
  • -appoff - makes the current running instance of the application inactive
  • -apptoggle - toggles the running state of the current running instance of the application
  • -apptoggleshowdlg - toggles the running state, and shows dialog
  • -replace - closes the current running instance, replacing it
  • -noicon - does not show a task tray icon
  • -useshift - simulate the shift key instead of F15
  • -showdlg - shows a dialog indicating whether caffeine is active
  • -ontaskbar - show a task bar button (use with -showdlg)
  • -allowss - prevent sleep, but allow the screensaver to start
  • -key:xx - simulate using virtual key code xx
      Note: the codes on the linked page are in Hex, convert them to decimal for use with this parameter
  • -keypress - simulate a full key press, not just a key up event

Windows 98: Caffeine works by simulating the F15 key down and up events every 59 seconds.
Windows 2000/XP/Vista/7/8: Caffeine works by simulating an F15 key up event every 59 seconds.

Of all the key presses available, F15 is probably the least intrusive (I've never seen a PC keyboard with that key!), and least likely to interfere with your work.


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